Merge v6.15.10linux-rolling-stable

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c
index 2e4122f8aa6b1..383afc41a718b 100644
--- a/arch/x86/coco/sev/shared.c
+++ b/arch/x86/coco/sev/shared.c
@@ -1254,6 +1254,24 @@ static void svsm_pval_terminate(struct svsm_pvalidate_call *pc, int ret, u64 svs
 	__pval_terminate(pfn, action, page_size, ret, svsm_ret);
 }
 
+static inline void sev_evict_cache(void *va, int npages)
+{
+	volatile u8 val __always_unused;
+	u8 *bytes = va;
+	int page_idx;
+
+	/*
+	 * For SEV guests, a read from the first/last cache-lines of a 4K page
+	 * using the guest key is sufficient to cause a flush of all cache-lines
+	 * associated with that 4K page without incurring all the overhead of a
+	 * full CLFLUSH sequence.
+	 */
+	for (page_idx = 0; page_idx < npages; page_idx++) {
+		val = bytes[page_idx * PAGE_SIZE];
+		val = bytes[page_idx * PAGE_SIZE + PAGE_SIZE - 1];
+	}
+}
+
 static void __head svsm_pval_4k_page(unsigned long paddr, bool validate)
 {
 	struct svsm_pvalidate_call *pc;
@@ -1307,6 +1325,13 @@ static void __head pvalidate_4k_page(unsigned long vaddr, unsigned long paddr,
 		if (ret)
 			sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE);
 	}
+
+	/*
+	 * If validating memory (making it private) and affected by the
+	 * cache-coherency vulnerability, perform the cache eviction mitigation.
+	 */
+	if (validate && !has_cpuflag(X86_FEATURE_COHERENCY_SFW_NO))
+		sev_evict_cache((void *)vaddr, 1);
 }
 
 static void pval_pages(struct snp_psc_desc *desc)
@@ -1491,10 +1516,31 @@ static void svsm_pval_pages(struct snp_psc_desc *desc)
 
 static void pvalidate_pages(struct snp_psc_desc *desc)
 {
+	struct psc_entry *e;
+	unsigned int i;
+
 	if (snp_vmpl)
 		svsm_pval_pages(desc);
 	else
 		pval_pages(desc);
+
+	/*
+	 * If not affected by the cache-coherency vulnerability there is no need
+	 * to perform the cache eviction mitigation.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_COHERENCY_SFW_NO))
+		return;
+
+	for (i = 0; i <= desc->hdr.end_entry; i++) {
+		e = &desc->entries[i];
+
+		/*
+		 * If validating memory (making it private) perform the cache
+		 * eviction mitigation.
+		 */
+		if (e->operation == SNP_PAGE_STATE_PRIVATE)
+			sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1);
+	}
 }
 
 static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc)