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KVM: SVM: Flush when freeing encrypted pages even on SME_COHERENT CPUs

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Use clflush_cache_range() to flush the confidential memory when
SME_COHERENT is supported in AMD CPU. Cache flush is still needed since
SME_COHERENT only support cache invalidation at CPU side. All confidential
cache lines are still incoherent with DMA devices.

Cc: stable@vger.kerel.org

Fixes: add5e2f045 ("KVM: SVM: Add support for the SEV-ES VMSA")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Message-Id: <20220421031407.2516575-3-mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Mingwei Zhang 2022-04-21 03:14:06 +00:00 committed by Paolo Bonzini
parent 4bbef7e8eb
commit d45829b351
1 changed files with 6 additions and 3 deletions
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9
arch/x86/kvm/svm/sev.c
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@ -2239,11 +2239,14 @@ static void sev_flush_encrypted_page(struct kvm_vcpu *vcpu, void *va)
unsigned long addr = (unsigned long)va;
/*
* If hardware enforced cache coherency for encrypted mappings of the
* same physical page is supported, nothing to do.
* If CPU enforced cache coherency for encrypted mappings of the
* same physical page is supported, use CLFLUSHOPT instead. NOTE: cache
* flush is still needed in order to work properly with DMA devices.
*/
if (boot_cpu_has(X86_FEATURE_SME_COHERENT))
if (boot_cpu_has(X86_FEATURE_SME_COHERENT)) {
clflush_cache_range(va, PAGE_SIZE);
return;
}
/*
* VM Page Flush takes a host virtual address and a guest ASID. Fall