From 093801ba8fe699233e13ca5db65c9dc7fcc0b5ba Mon Sep 17 00:00:00 2001
From: Quentin Perret <qperret@google.com>
Date: Tue, 5 Oct 2021 10:01:42 +0100
Subject: [PATCH] KVM: arm64: Report corrupted refcount at EL2
Git-commit: 7615c2a514788559c6684234b8fc27f3a843c2c6
Patch-mainline: v5.15-rc7
References: stable-5.14.19

[ Upstream commit 7615c2a514788559c6684234b8fc27f3a843c2c6 ]

Some of the refcount manipulation helpers used at EL2 are instrumented
to catch a corrupted state, but not all of them are treated equally. Let's
make things more consistent by instrumenting hyp_page_ref_dec_and_test()
as well.

Acked-by: Will Deacon <will@kernel.org>
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211005090155.734578-6-qperret@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 arch/arm64/kvm/hyp/nvhe/page_alloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index a6e874e61a40..0bd7701ad1df 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -152,6 +152,7 @@ static inline void hyp_page_ref_inc(struct hyp_page *p)
 
 static inline int hyp_page_ref_dec_and_test(struct hyp_page *p)
 {
+	BUG_ON(!p->refcount);
 	p->refcount--;
 	return (p->refcount == 0);
 }
-- 
2.26.2