Some hardware implementations may enforce cache coherency across encryption
domains. In such cases, it's not required to flush encrypted pages off
cache lines.
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
---
arch/x86/kvm/svm/sev.c | 3 ++-
arch/x86/mm/pat/set_memory.c | 6 ++++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 402dc4234e39..8aa2209f2637 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_HW_CACHE_COHERENCY) || npages == 0 ||
+ pages == NULL)
return;
for (i = 0; i < npages; i++) {
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index d1b2a889f035..5e2c618cbe84 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1999,7 +1999,8 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
/*
* Before changing the encryption attribute, we need to flush caches.
*/
- cpa_flush(&cpa, 1);
+ if (!this_cpu_has(X86_FEATURE_HW_CACHE_COHERENCY))
+ cpa_flush(&cpa, 1);
ret = __change_page_attr_set_clr(&cpa, 1);
@@ -2010,7 +2011,8 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
* flushing gets optimized in the cpa_flush() path use the same logic
* as above.
*/
- cpa_flush(&cpa, 0);
+ if (!this_cpu_has(X86_FEATURE_HW_CACHE_COHERENCY))
+ cpa_flush(&cpa, 0);
return ret;
}
--
2.18.4
