linux-kernel - [PATCH] KVM: arm64: Fix 64 bit mmio handle

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Date:   Fri,  1 Jul 2022 00:12:20 +0800
From:   Schspa Shi <schspa@...il.com>
To:     maz@...nel.org, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, catalin.marinas@....com, will@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, Schspa Shi <schspa@...il.com>
Subject: [PATCH] KVM: arm64: Fix 64 bit mmio handle

If the len is 8 bytes, we can't get the correct sign extend for
be system.

Fix the mask type len and the comparison of length.

Signed-off-by: Schspa Shi <schspa@...il.com>
---
 arch/arm64/kvm/mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
index 3dd38a151d2a6..0692f8b18f35c 100644
--- a/arch/arm64/kvm/mmio.c
+++ b/arch/arm64/kvm/mmio.c
@@ -81,8 +81,8 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len)
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
 {
 	unsigned long data;
+	unsigned long mask;
 	unsigned int len;
-	int mask;
 
 	/* Detect an already handled MMIO return */
 	if (unlikely(!vcpu->mmio_needed))
@@ -97,7 +97,7 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
 		data = kvm_mmio_read_buf(run->mmio.data, len);
 
 		if (kvm_vcpu_dabt_issext(vcpu) &&
-		    len < sizeof(unsigned long)) {
+		    len <= sizeof(unsigned long)) {
 			mask = 1U << ((len * 8) - 1);
 			data = (data ^ mask) - mask;
 		}
-- 
2.37.0