KVM: x86/pmu: Provide "error" semantics for unsupported-but-known PMU MSRs

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Provide "error" semantics (read zeros, drop writes) for userspace accesses
to MSRs that are ultimately unsupported for whatever reason, but for which
KVM told userspace to save and restore the MSR, i.e. for MSRs that KVM
included in KVM_GET_MSR_INDEX_LIST.

Previously, KVM special cased a few PMU MSRs that were problematic at one
point or another.  Extend the treatment to all PMU MSRs, e.g. to avoid
spurious unsupported accesses.

Note, the logic can also be used for non-PMU MSRs, but as of today only
PMU MSRs can end up being unsupported after KVM told userspace to save and
restore them.

Link: https://lore.kernel.org/r/20230124234905.3774678-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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Sean Christopherson 2023-01-24 23:49:05 +00:00

parent e33b6d79ac

commit 2de154f541

1 changed files with 29 additions and 22 deletions

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arch/x86/kvm/x86.c

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