linux-kernel - [PATCH 4/8] KVM: pfncache: base offset check on khva rather than gpa

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Message-Id: <20230914084946.200043-5-paul@xen.org>
Date:   Thu, 14 Sep 2023 08:49:42 +0000
From:   Paul Durrant <paul@....org>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Paul Durrant <pdurrant@...zon.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: [PATCH 4/8] KVM: pfncache: base offset check on khva rather than gpa

From: Paul Durrant <pdurrant@...zon.com>

After a subsequent patch, the gpa may not always be set whereas khva will
(as long as the cache valid flag is also set).

Signed-off-by: Paul Durrant <pdurrant@...zon.com>
---
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: David Woodhouse <dwmw2@...radead.org>
---
 virt/kvm/pfncache.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 17afbb464a70..37bcb4399780 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -83,15 +83,18 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
 	if (!gpc->active)
 		return false;
 
-	if ((gpc->gpa & ~PAGE_MASK) + len > PAGE_SIZE)
+	if (gpc->generation != slots->generation)
 		return false;
 
-	if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva))
+	if (kvm_is_error_hva(gpc->uhva))
 		return false;
 
 	if (!gpc->valid)
 		return false;
 
+	if (offset_in_page(gpc->khva) + len > PAGE_SIZE)
+		return false;
+
 	return true;
 }
 EXPORT_SYMBOL_GPL(kvm_gpc_check);
-- 
2.39.2