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KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put

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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 becomes the rare case, which has to
save/restore the register on each round trip.

Note that userspace accesses may see out-of-date values if the VCPU is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.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
This commit is contained in:
Christoffer Dall
2016-03-24 11:21:04 +01:00
committed by Christoffer Dall
parent 056aad67f8
commit 328e566479
11 changed files with 106 additions and 16 deletions
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3
arch/arm/include/asm/kvm_asm.h
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@@ -75,7 +75,10 @@ extern void __init_stage2_translation(void);
extern void __kvm_hyp_reset(unsigned long);
extern u64 __vgic_v3_get_ich_vtr_el2(void);
extern u64 __vgic_v3_read_vmcr(void);
extern void __vgic_v3_write_vmcr(u32 vmcr);
extern void __vgic_v3_init_lrs(void);
#endif
#endif /* __ARM_KVM_ASM_H__ */