diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-03-09 09:10:19 -0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-03-10 16:45:09 +0100 |
| commit | c8e2fe13d1d1f3a02842b7b909d4e4846a4b6a2c (patch) | |
| tree | 61e5e05f3c0fabb39dd8db94478c402632f9cd8a /arch/x86/kvm/vmx/vmx.c | |
| parent | afbef30149587ad46f4780b1e0cc5e219745ce90 (diff) | |
x86/perf: Use RET0 as default for guest_get_msrs to handle "no PMU" case
Initialize x86_pmu.guest_get_msrs to return 0/NULL to handle the "nop"
case. Patching in perf_guest_get_msrs_nop() during setup does not work
if there is no PMU, as setup bails before updating the static calls,
leaving x86_pmu.guest_get_msrs NULL and thus a complete nop. Ultimately,
this causes VMX abort on VM-Exit due to KVM putting random garbage from
the stack into the MSR load list.
Add a comment in KVM to note that nr_msrs is valid if and only if the
return value is non-NULL.
Fixes: abd562df94d1 ("x86/perf: Use static_call for x86_pmu.guest_get_msrs")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: syzbot+cce9ef2dd25246f815ee@syzkaller.appspotmail.com
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210309171019.1125243-1-seanjc@google.com
Diffstat (limited to 'arch/x86/kvm/vmx/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 50810d471462..32cf8287d4a7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6580,8 +6580,8 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx) int i, nr_msrs; struct perf_guest_switch_msr *msrs; + /* Note, nr_msrs may be garbage if perf_guest_get_msrs() returns NULL. */ msrs = perf_guest_get_msrs(&nr_msrs); - if (!msrs) return; |