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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Jan Glauber <jan.glauber@caviumnetworks.com>,
        Andre Przywara <andre.przywara@arm.com>,
        Christoffer Dall <christoffer.dall@arm.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH 4.16 017/110] KVM: arm/arm64: VGIC/ITS save/restore: protect kvm_read_guest() calls
Date:   Mon, 21 May 2018 23:11:14 +0200
Message-Id: <20180521210505.413676620@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

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

From: Andre Przywara <andre.przywara@arm.com>

commit 711702b57cc3c50b84bd648de0f1ca0a378805be upstream.

kvm_read_guest() will eventually look up in kvm_memslots(), which requires
either to hold the kvm->slots_lock or to be inside a kvm->srcu critical
section.
In contrast to x86 and s390 we don't take the SRCU lock on every guest
exit, so we have to do it individually for each kvm_read_guest() call.
Use the newly introduced wrapper for that.

Cc: Stable <stable@vger.kernel.org> # 4.12+
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 virt/kvm/arm/vgic/vgic-its.c |    4 ++--
 virt/kvm/arm/vgic/vgic-v3.c  |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1896,7 +1896,7 @@ static int scan_its_table(struct vgic_it
 		int next_offset;
 		size_t byte_offset;
 
-		ret = kvm_read_guest(kvm, gpa, entry, esz);
+		ret = kvm_read_guest_lock(kvm, gpa, entry, esz);
 		if (ret)
 			return ret;
 
@@ -2266,7 +2266,7 @@ static int vgic_its_restore_cte(struct v
 	int ret;
 
 	BUG_ON(esz > sizeof(val));
-	ret = kvm_read_guest(kvm, gpa, &val, esz);
+	ret = kvm_read_guest_lock(kvm, gpa, &val, esz);
 	if (ret)
 		return ret;
 	val = le64_to_cpu(val);
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -329,7 +329,7 @@ retry:
 	bit_nr = irq->intid % BITS_PER_BYTE;
 	ptr = pendbase + byte_offset;
 
-	ret = kvm_read_guest(kvm, ptr, &val, 1);
+	ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 	if (ret)
 		return ret;
 
@@ -382,7 +382,7 @@ int vgic_v3_save_pending_tables(struct k
 		ptr = pendbase + byte_offset;
 
 		if (byte_offset != last_byte_offset) {
-			ret = kvm_read_guest(kvm, ptr, &val, 1);
+			ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 			if (ret)
 				return ret;
 			last_byte_offset = byte_offset;