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  1. 21 Oct, 2021 2 commits
  3. 18 Oct, 2021 7 commits
    • Paolo Bonzini's avatar
      KVM: SEV-ES: reduce ghcb_sa_len to 32 bits · 9f1ee7b1
      Paolo Bonzini authored 
      The size of the GHCB scratch area is limited to 16 KiB (GHCB_SCRATCH_AREA_LIMIT),
so there is no need for it to be a u64.  This fixes a build error on 32-bit
systems:

i686-linux-gnu-ld: arch/x86/kvm/svm/sev.o: in function `sev_es_string_io:
sev.c:(.text+0x110f): undefined reference to `__udivdi3'

Cc: stable@vger.kernel.org
Fixes: 019057bd ("KVM: SEV-ES: fix length of string I/O")
Reported-by: default avatarNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      9f1ee7b1
    • Hao Xiang's avatar
      KVM: VMX: Remove redundant handling of bus lock vmexit · d61863c6
      Hao Xiang authored 
      Hardware may or may not set exit_reason.bus_lock_detected on BUS_LOCK
VM-Exits. Dealing with KVM_RUN_X86_BUS_LOCK in handle_bus_lock_vmexit
could be redundant when exit_reason.basic is EXIT_REASON_BUS_LOCK.

We can remove redundant handling of bus lock vmexit. Unconditionally Set
exit_reason.bus_lock_detected in handle_bus_lock_vmexit(), and deal with
KVM_RUN_X86_BUS_LOCK only in vmx_handle_exit().
Signed-off-by: default avatarHao Xiang <hao.xiang@linux.alibaba.com>
Message-Id: <1634299161-30101-1-git-send-email-hao.xiang@linux.alibaba.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d61863c6
    • Christian Borntraeger's avatar
      KVM: kvm_stat: do not show halt_wait_ns · 01c7d267
      Christian Borntraeger authored 
      Similar to commit 111d0bda ("tools/kvm_stat: Exempt time-based
counters"), we should not show timer values in kvm_stat. Remove the new
halt_wait_ns.

Fixes: 87bcc5fa ("KVM: stats: Add halt_wait_ns stats for all architectures")
Cc: Jing Zhang <jingzhangos@google.com>
Cc: Stefan Raspl <raspl@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarStefan Raspl <raspl@linux.ibm.com>
Message-Id: <20211006121724.4154-1-borntraeger@de.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      01c7d267
    • Sean Christopherson's avatar
      KVM: x86: WARN if APIC HW/SW disable static keys are non-zero on unload · 9139a7a6
      Sean Christopherson authored 
      WARN if the static keys used to track if any vCPU has disabled its APIC
are left elevated at module exit.  Unlike the underflow case, nothing in
the static key infrastructure will complain if a key is left elevated,
and because an elevated key only affects performance, nothing in KVM will
fail if either key is improperly incremented.
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211013003554.47705-3-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      9139a7a6
    • Sean Christopherson's avatar
      Revert "KVM: x86: Open code necessary bits of kvm_lapic_set_base() at vCPU RESET" · f7d8a19f
      Sean Christopherson authored 
      Revert a change to open code bits of kvm_lapic_set_base() when emulating
APIC RESET to fix an apic_hw_disabled underflow bug due to arch.apic_base
and apic_hw_disabled being unsyncrhonized when the APIC is created.  If
kvm_arch_vcpu_create() fails after creating the APIC, kvm_free_lapic()
will see the initialized-to-zero vcpu->arch.apic_base and decrement
apic_hw_disabled without KVM ever having incremented apic_hw_disabled.

Using kvm_lapic_set_base() in kvm_lapic_reset() is also desirable for a
potential future where KVM supports RESET outside of vCPU creation, in
which case all the side effects of kvm_lapic_set_base() are needed, e.g.
to handle the transition from x2APIC => xAPIC.

Alternatively, KVM could temporarily increment apic_hw_disabled (and call
kvm_lapic_set_base() at RESET), but that's a waste of cycles and would
impact the performance of other vCPUs and VMs.  The other subtle side
effect is that updating the xAPIC ID needs to be done at RESET regardless
of whether the APIC was previously enabled, i.e. kvm_lapic_reset() needs
an explicit call to kvm_apic_set_xapic_id() regardless of whether or not
kvm_lapic_set_base() also performs the update.  That makes stuffing the
enable bit at vCPU creation slightly more palatable, as doing so affects
only the apic_hw_disabled key.

Opportunistically tweak the comment to explicitly call out the connection
between vcpu->arch.apic_base and apic_hw_disabled, and add a comment to
call out the need to always do kvm_apic_set_xapic_id() at RESET.

Underflow scenario:

  kvm_vm_ioctl() {
    kvm_vm_ioctl_create_vcpu() {
      kvm_arch_vcpu_create() {
        if (something_went_wrong)
          goto fail_free_lapic;
        /* vcpu->arch.apic_base is initialized when something_went_wrong is false. */
        kvm_vcpu_reset() {
          kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) {
            vcpu->arch.apic_base = APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE;
          }
        }
        return 0;
      fail_free_lapic:
        kvm_free_lapic() {
          /* vcpu->arch.apic_base is not yet initialized when something_went_wrong is true. */
          if (!(vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE))
            static_branch_slow_dec_deferred(&apic_hw_disabled); // <= underflow bug.
        }
        return r;
      }
    }
  }

This (mostly) reverts commit 42122123.

Fixes: 42122123 ("KVM: x86: Open code necessary bits of kvm_lapic_set_base() at vCPU RESET")
Reported-by: syzbot+9fc046ab2b0cf295a063@syzkaller.appspotmail.com
Debugged-by: default avatarTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211013003554.47705-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f7d8a19f
    • Peter Gonda's avatar
      KVM: SEV-ES: Set guest_state_protected after VMSA update · baa1e5ca
      Peter Gonda authored 
      The refactoring in commit bb18a677 ("KVM: SEV: Acquire
vcpu mutex when updating VMSA") left behind the assignment to
svm->vcpu.arch.guest_state_protected; add it back.
Signed-off-by: default avatarPeter Gonda <pgonda@google.com>
[Delta between v2 and v3 of Peter's patch, which had already been
 committed; the commit message is my own. - Paolo]
Fixes: bb18a677 ("KVM: SEV: Acquire vcpu mutex when updating VMSA")
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      baa1e5ca
    • Paolo Bonzini's avatar
      KVM: X86: fix lazy allocation of rmaps · fa13843d
      Paolo Bonzini authored 
      If allocation of rmaps fails, but some of the pointers have already been written,
those pointers can be cleaned up when the memslot is freed, or even reused later
for another attempt at allocating the rmaps.  Therefore there is no need to
WARN, as done for example in memslot_rmap_alloc, but the allocation *must* be
skipped lest KVM will overwrite the previous pointer and will indeed leak memory.
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      fa13843d
  5. 15 Oct, 2021 2 commits
  7. 05 Oct, 2021 3 commits
  9. 04 Oct, 2021 1 commit
  11. 30 Sep, 2021 4 commits
    • Sean Christopherson's avatar
      KVM: selftests: Ensure all migrations are performed when test is affined · 7b0035ea
      Sean Christopherson authored 
      Rework the CPU selection in the migration worker to ensure the specified
number of migrations are performed when the test iteslf is affined to a
subset of CPUs.  The existing logic skips iterations if the target CPU is
not in the original set of possible CPUs, which causes the test to fail
if too many iterations are skipped.

  ==== Test Assertion Failure ====
  rseq_test.c:228: i > (NR_TASK_MIGRATIONS / 2)
  pid=10127 tid=10127 errno=4 - Interrupted system call
     1  0x00000000004018e5: main at rseq_test.c:227
     2  0x00007fcc8fc66bf6: ?? ??:0
     3  0x0000000000401959: _start at ??:?
  Only performed 4 KVM_RUNs, task stalled too much?

Calculate the min/max possible CPUs as a cheap "best effort" to avoid
high runtimes when the test is affined to a small percentage of CPUs.
Alternatively, a list or xarray of the possible CPUs could be used, but
even in a horrendously inefficient setup, such optimizations are not
needed because the runtime is completely dominated by the cost of
migrating the task, and the absolute runtime is well under a minute in
even truly absurd setups, e.g. running on a subset of vCPUs in a VM that
is heavily overcommited (16 vCPUs per pCPU).

Fixes: 61e52f16 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs")
Reported-by: default avatarDongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210929234112.1862848-1-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      7b0035ea
    • Sean Christopherson's avatar
      KVM: x86: Swap order of CPUID entry "index" vs. "significant flag" checks · e8a747d0
      Sean Christopherson authored 
      Check whether a CPUID entry's index is significant before checking for a
matching index to hack-a-fix an undefined behavior bug due to consuming
uninitialized data.  RESET/INIT emulation uses kvm_cpuid() to retrieve
CPUID.0x1, which does _not_ have a significant index, and fails to
initialize the dummy variable that doubles as EBX/ECX/EDX output _and_
ECX, a.k.a. index, input.

Practically speaking, it's _extremely_  unlikely any compiler will yield
code that causes problems, as the compiler would need to inline the
kvm_cpuid() call to detect the uninitialized data, and intentionally hose
the kernel, e.g. insert ud2, instead of simply ignoring the result of
the index comparison.

Although the sketchy "dummy" pattern was introduced in SVM by commit
66f7b72e ("KVM: x86: Make register state after reset conform to
specification"), it wasn't actually broken until commit 7ff6c035
("KVM: x86: Remove stateful CPUID handling") arbitrarily swapped the
order of operations such that "index" was checked before the significant
flag.

Avoid consuming uninitialized data by reverting to checking the flag
before the index purely so that the fix can be easily backported; the
offending RESET/INIT code has been refactored, moved, and consolidated
from vendor code to common x86 since the bug was introduced.  A future
patch will directly address the bad RESET/INIT behavior.

The undefined behavior was detected by syzbot + KernelMemorySanitizer.

  BUG: KMSAN: uninit-value in cpuid_entry2_find arch/x86/kvm/cpuid.c:68
  BUG: KMSAN: uninit-value in kvm_find_cpuid_entry arch/x86/kvm/cpuid.c:1103
  BUG: KMSAN: uninit-value in kvm_cpuid+0x456/0x28f0 arch/x86/kvm/cpuid.c:1183
   cpuid_entry2_find arch/x86/kvm/cpuid.c:68 [inline]
   kvm_find_cpuid_entry arch/x86/kvm/cpuid.c:1103 [inline]
   kvm_cpuid+0x456/0x28f0 arch/x86/kvm/cpuid.c:1183
   kvm_vcpu_reset+0x13fb/0x1c20 arch/x86/kvm/x86.c:10885
   kvm_apic_accept_events+0x58f/0x8c0 arch/x86/kvm/lapic.c:2923
   vcpu_enter_guest+0xfd2/0x6d80 arch/x86/kvm/x86.c:9534
   vcpu_run+0x7f5/0x18d0 arch/x86/kvm/x86.c:9788
   kvm_arch_vcpu_ioctl_run+0x245b/0x2d10 arch/x86/kvm/x86.c:10020

  Local variable ----dummy@kvm_vcpu_reset created at:
   kvm_vcpu_reset+0x1fb/0x1c20 arch/x86/kvm/x86.c:10812
   kvm_apic_accept_events+0x58f/0x8c0 arch/x86/kvm/lapic.c:2923

Reported-by: syzbot+f3985126b746b3d59c9d@syzkaller.appspotmail.com
Reported-by: default avatarAlexander Potapenko <glider@google.com>
Fixes: 2a24be79 ("KVM: VMX: Set EDX at INIT with CPUID.0x1, Family-Model-Stepping")
Fixes: 7ff6c035 ("KVM: x86: Remove stateful CPUID handling")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Message-Id: <20210929222426.1855730-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e8a747d0
    • Zelin Deng's avatar
      ptp: Fix ptp_kvm_getcrosststamp issue for x86 ptp_kvm · 773e89ab
      Zelin Deng authored 
      hv_clock is preallocated to have only HVC_BOOT_ARRAY_SIZE (64) elements;
if the PTP_SYS_OFFSET_PRECISE ioctl is executed on vCPUs whose index is
64 of higher, retrieving the struct pvclock_vcpu_time_info pointer with
"src = &hv_clock[cpu].pvti" will result in an out-of-bounds access and
a wild pointer.  Change it to "this_cpu_pvti()" which is guaranteed to
be valid.

Fixes: 95a3d445 ("Switch kvmclock data to a PER_CPU variable")
Signed-off-by: default avatarZelin Deng <zelin.deng@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Message-Id: <1632892429-101194-3-git-send-email-zelin.deng@linux.alibaba.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      773e89ab
    • Zelin Deng's avatar
      x86/kvmclock: Move this_cpu_pvti into kvmclock.h · ad9af930
      Zelin Deng authored 
      There're other modules might use hv_clock_per_cpu variable like ptp_kvm,
so move it into kvmclock.h and export the symbol to make it visiable to
other modules.
Signed-off-by: default avatarZelin Deng <zelin.deng@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Message-Id: <1632892429-101194-2-git-send-email-zelin.deng@linux.alibaba.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ad9af930
  13. 28 Sep, 2021 2 commits
  15. 27 Sep, 2021 1 commit
    • Zhenzhong Duan's avatar
      KVM: VMX: Fix a TSX_CTRL_CPUID_CLEAR field mask issue · 5c49d185
      Zhenzhong Duan authored 
      When updating the host's mask for its MSR_IA32_TSX_CTRL user return entry,
clear the mask in the found uret MSR instead of vmx->guest_uret_msrs[i].
Modifying guest_uret_msrs directly is completely broken as 'i' does not
point at the MSR_IA32_TSX_CTRL entry.  In fact, it's guaranteed to be an
out-of-bounds accesses as is always set to kvm_nr_uret_msrs in a prior
loop. By sheer dumb luck, the fallout is limited to "only" failing to
preserve the host's TSX_CTRL_CPUID_CLEAR.  The out-of-bounds access is
benign as it's guaranteed to clear a bit in a guest MSR value, which are
always zero at vCPU creation on both x86-64 and i386.

Cc: stable@vger.kernel.org
Fixes: 8ea8b8d6 ("KVM: VMX: Use common x86's uret MSR list as the one true list")
Signed-off-by: default avatarZhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210926015545.281083-1-zhenzhong.duan@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      5c49d185
  17. 24 Sep, 2021 3 commits
  19. 23 Sep, 2021 7 commits
  21. 22 Sep, 2021 8 commits
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