linux-kernel - [PATCH 3/3] kvm: arm/arm64: Fix locking for kvm_free_stage2

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Date:   Tue, 14 Mar 2017 14:52:34 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org, andreyknvl@...gle.com
Cc:     dvyukov@...gle.com, marc.zyngier@....com,
        christoffer.dall@...aro.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org, kcc@...gle.com,
        syzkaller@...glegroups.com, will.deacon@....com,
        catalin.marinas@....com, pbonzini@...hat.com, mark.rutland@....com,
        suzuki.poulose@....com, ard.biesheuvel@...aro.org,
        stable@...r.kernel.org
Subject: [PATCH 3/3] kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd

In kvm_free_stage2_pgd() we don't hold the kvm->mmu_lock while calling
unmap_stage2_range() on the entire memory range for the guest. This could
cause problems with other callers (e.g, munmap on a memslot) trying to
unmap a range.

Fixes: commit d5d8184d35c9 ("KVM: ARM: Memory virtualization setup")
Cc: stable@...r.kernel.org # v3.10+
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arch/arm/kvm/mmu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 13b9c1f..b361f71 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -831,7 +831,10 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
 	if (kvm->arch.pgd == NULL)
 		return;
 
+	spin_lock(&kvm->mmu_lock);
 	unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
+	spin_unlock(&kvm->mmu_lock);
+
 	/* Free the HW pgd, one page at a time */
 	free_pages_exact(kvm->arch.pgd, S2_PGD_SIZE);
 	kvm->arch.pgd = NULL;
-- 
2.7.4