linux-kernel - [PATCH v3 1/2] kvm: arm/arm64: Force reading uncached stage2 PGD

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Date:   Tue, 16 May 2017 10:34:54 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     christoffer.dall@...aro.org
Cc:     agraf@...e.de, andreyknvl@...gle.com, marc.zyngier@....com,
        mark.rutland@....com, pbonzini@...hat.com, rkrcmar@...hat.com,
        suzuki.poulose@....com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, Christoffer Dall <cdall@...aro.org>
Subject: [PATCH v3 1/2] kvm: arm/arm64: Force reading uncached stage2 PGD

Make sure we don't use a cached value of the KVM stage2 PGD while
resetting the PGD.

Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Christoffer Dall <cdall@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 virt/kvm/arm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 909a1a7..704e35f 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -837,7 +837,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
 	spin_lock(&kvm->mmu_lock);
 	if (kvm->arch.pgd) {
 		unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
-		pgd = kvm->arch.pgd;
+		pgd = READ_ONCE(kvm->arch.pgd);
 		kvm->arch.pgd = NULL;
 	}
 	spin_unlock(&kvm->mmu_lock);
-- 
2.7.4