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authorSean Christopherson <seanjc@google.com>2021-03-09 09:10:19 -0800
committerPeter Zijlstra <peterz@infradead.org>2021-03-10 16:45:09 +0100
commitc8e2fe13d1d1f3a02842b7b909d4e4846a4b6a2c (patch)
tree61e5e05f3c0fabb39dd8db94478c402632f9cd8a /arch/x86/kernel/sev-es.c
parentafbef30149587ad46f4780b1e0cc5e219745ce90 (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/kernel/sev-es.c')
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