diff options
| author | Krish Sadhukhan <krish.sadhukhan@oracle.com> | 2020-09-17 21:20:38 +0000 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-09-19 20:46:59 +0200 |
| commit | e1ebb2b49048c4767cfa0d8466f9c701e549fa5e (patch) | |
| tree | 2b9bf9e48ea3daa5d2fca77dd780a4b8d23b9631 | |
| parent | 75d1cc0e05af579301ce4e49cf6399be4b4e6e76 (diff) | |
KVM: SVM: Don't flush cache if hardware enforces cache coherency across encryption domains
In some hardware implementations, coherency between the encrypted and
unencrypted mappings of the same physical page in a VM is enforced. In
such a system, it is not required for software to flush the VM's page
from all CPU caches in the system prior to changing the value of the
C-bit for the page.
So check that bit before flushing the cache.
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lkml.kernel.org/r/20200917212038.5090-4-krish.sadhukhan@oracle.com
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 402dc4234e39..567792fbbc9f 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -384,7 +384,8 @@ static void sev_clflush_pages(struct page *pages[], unsigned long npages) uint8_t *page_virtual; unsigned long i; - if (npages == 0 || pages == NULL) + if (this_cpu_has(X86_FEATURE_SME_COHERENT) || npages == 0 || + pages == NULL) return; for (i = 0; i < npages; i++) { |