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authorChristoffer Dall <cdall@linaro.org>2017-08-02 17:28:42 +0300
committerMarc Zyngier <marc.zyngier@arm.com>2017-08-03 17:47:36 +0300
commit3af4e414af5ce014d1f88cd816d997048298b310 (patch)
tree91a2fbd1caccec08f58272dc19037bc98318442b
parent7e5a672289c9754d07e1c3b33649786d3d70f5e4 (diff)
downloadlinux-3af4e414af5ce014d1f88cd816d997048298b310.tar.xz
KVM: arm/arm64: vgic: Use READ_ONCE fo cmpxchg
There is a small chance that the compiler could generate separate loads for the dist->propbaser which could be modified from another CPU. As we want to make sure we atomically update the entire value, and don't race with other updates, guarantee that the cmpxchg operation compares against the original value. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Christoffer Dall <cdall@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
-rw-r--r--virt/kvm/arm/vgic/vgic-mmio-v3.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index 714fa3933546..408ef06638fc 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -369,7 +369,7 @@ static void vgic_mmio_write_propbase(struct kvm_vcpu *vcpu,
return;
do {
- old_propbaser = dist->propbaser;
+ old_propbaser = READ_ONCE(dist->propbaser);
propbaser = old_propbaser;
propbaser = update_64bit_reg(propbaser, addr & 4, len, val);
propbaser = vgic_sanitise_propbaser(propbaser);
@@ -397,7 +397,7 @@ static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu,
return;
do {
- old_pendbaser = vgic_cpu->pendbaser;
+ old_pendbaser = READ_ONCE(vgic_cpu->pendbaser);
pendbaser = old_pendbaser;
pendbaser = update_64bit_reg(pendbaser, addr & 4, len, val);
pendbaser = vgic_sanitise_pendbaser(pendbaser);