- 12 Jul, 2011 40 commits
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Paul Mackerras authored
This lifts the restriction that book3s_hv guests can only run one hardware thread per core, and allows them to use up to 4 threads per core on POWER7. The host still has to run single-threaded. This capability is advertised to qemu through a new KVM_CAP_PPC_SMT capability. The return value of the ioctl querying this capability is the number of vcpus per virtual CPU core (vcore), currently 4. To use this, the host kernel should be booted with all threads active, and then all the secondary threads should be offlined. This will put the secondary threads into nap mode. KVM will then wake them from nap mode and use them for running guest code (while they are still offline). To wake the secondary threads, we send them an IPI using a new xics_wake_cpu() function, implemented in arch/powerpc/sysdev/xics/icp-native.c. In other words, at this stage we assume that the platform has a XICS interrupt controller and we are using icp-native.c to drive it. Since the woken thread will need to acknowledge and clear the IPI, we also export the base physical address of the XICS registers using kvmppc_set_xics_phys() for use in the low-level KVM book3s code. When a vcpu is created, it is assigned to a virtual CPU core. The vcore number is obtained by dividing the vcpu number by the number of threads per core in the host. This number is exported to userspace via the KVM_CAP_PPC_SMT capability. If qemu wishes to run the guest in single-threaded mode, it should make all vcpu numbers be multiples of the number of threads per core. We distinguish three states of a vcpu: runnable (i.e., ready to execute the guest), blocked (that is, idle), and busy in host. We currently implement a policy that the vcore can run only when all its threads are runnable or blocked. This way, if a vcpu needs to execute elsewhere in the kernel or in qemu, it can do so without being starved of CPU by the other vcpus. When a vcore starts to run, it executes in the context of one of the vcpu threads. The other vcpu threads all go to sleep and stay asleep until something happens requiring the vcpu thread to return to qemu, or to wake up to run the vcore (this can happen when another vcpu thread goes from busy in host state to blocked). It can happen that a vcpu goes from blocked to runnable state (e.g. because of an interrupt), and the vcore it belongs to is already running. In that case it can start to run immediately as long as the none of the vcpus in the vcore have started to exit the guest. We send the next free thread in the vcore an IPI to get it to start to execute the guest. It synchronizes with the other threads via the vcore->entry_exit_count field to make sure that it doesn't go into the guest if the other vcpus are exiting by the time that it is ready to actually enter the guest. Note that there is no fixed relationship between the hardware thread number and the vcpu number. Hardware threads are assigned to vcpus as they become runnable, so we will always use the lower-numbered hardware threads in preference to higher-numbered threads if not all the vcpus in the vcore are runnable, regardless of which vcpus are runnable. Signed-off-by:
Paul Mackerras <paulus@samba.org> Signed-off-by:
Alexander Graf <agraf@suse.de>
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David Gibson authored
This improves I/O performance for guests using the PAPR paravirtualization interface by making the H_PUT_TCE hcall faster, by implementing it in real mode. H_PUT_TCE is used for updating virtual IOMMU tables, and is used both for virtual I/O and for real I/O in the PAPR interface. Since this moves the IOMMU tables into the kernel, we define a new KVM_CREATE_SPAPR_TCE ioctl to allow qemu to create the tables. The ioctl returns a file descriptor which can be used to mmap the newly created table. The qemu driver models use them in the same way as userspace managed tables, but they can be updated directly by the guest with a real-mode H_PUT_TCE implementation, reducing the number of host/guest context switches during guest IO. There are certain circumstances where it is useful for userland qemu to write to the TCE table even if the kernel H_PUT_TCE path is used most of the time. Specifically, allowing this will avoid awkwardness when we need to reset the table. More importantly, we will in the future need to write the table in order to restore its state after a checkpoint resume or migration. Signed-off-by:
David Gibson <david@gibson.dropbear.id.au> Signed-off-by:
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Paul Mackerras authored
This adds the infrastructure for handling PAPR hcalls in the kernel, either early in the guest exit path while we are still in real mode, or later once the MMU has been turned back on and we are in the full kernel context. The advantage of handling hcalls in real mode if possible is that we avoid two partition switches -- and this will become more important when we support SMT4 guests, since a partition switch means we have to pull all of the threads in the core out of the guest. The disadvantage is that we can only access the kernel linear mapping, not anything vmalloced or ioremapped, since the MMU is off. This also adds code to handle the following hcalls in real mode: H_ENTER Add an HPTE to the hashed page table H_REMOVE Remove an HPTE from the hashed page table H_READ Read HPTEs from the hashed page table H_PROTECT Change the protection bits in an HPTE H_BULK_REMOVE Remove up to 4 HPTEs from the hashed page table H_SET_DABR Set the data address breakpoint register Plus code to handle the following hcalls in the kernel: H_CEDE Idle the vcpu until an interrupt or H_PROD hcall arrives H_PROD Wake up a ceded vcpu H_REGISTER_VPA Register a virtual processor area (VPA) The code that runs in real mode has to be in the base kernel, not in the module, if KVM is compiled as a module. The real-mode code can only access the kernel linear mapping, not vmalloc or ioremap space. Signed-off-by:
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Paul Mackerras authored
This adds support for KVM running on 64-bit Book 3S processors, specifically POWER7, in hypervisor mode. Using hypervisor mode means that the guest can use the processor's supervisor mode. That means that the guest can execute privileged instructions and access privileged registers itself without trapping to the host. This gives excellent performance, but does mean that KVM cannot emulate a processor architecture other than the one that the hardware implements. This code assumes that the guest is running paravirtualized using the PAPR (Power Architecture Platform Requirements) interface, which is the interface that IBM's PowerVM hypervisor uses. That means that existing Linux distributions that run on IBM pSeries machines will also run under KVM without modification. In order to communicate the PAPR hypercalls to qemu, this adds a new KVM_EXIT_PAPR_HCALL exit code to include/linux/kvm.h. Currently the choice between book3s_hv support and book3s_pr support (i.e. the existing code, which runs the guest in user mode) has to be made at kernel configuration time, so a given kernel binary can only do one or the other. This new book3s_hv code doesn't support MMIO emulation at present. Since we are running paravirtualized guests, this isn't a serious restriction. With the guest running in supervisor mode, most exceptions go straight to the guest. We will never get data or instruction storage or segment interrupts, alignment interrupts, decrementer interrupts, program interrupts, single-step interrupts, etc., coming to the hypervisor from the guest. Therefore this introduces a new KVMTEST_NONHV macro for the exception entry path so that we don't have to do the KVM test on entry to those exception handlers. We do however get hypervisor decrementer, hypervisor data storage, hypervisor instruction storage, and hypervisor emulation assist interrupts, so we have to handle those. In hypervisor mode, real-mode accesses can access all of RAM, not just a limited amount. Therefore we put all the guest state in the vcpu.arch and use the shadow_vcpu in the PACA only for temporary scratch space. We allocate the vcpu with kzalloc rather than vzalloc, and we don't use anything in the kvmppc_vcpu_book3s struct, so we don't allocate it. We don't have a shared page with the guest, but we still need a kvm_vcpu_arch_shared struct to store the values of various registers, so we include one in the vcpu_arch struct. The POWER7 processor has a restriction that all threads in a core have to be in the same partition. MMU-on kernel code counts as a partition (partition 0), so we have to do a partition switch on every entry to and exit from the guest. At present we require the host and guest to run in single-thread mode because of this hardware restriction. This code allocates a hashed page table for the guest and initializes it with HPTEs for the guest's Virtual Real Memory Area (VRMA). We require that the guest memory is allocated using 16MB huge pages, in order to simplify the low-level memory management. This also means that we can get away without tracking paging activity in the host for now, since huge pages can't be paged or swapped. This also adds a few new exports needed by the book3s_hv code. Signed-off-by:
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Paul Mackerras authored
There are several fields in struct kvmppc_book3s_shadow_vcpu that temporarily store bits of host state while a guest is running, rather than anything relating to the particular guest or vcpu. This splits them out into a new kvmppc_host_state structure and modifies the definitions in asm-offsets.c to suit. On 32-bit, we have a kvmppc_host_state structure inside the kvmppc_book3s_shadow_vcpu since the assembly code needs to be able to get to them both with one pointer. On 64-bit they are separate fields in the PACA. This means that on 64-bit we don't need to copy the kvmppc_host_state in and out on vcpu load/unload, and in future will mean that the book3s_hv code doesn't need a shadow_vcpu struct in the PACA at all. That does mean that we have to be careful not to rely on any values persisting in the hstate field of the paca across any point where we could block or get preempted. Signed-off-by:
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Paul Mackerras authored
In hypervisor mode, the LPCR controls several aspects of guest partitions, including virtual partition memory mode, and also controls whether the hypervisor decrementer interrupts are enabled. This sets up LPCR at boot time so that guest partitions will use a virtual real memory area (VRMA) composed of 16MB large pages, and hypervisor decrementer interrupts are disabled. Signed-off-by:
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Paul Mackerras authored
Instead of doing the kvm_guest_enter/exit() and local_irq_dis/enable() calls in powerpc.c, this moves them down into the subarch-specific book3s_pr.c and booke.c. This eliminates an extra local_irq_enable() call in book3s_pr.c, and will be needed for when we do SMT4 guest support in the book3s hypervisor mode code. Signed-off-by:
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Paul Mackerras authored
This arranges for the top-level arch/powerpc/kvm/powerpc.c file to pass down some of the calls it gets to the lower-level subarchitecture specific code. The lower-level implementations (in booke.c and book3s.c) are no-ops. The coming book3s_hv.c will need this. Signed-off-by:
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Paul Mackerras authored
Doing so means that we don't have to save the flags anywhere and gets rid of the last reference to to_book3s(vcpu) in arch/powerpc/kvm/book3s.c. Doing so is OK because a program interrupt won't be generated at the same time as any other synchronous interrupt. If a program interrupt and an asynchronous interrupt (external or decrementer) are generated at the same time, the program interrupt will be delivered, which is correct because it has a higher priority, and then the asynchronous interrupt will be masked. We don't ever generate system reset or machine check interrupts to the guest, but if we did, then we would need to make sure they got delivered rather than the program interrupt. The current code would be wrong in this situation anyway since it would deliver the program interrupt as well as the reset/machine check interrupt. Signed-off-by:
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Paul Mackerras authored
Instead of branching out-of-line with the DO_KVM macro to check if we are in a KVM guest at the time of an interrupt, this moves the KVM check inline in the first-level interrupt handlers. This speeds up the non-KVM case and makes sure that none of the interrupt handlers are missing the check. Because the first-level interrupt handlers are now larger, some things had to be move out of line in exceptions-64s.S. This all necessitated some minor changes to the interrupt entry code in KVM. This also streamlines the book3s_32 KVM test. Signed-off-by:
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Paul Mackerras authored
In preparation for adding code to enable KVM to use hypervisor mode on 64-bit Book 3S processors, this splits book3s.c into two files, book3s.c and book3s_pr.c, where book3s_pr.c contains the code that is specific to running the guest in problem state (user mode) and book3s.c contains code which should apply to all Book 3S processors. In doing this, we abstract some details, namely the interrupt offset, updating the interrupt pending flag, and detecting if the guest is in a critical section. These are all things that will be different when we use hypervisor mode. Signed-off-by:
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Paul Mackerras authored
This moves the slb field, which represents the state of the emulated SLB, from the kvmppc_vcpu_book3s struct to the kvm_vcpu_arch, and the hpte_hash_[v]pte[_long] fields from kvm_vcpu_arch to kvmppc_vcpu_book3s. This is in accord with the principle that the kvm_vcpu_arch struct represents the state of the emulated CPU, and the kvmppc_vcpu_book3s struct holds the auxiliary data structures used in the emulation. Signed-off-by:
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Paul Mackerras authored
Commit 69acc0d3ba ("KVM: PPC: Resolve real-mode handlers through function exports") resulted in vcpu->arch.trampoline_lowmem and vcpu->arch.trampoline_enter ending up with kernel virtual addresses rather than physical addresses. This is OK on 64-bit Book3S machines, which ignore the top 4 bits of the effective address in real mode, but on 32-bit Book3S machines, accessing these addresses in real mode causes machine check interrupts, as the hardware uses the whole effective address as the physical address in real mode. This fixes the problem by using __pa() to convert these addresses to physical addresses. Signed-off-by: -
Takuya Yoshikawa authored
Suggested by Ingo and Avi. Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Signed-off-by:
Marcelo Tosatti <mtosatti@redhat.com>
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Takuya Yoshikawa authored
The current name does not explain the meaning well. So give it a better name "retry_walk" to show that we are trying the walk again. This was suggested by Ingo Molnar. Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Takuya Yoshikawa authored
Avoid two step jump to the error handling part. This eliminates the use of the variables present and rsvd_fault. We also use the const type qualifier to show that write/user/fetch_fault do not change in the function. Both of these were suggested by Ingo Molnar. Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Marcelo Tosatti authored
This reverts commit bee931d31e588b8eb86b7edee32fac2d16930cd7. TLB flush should be done lazily during guest entry, in kvm_mmu_load(). Signed-off-by: -
Scott Wood authored
Only look in the 4 entries that could possibly contain the entry we're looking for. Signed-off-by:
Scott Wood <scottwood@freescale.com> Signed-off-by:
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Liu Yu authored
Dynamically assign host PIDs to guest PIDs, splitting each guest PID into multiple host (shadow) PIDs based on kernel/user and MSR[IS/DS]. Use both PID0 and PID1 so that the shadow PIDs for the right mode can be selected, that correspond both to guest TID = zero and guest TID = guest PID. This allows us to significantly reduce the frequency of needing to invalidate the entire TLB. When the guest mode or PID changes, we just update the host PID0/PID1. And since the allocation of shadow PIDs is global, multiple guests can share the TLB without conflict. Note that KVM does not yet support the guest setting PID1 or PID2 to a value other than zero. This will need to be fixed for nested KVM to work. Until then, we enforce the requirement for guest PID1/PID2 to stay zero by failing the emulation if the guest tries to set them to something else. Signed-off-by:
Liu Yu <yu.liu@freescale.com> Signed-off-by:
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Liu Yu authored
Instead of a fully separate set of TLB entries, keep just the pfn and dirty status. Signed-off-by:
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Scott Wood authored
This is a shared page used for paravirtualization. It is always present in the guest kernel's effective address space at the address indicated by the hypercall that enables it. The physical address specified by the hypercall is not used, as e500 does not have real mode. Signed-off-by:
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Scott Wood authored
This allows large pages to be used on guest mappings backed by things like /dev/mem, resulting in a significant speedup when guest memory is mapped this way (it's useful for directly-assigned MMIO, too). This is not a substitute for hugetlbfs integration, but is useful for configurations where devices are directly assigned on chips without an IOMMU -- in these cases, we need guest physical and true physical to match, and be contiguous, so static reservation and mapping via /dev/mem is the most straightforward way to set things up. Signed-off-by:
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Scott Wood authored
This is in line with what other architectures do, and will allow us to map things other than ordinary, unreserved kernel pages -- such as dedicated devices, or large contiguous reserved regions. Signed-off-by:
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Scott Wood authored
This avoids races. It also means that we use the shadow TLB way, rather than the hardware hint -- if this is a problem, we could do a tlbsx before inserting a TLB0 entry. Signed-off-by:
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Scott Wood authored
Since TLB1 loading doesn't check the shadow TLB before allocating another entry, you can get duplicates. Once shadow PIDs are enabled in a later patch, we won't need to invalidate the TLB on every switch, so this optimization won't be needed anyway. Signed-off-by:
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Scott Wood authored
This is done lazily. The SPE save will be done only if the guest has used SPE since the last preemption or heavyweight exit. Restore will be done only on demand, when enabling MSR_SPE in the shadow MSR, in response to an SPE fault or mtmsr emulation. For SPEFSCR, Linux already switches it on context switch (non-lazily), so the only remaining bit is to save it between qemu and the guest. Signed-off-by:
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Scott Wood authored
Keep the guest MSR and the guest-mode true MSR separate, rather than modifying the guest MSR on each guest entry to produce a true MSR. Any bits which should be modified based on guest MSR must be explicitly propagated from vcpu->arch.shared->msr to vcpu->arch.shadow_msr in kvmppc_set_msr(). While we're modifying the guest entry code, reorder a few instructions to bury some load latencies. Signed-off-by:
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Scott Wood authored
Previously, these macros hardcoded THREAD_EVR0 as the base of the save area, relative to the base register passed. This base offset is now passed as a separate macro parameter, allowing reuse with other SPE save areas, such as used by KVM. Acked-by:
Kumar Gala <galak@kernel.crashing.org> Signed-off-by:
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yu liu authored
giveup_spe() saves the SPE state which is protected by MSR[SPE]. However, modifying SPEFSCR does not trap when MSR[SPE]=0. And since SPEFSCR is already saved/restored in _switch(), not all the callers want to save SPEFSCR again. Thus, saving SPEFSCR should not belong to giveup_spe(). This patch moves SPEFSCR saving to flush_spe_to_thread(), and cleans up the caller that needs to save SPEFSCR accordingly. Signed-off-by:
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Alexander Graf authored
Up until now, Book3S KVM had variables stored in the kernel that a kernel module or the kvm code in the kernel could read from to figure out where some real mode helper functions are located. This is all unnecessary. The high bits of the EA get ignore in real mode, so we can just use the pointer as is. Also, it's a lot easier on relocations when we use the normal way of resolving the address to a function, instead of jumping through hoops. This patch fixes compilation with CONFIG_RELOCATABLE=y. Signed-off-by: -
Stuart Yoder authored
When http://www.spinics.net/lists/kvm-ppc/msg02664.html was applied to produce commit b51e7aa7ed6d8d134d02df78300ab0f91cfff4d2, the removal of the conversion in add_exit_timing was left out. Signed-off-by:
Stuart Yoder <stuart.yoder@freescale.com> Signed-off-by:
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Avi Kivity authored
kvm_set_cr0() and kvm_set_cr4(), and possible other functions, assume that kvm_mmu_reset_context() flushes the guest TLB. However, it does not. Fix by flushing the tlb (and syncing the new root as well). Signed-off-by:Avi Kivity <avi@redhat.com>
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Avi Kivity authored
When CR0.WP=0, we sometimes map user pages as kernel pages (to allow the kernel to write to them). Unfortunately this also allows the kernel to fetch from these pages, even if CR4.SMEP is set. Adjust for this by also setting NX on the spte in these circumstances. Signed-off-by: -
Yang, Wei authored
This patch exposes ERMS feature to KVM guests. The REP MOVSB/STOSB instruction can enhance fast strings attempts to move as much of the data with larger size load/stores as possible. Signed-off-by:
Yang, Wei <wei.y.yang@intel.com> Signed-off-by:
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Yang, Wei authored
This patch exposes RDWRGSFS bit to KVM guests. Signed-off-by:
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Yang, Wei authored
This patch adds RDWRGSFS support when setting CR4. Signed-off-by:
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Yang, Wei authored
This patch removes RDWRGSFS bit from CR4_RESERVED_BITS. Signed-off-by:
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Yang, Wei Y authored
This patch exposes DRNG feature to KVM guests. The RDRAND instruction can provide software with sequences of random numbers generated from white noise. Signed-off-by:
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Andre Przywara authored
commit 123108f1c1aafd51d6a5c79cc04d7999dd88a930 tried to fix KVMs XSAVE valid feature scanning, but it was wrong. It was not considering the sparse nature of this bitfield, instead reading values from uninitialized members of the entries array. This patch now separates subleaf indicies from KVM's array indicies and fills the entry before querying it's value. This fixes AVX support in KVM guests. Signed-off-by:
Andre Przywara <andre.przywara@amd.com> Signed-off-by:
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Jan Kiszka authored
The documented behavior did not match the implemented one (which also never changed). Signed-off-by:
Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by:
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