- 20 5月, 2016 1 次提交
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由 Dave Hansen 提交于
This erratum essentially causes the CPU to forget which privilege level it is operating on (kernel vs. user) for the purposes of MPX. This erratum can only be triggered when a system is not using Supervisor Mode Execution Prevention (SMEP). Our workaround for the erratum is to ensure that MPX can only be used in cases where SMEP is present in the processor and is enabled. This erratum only affects Core processors. Atom is unaffected. But, there is no architectural way to determine Atom vs. Core. So, we just apply this workaround to all processors. It's possible that it will mistakenly disable MPX on some Atom processsors or future unaffected Core processors. There are currently no processors that have MPX and not SMEP. It would take something akin to a hypervisor masking SMEP out on an Atom processor for this to present itself on current hardware. More details can be found at: http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/desktop-6th-gen-core-family-spec-update.pdf " SKD046 Branch Instructions May Initialize MPX Bound Registers Incorrectly Problem: Depending on the current Intel MPX (Memory Protection Extensions) configuration, execution of certain branch instructions (near CALL, near RET, near JMP, and Jcc instructions) without a BND prefix (F2H) initialize the MPX bound registers. Due to this erratum, such a branch instruction that is executed both with CPL = 3 and with CPL < 3 may not use the correct MPX configuration register (BNDCFGU or BNDCFGS, respectively) for determining whether to initialize the bound registers; it may thus initialize the bound registers when it should not, or fail to initialize them when it should. Implication: A branch instruction that has executed both in user mode and in supervisor mode (from the same linear address) may cause a #BR (bound range fault) when it should not have or may not cause a #BR when it should have. Workaround An operating system can avoid this erratum by setting CR4.SMEP[bit 20] to enable supervisor-mode execution prevention (SMEP). When SMEP is enabled, no code can be executed both with CPL = 3 and with CPL < 3. " Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160512220400.3B35F1BC@viggo.jf.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 19 5月, 2016 1 次提交
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由 Josh Poimboeuf 提交于
With CONFIG_FRAME_POINTER enabled, a thunk can pass a bad return address value to the called function. '9*8(%rsp)' actually gets the frame pointer, not the return address. The only users of the 'put_ret_addr_in_rdi' option are two functions which trace the enabling and disabling of interrupts, so this bug can result in bad debug or tracing information with CONFIG_IRQSOFF_TRACER or CONFIG_PROVE_LOCKING. Fix this by implementing the suggestion of Linus: explicitly push the frame pointer all the time and constify the stack offsets that way. This is both correct and easier to read. Reported-by: NMatt Fleming <matt@codeblueprint.co.uk> Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com> [ Extended the changelog a bit. ] Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Alex Thorlton <athorlton@sgi.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 058fb732 ("x86/asm/entry: Create stack frames in thunk functions") Link: http://lkml.kernel.org/r/20160517180606.v5o7wcgdni7443ol@trebleSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 17 5月, 2016 1 次提交
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由 Linus Torvalds 提交于
Alex Thorlton reported that the SGI/UV code crashes in the efi_call() code when invoked with 7 parameters, due to: mov (%rsp), %rax mov 8(%rax), %rax ... mov %rax, 40(%rsp) Offset 8 is only true if CONFIG_FRAME_POINTERS is disabled, with frame pointers enabled it should be 16. Furthermore, the SAVE_XMM code saves the old stack pointer, but that's just crazy. It saves the stack pointer *AFTER* we've done the: FRAME_BEGIN ... which will have *changed* the stack pointer, depending on whether stack frames are enabled or not. So when the code then does: mov (%rsp), %rax ... we now move that old stack pointer into %rax, but the offset off that stack pointer will depend on whether that FRAME_BEGIN saved off %rbp or not. So that whole 8-vs-16 offset confusion depends on the frame pointer! If frame pointers were enabled, it will be 16. If they weren't, it will be 8. The right fix is to just get rid of that silly conditional frame pointer thing, and always use frame pointers in this stub function. And then we don't need that (odd) load to get the old stack pointer into %rax - we can just use the frame pointer. Reported-by: NAlex Thorlton <athorlton@sgi.com> Tested-by: NAlex Thorlton <athorlton@sgi.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/CA%2B55aFzBS2v%3DWnEH83cUDg7XkOremFqJ30BJwF40dCYjReBkUQ@mail.gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 16 5月, 2016 1 次提交
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由 Dave Hansen 提交于
When I added support for the Memory Protection Keys processor feature, I had to reindent the REQUIRED/DISABLED_MASK macros, and also consult the later cpufeature words. I'm not quite sure how I bungled it, but I consulted the wrong word at the end. This only affected required or disabled cpu features in cpufeature words 14, 15 and 16. So, only Protection Keys itself was screwed over here. The result was that if you disabled pkeys in your .config, you might still see some code show up that should have been compiled out. There should be no functional problems, though. In verifying this patch I also realized that the DISABLE_PKU/OSPKE macros were defined backwards and that the cpu_has() check in setup_pku() was not doing the compile-time disabled checks. So also fix the macro for DISABLE_PKU/OSPKE and add a compile-time check for pkeys being enabled in setup_pku(). Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Dave Hansen <dave@sr71.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Fixes: dfb4a70f ("x86/cpufeature, x86/mm/pkeys: Add protection keys related CPUID definitions") Link: http://lkml.kernel.org/r/20160513221328.C200930B@viggo.jf.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 12 5月, 2016 3 次提交
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由 Jeremy Compostella 提交于
Intel Cherrytrail is based on Airmont core so MSR_FSB_FREQ[2:0] = 4 means that the CPU reference clock runs at 80MHz. Add this missing frequency to the table. Signed-off-by: NJeremy Compostella <jeremy.compostella@intel.com> Link: http://lkml.kernel.org/r/87y47gty89.fsf@intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Dmitry V. Levin 提交于
Similar to preadv and pwritev, preadv2 and pwritev2 need compat entries in the 32-bit syscall table. This bug was found by strace test suite. Fixes: 4babf2c5 ("x86: wire up preadv2 and pwritev2") Signed-off-by: NDmitry V. Levin <ldv@altlinux.org> Acked-by: NChristoph Hellwig <hch@lst.de> Link: http://lkml.kernel.org/r/20160511084817.GA29823@altlinux.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Mathias Krause 提交于
The x86 exception table sorting was changed in commit 29934b0f ("x86/extable: use generic search and sort routines") to use the arch independent code in lib/extable.c. However, the patch was mangled somehow on its way into the kernel from the last version posted at [1]. The committed version kind of attempted to incorporate the changes of commit 548acf19 ("x86/mm: Expand the exception table logic to allow new handling options") as in _completely_ _ignoring_ the x86 specific 'handler' member of struct exception_table_entry. This effectively broke the sorting as entries will only partly be swapped now. Fortunately, the x86 Kconfig selects BUILDTIME_EXTABLE_SORT, so the exception table doesn't need to be sorted at runtime. However, in case that ever changes, we better not break the exception table sorting just because of that. [ Ard Biesheuvel points out that BUILDTIME_EXTABLE_SORT applies to the core image only, but we still rely on the sorting routines for modules in that case - Linus ] Fix this by providing a swap_ex_entry_fixup() macro that takes care of the 'handler' member. [1] https://lkml.org/lkml/2016/1/27/232Signed-off-by: NMathias Krause <minipli@googlemail.com> Fixes: 29934b0f ("x86/extable: use generic search and sort routines") Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 11 5月, 2016 2 次提交
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由 Andrey Utkin 提交于
"make defconfig kvmconfig" is supposed to end up with usable kernel for KVM guest. In practice, it won't work for e.g. Hetzner VPS (KVM-based) unless you add these options. Signed-off-by: NAndrey Utkin <andrey_utkin@fastmail.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Josh Poimboeuf 提交于
The kbuild test robot reported this objtool warning [1]: arch/x86/kvm/emulate.o: warning: objtool: fastop()+0x69: call without frame pointer save/setup The issue seems to be caused by CONFIG_PROFILE_ALL_BRANCHES. With that option, for some reason gcc decides not to create a stack frame in fastop() before doing the inline asm call, which can result in a bad stack trace. Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement. This change has no effect for !CONFIG_PROFILE_ALL_BRANCHES. [1] https://lists.01.org/pipermail/kbuild-all/2016-March/018249.htmlReported-by: Nkbuild test robot <fengguang.wu@intel.com> Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com> Acked-by: NIngo Molnar <mingo@kernel.org> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 10 5月, 2016 1 次提交
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由 Thomas Gleixner 提交于
Josef reported that the uncore driver trips over with CONFIG_SMP=n because x86_max_cores is 16 instead of 12. The reason is, that for SMP=n the extended topology detection is a NOOP and the cache leaf is used to determine the number of cores. That's wrong in two aspects: 1) The cache leaf enumerates the maximum addressable number of cores in the package, which is obviously not correct 2) UP has no business with topology bits at all. Make intel_num_cpu_cores() return 1 for CONFIG_SMP=n Reported-by: NJosef Bacik <jbacik@fb.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: kernel-team <Kernel-team@fb.com> Cc: Kan Liang <kan.liang@intel.com> Link: http://lkml.kernel.org/r/761b4a2a-0332-7954-f030-c6639f949612@fb.com
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- 07 5月, 2016 1 次提交
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由 Thomas Gleixner 提交于
Joseph reported that a XEN guest dies with a division by 0 in the package topology setup code. This happens if cpu_info.x86_max_cores is zero. Handle that case and emit a warning. This does not fix the underlying XEN bug, but makes the code more robust. Reported-and-tested-by: NJoseph Salisbury <joseph.salisbury@canonical.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1605062046270.3540@nanosSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 06 5月, 2016 2 次提交
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由 Chen Yu 提交于
Currently we read the tsc radio: ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f; Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the SDM (35.5), the ratio bits are bit 8-15. Ignoring the upper bits can result in an incorrect tsc ratio, which causes the TSC calibration and the Local APIC timer frequency to be incorrect. Fix this problem by masking 0xff instead. [ tglx: Massaged changelog ] Fixes: 7da7c156 "x86, tsc: Add static (MSR) TSC calibration on Intel Atom SoCs" Signed-off-by: NChen Yu <yu.c.chen@intel.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: stable@vger.kernel.org Cc: Bin Gao <bin.gao@intel.com> Cc: Len Brown <lenb@kernel.org> Link: http://lkml.kernel.org/r/1462505619-5516-1-git-send-email-yu.c.chen@intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Andrea Arcangeli 提交于
After the THP refcounting change, obtaining a compound pages from get_user_pages() no longer allows us to assume the entire compound page is immediately mappable from a secondary MMU. A secondary MMU doesn't want to call get_user_pages() more than once for each compound page, in order to know if it can map the whole compound page. So a secondary MMU needs to know from a single get_user_pages() invocation when it can map immediately the entire compound page to avoid a flood of unnecessary secondary MMU faults and spurious atomic_inc()/atomic_dec() (pages don't have to be pinned by MMU notifier users). Ideally instead of the page->_mapcount < 1 check, get_user_pages() should return the granularity of the "page" mapping in the "mm" passed to get_user_pages(). However it's non trivial change to pass the "pmd" status belonging to the "mm" walked by get_user_pages up the stack (up to the caller of get_user_pages). So the fix just checks if there is not a single pte mapping on the page returned by get_user_pages, and in turn if the caller can assume that the whole compound page is mapped in the current "mm" (in a pmd_trans_huge()). In such case the entire compound page is safe to map into the secondary MMU without additional get_user_pages() calls on the surrounding tail/head pages. In addition of being faster, not having to run other get_user_pages() calls also reduces the memory footprint of the secondary MMU fault in case the pmd split happened as result of memory pressure. Without this fix after a MADV_DONTNEED (like invoked by QEMU during postcopy live migration or balloning) or after generic swapping (with a failure in split_huge_page() that would only result in pmd splitting and not a physical page split), KVM would map the whole compound page into the shadow pagetables, despite regular faults or userfaults (like UFFDIO_COPY) may map regular pages into the primary MMU as result of the pte faults, leading to the guest mode and userland mode going out of sync and not working on the same memory at all times. Any other secondary MMU notifier manager (KVM is just one of the many MMU notifier users) will need the same information if it doesn't want to run a flood of get_user_pages_fast and it can support multiple granularity in the secondary MMU mappings, so I think it is justified to be exposed not just to KVM. The other option would be to move transparent_hugepage_adjust to mm/huge_memory.c but that currently has all kind of KVM data structures in it, so it's definitely not a cut-and-paste work, so I couldn't do a fix as cleaner as this one for 4.6. Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: "Li, Liang Z" <liang.z.li@intel.com> Cc: Amit Shah <amit.shah@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 05 5月, 2016 4 次提交
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由 Wang YanQing 提交于
The code for checking whether a BAR address range is valid will break out of the loop when a start address of 0x0 is encountered. This behaviour is wrong since by breaking out of the loop we may miss the BAR that describes the EFI frame buffer in a later iteration. Because of this bug I can't use video=efifb: boot parameter to get efifb on my new ThinkPad E550 for my old linux system hard disk with 3.10 kernel. In 3.10, efifb is the only choice due to DRM/I915 not supporting the GPU. This patch also add a trivial optimization to break out after we find the frame buffer address range without testing later BARs. Signed-off-by: NWang YanQing <udknight@gmail.com> [ Rewrote changelog. ] Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk> Reviewed-by: NPeter Jones <pjones@redhat.com> Cc: <stable@vger.kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: David Herrmann <dh.herrmann@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1462454061-21561-2-git-send-email-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Peter Zijlstra 提交于
The new sanity check introduced by: 26657848 ("perf/core: Verify we have a single perf_hw_context PMU") ... triggered on the AMD IOMMU driver. IOMMUs are not per logical CPU, they cannot have per-task counters. Fix it. Reported-by: NBorislav Petkov <bp@alien8.de> Tested-by: NBorislav Petkov <bp@suse.de> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: jroedel@suse.de Cc: suravee.suthikulpanit@amd.com Link: http://lkml.kernel.org/r/20160423224255.GB3430@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Alex Thorlton 提交于
A while back the following commit: d394f2d9 ("x86/platform/UV: Remove EFI memmap quirk for UV2+") changed uv_system_init() to only call map_low_mmrs() on older UV1 hardware, which requires EFI_OLD_MEMMAP to be set in order to boot. The recent changes to the EFI memory mapping code in: d2f7cbe7 ("x86/efi: Runtime services virtual mapping") exposed some issues with the fact that we were relying on the EFI memory mapping mechanisms to map in our MMRs for us, after commit d394f2d9. Rather than revert the entire commit and go back to forcing EFI_OLD_MEMMAP on all UVs, we're going to add the call to map_low_mmrs() back into uv_system_init(), and then fix up our EFI runtime calls to use the appropriate page table. For now, UV2+ will still need efi=old_map to boot, but there will be other changes soon that should eliminate the need for this. Signed-off-by: NAlex Thorlton <athorlton@sgi.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Adam Buchbinder <adam.buchbinder@gmail.com> Cc: Len Brown <len.brown@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Russ Anderson <rja@sgi.com> Cc: Dimitri Sivanich <sivanich@sgi.com> Link: http://lkml.kernel.org/r/1462401592-120735-1-git-send-email-athorlton@sgi.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Andi Kleen 提交于
Everything the same as Skylake, just new model numbers. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1461977748-17616-1-git-send-email-andi@firstfloor.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 04 5月, 2016 1 次提交
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由 Josh Boyer 提交于
The promise of pretty boot splashes from firmware via BGRT was at best only that; a promise. The kernel diligently checks to make sure the BGRT data firmware gives it is valid, and dutifully warns the user when it isn't. However, it does so via the pr_err log level which seems unnecessary. The user cannot do anything about this and there really isn't an error on the part of Linux to correct. This lowers the log level by using pr_notice instead. Users will no longer have their boot process uglified by the kernel reminding us that firmware can and often is broken when the 'quiet' kernel parameter is specified. Ironic, considering BGRT is supposed to make boot pretty to begin with. Signed-off-by: NJosh Boyer <jwboyer@fedoraproject.org> Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk> Reviewed-by: NJosh Triplett <josh@joshtriplett.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Môshe van der Sterre <me@moshe.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1462303781-8686-4-git-send-email-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 28 4月, 2016 4 次提交
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由 Kan Liang 提交于
This patch fixes a bug which was introduced by: b16a5b52 ("perf/x86: Add option to disable reading branch flags/cycles") In this patch, lbr_sel_mask is used to mask the lbr_select. But LBR_SEL_MASK doesn't include the bit for LBR_CALL_STACK. So LBR call stack will never be set in lbr_select. This patch corrects the LBR_SEL_MASK by including all valid bits in LBR_SELECT. Also, the LBR_CALL_STACK bit is different as other bit in LBR_SELECT. It does not operate in suppress mode, so it needs to be specially handled in intel_pmu_setup_hw_lbr_filter. Signed-off-by: NKan Liang <kan.liang@intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/1461231010-4399-1-git-send-email-kan.liang@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Alexander Shishkin 提交于
Some versions of Intel PT do not support tracing across VMXON, more specifically, VMXON will clear TraceEn control bit and any attempt to set it before VMXOFF will throw a #GP, which in the current state of things will crash the kernel. Namely: $ perf record -e intel_pt// kvm -nographic on such a machine will kill it. To avoid this, notify the intel_pt driver before VMXON and after VMXOFF so that it knows when not to enable itself. Signed-off-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Gleb Natapov <gleb@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: hpa@zytor.com Link: http://lkml.kernel.org/r/87oa9dwrfk.fsf@ashishki-desk.ger.corp.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Adam Borowski 提交于
The entry for PERF_COUNT_HW_REF_CPU_CYCLES is not used on AMD, but is referenced by filter_events() which expects undefined events to have a value of 0. Found via KASAN: UBSAN: Undefined behaviour in arch/x86/events/amd/core.c:132:30 index 9 is out of range for type 'u64 [9]' UBSAN: Undefined behaviour in arch/x86/events/amd/core.c:132:9 load of address ffffffff81c021c8 with insufficient space for an object of type 'const u64' Signed-off-by: NAdam Borowski <kilobyte@angband.pl> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/1461749731-30979-1-git-send-email-kilobyte@angband.plSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Keith Busch 提交于
If x86_vector_alloc_irq() fails x86_vector_free_irqs() is invoked to cleanup the already allocated vectors. This subsequently calls clear_vector_irq(). The failed irq has no vector assigned, which triggers the BUG_ON(!vector) in clear_vector_irq(). We cannot suppress the call to x86_vector_free_irqs() for the failed interrupt, because the other data related to this irq must be cleaned up as well. So calling clear_vector_irq() with vector == 0 is legitimate. Remove the BUG_ON and return if vector is zero, [ tglx: Massaged changelog ] Fixes: b5dc8e6c "x86/irq: Use hierarchical irqdomain to manage CPU interrupt vectors" Signed-off-by: NKeith Busch <keith.busch@intel.com> Cc: stable@vger.kernel.org Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 27 4月, 2016 1 次提交
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由 Andy Lutomirski 提交于
This reverts commit 320d25b6. This change was problematic for a couple of reasons: 1. It missed a some entry points (Xen things and 64-bit native). 2. The entry it changed can be executed more than once. This isn't really a problem, but it conflated per-cpu state setup and global state setup. 3. It broke 64-bit non-NX. 64-bit non-NX worked the other way around from 32-bit -- __supported_pte_mask had NX set initially and was *cleared* in x86_configure_nx. With the patch applied, it never got cleared. Reported-and-tested-by: NMeelis Roos <mroos@linux.ee> Signed-off-by: NAndy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/59bd15f7f4b56b633a611b7f70876c6d2ad01a98.1461685884.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 23 4月, 2016 3 次提交
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由 Srinivas Pandruvada 提交于
Added one missing Haswell model. Signed-off-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: bp@alien8.de Cc: hpa@zytor.com Link: http://lkml.kernel.org/r/1460907809-11897-1-git-send-email-srinivas.pandruvada@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Andi Kleen 提交于
Everything the same as base Skylake, just a new model number. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/1460751933-2264-1-git-send-email-andi@firstfloor.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Ross Lagerwall 提交于
The following commit: 1fb3a8b2 ("xen/spinlock: Fix locking path engaging too soon under PVHVM.") ... moved the initalization of the kicker interrupt until after native_cpu_up() is called. However, when using qspinlocks, a CPU may try to kick another CPU that is spinning (because it has not yet initialized its kicker interrupt), resulting in the following crash during boot: kernel BUG at /build/linux-Ay7j_C/linux-4.4.0/drivers/xen/events/events_base.c:1210! invalid opcode: 0000 [#1] SMP ... RIP: 0010:[<ffffffff814c97c9>] [<ffffffff814c97c9>] xen_send_IPI_one+0x59/0x60 ... Call Trace: [<ffffffff8102be9e>] xen_qlock_kick+0xe/0x10 [<ffffffff810cabc2>] __pv_queued_spin_unlock+0xb2/0xf0 [<ffffffff810ca6d1>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20 [<ffffffff81052936>] ? check_tsc_warp+0x76/0x150 [<ffffffff81052aa6>] check_tsc_sync_source+0x96/0x160 [<ffffffff81051e28>] native_cpu_up+0x3d8/0x9f0 [<ffffffff8102b315>] xen_hvm_cpu_up+0x35/0x80 [<ffffffff8108198c>] _cpu_up+0x13c/0x180 [<ffffffff81081a4a>] cpu_up+0x7a/0xa0 [<ffffffff81f80dfc>] smp_init+0x7f/0x81 [<ffffffff81f5a121>] kernel_init_freeable+0xef/0x212 [<ffffffff81817f30>] ? rest_init+0x80/0x80 [<ffffffff81817f3e>] kernel_init+0xe/0xe0 [<ffffffff8182488f>] ret_from_fork+0x3f/0x70 [<ffffffff81817f30>] ? rest_init+0x80/0x80 To fix this, only send the kick if the target CPU's interrupt has been initialized. This check isn't racy, because the target is waiting for the spinlock, so it won't have initialized the interrupt in the meantime. Signed-off-by: NRoss Lagerwall <ross.lagerwall@citrix.com> Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Cc: xen-devel@lists.xenproject.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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- 22 4月, 2016 1 次提交
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由 Jan Beulich 提交于
Huge pages are not normally available to PV guests. Not suppressing hugetlbfs use results in an endless loop of page faults when user mode code tries to access a hugetlbfs mapped area (since the hypervisor denies such PTEs to be created, but error indications can't be propagated out of xen_set_pte_at(), just like for various of its siblings), and - once killed in an oops like this: kernel BUG at .../fs/hugetlbfs/inode.c:428! invalid opcode: 0000 [#1] SMP ... RIP: e030:[<ffffffff811c333b>] [<ffffffff811c333b>] remove_inode_hugepages+0x25b/0x320 ... Call Trace: [<ffffffff811c3415>] hugetlbfs_evict_inode+0x15/0x40 [<ffffffff81167b3d>] evict+0xbd/0x1b0 [<ffffffff8116514a>] __dentry_kill+0x19a/0x1f0 [<ffffffff81165b0e>] dput+0x1fe/0x220 [<ffffffff81150535>] __fput+0x155/0x200 [<ffffffff81079fc0>] task_work_run+0x60/0xa0 [<ffffffff81063510>] do_exit+0x160/0x400 [<ffffffff810637eb>] do_group_exit+0x3b/0xa0 [<ffffffff8106e8bd>] get_signal+0x1ed/0x470 [<ffffffff8100f854>] do_signal+0x14/0x110 [<ffffffff810030e9>] prepare_exit_to_usermode+0xe9/0xf0 [<ffffffff814178a5>] retint_user+0x8/0x13 This is CVE-2016-3961 / XSA-174. Reported-by: NVitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: NJan Beulich <jbeulich@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Juergen Gross <JGross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Toshi Kani <toshi.kani@hp.com> Cc: stable@vger.kernel.org Cc: xen-devel <xen-devel@lists.xenproject.org> Link: http://lkml.kernel.org/r/57188ED802000078000E431C@prv-mh.provo.novell.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 16 4月, 2016 1 次提交
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由 Vitaly Kuznetsov 提交于
Generation2 instances don't support reporting the NMI status on port 0x61, read from there returns 'ff' and we end up reporting nonsensical PCI error (as there is no PCI bus in these instances) on all NMIs: NMI: PCI system error (SERR) for reason ff on CPU 0. Dazed and confused, but trying to continue Fix the issue by overriding x86_platform.get_nmi_reason. Use 'booted on EFI' flag to detect Gen2 instances. Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Cathy Avery <cavery@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: devel@linuxdriverproject.org Link: http://lkml.kernel.org/r/1460728232-31433-1-git-send-email-vkuznets@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 15 4月, 2016 2 次提交
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由 Xiaodong Liu 提交于
In sha_complete_job, incorrect mcryptd_hash_request_ctx pointer is used when check and complete other jobs. If the memory of first completed req is freed, while still completing other jobs in the func, kernel will crash since NULL pointer is assigned to RIP. Cc: <stable@vger.kernel.org> Signed-off-by: NXiaodong Liu <xiaodong.liu@intel.com> Acked-by: NTim Chen <tim.c.chen@linux.intel.com> Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
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由 Linus Torvalds 提交于
This reverts commit c4004b02. Sadly, my hope that nobody would actually use the special kernel entries in /proc/iomem were dashed by kexec. Which reads /proc/iomem explicitly to find the kernel base address. Nasty. Anyway, that means we can't do the sane and simple thing and just remove the entries, and we'll instead have to mask them out based on permissions. Reported-by: NZhengyu Zhang <zhezhang@redhat.com> Reported-by: NDave Young <dyoung@redhat.com> Reported-by: NFreeman Zhang <freeman.zhang1992@gmail.com> Reported-by: NEmrah Demir <ed@abdsec.com> Reported-by: NBaoquan He <bhe@redhat.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 13 4月, 2016 1 次提交
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由 Tony Luck 提交于
When we loop over all queued machine check error records to pass them to the registered notifiers we use llist_for_each_entry(). But the loop calls gen_pool_free() for the entry in the body of the loop - and then the iterator looks at node->next after the free. Use llist_for_each_entry_safe() instead. Signed-off-by: NTony Luck <tony.luck@intel.com> Signed-off-by: NBorislav Petkov <bp@suse.de> Cc: <stable@vger.kernel.org> Cc: Gong Chen <gong.chen@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-edac <linux-edac@vger.kernel.org> Link: http://lkml.kernel.org/r/0205920@agluck-desk.sc.intel.com Link: http://lkml.kernel.org/r/1459929916-12852-4-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
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- 11 4月, 2016 3 次提交
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由 Paolo Bonzini 提交于
This ensures that the guest doesn't see XSAVE extensions (e.g. xgetbv1 or xsavec) that the host lacks. Cc: stable@vger.kernel.org Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 David Matlack 提交于
An interrupt handler that uses the fpu can kill a KVM VM, if it runs under the following conditions: - the guest's xcr0 register is loaded on the cpu - the guest's fpu context is not loaded - the host is using eagerfpu Note that the guest's xcr0 register and fpu context are not loaded as part of the atomic world switch into "guest mode". They are loaded by KVM while the cpu is still in "host mode". Usage of the fpu in interrupt context is gated by irq_fpu_usable(). The interrupt handler will look something like this: if (irq_fpu_usable()) { kernel_fpu_begin(); [... code that uses the fpu ...] kernel_fpu_end(); } As long as the guest's fpu is not loaded and the host is using eager fpu, irq_fpu_usable() returns true (interrupted_kernel_fpu_idle() returns true). The interrupt handler proceeds to use the fpu with the guest's xcr0 live. kernel_fpu_begin() saves the current fpu context. If this uses XSAVE[OPT], it may leave the xsave area in an undesirable state. According to the SDM, during XSAVE bit i of XSTATE_BV is not modified if bit i is 0 in xcr0. So it's possible that XSTATE_BV[i] == 1 and xcr0[i] == 0 following an XSAVE. kernel_fpu_end() restores the fpu context. Now if any bit i in XSTATE_BV == 1 while xcr0[i] == 0, XRSTOR generates a #GP. The fault is trapped and SIGSEGV is delivered to the current process. Only pre-4.2 kernels appear to be vulnerable to this sequence of events. Commit 653f52c3 ("kvm,x86: load guest FPU context more eagerly") from 4.2 forces the guest's fpu to always be loaded on eagerfpu hosts. This patch fixes the bug by keeping the host's xcr0 loaded outside of the interrupts-disabled region where KVM switches into guest mode. Cc: stable@vger.kernel.org Suggested-by: NAndy Lutomirski <luto@amacapital.net> Signed-off-by: NDavid Matlack <dmatlack@google.com> [Move load after goto cancel_injection. - Paolo] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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由 Xiao Guangrong 提交于
kvm-unit-tests complained about the PFEC is not set properly, e.g,: test pte.rw pte.d pte.nx pde.p pde.rw pde.pse user fetch: FAIL: error code 15 expected 5 Dump mapping: address: 0x123400000000 ------L4: 3e95007 ------L3: 3e96007 ------L2: 2000083 It's caused by the reason that PFEC returned to guest is copied from the PFEC triggered by shadow page table This patch fixes it and makes the logic of updating errcode more clean Signed-off-by: NXiao Guangrong <guangrong.xiao@linux.intel.com> [Do not assume pfec.p=1. - Paolo] Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 08 4月, 2016 1 次提交
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由 Len Brown 提交于
Some processors use the Interrupt Response Time Limit (IRTL) MSR value to describe the maximum IRQ response time latency for deep package C-states. (Though others have the register, but do not use it) Lets print it out to give insight into the cases where it is used. IRTL begain in SNB, with PC3/PC6/PC7, and HSW added PC8/PC9/PC10. Signed-off-by: NLen Brown <len.brown@intel.com> Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
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- 07 4月, 2016 1 次提交
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由 Linus Torvalds 提交于
Let's see if anybody even notices. I doubt anybody uses this, and it does expose addresses that should be randomized, so let's just remove the code. It's old and traditional, and it used to be cute, but we should have removed this long ago. If it turns out anybody notices and this breaks something, we'll have to revert this, and maybe we'll end up using other approaches instead (using %pK or similar). But removing unnecessary code is always the preferred option. Noted-by: NEmrah Demir <ed@abdsec.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 05 4月, 2016 1 次提交
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由 Luiz Capitulino 提交于
When a vCPU runs on a nohz_full core, the hrtimer used by the lapic emulation code can be migrated to another core. When this happens, it's possible to observe milisecond latency when delivering timer IRQs to KVM guests. The huge latency is mainly due to the fact that apic_timer_fn() expects to run during a kvm exit. It sets KVM_REQ_PENDING_TIMER and let it be handled on kvm entry. However, if the timer fires on a different core, we have to wait until the next kvm exit for the guest to see KVM_REQ_PENDING_TIMER set. This problem became visible after commit 9642d18e. This commit changed the timer migration code to always attempt to migrate timers away from nohz_full cores. While it's discussable if this is correct/desirable (I don't think it is), it's clear that the lapic emulation code has a requirement on firing the hrtimer in the same core where it was started. This is achieved by making the hrtimer pinned. Lastly, note that KVM has code to migrate timers when a vCPU is scheduled to run in different core. However, this forced migration may fail. When this happens, we can have the same problem. If we want 100% correctness, we'll have to modify apic_timer_fn() to cause a kvm exit when it runs on a different core than the vCPU. Not sure if this is possible. Here's a reproducer for the issue being fixed: 1. Set all cores but core0 to be nohz_full cores 2. Start a guest with a single vCPU 3. Trace apic_timer_fn() and kvm_inject_apic_timer_irqs() You'll see that apic_timer_fn() will run in core0 while kvm_inject_apic_timer_irqs() runs in a different core. If you get both on core0, try running a program that takes 100% of the CPU and pin it to core0 to force the vCPU out. Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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- 02 4月, 2016 2 次提交
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由 Nadav Amit 提交于
The recently introduced batched invalidations mechanism uses its own mechanism for shootdown. However, it does wrong accounting of interrupts (e.g., inc_irq_stat is called for local invalidations), trace-points (e.g., TLB_REMOTE_SHOOTDOWN for local invalidations) and may break some platforms as it bypasses the invalidation mechanisms of Xen and SGI UV. This patch reuses the existing TLB flushing mechnaisms instead. We use NULL as mm to indicate a global invalidation is required. Fixes 72b252ae ("mm: send one IPI per CPU to TLB flush all entries after unmapping pages") Signed-off-by: NNadav Amit <namit@vmware.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Nadav Amit 提交于
TLB_REMOTE_SEND_IPI was recently introduced, but it counts bytes instead of pages. In addition, it does not report correctly the case in which flush_tlb_page flushes a page. Fix it to be consistent with other TLB counters. Fixes: 5b74283a ("x86, mm: trace when an IPI is about to be sent") Signed-off-by: NNadav Amit <namit@vmware.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 01 4月, 2016 1 次提交
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由 Yu Zhao 提交于
In absence of shadow dirty mask, there is no need to set page dirty if page has never been writable. This is a tiny optimization but good to have for people who care much about dirty page tracking. Signed-off-by: NYu Zhao <yuzhao@google.com> Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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