[PATCH v2 01/10] KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put

[Marc Zyngier]

On 21/03/17 21:10, Christoffer Dall wrote:
> From: Christoffer Dall <cdall at cs.columbia.edu>
> 
> We don't have to save/restore the VMCR on every entry to/from the guest,
> since on GICv2 we can access the control interface from EL1 and on VHE
> systems with GICv3 we can access the control interface from KVM running
> in EL2.
> 
> GICv3 systems without VHE become the rare case, which have to
> save/restore the register in the put/load functions by doing an extra
> jump to EL2 to access the EL2-only register state.
> 
> Note that userspace accesses may see out-of-date values if the VCPU is
> running while accessing the VGIC state via the KVM device API, but this
> is already the case and it is up to userspace to quiesce the CPUs before
> reading the CPU registers from the GIC for an up-to-date view.
> 
> Signed-off-by: Christoffer Dall <cdall at cs.columbia.edu>
> Signed-off-by: Christoffer Dall <cdall at linaro.org>

Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>

	M.
-- 
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