- 07 Aug, 2013 11 commits
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Gleb Natapov authored
need_remote_flush() assumes that shadow page is in PT64 format, but with addition of nested EPT this is no longer always true. Fix it by bits definitions that depend on host shadow page type. Reported-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Yang Zhang authored
Since nEPT doesn't support A/D bit, so we should not set those bit when build shadow page table. Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Nadav Har'El authored
This is the first patch in a series which adds nested EPT support to KVM's nested VMX. Nested EPT means emulating EPT for an L1 guest so that L1 can use EPT when running a nested guest L2. When L1 uses EPT, it allows the L2 guest to set its own cr3 and take its own page faults without either of L0 or L1 getting involved. This often significanlty improves L2's performance over the previous two alternatives (shadow page tables over EPT, and shadow page tables over shadow page tables). This patch adds EPT support to paging_tmpl.h. paging_tmpl.h contains the code for reading and writing page tables. The code for 32-bit and 64-bit tables is very similar, but not identical, so paging_tmpl.h is #include'd twice in mmu.c, once with PTTTYPE=32 and once with PTTYPE=64, and this generates the two sets of similar functions. There are subtle but important differences between the format of EPT tables and that of ordinary x86 64-bit page tables, so for nested EPT we need a third set of functions to read the guest EPT table and to write the shadow EPT table. So this patch adds third PTTYPE, PTTYPE_EPT, which creates functions (prefixed with "EPT") which correctly read and write EPT tables. Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Nadav Har'El <nyh@il.ibm.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Gleb Natapov authored
Some guest paging modes do not support A/D bits. Add support for such modes in shadow page code. For such modes PT_GUEST_DIRTY_MASK, PT_GUEST_ACCESSED_MASK, PT_GUEST_DIRTY_SHIFT and PT_GUEST_ACCESSED_SHIFT should be set to zero. Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Gleb Natapov authored
This patch makes guest A/D bits definition to be dependable on paging mode, so when EPT support will be added it will be able to define them differently. Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Nadav Har'El authored
For preparation, we just move gpte_access(), prefetch_invalid_gpte(), s_rsvd_bits_set(), protect_clean_gpte() and is_dirty_gpte() from mmu.c to paging_tmpl.h. Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Nadav Har'El <nyh@il.ibm.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Nadav Har'El authored
kvm_set_cr3() attempts to check if the new cr3 is a valid guest physical address. The problem is that with nested EPT, cr3 is an *L2* physical address, not an L1 physical address as this test expects. As the comment above this test explains, it isn't necessary, and doesn't correspond to anything a real processor would do. So this patch removes it. Note that this wrong test could have also theoretically caused problems in nested NPT, not just in nested EPT. However, in practice, the problem was avoided: nested_svm_vmexit()/vmrun() do not call kvm_set_cr3 in the nested NPT case, and instead set the vmcb (and arch.cr3) directly, thus circumventing the problem. Additional potential calls to the buggy function are avoided in that we don't trap cr3 modifications when nested NPT is enabled. However, because in nested VMX we did want to use kvm_set_cr3() (as requested in Avi Kivity's review of the original nested VMX patches), we can't avoid this problem and need to fix it. Reviewed-by: Orit Wasserman <owasserm@redhat.com> Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Nadav Har'El <nyh@il.ibm.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Nadav Har'El authored
The existing code for handling cr3 and related VMCS fields during nested exit and entry wasn't correct in all cases: If L2 is allowed to control cr3 (and this is indeed the case in nested EPT), during nested exit we must copy the modified cr3 from vmcs02 to vmcs12, and we forgot to do so. This patch adds this copy. If L0 isn't controlling cr3 when running L2 (i.e., L0 is using EPT), and whoever does control cr3 (L1 or L2) is using PAE, the processor might have saved PDPTEs and we should also save them in vmcs12 (and restore later). Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Reviewed-by: Orit Wasserman <owasserm@redhat.com> Signed-off-by: Nadav Har'El <nyh@il.ibm.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Nadav Har'El authored
Recent KVM, since http://kerneltrap.org/mailarchive/linux-kvm/2010/5/2/6261577 switch the EFER MSR when EPT is used and the host and guest have different NX bits. So if we add support for nested EPT (L1 guest using EPT to run L2) and want to be able to run recent KVM as L1, we need to allow L1 to use this EFER switching feature. To do this EFER switching, KVM uses VM_ENTRY/EXIT_LOAD_IA32_EFER if available, and if it isn't, it uses the generic VM_ENTRY/EXIT_MSR_LOAD. This patch adds support for the former (the latter is still unsupported). Nested entry and exit emulation (prepare_vmcs_02 and load_vmcs12_host_state, respectively) already handled VM_ENTRY/EXIT_LOAD_IA32_EFER correctly. So all that's left to do in this patch is to properly advertise this feature to L1. Note that vmcs12's VM_ENTRY/EXIT_LOAD_IA32_EFER are emulated by L0, by using vmx_set_efer (which itself sets one of several vmcs02 fields), so we always support this feature, regardless of whether the host supports it. Reviewed-by: Orit Wasserman <owasserm@redhat.com> Signed-off-by: Nadav Har'El <nyh@il.ibm.com> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Xiao Guangrong authored
Current code always uses arch.mmu to check the reserved bits on guest gpte which is valid only for L1 guest, we should use arch.nested_mmu instead when we translate gva to gpa for the L2 guest Fix it by using @mmu instead since it is adapted to the current mmu mode automatically The bug can be triggered when nested npt is used and L1 guest and L2 guest use different mmu mode Reported-by: Jan Kiszka <jan.kiszka@siemens.com> Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Gleb Natapov authored
After commit 21feb4eb tr base is zeroed during vmexit. Set it to L1's HOST_TR_BASE. This should fix https://bugzilla.kernel.org/show_bug.cgi?id=60679Reported-by: Yongjie Ren <yongjie.ren@intel.com> Reviewed-by: Arthur Chunqi Li <yzt356@gmail.com> Tested-by: Yongjie Ren <yongjie.ren@intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 29 Jul, 2013 11 commits
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Gleb Natapov authored
During nested vmentry into vm86 mode a vcpu state is found to be incorrect because rflags does not have VM flag set since it is read from the cache and has L1's value instead of L2's. If emulate_invalid_guest_state=1 L0 KVM tries to emulate it, but emulation does not work for nVMX and it never should happen anyway. Fix that by using vmx_set_rflags() to set rflags during nested vmentry which takes care of updating register cache. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Dominik Dingel authored
Current common code uses PAGE_OFFSET to indicate a bad host virtual address. As this check won't work on architectures that don't map kernel and user memory into the same address space (e.g. s390), such architectures can now provide their own KVM_HVA_ERR_BAD defines. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Thomas Huth authored
Introduced a helper function for setting the CC in the guest PSW to improve the readability of the code. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Thomas Huth authored
sparse complained about the missing UL postfix for long constants. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Michael Mueller authored
The patch renames the array holding the HW facility bitmaps. This allows to interprete the variable as set of virtual machine specific "virtual" facilities. The basic idea is to make virtual facilities externally managable in future. An availability test for virtual facilites has been added as well. Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Martin Schwidefsky authored
The gmap_map_segment function uses PGDIR_SIZE in the check for the maximum address in the tasks address space. This incorrectly limits the amount of memory usable for a kvm guest to 4TB. The correct limit is (1UL << 53). As the TASK_SIZE has different values (4TB vs 8PB) dependent on the existance of the fourth page table level, create a new define 'TASK_MAX_SIZE' for (1UL << 53). Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Martin Schwidefsky authored
Improve the code to upgrade the standard 2K page tables to 4K page tables with PGSTEs to allow the operation to happen when the program is already multi-threaded. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini authored
This lets debugging work better during emulation of invalid guest state. This time the check is done after emulation, but before writeback of the flags; we need to check the flags *before* execution of the instruction, we cannot check singlestep_rip because the CS base may have already been modified. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Conflicts: arch/x86/kvm/x86.c
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Paolo Bonzini authored
This lets debugging work better during emulation of invalid guest state. The check is done before emulating the instruction, and (in the case of guest debugging) reuses EMULATE_DO_MMIO to exit with KVM_EXIT_DEBUG. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini authored
The next patch will reuse it for other userspace exits than MMIO, namely debug events. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini authored
kvm_io_bus_sort_cmp is used also directly, not just as a callback for sort and bsearch. In these cases, it is handy to have a type-safe variant. This patch introduces such a variant, __kvm_io_bus_sort_cmp, and uses it throughout kvm_main.c. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 25 Jul, 2013 2 commits
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Jan Kiszka authored
Both have no users anymore. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Jan Kiszka authored
If posted interrupts are enabled, we can no longer track if an IRQ was coalesced based on IRR. So drop this logic also from the classic software path and simplify apic_test_and_set_irr to apic_set_irr. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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- 19 Jul, 2013 1 commit
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Andi Kleen authored
[KVM maintainers: The underlying support for this is in perf/core now. So please merge this patch into the KVM tree.] This is not arch perfmon, but older CPUs will just ignore it. This makes it possible to do at least some TSX measurements from a KVM guest v2: Various fixes to address review feedback v3: Ignore the bits when no CPUID. No #GP. Force raw events with TSX bits. v4: Use reserved bits for #GP v5: Remove obsolete argument Acked-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 18 Jul, 2013 12 commits
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Arthur Chunqi Li authored
When L2 exits to L1, segment infomations of L1 are not set correctly. According to Intel SDM 27.5.2(Loading Host Segment and Descriptor Table Registers), segment base/limit/access right of L1 should be set to some designed value when L2 exits to L1. This patch fixes this. Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com> Reviewed-by: Gleb Natapov <gnatapov@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Marcelo Tosatti authored
Linux as a guest on KVM hypervisor, the only user of the pvclock vsyscall interface, does not require notification on task migration because: 1. cpu ID number maps 1:1 to per-CPU pvclock time info. 2. per-CPU pvclock time info is updated if the underlying CPU changes. 3. that version is increased whenever underlying CPU changes. Which is sufficient to guarantee nanoseconds counter is calculated properly. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Nadav Har'El authored
Fix read/write to IA32_FEATURE_CONTROL MSR in nested environment. This patch simulate this MSR in nested_vmx and the default value is 0x0. BIOS should set it to 0x5 before VMXON. After setting the lock bit, write to it will cause #GP(0). Another QEMU patch is also needed to handle emulation of reset and migration. Reset to vCPU should clear this MSR and migration should reserve value of it. This patch is based on Nadav's previous commit. http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/88478Signed-off-by: Nadav Har'El <nyh@math.technion.ac.il> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Mathias Krause authored
Void pointers don't need no casting, drop it. Signed-off-by: Mathias Krause <minipli@googlemail.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Mathias Krause authored
Use a const pointer type instead of casting away the const qualifier from const arrays. Keep the pointer array on the stack, nonetheless. Making it static just increases the object size. Signed-off-by: Mathias Krause <minipli@googlemail.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Arthur Chunqi Li authored
Set rflags after successfully emulateing VMXON/VMXOFF in VMX. Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Arthur Chunqi Li authored
Move nested_vmx_succeed/nested_vmx_failInvalid/nested_vmx_failValid ahead of handle_vmon to eliminate double declaration in the same file Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Takuya Yoshikawa authored
Now that kvm_arch_memslots_updated() catches every increment of the memslots->generation, checking if the mmio generation has reached its maximum value is enough. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Takuya Yoshikawa authored
This is called right after the memslots is updated, i.e. when the result of update_memslots() gets installed in install_new_memslots(). Since the memslots needs to be updated twice when we delete or move a memslot, kvm_arch_commit_memory_region() does not correspond to this exactly. In the following patch, x86 will use this new API to check if the mmio generation has reached its maximum value, in which case mmio sptes need to be flushed out. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Acked-by: Alexander Graf <agraf@suse.de> Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Cornelia Huck authored
Make use of cookies for the virtio ccw notification hypercall to speed up lookup of devices on the io bus. Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> [Small fix to a comment. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Cornelia Huck authored
Add new functions kvm_io_bus_{read,write}_cookie() that allows users of the kvm io infrastructure to use a cookie value to speed up lookup of a device on an io bus. Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
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Xiao Guangrong authored
Currently, fast page fault incorrectly tries to fix mmio page fault when the generation number is invalid (spte.gen != kvm.gen). It then returns to guest to retry the fault since it sees the last spte is nonpresent. This causes an infinite loop. Since fast page fault only works for direct mmu, the issue exists when 1) tdp is enabled. It is only triggered only on AMD host since on Intel host the mmio page fault is recognized as ept-misconfig whose handler call fault-page path with error_code = 0 2) guest paging is disabled. Under this case, the issue is hardly discovered since paging disable is short-lived and the sptes will be invalid after memslot changed for 150 times Fix it by filtering out MMIO page faults in page_fault_can_be_fast. Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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- 14 Jul, 2013 3 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linuxLinus Torvalds authored
Pull slab update from Pekka Enberg: "Highlights: - Fix for boot-time problems on some architectures due to init_lock_keys() not respecting kmalloc_caches boundaries (Christoph Lameter) - CONFIG_SLUB_CPU_PARTIAL requested by RT folks (Joonsoo Kim) - Fix for excessive slab freelist draining (Wanpeng Li) - SLUB and SLOB cleanups and fixes (various people)" I ended up editing the branch, and this avoids two commits at the end that were immediately reverted, and I instead just applied the oneliner fix in between myself. * 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux slub: Check for page NULL before doing the node_match check mm/slab: Give s_next and s_stop slab-specific names slob: Check for NULL pointer before calling ctor() slub: Make cpu partial slab support configurable slab: add kmalloc() to kernel API documentation slab: fix init_lock_keys slob: use DIV_ROUND_UP where possible slub: do not put a slab to cpu partial list when cpu_partial is 0 mm/slub: Use node_nr_slabs and node_nr_objs in get_slabinfo mm/slub: Drop unnecessary nr_partials mm/slab: Fix /proc/slabinfo unwriteable for slab mm/slab: Sharing s_next and s_stop between slab and slub mm/slab: Fix drain freelist excessively slob: Rework #ifdeffery in slab.h mm, slab: moved kmem_cache_alloc_node comment to correct place
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Steven Rostedt authored
In the -rt kernel (mrg), we hit the following dump: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff811573f1>] kmem_cache_alloc_node+0x51/0x180 PGD a2d39067 PUD b1641067 PMD 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: sunrpc cpufreq_ondemand ipv6 tg3 joydev sg serio_raw pcspkr k8temp amd64_edac_mod edac_core i2c_piix4 e100 mii shpchp ext4 mbcache jbd2 sd_mod crc_t10dif sr_mod cdrom sata_svw ata_generic pata_acpi pata_serverworks radeon ttm drm_kms_helper drm hwmon i2c_algo_bit i2c_core dm_mirror dm_region_hash dm_log dm_mod CPU 3 Pid: 20878, comm: hackbench Not tainted 3.6.11-rt25.14.el6rt.x86_64 #1 empty empty/Tyan Transport GT24-B3992 RIP: 0010:[<ffffffff811573f1>] [<ffffffff811573f1>] kmem_cache_alloc_node+0x51/0x180 RSP: 0018:ffff8800a9b17d70 EFLAGS: 00010213 RAX: 0000000000000000 RBX: 0000000001200011 RCX: ffff8800a06d8000 RDX: 0000000004d92a03 RSI: 00000000000000d0 RDI: ffff88013b805500 RBP: ffff8800a9b17dc0 R08: ffff88023fd14d10 R09: ffffffff81041cbd R10: 00007f4e3f06e9d0 R11: 0000000000000246 R12: ffff88013b805500 R13: ffff8801ff46af40 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f4e3f06e700(0000) GS:ffff88023fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 00000000a2d3a000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process hackbench (pid: 20878, threadinfo ffff8800a9b16000, task ffff8800a06d8000) Stack: ffff8800a9b17da0 ffffffff81202e08 ffff8800a9b17de0 000000d001200011 0000000001200011 0000000001200011 0000000000000000 0000000000000000 00007f4e3f06e9d0 0000000000000000 ffff8800a9b17e60 ffffffff81041cbd Call Trace: [<ffffffff81202e08>] ? current_has_perm+0x68/0x80 [<ffffffff81041cbd>] copy_process+0xdd/0x15b0 [<ffffffff810a2125>] ? rt_up_read+0x25/0x30 [<ffffffff8104369a>] do_fork+0x5a/0x360 [<ffffffff8107c66b>] ? migrate_enable+0xeb/0x220 [<ffffffff8100b068>] sys_clone+0x28/0x30 [<ffffffff81527423>] stub_clone+0x13/0x20 [<ffffffff81527152>] ? system_call_fastpath+0x16/0x1b Code: 89 fc 89 75 cc 41 89 d6 4d 8b 04 24 65 4c 03 04 25 48 ae 00 00 49 8b 50 08 4d 8b 28 49 8b 40 10 4d 85 ed 74 12 41 83 fe ff 74 27 <48> 8b 00 48 c1 e8 3a 41 39 c6 74 1b 8b 75 cc 4c 89 c9 44 89 f2 RIP [<ffffffff811573f1>] kmem_cache_alloc_node+0x51/0x180 RSP <ffff8800a9b17d70> CR2: 0000000000000000 ---[ end trace 0000000000000002 ]--- Now, this uses SLUB pretty much unmodified, but as it is the -rt kernel with CONFIG_PREEMPT_RT set, spinlocks are mutexes, although they do disable migration. But the SLUB code is relatively lockless, and the spin_locks there are raw_spin_locks (not converted to mutexes), thus I believe this bug can happen in mainline without -rt features. The -rt patch is just good at triggering mainline bugs ;-) Anyway, looking at where this crashed, it seems that the page variable can be NULL when passed to the node_match() function (which does not check if it is NULL). When this happens we get the above panic. As page is only used in slab_alloc() to check if the node matches, if it's NULL I'm assuming that we can say it doesn't and call the __slab_alloc() code. Is this a correct assumption? Acked-by: Christoph Lameter <cl@linux.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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