x86/lguest: Remove lguest support

Lguest seems to be rather unused these days. It has seen only patches
ensuring it still builds the last two years and its official state is
"Odd Fixes".

Remove it in order to be able to clean up the paravirt code.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: boris.ostrovsky@oracle.com
Cc: lguest@lists.ozlabs.org
Cc: rusty@rustcorp.com.au
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20170816173157.8633-3-jgross@suse.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

MAINTAINERS

@@ -7640,17 +7640,6 @@ T:	git git://linuxtv.org/mkrufky/tuners.git
 S:	Maintained
 F:	drivers/media/dvb-frontends/lgdt3305.*
 
-LGUEST
-M:	Rusty Russell <rusty@rustcorp.com.au>
-L:	lguest@lists.ozlabs.org
-W:	http://lguest.ozlabs.org/
-S:	Odd Fixes
-F:	arch/x86/include/asm/lguest*.h
-F:	arch/x86/lguest/
-F:	drivers/lguest/
-F:	include/linux/lguest*.h
-F:	tools/lguest/
-
 LIBATA PATA ARASAN COMPACT FLASH CONTROLLER
 M:	Viresh Kumar <vireshk@kernel.org>
 L:	linux-ide@vger.kernel.org

arch/x86/Kbuild

@@ -10,9 +10,6 @@ obj-$(CONFIG_XEN) += xen/
 # Hyper-V paravirtualization support
 obj-$(CONFIG_HYPERVISOR_GUEST) += hyperv/
 
-# lguest paravirtualization support
-obj-$(CONFIG_LGUEST_GUEST) += lguest/
-
 obj-y += realmode/
 obj-y += kernel/
 obj-y += mm/

arch/x86/Kconfig

@@ -777,8 +777,6 @@ config KVM_DEBUG_FS
 	  Statistics are displayed in debugfs filesystem. Enabling this option
 	  may incur significant overhead.
 
-source "arch/x86/lguest/Kconfig"
-
 config PARAVIRT_TIME_ACCOUNTING
 	bool "Paravirtual steal time accounting"
 	depends on PARAVIRT

arch/x86/include/asm/lguest.h

-#ifndef _ASM_X86_LGUEST_H
-#define _ASM_X86_LGUEST_H
-
-#define GDT_ENTRY_LGUEST_CS	10
-#define GDT_ENTRY_LGUEST_DS	11
-#define LGUEST_CS		(GDT_ENTRY_LGUEST_CS * 8)
-#define LGUEST_DS		(GDT_ENTRY_LGUEST_DS * 8)
-
-#ifndef __ASSEMBLY__
-#include <asm/desc.h>
-
-#define GUEST_PL 1
-
-/* Page for Switcher text itself, then two pages per cpu */
-#define SWITCHER_TEXT_PAGES (1)
-#define SWITCHER_STACK_PAGES (2 * nr_cpu_ids)
-#define TOTAL_SWITCHER_PAGES (SWITCHER_TEXT_PAGES + SWITCHER_STACK_PAGES)
-
-/* Where we map the Switcher, in both Host and Guest. */
-extern unsigned long switcher_addr;
-
-/* Found in switcher.S */
-extern unsigned long default_idt_entries[];
-
-/* Declarations for definitions in arch/x86/lguest/head_32.S */
-extern char lguest_noirq_iret[];
-extern const char lgstart_cli[], lgend_cli[];
-extern const char lgstart_pushf[], lgend_pushf[];
-
-extern void lguest_iret(void);
-extern void lguest_init(void);
-
-struct lguest_regs {
-	/* Manually saved part. */
-	unsigned long eax, ebx, ecx, edx;
-	unsigned long esi, edi, ebp;
-	unsigned long gs;
-	unsigned long fs, ds, es;
-	unsigned long trapnum, errcode;
-	/* Trap pushed part */
-	unsigned long eip;
-	unsigned long cs;
-	unsigned long eflags;
-	unsigned long esp;
-	unsigned long ss;
-};
-
-/* This is a guest-specific page (mapped ro) into the guest. */
-struct lguest_ro_state {
-	/* Host information we need to restore when we switch back. */
-	u32 host_cr3;
-	struct desc_ptr host_idt_desc;
-	struct desc_ptr host_gdt_desc;
-	u32 host_sp;
-
-	/* Fields which are used when guest is running. */
-	struct desc_ptr guest_idt_desc;
-	struct desc_ptr guest_gdt_desc;
-	struct x86_hw_tss guest_tss;
-	struct desc_struct guest_idt[IDT_ENTRIES];
-	struct desc_struct guest_gdt[GDT_ENTRIES];
-};
-
-struct lg_cpu_arch {
-	/* The GDT entries copied into lguest_ro_state when running. */
-	struct desc_struct gdt[GDT_ENTRIES];
-
-	/* The IDT entries: some copied into lguest_ro_state when running. */
-	struct desc_struct idt[IDT_ENTRIES];
-
-	/* The address of the last guest-visible pagefault (ie. cr2). */
-	unsigned long last_pagefault;
-};
-
-static inline void lguest_set_ts(void)
-{
-	u32 cr0;
-
-	cr0 = read_cr0();
-	if (!(cr0 & 8))
-		write_cr0(cr0 | 8);
-}
-
-/* Full 4G segment descriptors, suitable for CS and DS. */
-#define FULL_EXEC_SEGMENT \
-	((struct desc_struct)GDT_ENTRY_INIT(0xc09b, 0, 0xfffff))
-#define FULL_SEGMENT ((struct desc_struct)GDT_ENTRY_INIT(0xc093, 0, 0xfffff))
-
-#endif /* __ASSEMBLY__ */
-
-#endif /* _ASM_X86_LGUEST_H */

arch/x86/include/asm/lguest_hcall.h

-/* Architecture specific portion of the lguest hypercalls */
-#ifndef _ASM_X86_LGUEST_HCALL_H
-#define _ASM_X86_LGUEST_HCALL_H
-
-#define LHCALL_FLUSH_ASYNC	0
-#define LHCALL_LGUEST_INIT	1
-#define LHCALL_SHUTDOWN		2
-#define LHCALL_NEW_PGTABLE	4
-#define LHCALL_FLUSH_TLB	5
-#define LHCALL_LOAD_IDT_ENTRY	6
-#define LHCALL_SET_STACK	7
-#define LHCALL_SET_CLOCKEVENT	9
-#define LHCALL_HALT		10
-#define LHCALL_SET_PMD		13
-#define LHCALL_SET_PTE		14
-#define LHCALL_SET_PGD		15
-#define LHCALL_LOAD_TLS		16
-#define LHCALL_LOAD_GDT_ENTRY	18
-#define LHCALL_SEND_INTERRUPTS	19
-
-#define LGUEST_TRAP_ENTRY 0x1F
-
-/* Argument number 3 to LHCALL_LGUEST_SHUTDOWN */
-#define LGUEST_SHUTDOWN_POWEROFF	1
-#define LGUEST_SHUTDOWN_RESTART		2
-
-#ifndef __ASSEMBLY__
-#include <asm/hw_irq.h>
-
-/*G:030
- * But first, how does our Guest contact the Host to ask for privileged
- * operations?  There are two ways: the direct way is to make a "hypercall",
- * to make requests of the Host Itself.
- *
- * Our hypercall mechanism uses the highest unused trap code (traps 32 and
- * above are used by real hardware interrupts).  Seventeen hypercalls are
- * available: the hypercall number is put in the %eax register, and the
- * arguments (when required) are placed in %ebx, %ecx, %edx and %esi.
- * If a return value makes sense, it's returned in %eax.
- *
- * Grossly invalid calls result in Sudden Death at the hands of the vengeful
- * Host, rather than returning failure.  This reflects Winston Churchill's
- * definition of a gentleman: "someone who is only rude intentionally".
- */
-static inline unsigned long
-hcall(unsigned long call,
-      unsigned long arg1, unsigned long arg2, unsigned long arg3,
-      unsigned long arg4)
-{
-	/* "int" is the Intel instruction to trigger a trap. */
-	asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
-		     /* The call in %eax (aka "a") might be overwritten */
-		     : "=a"(call)
-		       /* The arguments are in %eax, %ebx, %ecx, %edx & %esi */
-		     : "a"(call), "b"(arg1), "c"(arg2), "d"(arg3), "S"(arg4)
-		       /* "memory" means this might write somewhere in memory.
-			* This isn't true for all calls, but it's safe to tell
-			* gcc that it might happen so it doesn't get clever. */
-		     : "memory");
-	return call;
-}
-/*:*/
-
-/* Can't use our min() macro here: needs to be a constant */
-#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
-
-#define LHCALL_RING_SIZE 64
-struct hcall_args {
-	/* These map directly onto eax/ebx/ecx/edx/esi in struct lguest_regs */
-	unsigned long arg0, arg1, arg2, arg3, arg4;
-};
-
-#endif /* !__ASSEMBLY__ */
-#endif /* _ASM_X86_LGUEST_HCALL_H */

arch/x86/include/asm/processor.h

@@ -662,7 +662,7 @@ static inline void sync_core(void)
 	 * In case NMI unmasking or performance ever becomes a problem,
 	 * the next best option appears to be MOV-to-CR2 and an
 	 * unconditional jump.  That sequence also works on all CPUs,
-	 * but it will fault at CPL3 (i.e. Xen PV and lguest).
+	 * but it will fault at CPL3 (i.e. Xen PV).
 	 *
 	 * CPUID is the conventional way, but it's nasty: it doesn't
 	 * exist on some 486-like CPUs, and it usually exits to a

arch/x86/include/uapi/asm/bootparam.h

@@ -201,7 +201,7 @@ struct boot_params {
  *
  * @X86_SUBARCH_PC: Should be used if the hardware is enumerable using standard
  *	PC mechanisms (PCI, ACPI) and doesn't need a special boot flow.
- * @X86_SUBARCH_LGUEST: Used for x86 hypervisor demo, lguest
+ * @X86_SUBARCH_LGUEST: Used for x86 hypervisor demo, lguest, deprecated
  * @X86_SUBARCH_XEN: Used for Xen guest types which follow the PV boot path,
  * 	which start at asm startup_xen() entry point and later jump to the C
  * 	xen_start_kernel() entry point. Both domU and dom0 type of guests are

arch/x86/kernel/asm-offsets_32.c

@@ -4,9 +4,6 @@
 
 #include <asm/ucontext.h>
 
-#include <linux/lguest.h>
-#include "../../../drivers/lguest/lg.h"
-
 #define __SYSCALL_I386(nr, sym, qual) [nr] = 1,
 static char syscalls[] = {
 #include <asm/syscalls_32.h>
@@ -62,23 +59,6 @@ void foo(void)
 	OFFSET(stack_canary_offset, stack_canary, canary);
 #endif
 
-#if defined(CONFIG_LGUEST) || defined(CONFIG_LGUEST_GUEST) || defined(CONFIG_LGUEST_MODULE)
-	BLANK();
-	OFFSET(LGUEST_DATA_irq_enabled, lguest_data, irq_enabled);
-	OFFSET(LGUEST_DATA_irq_pending, lguest_data, irq_pending);
-
-	BLANK();
-	OFFSET(LGUEST_PAGES_host_gdt_desc, lguest_pages, state.host_gdt_desc);
-	OFFSET(LGUEST_PAGES_host_idt_desc, lguest_pages, state.host_idt_desc);
-	OFFSET(LGUEST_PAGES_host_cr3, lguest_pages, state.host_cr3);
-	OFFSET(LGUEST_PAGES_host_sp, lguest_pages, state.host_sp);
-	OFFSET(LGUEST_PAGES_guest_gdt_desc, lguest_pages,state.guest_gdt_desc);
-	OFFSET(LGUEST_PAGES_guest_idt_desc, lguest_pages,state.guest_idt_desc);
-	OFFSET(LGUEST_PAGES_guest_gdt, lguest_pages, state.guest_gdt);
-	OFFSET(LGUEST_PAGES_regs_trapnum, lguest_pages, regs.trapnum);
-	OFFSET(LGUEST_PAGES_regs_errcode, lguest_pages, regs.errcode);
-	OFFSET(LGUEST_PAGES_regs, lguest_pages, regs);
-#endif
 	BLANK();
 	DEFINE(__NR_syscall_max, sizeof(syscalls) - 1);
 	DEFINE(NR_syscalls, sizeof(syscalls));

arch/x86/kernel/head_32.S

@@ -155,7 +155,6 @@ ENTRY(startup_32)
 	jmp *%eax
 
 .Lbad_subarch:
-WEAK(lguest_entry)
 WEAK(xen_entry)
 	/* Unknown implementation; there's really
 	   nothing we can do at this point. */
@@ -165,7 +164,6 @@ WEAK(xen_entry)
 
 subarch_entries:
 	.long .Ldefault_entry		/* normal x86/PC */
-	.long lguest_entry		/* lguest hypervisor */
 	.long xen_entry			/* Xen hypervisor */
 	.long .Ldefault_entry		/* Moorestown MID */
 num_subarch_entries = (. - subarch_entries) / 4

arch/x86/kernel/platform-quirks.c

@@ -16,7 +16,6 @@ void __init x86_early_init_platform_quirks(void)
 		x86_platform.legacy.reserve_bios_regions = 1;
 		break;
 	case X86_SUBARCH_XEN:
-	case X86_SUBARCH_LGUEST:
 		x86_platform.legacy.devices.pnpbios = 0;
 		x86_platform.legacy.rtc = 0;
 		break;

arch/x86/kvm/Kconfig

@@ -89,6 +89,5 @@ config KVM_MMU_AUDIT
 # OK, it's a little counter-intuitive to do this, but it puts it neatly under
 # the virtualization menu.
 source drivers/vhost/Kconfig
-source drivers/lguest/Kconfig
 
 endif # VIRTUALIZATION

arch/x86/lguest/Kconfig

-config LGUEST_GUEST
-	bool "Lguest guest support"
-	depends on X86_32 && PARAVIRT && PCI
-	select TTY
-	select VIRTUALIZATION
-	select VIRTIO
-	select VIRTIO_CONSOLE
-	help
-	  Lguest is a tiny in-kernel hypervisor.  Selecting this will
-	  allow your kernel to boot under lguest.  This option will increase
-	  your kernel size by about 10k.  If in doubt, say N.
-
-	  If you say Y here, make sure you say Y (or M) to the virtio block
-	  and net drivers which lguest needs.

arch/x86/lguest/Makefile

-obj-y		:= head_32.o boot.o
-CFLAGS_boot.o	:= $(call cc-option, -fno-stack-protector)

arch/x86/lguest/head_32.S

-#include <linux/linkage.h>
-#include <linux/lguest.h>
-#include <asm/lguest_hcall.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
-#include <asm/processor-flags.h>
-
-/*G:020
-
- * Our story starts with the bzImage: booting starts at startup_32 in
- * arch/x86/boot/compressed/head_32.S.  This merely uncompresses the real
- * kernel in place and then jumps into it: startup_32 in
- * arch/x86/kernel/head_32.S.  Both routines expects a boot header in the %esi
- * register, which is created by the bootloader (the Launcher in our case).
- *
- * The startup_32 function does very little: it clears the uninitialized global
- * C variables which we expect to be zero (ie. BSS) and then copies the boot
- * header and kernel command line somewhere safe, and populates some initial
- * page tables.  Finally it checks the 'hardware_subarch' field.  This was
- * introduced in 2.6.24 for lguest and Xen: if it's set to '1' (lguest's
- * assigned number), then it calls us here.
- *
- * WARNING: be very careful here!  We're running at addresses equal to physical
- * addresses (around 0), not above PAGE_OFFSET as most code expects
- * (eg. 0xC0000000).  Jumps are relative, so they're OK, but we can't touch any
- * data without remembering to subtract __PAGE_OFFSET!
- *
- * The .section line puts this code in .init.text so it will be discarded after
- * boot.
- */
-.section .init.text, "ax", @progbits
-ENTRY(lguest_entry)
-	/*
-	 * We make the "initialization" hypercall now to tell the Host where
-	 * our lguest_data struct is.
-	 */
-	movl $LHCALL_LGUEST_INIT, %eax
-	movl $lguest_data - __PAGE_OFFSET, %ebx
-	int $LGUEST_TRAP_ENTRY
-
-	/* Now turn our pagetables on; setup by arch/x86/kernel/head_32.S. */
-	movl $LHCALL_NEW_PGTABLE, %eax
-	movl $(initial_page_table - __PAGE_OFFSET), %ebx
-	int $LGUEST_TRAP_ENTRY
-
-	/* Set up the initial stack so we can run C code. */
-	movl $(init_thread_union+THREAD_SIZE),%esp
-
-	/* Jumps are relative: we're running __PAGE_OFFSET too low. */
-	jmp lguest_init+__PAGE_OFFSET
-
-/*G:055
- * We create a macro which puts the assembler code between lgstart_ and lgend_
- * markers.  These templates are put in the .text section: they can't be
- * discarded after boot as we may need to patch modules, too.
- */
-.text
-#define LGUEST_PATCH(name, insns...)			\
-	lgstart_##name:	insns; lgend_##name:;		\
-	.globl lgstart_##name; .globl lgend_##name
-
-LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
-LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax)
-
-/*G:033
- * But using those wrappers is inefficient (we'll see why that doesn't matter
- * for save_fl and irq_disable later).  If we write our routines carefully in
- * assembler, we can avoid clobbering any registers and avoid jumping through
- * the wrapper functions.
- *
- * I skipped over our first piece of assembler, but this one is worth studying
- * in a bit more detail so I'll describe in easy stages.  First, the routine to
- * enable interrupts:
- */
-ENTRY(lg_irq_enable)
-	/*
-	 * The reverse of irq_disable, this sets lguest_data.irq_enabled to
-	 * X86_EFLAGS_IF (ie. "Interrupts enabled").
-	 */
-	movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled
-	/*
-	 * But now we need to check if the Host wants to know: there might have
-	 * been interrupts waiting to be delivered, in which case it will have
-	 * set lguest_data.irq_pending to X86_EFLAGS_IF.  If it's not zero, we
-	 * jump to send_interrupts, otherwise we're done.
-	 */
-	cmpl $0, lguest_data+LGUEST_DATA_irq_pending
-	jnz send_interrupts
-	/*
-	 * One cool thing about x86 is that you can do many things without using
-	 * a register.  In this case, the normal path hasn't needed to save or
-	 * restore any registers at all!
-	 */
-	ret
-send_interrupts:
-	/*
-	 * OK, now we need a register: eax is used for the hypercall number,
-	 * which is LHCALL_SEND_INTERRUPTS.
-	 *
-	 * We used not to bother with this pending detection at all, which was
-	 * much simpler.  Sooner or later the Host would realize it had to
-	 * send us an interrupt.  But that turns out to make performance 7
-	 * times worse on a simple tcp benchmark.  So now we do this the hard
-	 * way.
-	 */
-	pushl %eax
-	movl $LHCALL_SEND_INTERRUPTS, %eax
-	/* This is the actual hypercall trap. */
-	int  $LGUEST_TRAP_ENTRY
-	/* Put eax back the way we found it. */
-	popl %eax
-	ret
-
-/*
- * Finally, the "popf" or "restore flags" routine.  The %eax register holds the
- * flags (in practice, either X86_EFLAGS_IF or 0): if it's X86_EFLAGS_IF we're
- * enabling interrupts again, if it's 0 we're leaving them off.
- */
-ENTRY(lg_restore_fl)
-	/* This is just "lguest_data.irq_enabled = flags;" */
-	movl %eax, lguest_data+LGUEST_DATA_irq_enabled
-	/*
-	 * Now, if the %eax value has enabled interrupts and
-	 * lguest_data.irq_pending is set, we want to tell the Host so it can
-	 * deliver any outstanding interrupts.  Fortunately, both values will
-	 * be X86_EFLAGS_IF (ie. 512) in that case, and the "testl"
-	 * instruction will AND them together for us.  If both are set, we
-	 * jump to send_interrupts.
-	 */
-	testl lguest_data+LGUEST_DATA_irq_pending, %eax
-	jnz send_interrupts
-	/* Again, the normal path has used no extra registers.  Clever, huh? */
-	ret
-/*:*/
-
-/* These demark the EIP where host should never deliver interrupts. */
-.global lguest_noirq_iret
-
-/*M:004
- * When the Host reflects a trap or injects an interrupt into the Guest, it
- * sets the eflags interrupt bit on the stack based on lguest_data.irq_enabled,
- * so the Guest iret logic does the right thing when restoring it.  However,
- * when the Host sets the Guest up for direct traps, such as system calls, the
- * processor is the one to push eflags onto the stack, and the interrupt bit
- * will be 1 (in reality, interrupts are always enabled in the Guest).
- *
- * This turns out to be harmless: the only trap which should happen under Linux
- * with interrupts disabled is Page Fault (due to our lazy mapping of vmalloc
- * regions), which has to be reflected through the Host anyway.  If another
- * trap *does* go off when interrupts are disabled, the Guest will panic, and
- * we'll never get to this iret!
-:*/
-
-/*G:045
- * There is one final paravirt_op that the Guest implements, and glancing at it
- * you can see why I left it to last.  It's *cool*!  It's in *assembler*!
- *
- * The "iret" instruction is used to return from an interrupt or trap.  The
- * stack looks like this:
- *   old address
- *   old code segment & privilege level
- *   old processor flags ("eflags")
- *
- * The "iret" instruction pops those values off the stack and restores them all
- * at once.  The only problem is that eflags includes the Interrupt Flag which
- * the Guest can't change: the CPU will simply ignore it when we do an "iret".
- * So we have to copy eflags from the stack to lguest_data.irq_enabled before
- * we do the "iret".
- *
- * There are two problems with this: firstly, we can't clobber any registers
- * and secondly, the whole thing needs to be atomic.  The first problem
- * is solved by using "push memory"/"pop memory" instruction pair for copying.
- *
- * The second is harder: copying eflags to lguest_data.irq_enabled will turn
- * interrupts on before we're finished, so we could be interrupted before we
- * return to userspace or wherever.  Our solution to this is to tell the
- * Host that it is *never* to interrupt us there, even if interrupts seem to be
- * enabled. (It's not necessary to protect pop instruction, since
- * data gets updated only after it completes, so we only need to protect
- * one instruction, iret).
- */
-ENTRY(lguest_iret)
-	pushl	2*4(%esp)
-	/*
-	 * Note the %ss: segment prefix here.  Normal data accesses use the
-	 * "ds" segment, but that will have already been restored for whatever
-	 * we're returning to (such as userspace): we can't trust it.  The %ss:
-	 * prefix makes sure we use the stack segment, which is still valid.
-	 */
-	popl	%ss:lguest_data+LGUEST_DATA_irq_enabled
-lguest_noirq_iret:
-	iret

drivers/Makefile

@@ -125,7 +125,6 @@ obj-$(CONFIG_ACCESSIBILITY)	+= accessibility/
 obj-$(CONFIG_ISDN)		+= isdn/
 obj-$(CONFIG_EDAC)		+= edac/
 obj-$(CONFIG_EISA)		+= eisa/
-obj-y				+= lguest/
 obj-$(CONFIG_CPU_FREQ)		+= cpufreq/
 obj-$(CONFIG_CPU_IDLE)		+= cpuidle/
 obj-y				+= mmc/

drivers/block/Kconfig

@@ -470,7 +470,7 @@ config VIRTIO_BLK
 	depends on VIRTIO
 	---help---
 	  This is the virtual block driver for virtio.  It can be used with
-          lguest or QEMU based VMMs (like KVM or Xen).  Say Y or M.
+          QEMU based VMMs (like KVM or Xen).  Say Y or M.
 
 config VIRTIO_BLK_SCSI
 	bool "SCSI passthrough request for the Virtio block driver"

drivers/char/Kconfig

@@ -161,7 +161,7 @@ config VIRTIO_CONSOLE
 	depends on VIRTIO && TTY
 	select HVC_DRIVER
 	help
-	  Virtio console for use with lguest and other hypervisors.
+	  Virtio console for use with hypervisors.
 
 	  Also serves as a general-purpose serial device for data
 	  transfer between the guest and host.  Character devices at

drivers/char/virtio_console.c

@@ -1130,7 +1130,7 @@ static const struct file_operations port_fops = {
  * We turn the characters into a scatter-gather list, add it to the
  * output queue and then kick the Host.  Then we sit here waiting for
  * it to finish: inefficient in theory, but in practice
- * implementations will do it immediately (lguest's Launcher does).
+ * implementations will do it immediately.
  */
 static int put_chars(u32 vtermno, const char *buf, int count)
 {

drivers/lguest/Kconfig

-config LGUEST
-	tristate "Linux hypervisor example code"
-	depends on X86_32 && EVENTFD && TTY && PCI_DIRECT
-	select HVC_DRIVER
-	---help---
-	  This is a very simple module which allows you to run
-	  multiple instances of the same Linux kernel, using the
-	  "lguest" command found in the tools/lguest directory.
-
-	  Note that "lguest" is pronounced to rhyme with "fell quest",
-	  not "rustyvisor". See tools/lguest/lguest.txt.
-
-	  If unsure, say N.  If curious, say M.  If masochistic, say Y.

drivers/lguest/Makefile

-# Host requires the other files, which can be a module.
-obj-$(CONFIG_LGUEST)	+= lg.o
-lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \
-	segments.o lguest_user.o
-
-lg-$(CONFIG_X86_32) += x86/switcher_32.o x86/core.o
-
-Preparation Preparation!: PREFIX=P
-Guest: PREFIX=G
-Drivers: PREFIX=D
-Launcher: PREFIX=L
-Host: PREFIX=H
-Switcher: PREFIX=S
-Mastery: PREFIX=M
-Beer:
-	@for f in Preparation Guest Drivers Launcher Host Switcher Mastery; do echo "{==- $$f -==}"; make -s $$f; done; echo "{==-==}"
-Preparation Preparation! Guest Drivers Launcher Host Switcher Mastery:
-	@sh ../../tools/lguest/extract $(PREFIX) `find ../../* -name '*.[chS]' -wholename '*lguest*'`
-Puppy:
-	@clear
-	@printf "      __  \n (___()'\`;\n /,    /\`\n \\\\\\\"--\\\\\\   \n"
-	@sleep 2; clear; printf "\n\n   Sit!\n\n"; sleep 1; clear
-	@printf "    __    \n   ()'\`;  \n   /\\|\` \n  /  |  \n(/_)_|_   \n"
-	@sleep 2; clear; printf "\n\n  Stand!\n\n"; sleep 1; clear
-	@printf "    __    \n   ()'\`;  \n   /\\|\` \n  /._.= \n /| /     \n(_\_)_    \n"
-	@sleep 2; clear; printf "\n\n  Good puppy!\n\n"; sleep 1; clear

drivers/lguest/README

-Welcome, friend reader, to lguest.
-
-Lguest is an adventure, with you, the reader, as Hero.  I can't think of many
-5000-line projects which offer both such capability and glimpses of future
-potential; it is an exciting time to be delving into the source!
-
-But be warned; this is an arduous journey of several hours or more!  And as we
-know, all true Heroes are driven by a Noble Goal.  Thus I offer a Beer (or
-equivalent) to anyone I meet who has completed this documentation.
-
-So get comfortable and keep your wits about you (both quick and humorous).
-Along your way to the Noble Goal, you will also gain masterly insight into
-lguest, and hypervisors and x86 virtualization in general.
-
-Our Quest is in seven parts: (best read with C highlighting turned on)
-
-I) Preparation
-	- In which our potential hero is flown quickly over the landscape for a
-	  taste of its scope.  Suitable for the armchair coders and other such
-	  persons of faint constitution.
-
-II) Guest
-	- Where we encounter the first tantalising wisps of code, and come to
-	  understand the details of the life of a Guest kernel.
-
-III) Drivers
-	- Whereby the Guest finds its voice and become useful, and our
-	  understanding of the Guest is completed.
-
-IV) Launcher
-	- Where we trace back to the creation of the Guest, and thus begin our
-	  understanding of the Host.
-
-V) Host
-	- Where we master the Host code, through a long and tortuous journey.
-	  Indeed, it is here that our hero is tested in the Bit of Despair.
-
-VI) Switcher
-	- Where our understanding of the intertwined nature of Guests and Hosts
-	  is completed.
-
-VII) Mastery
-	- Where our fully fledged hero grapples with the Great Question:
-	  "What next?"
-
-make Preparation!
-Rusty Russell.

drivers/lguest/hypercalls.c

-/*P:500
- * Just as userspace programs request kernel operations through a system
- * call, the Guest requests Host operations through a "hypercall".  You might
- * notice this nomenclature doesn't really follow any logic, but the name has
- * been around for long enough that we're stuck with it.  As you'd expect, this
- * code is basically a one big switch statement.
-:*/
-
-/*  Copyright (C) 2006 Rusty Russell IBM Corporation
-
-    This program is free software; you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation; either version 2 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program; if not, write to the Free Software
-    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
-*/
-#include <linux/uaccess.h>
-#include <linux/syscalls.h>
-#include <linux/mm.h>
-#include <linux/ktime.h>
-#include <asm/page.h>
-#include <asm/pgtable.h>
-#include "lg.h"
-
-/*H:120
- * This is the core hypercall routine: where the Guest gets what it wants.
- * Or gets killed.  Or, in the case of LHCALL_SHUTDOWN, both.
- */
-static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
-{
-	switch (args->arg0) {
-	case LHCALL_FLUSH_ASYNC:
-		/*
-		 * This call does nothing, except by breaking out of the Guest
-		 * it makes us process all the asynchronous hypercalls.
-		 */
-		break;
-	case LHCALL_SEND_INTERRUPTS:
-		/*
-		 * This call does nothing too, but by breaking out of the Guest
-		 * it makes us process any pending interrupts.
-		 */
-		break;
-	case LHCALL_LGUEST_INIT:
-		/*
-		 * You can't get here unless you're already initialized.  Don't
-		 * do that.
-		 */
-		kill_guest(cpu, "already have lguest_data");
-		break;
-	case LHCALL_SHUTDOWN: {
-		char msg[128];
-		/*
-		 * Shutdown is such a trivial hypercall that we do it in five
-		 * lines right here.
-		 *
-		 * If the lgread fails, it will call kill_guest() itself; the
-		 * kill_guest() with the message will be ignored.
-		 */
-		__lgread(cpu, msg, args->arg1, sizeof(msg));
-		msg[sizeof(msg)-1] = '\0';
-		kill_guest(cpu, "CRASH: %s", msg);
-		if (args->arg2 == LGUEST_SHUTDOWN_RESTART)
-			cpu->lg->dead = ERR_PTR(-ERESTART);
-		break;
-	}
-	case LHCALL_FLUSH_TLB:
-		/* FLUSH_TLB comes in two flavors, depending on the argument: */
-		if (args->arg1)
-			guest_pagetable_clear_all(cpu);
-		else
-			guest_pagetable_flush_user(cpu);
-		break;
-
-	/*
-	 * All these calls simply pass the arguments through to the right
-	 * routines.
-	 */
-	case LHCALL_NEW_PGTABLE:
-		guest_new_pagetable(cpu, args->arg1);
-		break;
-	case LHCALL_SET_STACK:
-		guest_set_stack(cpu, args->arg1, args->arg2, args->arg3);
-		break;
-	case LHCALL_SET_PTE:
-#ifdef CONFIG_X86_PAE
-		guest_set_pte(cpu, args->arg1, args->arg2,
-				__pte(args->arg3 | (u64)args->arg4 << 32));
-#else
-		guest_set_pte(cpu, args->arg1, args->arg2, __pte(args->arg3));
-#endif
-		break;
-	case LHCALL_SET_PGD:
-		guest_set_pgd(cpu->lg, args->arg1, args->arg2);
-		break;
-#ifdef CONFIG_X86_PAE
-	case LHCALL_SET_PMD:
-		guest_set_pmd(cpu->lg, args->arg1, args->arg2);
-		break;
-#endif
-	case LHCALL_SET_CLOCKEVENT:
-		guest_set_clockevent(cpu, args->arg1);
-		break;
-	case LHCALL_HALT:
-		/* Similarly, this sets the halted flag for run_guest(). */
-		cpu->halted = 1;
-		break;
-	default:
-		/* It should be an architecture-specific hypercall. */
-		if (lguest_arch_do_hcall(cpu, args))
-			kill_guest(cpu, "Bad hypercall %li\n", args->arg0);
-	}
-}
-
-/*H:124
- * Asynchronous hypercalls are easy: we just look in the array in the
- * Guest's "struct lguest_data" to see if any new ones are marked "ready".
- *
- * We are careful to do these in order: obviously we respect the order the
- * Guest put them in the ring, but we also promise the Guest that they will
- * happen before any normal hypercall (which is why we check this before
- * checking for a normal hcall).
- */
-static void do_async_hcalls(struct lg_cpu *cpu)
-{
-	unsigned int i;
-	u8 st[LHCALL_RING_SIZE];
-
-	/* For simplicity, we copy the entire call status array in at once. */
-	if (copy_from_user(&st, &cpu->lg->lguest_data->hcall_status, sizeof(st)))
-		return;
-
-	/* We process "struct lguest_data"s hcalls[] ring once. */
-	for (i = 0; i < ARRAY_SIZE(st); i++) {
-		struct hcall_args args;
-		/*
-		 * We remember where we were up to from last time.  This makes
-		 * sure that the hypercalls are done in the order the Guest
-		 * places them in the ring.
-		 */
-		unsigned int n = cpu->next_hcall;
-
-		/* 0xFF means there's no call here (yet). */
-		if (st[n] == 0xFF)
-			break;
-
-		/*
-		 * OK, we have hypercall.  Increment the "next_hcall" cursor,
-		 * and wrap back to 0 if we reach the end.
-		 */
-		if (++cpu->next_hcall == LHCALL_RING_SIZE)
-			cpu->next_hcall = 0;
-
-		/*
-		 * Copy the hypercall arguments into a local copy of the
-		 * hcall_args struct.
-		 */
-		if (copy_from_user(&args, &cpu->lg->lguest_data->hcalls[n],
-				   sizeof(struct hcall_args))) {
-			kill_guest(cpu, "Fetching async hypercalls");
-			break;
-		}
-
-		/* Do the hypercall, same as a normal one. */
-		do_hcall(cpu, &args);
-
-		/* Mark the hypercall done. */
-		if (put_user(0xFF, &cpu->lg->lguest_data->hcall_status[n])) {
-			kill_guest(cpu, "Writing result for async hypercall");
-			break;
-		}
-
-		/*
-		 * Stop doing hypercalls if they want to notify the Launcher:
-		 * it needs to service this first.
-		 */
-		if (cpu->pending.trap)
-			break;
-	}
-}
-
-/*
- * Last of all, we look at what happens first of all.  The very first time the
- * Guest makes a hypercall, we end up here to set things up:
- */
-static void initialize(struct lg_cpu *cpu)
-{
-	/*
-	 * You can't do anything until you're initialized.  The Guest knows the
-	 * rules, so we're unforgiving here.
-	 */
-	if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) {
-		kill_guest(cpu, "hypercall %li before INIT", cpu->hcall->arg0);
-		return;
-	}
-
-	if (lguest_arch_init_hypercalls(cpu))
-		kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
-
-	/*
-	 * The Guest tells us where we're not to deliver interrupts by putting
-	 * the instruction address into "struct lguest_data".
-	 */
-	if (get_user(cpu->lg->noirq_iret, &cpu->lg->lguest_data->noirq_iret))
-		kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
-
-	/*
-	 * We write the current time into the Guest's data page once so it can
-	 * set its clock.
-	 */
-	write_timestamp(cpu);
-
-	/* page_tables.c will also do some setup. */
-	page_table_guest_data_init(cpu);
-
-	/*
-	 * This is the one case where the above accesses might have been the
-	 * first write to a Guest page.  This may have caused a copy-on-write
-	 * fault, but the old page might be (read-only) in the Guest
-	 * pagetable.
-	 */
-	guest_pagetable_clear_all(cpu);
-}
-/*:*/
-
-/*M:013
- * If a Guest reads from a page (so creates a mapping) that it has never
- * written to, and then the Launcher writes to it (ie. the output of a virtual
- * device), the Guest will still see the old page.  In practice, this never
- * happens: why would the Guest read a page which it has never written to?  But
- * a similar scenario might one day bite us, so it's worth mentioning.
- *
- * Note that if we used a shared anonymous mapping in the Launcher instead of
- * mapping /dev/zero private, we wouldn't worry about cop-on-write.  And we
- * need that to switch the Launcher to processes (away from threads) anyway.
-:*/
-
-/*H:100
- * Hypercalls
- *
- * Remember from the Guest, hypercalls come in two flavors: normal and
- * asynchronous.  This file handles both of types.
- */
-void do_hypercalls(struct lg_cpu *cpu)
-{
-	/* Not initialized yet?  This hypercall must do it. */
-	if (unlikely(!cpu->lg->lguest_data)) {
-		/* Set up the "struct lguest_data" */
-		initialize(cpu);
-		/* Hcall is done. */
-		cpu->hcall = NULL;
-		return;
-	}
-
-	/*
-	 * The Guest has initialized.
-	 *
-	 * Look in the hypercall ring for the async hypercalls:
-	 */
-	do_async_hcalls(cpu);
-
-	/*
-	 * If we stopped reading the hypercall ring because the Guest did a
-	 * NOTIFY to the Launcher, we want to return now.  Otherwise we do
-	 * the hypercall.
-	 */
-	if (!cpu->pending.trap) {
-		do_hcall(cpu, cpu->hcall);
-		/*
-		 * Tricky point: we reset the hcall pointer to mark the
-		 * hypercall as "done".  We use the hcall pointer rather than
-		 * the trap number to indicate a hypercall is pending.
-		 * Normally it doesn't matter: the Guest will run again and
-		 * update the trap number before we come back here.
-		 *
-		 * However, if we are signalled or the Guest sends I/O to the
-		 * Launcher, the run_guest() loop will exit without running the
-		 * Guest.  When it comes back it would try to re-run the
-		 * hypercall.  Finding that bug sucked.
-		 */
-		cpu->hcall = NULL;
-	}
-}
-
-/*
- * This routine supplies the Guest with time: it's used for wallclock time at
- * initial boot and as a rough time source if the TSC isn't available.
- */
-void write_timestamp(struct lg_cpu *cpu)
-{
-	struct timespec now;
-	ktime_get_real_ts(&now);
-	if (copy_to_user(&cpu->lg->lguest_data->time,
-			 &now, sizeof(struct timespec)))
-		kill_guest(cpu, "Writing timestamp");
-}

drivers/lguest/lg.h

-#ifndef _LGUEST_H
-#define _LGUEST_H
-
-#ifndef __ASSEMBLY__
-#include <linux/types.h>
-#include <linux/init.h>
-#include <linux/stringify.h>
-#include <linux/lguest.h>
-#include <linux/lguest_launcher.h>
-#include <linux/wait.h>
-#include <linux/hrtimer.h>
-#include <linux/err.h>
-#include <linux/slab.h>
-
-#include <asm/lguest.h>
-
-struct pgdir {
-	unsigned long gpgdir;
-	bool switcher_mapped;
-	int last_host_cpu;
-	pgd_t *pgdir;
-};
-
-/* We have two pages shared with guests, per cpu.  */
-struct lguest_pages {
-	/* This is the stack page mapped rw in guest */
-	char spare[PAGE_SIZE - sizeof(struct lguest_regs)];
-	struct lguest_regs regs;
-
-	/* This is the host state & guest descriptor page, ro in guest */
-	struct lguest_ro_state state;
-} __attribute__((aligned(PAGE_SIZE)));
-
-#define CHANGED_IDT		1
-#define CHANGED_GDT		2
-#define CHANGED_GDT_TLS		4 /* Actually a subset of CHANGED_GDT */
-#define CHANGED_ALL	        3
-
-struct lg_cpu {
-	unsigned int id;
-	struct lguest *lg;
-	struct task_struct *tsk;
-	struct mm_struct *mm; 	/* == tsk->mm, but that becomes NULL on exit */
-
-	u32 cr2;
-	u32 esp1;
-	u16 ss1;
-
-	/* Bitmap of what has changed: see CHANGED_* above. */
-	int changed;
-
-	/* Pending operation. */
-	struct lguest_pending pending;
-
-	unsigned long *reg_read; /* register from LHREQ_GETREG */
-
-	/* At end of a page shared mapped over lguest_pages in guest. */
-	unsigned long regs_page;
-	struct lguest_regs *regs;
-
-	struct lguest_pages *last_pages;
-
-	/* Initialization mode: linear map everything. */
-	bool linear_pages;
-	int cpu_pgd; /* Which pgd this cpu is currently using */
-
-	/* If a hypercall was asked for, this points to the arguments. */
-	struct hcall_args *hcall;
-	u32 next_hcall;
-
-	/* Virtual clock device */
-	struct hrtimer hrt;
-
-	/* Did the Guest tell us to halt? */
-	int halted;
-
-	/* Pending virtual interrupts */
-	DECLARE_BITMAP(irqs_pending, LGUEST_IRQS);
-
-	struct lg_cpu_arch arch;
-};
-
-/* The private info the thread maintains about the guest. */
-struct lguest {
-	struct lguest_data __user *lguest_data;
-	struct lg_cpu cpus[NR_CPUS];
-	unsigned int nr_cpus;
-
-	/* Valid guest memory pages must be < this. */
-	u32 pfn_limit;
-
-	/* Device memory is >= pfn_limit and < device_limit. */
-	u32 device_limit;
-
-	/*
-	 * This provides the offset to the base of guest-physical memory in the
-	 * Launcher.
-	 */
-	void __user *mem_base;
-	unsigned long kernel_address;
-
-	struct pgdir pgdirs[4];
-
-	unsigned long noirq_iret;
-
-	unsigned int stack_pages;
-	u32 tsc_khz;
-
-	/* Dead? */
-	const char *dead;
-};
-
-extern struct mutex lguest_lock;
-
-/* core.c: */
-bool lguest_address_ok(const struct lguest *lg,
-		       unsigned long addr, unsigned long len);
-void __lgread(struct lg_cpu *, void *, unsigned long, unsigned);
-void __lgwrite(struct lg_cpu *, unsigned long, const void *, unsigned);
-extern struct page **lg_switcher_pages;
-
-/*H:035
- * Using memory-copy operations like that is usually inconvient, so we
- * have the following helper macros which read and write a specific type (often
- * an unsigned long).
- *
- * This reads into a variable of the given type then returns that.
- */
-#define lgread(cpu, addr, type)						\
-	({ type _v; __lgread((cpu), &_v, (addr), sizeof(_v)); _v; })
-
-/* This checks that the variable is of the given type, then writes it out. */
-#define lgwrite(cpu, addr, type, val)				\
-	do {							\
-		typecheck(type, val);				\
-		__lgwrite((cpu), (addr), &(val), sizeof(val));	\
-	} while(0)
-/* (end of memory access helper routines) :*/
-
-int run_guest(struct lg_cpu *cpu, unsigned long __user *user);
-
-/*
- * Helper macros to obtain the first 12 or the last 20 bits, this is only the
- * first step in the migration to the kernel types.  pte_pfn is already defined
- * in the kernel.
- */
-#define pgd_flags(x)	(pgd_val(x) & ~PAGE_MASK)
-#define pgd_pfn(x)	(pgd_val(x) >> PAGE_SHIFT)
-#define pmd_flags(x)    (pmd_val(x) & ~PAGE_MASK)
-#define pmd_pfn(x)	(pmd_val(x) >> PAGE_SHIFT)
-
-/* interrupts_and_traps.c: */
-unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more);
-void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more);
-void set_interrupt(struct lg_cpu *cpu, unsigned int irq);
-bool deliver_trap(struct lg_cpu *cpu, unsigned int num);
-void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int i,
-			  u32 low, u32 hi);
-void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages);
-void pin_stack_pages(struct lg_cpu *cpu);
-void setup_default_idt_entries(struct lguest_ro_state *state,
-			       const unsigned long *def);
-void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
-		const unsigned long *def);
-void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta);
-bool send_notify_to_eventfd(struct lg_cpu *cpu);
-void init_clockdev(struct lg_cpu *cpu);
-bool check_syscall_vector(struct lguest *lg);
-bool could_be_syscall(unsigned int num);
-int init_interrupts(void);
-void free_interrupts(void);
-
-/* segments.c: */
-void setup_default_gdt_entries(struct lguest_ro_state *state);
-void setup_guest_gdt(struct lg_cpu *cpu);
-void load_guest_gdt_entry(struct lg_cpu *cpu, unsigned int i,
-			  u32 low, u32 hi);
-void guest_load_tls(struct lg_cpu *cpu, unsigned long tls_array);
-void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt);
-void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt);
-
-/* page_tables.c: */
-int init_guest_pagetable(struct lguest *lg);
-void free_guest_pagetable(struct lguest *lg);
-void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable);
-void guest_set_pgd(struct lguest *lg, unsigned long gpgdir, u32 i);
-#ifdef CONFIG_X86_PAE
-void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 i);
-#endif
-void guest_pagetable_clear_all(struct lg_cpu *cpu);
-void guest_pagetable_flush_user(struct lg_cpu *cpu);
-void guest_set_pte(struct lg_cpu *cpu, unsigned long gpgdir,
-		   unsigned long vaddr, pte_t val);
-void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages);
-bool demand_page(struct lg_cpu *cpu, unsigned long cr2, int errcode,
-		 unsigned long *iomem);
-void pin_page(struct lg_cpu *cpu, unsigned long vaddr);
-bool __guest_pa(struct lg_cpu *cpu, unsigned long vaddr, unsigned long *paddr);
-unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr);
-void page_table_guest_data_init(struct lg_cpu *cpu);
-
-/* <arch>/core.c: */
-void lguest_arch_host_init(void);
-void lguest_arch_host_fini(void);
-void lguest_arch_run_guest(struct lg_cpu *cpu);
-void lguest_arch_handle_trap(struct lg_cpu *cpu);
-int lguest_arch_init_hypercalls(struct lg_cpu *cpu);
-int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args);
-void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start);
-unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any);
-
-/* <arch>/switcher.S: */
-extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];
-
-/* lguest_user.c: */
-int lguest_device_init(void);
-void lguest_device_remove(void);
-
-/* hypercalls.c: */
-void do_hypercalls(struct lg_cpu *cpu);
-void write_timestamp(struct lg_cpu *cpu);
-
-/*L:035
- * Let's step aside for the moment, to study one important routine that's used
- * widely in the Host code.
- *
- * There are many cases where the Guest can do something invalid, like pass crap
- * to a hypercall.  Since only the Guest kernel can make hypercalls, it's quite
- * acceptable to simply terminate the Guest and give the Launcher a nicely
- * formatted reason.  It's also simpler for the Guest itself, which doesn't
- * need to check most hypercalls for "success"; if you're still running, it
- * succeeded.
- *
- * Once this is called, the Guest will never run again, so most Host code can
- * call this then continue as if nothing had happened.  This means many
- * functions don't have to explicitly return an error code, which keeps the
- * code simple.
- *
- * It also means that this can be called more than once: only the first one is
- * remembered.  The only trick is that we still need to kill the Guest even if
- * we can't allocate memory to store the reason.  Linux has a neat way of
- * packing error codes into invalid pointers, so we use that here.
- *
- * Like any macro which uses an "if", it is safely wrapped in a run-once "do {
- * } while(0)".
- */
-#define kill_guest(cpu, fmt...)					\
-do {								\
-	if (!(cpu)->lg->dead) {					\
-		(cpu)->lg->dead = kasprintf(GFP_ATOMIC, fmt);	\
-		if (!(cpu)->lg->dead)				\
-			(cpu)->lg->dead = ERR_PTR(-ENOMEM);	\
-	}							\
-} while(0)
-/* (End of aside) :*/
-
-#endif	/* __ASSEMBLY__ */
-#endif	/* _LGUEST_H */

drivers/lguest/segments.c

-/*P:600
- * The x86 architecture has segments, which involve a table of descriptors
- * which can be used to do funky things with virtual address interpretation.
- * We originally used to use segments so the Guest couldn't alter the
- * Guest<->Host Switcher, and then we had to trim Guest segments, and restore
- * for userspace per-thread segments, but trim again for on userspace->kernel
- * transitions...  This nightmarish creation was contained within this file,
- * where we knew not to tread without heavy armament and a change of underwear.
- *
- * In these modern times, the segment handling code consists of simple sanity
- * checks, and the worst you'll experience reading this code is butterfly-rash
- * from frolicking through its parklike serenity.
-:*/
-#include "lg.h"
-
-/*H:600
- * Segments & The Global Descriptor Table
- *
- * (That title sounds like a bad Nerdcore group.  Not to suggest that there are
- * any good Nerdcore groups, but in high school a friend of mine had a band
- * called Joe Fish and the Chips, so there are definitely worse band names).
- *
- * To refresh: the GDT is a table of 8-byte values describing segments.  Once
- * set up, these segments can be loaded into one of the 6 "segment registers".
- *
- * GDT entries are passed around as "struct desc_struct"s, which like IDT
- * entries are split into two 32-bit members, "a" and "b".  One day, someone
- * will clean that up, and be declared a Hero.  (No pressure, I'm just saying).
- *
- * Anyway, the GDT entry contains a base (the start address of the segment), a
- * limit (the size of the segment - 1), and some flags.  Sounds simple, and it
- * would be, except those zany Intel engineers decided that it was too boring
- * to put the base at one end, the limit at the other, and the flags in
- * between.  They decided to shotgun the bits at random throughout the 8 bytes,
- * like so:
- *
- * 0               16                     40       48  52  56     63
- * [ limit part 1 ][     base part 1     ][ flags ][li][fl][base ]
- *                                                  mit ags part 2
- *                                                part 2
- *
- * As a result, this file contains a certain amount of magic numeracy.  Let's
- * begin.
- */
-
-/*
- * There are several entries we don't let the Guest set.  The TSS entry is the
- * "Task State Segment" which controls all kinds of delicate things.  The
- * LGUEST_CS and LGUEST_DS entries are reserved for the Switcher, and the
- * the Guest can't be trusted to deal with double faults.
- */
-static bool ignored_gdt(unsigned int num)
-{
-	return (num == GDT_ENTRY_TSS
-		|| num == GDT_ENTRY_LGUEST_CS
-		|| num == GDT_ENTRY_LGUEST_DS
-		|| num == GDT_ENTRY_DOUBLEFAULT_TSS);
-}
-
-/*H:630
- * Once the Guest gave us new GDT entries, we fix them up a little.  We
- * don't care if they're invalid: the worst that can happen is a General
- * Protection Fault in the Switcher when it restores a Guest segment register
- * which tries to use that entry.  Then we kill the Guest for causing such a
- * mess: the message will be "unhandled trap 256".
- */
-static void fixup_gdt_table(struct lg_cpu *cpu, unsigned start, unsigned end)
-{
-	unsigned int i;
-
-	for (i = start; i < end; i++) {
-		/*
-		 * We never copy these ones to real GDT, so we don't care what
-		 * they say
-		 */
-		if (ignored_gdt(i))
-			continue;
-
-		/*
-		 * Segment descriptors contain a privilege level: the Guest is
-		 * sometimes careless and leaves this as 0, even though it's
-		 * running at privilege level 1.  If so, we fix it here.
-		 */
-		if (cpu->arch.gdt[i].dpl == 0)
-			cpu->arch.gdt[i].dpl |= GUEST_PL;
-
-		/*
-		 * Each descriptor has an "accessed" bit.  If we don't set it
-		 * now, the CPU will try to set it when the Guest first loads
-		 * that entry into a segment register.  But the GDT isn't
-		 * writable by the Guest, so bad things can happen.
-		 */
-		cpu->arch.gdt[i].type |= 0x1;
-	}
-}
-
-/*H:610
- * Like the IDT, we never simply use the GDT the Guest gives us.  We keep
- * a GDT for each CPU, and copy across the Guest's entries each time we want to
- * run the Guest on that CPU.
- *
- * This routine is called at boot or modprobe time for each CPU to set up the
- * constant GDT entries: the ones which are the same no matter what Guest we're
- * running.
- */
-void setup_default_gdt_entries(struct lguest_ro_state *state)
-{
-	struct desc_struct *gdt = state->guest_gdt;
-	unsigned long tss = (unsigned long)&state->guest_tss;
-
-	/* The Switcher segments are full 0-4G segments, privilege level 0 */
-	gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
-	gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
-
-	/*
-	 * The TSS segment refers to the TSS entry for this particular CPU.
-	 */
-	gdt[GDT_ENTRY_TSS].a = 0;
-	gdt[GDT_ENTRY_TSS].b = 0;
-
-	gdt[GDT_ENTRY_TSS].limit0 = 0x67;
-	gdt[GDT_ENTRY_TSS].base0  = tss & 0xFFFF;
-	gdt[GDT_ENTRY_TSS].base1  = (tss >> 16) & 0xFF;
-	gdt[GDT_ENTRY_TSS].base2  = tss >> 24;
-	gdt[GDT_ENTRY_TSS].type   = 0x9; /* 32-bit TSS (available) */
-	gdt[GDT_ENTRY_TSS].p      = 0x1; /* Entry is present */
-	gdt[GDT_ENTRY_TSS].dpl    = 0x0; /* Privilege level 0 */
-	gdt[GDT_ENTRY_TSS].s      = 0x0; /* system segment */
-
-}
-
-/*
- * This routine sets up the initial Guest GDT for booting.  All entries start
- * as 0 (unusable).
- */
-void setup_guest_gdt(struct lg_cpu *cpu)
-{
-	/*
-	 * Start with full 0-4G segments...except the Guest is allowed to use
-	 * them, so set the privilege level appropriately in the flags.
-	 */
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS].dpl |= GUEST_PL;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS].dpl |= GUEST_PL;
-}
-
-/*H:650
- * An optimization of copy_gdt(), for just the three "thead-local storage"
- * entries.
- */
-void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt)
-{
-	unsigned int i;
-
-	for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
-		gdt[i] = cpu->arch.gdt[i];
-}
-
-/*H:640
- * When the Guest is run on a different CPU, or the GDT entries have changed,
- * copy_gdt() is called to copy the Guest's GDT entries across to this CPU's
- * GDT.
- */
-void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt)
-{
-	unsigned int i;
-
-	/*
-	 * The default entries from setup_default_gdt_entries() are not
-	 * replaced.  See ignored_gdt() above.
-	 */
-	for (i = 0; i < GDT_ENTRIES; i++)
-		if (!ignored_gdt(i))
-			gdt[i] = cpu->arch.gdt[i];
-}
-
-/*H:620
- * This is where the Guest asks us to load a new GDT entry
- * (LHCALL_LOAD_GDT_ENTRY).  We tweak the entry and copy it in.
- */
-void load_guest_gdt_entry(struct lg_cpu *cpu, u32 num, u32 lo, u32 hi)
-{
-	/*
-	 * We assume the Guest has the same number of GDT entries as the
-	 * Host, otherwise we'd have to dynamically allocate the Guest GDT.
-	 */
-	if (num >= ARRAY_SIZE(cpu->arch.gdt)) {
-		kill_guest(cpu, "too many gdt entries %i", num);
-		return;
-	}
-
-	/* Set it up, then fix it. */
-	cpu->arch.gdt[num].a = lo;
-	cpu->arch.gdt[num].b = hi;
-	fixup_gdt_table(cpu, num, num+1);
-	/*
-	 * Mark that the GDT changed so the core knows it has to copy it again,
-	 * even if the Guest is run on the same CPU.
-	 */
-	cpu->changed |= CHANGED_GDT;
-}
-
-/*
- * This is the fast-track version for just changing the three TLS entries.
- * Remember that this happens on every context switch, so it's worth
- * optimizing.  But wouldn't it be neater to have a single hypercall to cover
- * both cases?
- */
-void guest_load_tls(struct lg_cpu *cpu, unsigned long gtls)
-{
-	struct desc_struct *tls = &cpu->arch.gdt[GDT_ENTRY_TLS_MIN];
-
-	__lgread(cpu, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
-	fixup_gdt_table(cpu, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
-	/* Note that just the TLS entries have changed. */
-	cpu->changed |= CHANGED_GDT_TLS;
-}
-
-/*H:660
- * With this, we have finished the Host.
- *
- * Five of the seven parts of our task are complete.  You have made it through
- * the Bit of Despair (I think that's somewhere in the page table code,
- * myself).
- *
- * Next, we examine "make Switcher".  It's short, but intense.
- */

drivers/net/Kconfig

@@ -333,7 +333,7 @@ config VIRTIO_NET
 	depends on VIRTIO
 	---help---
 	  This is the virtual network driver for virtio.  It can be used with
-	  lguest or QEMU based VMMs (like KVM or Xen).  Say Y or M.
+	  QEMU based VMMs (like KVM or Xen).  Say Y or M.
 
 config NLMON
 	tristate "Virtual netlink monitoring device"

drivers/tty/hvc/Kconfig

@@ -4,7 +4,7 @@ config HVC_DRIVER
 	bool
 	help
 	  Generic "hypervisor virtual console" infrastructure for various
-	  hypervisors (pSeries, iSeries, Xen, lguest).
+	  hypervisors (pSeries, iSeries, Xen).
 	  It will automatically be selected if one of the back-end console drivers
 	  is selected.
 

drivers/virtio/Kconfig

@@ -2,8 +2,8 @@ config VIRTIO
 	tristate
 	---help---
 	  This option is selected by any driver which implements the virtio
-	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_LGUEST,
-	  CONFIG_RPMSG or CONFIG_S390_GUEST.
+	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
+	  or CONFIG_S390_GUEST.
 
 menu "Virtio drivers"
 

include/linux/lguest.h

-/*
- * Things the lguest guest needs to know.  Note: like all lguest interfaces,
- * this is subject to wild and random change between versions.
- */
-#ifndef _LINUX_LGUEST_H
-#define _LINUX_LGUEST_H
-
-#ifndef __ASSEMBLY__
-#include <linux/time.h>
-#include <asm/irq.h>
-#include <asm/lguest_hcall.h>
-
-#define LG_CLOCK_MIN_DELTA	100UL
-#define LG_CLOCK_MAX_DELTA	ULONG_MAX
-
-/*G:031
- * The second method of communicating with the Host is to via "struct
- * lguest_data".  Once the Guest's initialization hypercall tells the Host where
- * this is, the Guest and Host both publish information in it.
-:*/
-struct lguest_data {
-	/*
-	 * 512 == enabled (same as eflags in normal hardware).  The Guest
-	 * changes interrupts so often that a hypercall is too slow.
-	 */
-	unsigned int irq_enabled;
-	/* Fine-grained interrupt disabling by the Guest */
-	DECLARE_BITMAP(blocked_interrupts, LGUEST_IRQS);
-
-	/*
-	 * The Host writes the virtual address of the last page fault here,
-	 * which saves the Guest a hypercall.  CR2 is the native register where
-	 * this address would normally be found.
-	 */
-	unsigned long cr2;
-
-	/* Wallclock time set by the Host. */
-	struct timespec time;
-
-	/*
-	 * Interrupt pending set by the Host.  The Guest should do a hypercall
-	 * if it re-enables interrupts and sees this set (to X86_EFLAGS_IF).
-	 */
-	int irq_pending;
-
-	/*
-	 * Async hypercall ring.  Instead of directly making hypercalls, we can
-	 * place them in here for processing the next time the Host wants.
-	 * This batching can be quite efficient.
-	 */
-
-	/* 0xFF == done (set by Host), 0 == pending (set by Guest). */
-	u8 hcall_status[LHCALL_RING_SIZE];
-	/* The actual registers for the hypercalls. */
-	struct hcall_args hcalls[LHCALL_RING_SIZE];
-
-/* Fields initialized by the Host at boot: */
-	/* Memory not to try to access */
-	unsigned long reserve_mem;
-	/* KHz for the TSC clock. */
-	u32 tsc_khz;
-
-/* Fields initialized by the Guest at boot: */
-	/* Instruction to suppress interrupts even if enabled */
-	unsigned long noirq_iret;
-	/* Address above which page tables are all identical. */
-	unsigned long kernel_address;
-	/* The vector to try to use for system calls (0x40 or 0x80). */
-	unsigned int syscall_vec;
-};
-extern struct lguest_data lguest_data;
-#endif /* __ASSEMBLY__ */
-#endif	/* _LINUX_LGUEST_H */

include/uapi/linux/virtio_ring.h

 #ifndef _UAPI_LINUX_VIRTIO_RING_H
 #define _UAPI_LINUX_VIRTIO_RING_H
-/* An interface for efficient virtio implementation, currently for use by KVM
- * and lguest, but hopefully others soon.  Do NOT change this since it will
+/* An interface for efficient virtio implementation, currently for use by KVM,
+ * but hopefully others soon.  Do NOT change this since it will
  * break existing servers and clients.
  *
  * This header is BSD licensed so anyone can use the definitions to implement

tools/lguest/.gitignore

-lguest
-include