[PATCH v2 5/5] KVM: SNP: Mark source page dirty in sev_gmem_post_populate

[Ackerley Tng via B4 Relay]

From: Ackerley Tng <ackerleytng@xxxxxxxxxx>

Mark the folio as dirty after copying data into the source page in
sev_gmem_post_populate. After the memcpy, failing to mark the page dirty
can lead to the memory management subsystem discarding the changes if the
page is reclaimed or otherwise processed by the swap subsystem.

Fixes: 2a62345b3052 ("KVM: guest_memfd: GUP source pages prior to populating guest memory")
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 arch/x86/kvm/svm/sev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index dbf75326a40f4..1a361f08c7a3d 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2395,6 +2395,7 @@ static int sev_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
 		void *dst_vaddr = kmap_local_pfn(pfn);
 
 		memcpy(src_vaddr, dst_vaddr, PAGE_SIZE);
+		folio_mark_dirty(page_folio(src_page));
 
 		kunmap_local(dst_vaddr);
 		kunmap_local(src_vaddr);

-- 
2.54.0.794.g4f17f83d09-goog