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  1. 05 8月, 2019 1 次提交
  3. 24 7月, 2019 2 次提交
    • W
      KVM: X86: Boost queue head vCPU to mitigate lock waiter preemption · 266e85a5
      由 Wanpeng Li 提交于 
      Commit 11752adb (locking/pvqspinlock: Implement hybrid PV queued/unfair locks)
introduces hybrid PV queued/unfair locks
 - queued mode (no starvation)
 - unfair mode (good performance on not heavily contended lock)
The lock waiter goes into the unfair mode especially in VMs with over-commit
vCPUs since increaing over-commitment increase the likehood that the queue
head vCPU may have been preempted and not actively spinning.

However, reschedule queue head vCPU timely to acquire the lock still can get
better performance than just depending on lock stealing in over-subscribe
scenario.

Testing on 80 HT 2 socket Xeon Skylake server, with 80 vCPUs VM 80GB RAM:
ebizzy -M
             vanilla     boosting    improved
 1VM          23520        25040         6%
 2VM           8000        13600        70%
 3VM           3100         5400        74%

The lock holder vCPU yields to the queue head vCPU when unlock, to boost queue
head vCPU which is involuntary preemption or the one which is voluntary halt
due to fail to acquire the lock after a short spin in the guest.

Cc: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      266e85a5
    • C
      Documentation: move Documentation/virtual to Documentation/virt · 2f5947df
      由 Christoph Hellwig 提交于 
      Renaming docs seems to be en vogue at the moment, so fix on of the
grossly misnamed directories.  We usually never use "virtual" as
a shortcut for virtualization in the kernel, but always virt,
as seen in the virt/ top-level directory.  Fix up the documentation
to match that.

Fixes: ed16648e ("Move kvm, uml, and lguest subdirectories under a common "virtual" directory, I.E:")
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      2f5947df
  5. 22 7月, 2019 5 次提交
  7. 20 7月, 2019 6 次提交
    • E
      KVM: x86: Add fixed counters to PMU filter · 30cd8604
      由 Eric Hankland 提交于 
      Updates KVM_CAP_PMU_EVENT_FILTER so it can also whitelist or blacklist
fixed counters.
Signed-off-by: NEric Hankland <ehankland@google.com>
[No need to check padding fields for zero. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      30cd8604
    • P
      KVM: nVMX: do not use dangling shadow VMCS after guest reset · 88dddc11
      由 Paolo Bonzini 提交于 
      If a KVM guest is reset while running a nested guest, free_nested will
disable the shadow VMCS execution control in the vmcs01.  However,
on the next KVM_RUN vmx_vcpu_run would nevertheless try to sync
the VMCS12 to the shadow VMCS which has since been freed.

This causes a vmptrld of a NULL pointer on my machime, but Jan reports
the host to hang altogether.  Let's see how much this trivial patch fixes.
Reported-by: NJan Kiszka <jan.kiszka@siemens.com>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      88dddc11
    • P
      KVM: VMX: dump VMCS on failed entry · 3b20e03a
      由 Paolo Bonzini 提交于 
      This is useful for debugging, and is ratelimited nowadays.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      3b20e03a
    • L
      KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed · 6fc3977c
      由 Like Xu 提交于 
      If a perf_event creation fails due to any reason of the host perf
subsystem, it has no chance to log the corresponding event for guest
which may cause abnormal sampling data in guest result. In debug mode,
this message helps to understand the state of vPMC and we may not
limit the number of occurrences but not in a spamming style.
Suggested-by: NJoe Perches <joe@perches.com>
Signed-off-by: NLike Xu <like.xu@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      6fc3977c
    • L
      KVM: SVM: Fix detection of AMD Errata 1096 · 118154bd
      由 Liran Alon 提交于 
      When CPU raise #NPF on guest data access and guest CR4.SMAP=1, it is
possible that CPU microcode implementing DecodeAssist will fail
to read bytes of instruction which caused #NPF. This is AMD errata
1096 and it happens because CPU microcode reading instruction bytes
incorrectly attempts to read code as implicit supervisor-mode data
accesses (that is, just like it would read e.g. a TSS), which are
susceptible to SMAP faults. The microcode reads CS:RIP and if it is
a user-mode address according to the page tables, the processor
gives up and returns no instruction bytes.  In this case,
GuestIntrBytes field of the VMCB on a VMEXIT will incorrectly
return 0 instead of the correct guest instruction bytes.

Current KVM code attemps to detect and workaround this errata, but it
has multiple issues:

1) It mistakenly checks if guest CR4.SMAP=0 instead of guest CR4.SMAP=1,
which is required for encountering a SMAP fault.

2) It assumes SMAP faults can only occur when guest CPL==3.
However, in case guest CR4.SMEP=0, the guest can execute an instruction
which reside in a user-accessible page with CPL<3 priviledge. If this
instruction raise a #NPF on it's data access, then CPU DecodeAssist
microcode will still encounter a SMAP violation.  Even though no sane
OS will do so (as it's an obvious priviledge escalation vulnerability),
we still need to handle this semanticly correct in KVM side.

Note that (2) *is* a useful optimization, because CR4.SMAP=1 is an easy
triggerable condition and guests usually enable SMAP together with SMEP.
If the vCPU has CR4.SMEP=1, the errata could indeed be encountered onlt
at guest CPL==3; otherwise, the CPU would raise a SMEP fault to guest
instead of #NPF.  We keep this condition to avoid false positives in
the detection of the errata.

In addition, to avoid future confusion and improve code readbility,
include details of the errata in code and not just in commit message.

Fixes: 05d5a486 ("KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)")
Cc: Singh Brijesh <brijesh.singh@amd.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Reviewed-by: NBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      118154bd
    • W
      KVM: LAPIC: Inject timer interrupt via posted interrupt · 0c5f81da
      由 Wanpeng Li 提交于 
      Dedicated instances are currently disturbed by unnecessary jitter due
to the emulated lapic timers firing on the same pCPUs where the
vCPUs reside.  There is no hardware virtual timer on Intel for guest
like ARM, so both programming timer in guest and the emulated timer fires
incur vmexits.  This patch tries to avoid vmexit when the emulated timer
fires, at least in dedicated instance scenario when nohz_full is enabled.

In that case, the emulated timers can be offload to the nearest busy
housekeeping cpus since APICv has been found for several years in server
processors. The guest timer interrupt can then be injected via posted interrupts,
which are delivered by the housekeeping cpu once the emulated timer fires.

The host should tuned so that vCPUs are placed on isolated physical
processors, and with several pCPUs surplus for busy housekeeping.
If disabled mwait/hlt/pause vmexits keep the vCPUs in non-root mode,
~3% redis performance benefit can be observed on Skylake server, and the
number of external interrupt vmexits drops substantially.  Without patch

            VM-EXIT  Samples  Samples%  Time%   Min Time  Max Time   Avg time
EXTERNAL_INTERRUPT    42916    49.43%   39.30%   0.47us   106.09us   0.71us ( +-   1.09% )

While with patch:

            VM-EXIT  Samples  Samples%  Time%   Min Time  Max Time         Avg time
EXTERNAL_INTERRUPT    6871     9.29%     2.96%   0.44us    57.88us   0.72us ( +-   4.02% )

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      0c5f81da
  9. 18 7月, 2019 1 次提交
    • W
      KVM: LAPIC: Make lapic timer unpinned · 4d151bf3
      由 Wanpeng Li 提交于 
      Commit 61abdbe0 ("kvm: x86: make lapic hrtimer pinned") pinned the
lapic timer to avoid to wait until the next kvm exit for the guest to
see KVM_REQ_PENDING_TIMER set. There is another solution to give a kick
after setting the KVM_REQ_PENDING_TIMER bit, make lapic timer unpinned
will be used in follow up patches.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      4d151bf3
  11. 17 7月, 2019 1 次提交
  13. 16 7月, 2019 2 次提交
  15. 15 7月, 2019 5 次提交
    • Y
      kvm: x86: some tsc debug cleanup · 9a5611af
      由 Yi Wang 提交于 
      There are some pr_debug in TSC code, which may have
been no use, so remove them as Paolo suggested.
Signed-off-by: NYi Wang <wang.yi59@zte.com.cn>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      9a5611af
    • Y
      kvm: vmx: fix coccinelle warnings · 9481b7f1
      由 Yi Wang 提交于 
      This fixes the following coccinelle warning:

WARNING: return of 0/1 in function 'vmx_need_emulation_on_page_fault'
with return type bool

Return false instead of 0.
Signed-off-by: NYi Wang <wang.yi59@zte.com.cn>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      9481b7f1
    • A
      x86: kvm: avoid constant-conversion warning · a6a6d3b1
      由 Arnd Bergmann 提交于 
      clang finds a contruct suspicious that converts an unsigned
character to a signed integer and back, causing an overflow:

arch/x86/kvm/mmu.c:4605:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -205 to 51 [-Werror,-Wconstant-conversion]
                u8 wf = (pfec & PFERR_WRITE_MASK) ? ~w : 0;
                   ~~                               ^~
arch/x86/kvm/mmu.c:4607:38: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -241 to 15 [-Werror,-Wconstant-conversion]
                u8 uf = (pfec & PFERR_USER_MASK) ? ~u : 0;
                   ~~                              ^~
arch/x86/kvm/mmu.c:4609:39: error: implicit conversion from 'int' to 'u8' (aka 'unsigned char') changes value from -171 to 85 [-Werror,-Wconstant-conversion]
                u8 ff = (pfec & PFERR_FETCH_MASK) ? ~x : 0;
                   ~~                               ^~

Add an explicit cast to tell clang that everything works as
intended here.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Link: https://github.com/ClangBuiltLinux/linux/issues/95Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      a6a6d3b1
    • A
      x86: kvm: avoid -Wsometimes-uninitized warning · f4e4805e
      由 Arnd Bergmann 提交于 
      Clang notices a code path in which some variables are never
initialized, but fails to figure out that this can never happen
on i386 because is_64_bit_mode() always returns false.

arch/x86/kvm/hyperv.c:1610:6: error: variable 'ingpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
        if (!longmode) {
            ^~~~~~~~~
arch/x86/kvm/hyperv.c:1632:55: note: uninitialized use occurs here
        trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
                                                             ^~~~~
arch/x86/kvm/hyperv.c:1610:2: note: remove the 'if' if its condition is always true
        if (!longmode) {
        ^~~~~~~~~~~~~~~
arch/x86/kvm/hyperv.c:1595:18: note: initialize the variable 'ingpa' to silence this warning
        u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
                        ^
                         = 0
arch/x86/kvm/hyperv.c:1610:6: error: variable 'outgpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
arch/x86/kvm/hyperv.c:1610:6: error: variable 'param' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]

Flip the condition around to avoid the conditional execution on i386.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      f4e4805e
    • J
      KVM: x86: expose AVX512_BF16 feature to guest · 0b774629
      由 Jing Liu 提交于 
      AVX512 BFLOAT16 instructions support 16-bit BFLOAT16 floating-point
format (BF16) for deep learning optimization.

Intel adds AVX512 BFLOAT16 feature in CooperLake, which is CPUID.7.1.EAX[5].

Detailed information of the CPUID bit can be found here,
https://software.intel.com/sites/default/files/managed/c5/15/\
architecture-instruction-set-extensions-programming-reference.pdf.
Signed-off-by: NJing Liu <jing2.liu@linux.intel.com>
[Fix type mismatch in min, changing constant "1" to "1u". - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      0b774629
  17. 13 7月, 2019 7 次提交
  19. 11 7月, 2019 4 次提交
  21. 10 7月, 2019 3 次提交
    • A
      x86/pgtable/32: Fix LOWMEM_PAGES constant · 26515699
      由 Arnd Bergmann 提交于 
      clang points out that the computation of LOWMEM_PAGES causes a signed
integer overflow on 32-bit x86:

arch/x86/kernel/head32.c:83:20: error: signed shift result (0x100000000) requires 34 bits to represent, but 'int' only has 32 bits [-Werror,-Wshift-overflow]
                (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
                                 ^~~~~~~~~~~~
arch/x86/include/asm/pgtable_32.h:109:27: note: expanded from macro 'LOWMEM_PAGES'
 #define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
                         ~^ ~~
arch/x86/include/asm/pgtable_32.h:98:34: note: expanded from macro 'PAGE_TABLE_SIZE'
 #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)

Use the _ULL() macro to make it a 64-bit constant.

Fixes: 1e620f9b ("x86/boot/32: Convert the 32-bit pgtable setup code from assembly to C")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190710130522.1802800-1-arnd@arndb.de
      26515699
    • Y
      kvm: x86: Fix -Wmissing-prototypes warnings · cdc238eb
      由 Yi Wang 提交于 
      We get a warning when build kernel W=1:

arch/x86/kvm/../../../virt/kvm/eventfd.c:48:1: warning: no previous prototype for ‘kvm_arch_irqfd_allowed’ [-Wmissing-prototypes]
 kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
 ^

The reason is kvm_arch_irqfd_allowed() is declared in arch/x86/kvm/irq.h,
which is not included by eventfd.c. Considering kvm_arch_irqfd_allowed()
is a weakly defined function in eventfd.c, remove the declaration to
kvm_host.h can fix this.
Signed-off-by: NYi Wang <wang.yi59@zte.com.cn>
Reviewed-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      cdc238eb
    • P
      x86/alternatives: Fix int3_emulate_call() selftest stack corruption · ecc60610
      由 Peter Zijlstra 提交于 
      KASAN shows the following splat during boot:

  BUG: KASAN: unknown-crash in unwind_next_frame+0x3f6/0x490
  Read of size 8 at addr ffffffff84007db0 by task swapper/0

  CPU: 0 PID: 0 Comm: swapper Tainted: G                T 5.2.0-rc6-00013-g7457c0da #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  Call Trace:
   dump_stack+0x19/0x1b
   print_address_description+0x1b0/0x2b2
   __kasan_report+0x10f/0x171
   kasan_report+0x12/0x1c
   __asan_load8+0x54/0x81
   unwind_next_frame+0x3f6/0x490
   unwind_next_frame+0x1b/0x23
   arch_stack_walk+0x68/0xa5
   stack_trace_save+0x7b/0xa0
   save_trace+0x3c/0x93
   mark_lock+0x1ef/0x9b1
   lock_acquire+0x122/0x221
   __mutex_lock+0xb6/0x731
   mutex_lock_nested+0x16/0x18
   _vm_unmap_aliases+0x141/0x183
   vm_unmap_aliases+0x14/0x16
   change_page_attr_set_clr+0x15e/0x2f2
   set_memory_4k+0x2a/0x2c
   check_bugs+0x11fd/0x1298
   start_kernel+0x793/0x7eb
   x86_64_start_reservations+0x55/0x76
   x86_64_start_kernel+0x87/0xaa
   secondary_startup_64+0xa4/0xb0

  Memory state around the buggy address:
   ffffffff84007c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1
   ffffffff84007d00: f1 00 00 00 00 00 00 00 00 00 f2 f2 f2 f3 f3 f3
  >ffffffff84007d80: f3 79 be 52 49 79 be 00 00 00 00 00 00 00 00 f1

It turns out that int3_selftest() is corrupting the stack.  The problem is
that the KASAN-ified version of int3_magic() is much less trivial than the
C code appears.  It clobbers several unexpected registers.  So when the
selftest's INT3 is converted to an emulated call to int3_magic(), the
registers are clobbered and Bad Things happen when the function returns.

Fix this by converting int3_magic() to the trivial ASM function it should
be, avoiding all calling convention issues. Also add ASM_CALL_CONSTRAINT to
the INT3 ASM, since it contains a 'CALL'.

[peterz: cribbed changelog from josh]

Fixes: 7457c0da ("x86/alternatives: Add int3_emulate_call() selftest")
Reported-by: Nkernel test robot <rong.a.chen@intel.com>
Debugged-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20190709125744.GB3402@hirez.programming.kicks-ass.net
      ecc60610
  23. 09 7月, 2019 3 次提交