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| author | Maxim Levitsky <mlevitsk@redhat.com> | 2022-06-06 21:11:49 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-06-07 11:28:50 -0400 |
| commit | 11d39e8cc43e1c6737af19ca9372e590061b5ad2 (patch) | |
| tree | feee041f9516abcf98426e67cd4038c5a99bcac7 /arch/x86/kvm/svm/nested.c | |
| parent | eae260be3a0111a28fe95923e117a55dddec0384 (diff) | |
| download | linux-11d39e8cc43e1c6737af19ca9372e590061b5ad2.tar.gz linux-11d39e8cc43e1c6737af19ca9372e590061b5ad2.tar.bz2 linux-11d39e8cc43e1c6737af19ca9372e590061b5ad2.zip | |
KVM: SVM: fix tsc scaling cache logic
SVM uses a per-cpu variable to cache the current value of the
tsc scaling multiplier msr on each cpu.
Commit 1ab9287add5e2
("KVM: X86: Add vendor callbacks for writing the TSC multiplier")
broke this caching logic.
Refactor the code so that all TSC scaling multiplier writes go through
a single function which checks and updates the cache.
This fixes the following scenario:
1. A CPU runs a guest with some tsc scaling ratio.
2. New guest with different tsc scaling ratio starts on this CPU
and terminates almost immediately.
This ensures that the short running guest had set the tsc scaling ratio just
once when it was set via KVM_SET_TSC_KHZ. Due to the bug,
the per-cpu cache is not updated.
3. The original guest continues to run, it doesn't restore the msr
value back to its own value, because the cache matches,
and thus continues to run with a wrong tsc scaling ratio.
Fixes: 1ab9287add5e2 ("KVM: X86: Add vendor callbacks for writing the TSC multiplier")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220606181149.103072-1-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/svm/nested.c')
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index bed5e1692cef..3361258640a2 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -982,7 +982,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm) if (svm->tsc_ratio_msr != kvm_default_tsc_scaling_ratio) { WARN_ON(!svm->tsc_scaling_enabled); vcpu->arch.tsc_scaling_ratio = vcpu->arch.l1_tsc_scaling_ratio; - svm_write_tsc_multiplier(vcpu, vcpu->arch.tsc_scaling_ratio); + __svm_write_tsc_multiplier(vcpu->arch.tsc_scaling_ratio); } svm->nested.ctl.nested_cr3 = 0; @@ -1387,7 +1387,7 @@ void nested_svm_update_tsc_ratio_msr(struct kvm_vcpu *vcpu) vcpu->arch.tsc_scaling_ratio = kvm_calc_nested_tsc_multiplier(vcpu->arch.l1_tsc_scaling_ratio, svm->tsc_ratio_msr); - svm_write_tsc_multiplier(vcpu, vcpu->arch.tsc_scaling_ratio); + __svm_write_tsc_multiplier(vcpu->arch.tsc_scaling_ratio); } /* Inverse operation of nested_copy_vmcb_control_to_cache(). asid is copied too. */ |