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| author |   Christoffer Dall <cdall@linaro.org> | 2017-03-21 22:05:22 +0100 |
|---|---|---|
| committer | Christoffer Dall <cdall@linaro.org> | 2017-04-04 14:33:59 +0200 |
| commit | 6d56111c92d247bb64301029fe88365aa4caf16e (patch) | |
| tree | 0ceec9bfeae39452c020baa35b99f91d9e4bae76 /virt/kvm/arm/vgic/vgic-mmio-v2.c | |
| parent | KVM: arm64: Ensure LRs are clear when they should be (diff) | |
| download | wireguard-linux-6d56111c92d247bb64301029fe88365aa4caf16e.tar.xz wireguard-linux-6d56111c92d247bb64301029fe88365aa4caf16e.zip | |
KVM: arm/arm64: vgic: Fix GICC_PMR uaccess on GICv3 and clarify ABI
As an oversight, for GICv2, we accidentally export the GICC_PMR register
in the format of the GICH_VMCR.VMPriMask field in the lower 5 bits of a
word, meaning that userspace must always use the lower 5 bits to
communicate with the KVM device and must shift the value left by 3
places to obtain the actual priority mask level.
Since GICv3 supports the full 8 bits of priority masking in the ICH_VMCR,
we have to fix the value we export when emulating a GICv2 on top of a
hardware GICv3 and exporting the emulated GICv2 state to userspace.
Take the chance to clarify this aspect of the ABI.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Diffstat (limited to 'virt/kvm/arm/vgic/vgic-mmio-v2.c')
| -rw-r--r-- | virt/kvm/arm/vgic/vgic-mmio-v2.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c index a3ad7ff95c9b..0a4283ed9aa7 100644 --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c @@ -229,7 +229,15 @@ static unsigned long vgic_mmio_read_vcpuif(struct kvm_vcpu *vcpu, val = vmcr.ctlr; break; case GIC_CPU_PRIMASK: - val = vmcr.pmr; + /* + * Our KVM_DEV_TYPE_ARM_VGIC_V2 device ABI exports the + * the PMR field as GICH_VMCR.VMPriMask rather than + * GICC_PMR.Priority, so we expose the upper five bits of + * priority mask to userspace using the lower bits in the + * unsigned long. + */ + val = (vmcr.pmr & GICV_PMR_PRIORITY_MASK) >> + GICV_PMR_PRIORITY_SHIFT; break; case GIC_CPU_BINPOINT: val = vmcr.bpr; @@ -262,7 +270,15 @@ static void vgic_mmio_write_vcpuif(struct kvm_vcpu *vcpu, vmcr.ctlr = val; break; case GIC_CPU_PRIMASK: - vmcr.pmr = val; + /* + * Our KVM_DEV_TYPE_ARM_VGIC_V2 device ABI exports the + * the PMR field as GICH_VMCR.VMPriMask rather than + * GICC_PMR.Priority, so we expose the upper five bits of + * priority mask to userspace using the lower bits in the + * unsigned long. + */ + vmcr.pmr = (val << GICV_PMR_PRIORITY_SHIFT) & + GICV_PMR_PRIORITY_MASK; break; case GIC_CPU_BINPOINT: vmcr.bpr = val; |