linux-kernel - [PATCH AUTOSEL 5.14 01/18] KVM: arm64: Report corrupted refcount at EL2

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Date:   Mon, 25 Oct 2021 12:59:14 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Quentin Perret <qperret@...gle.com>, Will Deacon <will@...nel.org>,
        Marc Zyngier <maz@...nel.org>, Sasha Levin <sashal@...nel.org>,
        catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu
Subject: [PATCH AUTOSEL 5.14 01/18] KVM: arm64: Report corrupted refcount at EL2

From: Quentin Perret <qperret@...gle.com>

[ 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@...nel.org>
Suggested-by: Will Deacon <will@...nel.org>
Signed-off-by: Quentin Perret <qperret@...gle.com>
Signed-off-by: Marc Zyngier <maz@...nel.org>
Link: https://lore.kernel.org/r/20211005090155.734578-6-qperret@google.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 41fc25bdfb34..da2d3c0bfb7f 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);
 }
-- 
2.33.0