[RFC PATCH 2/4] KVM: SEV: Skip SNP-safe allocation when HvInUseWrAllowed is supported

[Nikunj A Dadhania <nikunj@amd.com>]

When HvInUseWrAllowed (CPUID 8000001F EAX[30]) is supported, the CPU allows
hypervisor writes to in-use pages without RMP violations, making the 2MB
alignment workaround unnecessary. Check for this capability to avoid the
allocation overhead when it's not needed.

Suggested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
---
 arch/x86/kvm/svm/sev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2fbdebf79fbb..c5477efc90b9 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -4666,7 +4666,8 @@ struct page *snp_safe_alloc_page_node(int node, gfp_t gfp)
 	unsigned long pfn;
 	struct page *p;
 
-	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
+	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP) ||
+	    cpu_feature_enabled(X86_FEATURE_HV_INUSE_WR_ALLOWED))
 		return alloc_pages_node(node, gfp | __GFP_ZERO, 0);
 
 	/*
-- 
2.43.0