kvm: arm/arm64: Force reading uncached stage2 PGD

Suzuki K Poulose · gregkh · commit 628212c89fae · 2017-09-07T08:34:10.000+02:00
commit 2952a6070e07ebdd5896f1f5b861acad677caded upstream.

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

Cc: Marc Zyngier &lt;marc.zyngier@arm.com&gt;
Signed-off-by: Suzuki K Poulose &lt;suzuki.poulose@arm.com&gt;
Reviewed-by: Christoffer Dall &lt;cdall@linaro.org&gt;
Signed-off-by: Christoffer Dall &lt;cdall@linaro.org&gt;
Signed-off-by: Suzuki K Poulose &lt;suzuki.poulose@arm.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
@@ -833,7 +833,7 @@ 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);
 		hwpgd = kvm_get_hwpgd(kvm);
 		kvm->arch.pgd = NULL;
 	}

Original file line number	Diff line number	Diff line change
`@@ -833,7 +833,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)`
`833`	`833`	`spin_lock(&kvm->mmu_lock);`
`834`	`834`	`if (kvm->arch.pgd) {`
`835`	`835`	`unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);`
`836`		`- pgd = kvm->arch.pgd;`
	`836`	`+ pgd = READ_ONCE(kvm->arch.pgd);`
`837`	`837`	`hwpgd = kvm_get_hwpgd(kvm);`
`838`	`838`	`kvm->arch.pgd = NULL;`
`839`	`839`	`}`