linux-kernel - [PATCH 4.4 12/15] KVM: arm/arm64: Handle hva aging while destroying the vm

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Date:   Fri, 11 Aug 2017 15:02:26 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alex Graf <agraf@...e.de>,
        Christoffer Dall <cdall@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Marc Zyngier <marc.zyngier@....com>
Subject: [PATCH 4.4 12/15] KVM: arm/arm64: Handle hva aging while destroying the vm

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Suzuki K Poulose <Suzuki.Poulose@....com>

commit 7e5a672289c9754d07e1c3b33649786d3d70f5e4 upstream.

The mmu_notifier_release() callback of KVM triggers cleaning up
the stage2 page table on kvm-arm. However there could be other
notifier callbacks in parallel with the mmu_notifier_release(),
which could cause the call backs ending up in an empty stage2
page table. Make sure we check it for all the notifier callbacks.

Fixes: commit 293f29363 ("kvm-arm: Unmap shadow pagetables properly")
Reported-by: Alex Graf <agraf@...e.de>
Reviewed-by: Christoffer Dall <cdall@...aro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 arch/arm/kvm/mmu.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -1629,12 +1629,16 @@ static int kvm_test_age_hva_handler(stru
 
 int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
 {
+	if (!kvm->arch.pgd)
+		return 0;
 	trace_kvm_age_hva(start, end);
 	return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL);
 }
 
 int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
 {
+	if (!kvm->arch.pgd)
+		return 0;
 	trace_kvm_test_age_hva(hva);
 	return handle_hva_to_gpa(kvm, hva, hva, kvm_test_age_hva_handler, NULL);
 }