diff options
| author | Krish Sadhukhan <krish.sadhukhan@oracle.com> | 2020-09-17 21:20:38 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-16 13:21:48 +0100 |
| commit | afb684cb976a9c36b53e7ee7bd0c40591c38a402 (patch) | |
| tree | cc27534b5dfc5fde2648ba7bbf77ebf1e78885fe | |
| parent | 690909c6d9718a9501381be361ab453f8f69083b (diff) | |
KVM: SVM: Don't flush cache if hardware enforces cache coherency across encryption domains
commit e1ebb2b49048c4767cfa0d8466f9c701e549fa5e upstream.
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
[ The linux-5.4.y stable branch does not have the Linux 5.7 refactoring commit
eaf78265a4ab ("KVM: SVM: Move SEV code to separate file") so the
change was manually applied to sev_clflush_pages() in arch/x86/kvm/svm.c. ]
Signed-off-by: Liam Merwick <liam.merwick@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/svm.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 2f84509f2828..125970286f28 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1904,7 +1904,8 @@ 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++) { |