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Commit 328e5664 authored by Christoffer Dall's avatar Christoffer Dall Committed by Christoffer Dall
Browse files

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



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Note that userspace accesses may see out-of-date values if the VCPU is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: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: default avatarChristoffer Dall <cdall@linaro.org>
parent 056aad67

arch/arm/include/asm/kvm_asm.h

+3 −0
Original line number Diff line number Diff line
@@ -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__ */

arch/arm/kvm/arm.c

+6 −5
Original line number Diff line number Diff line
@@ -351,15 +351,14 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
	vcpu->arch.host_cpu_context = this_cpu_ptr(kvm_host_cpu_state);



	kvm_arm_set_running_vcpu(vcpu);



	kvm_vgic_load(vcpu);

}



void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)

{

	/*

	 * The arch-generic KVM code expects the cpu field of a vcpu to be -1

	 * if the vcpu is no longer assigned to a cpu.  This is used for the

	 * optimized make_all_cpus_request path.

	 */

	kvm_vgic_put(vcpu);



	vcpu->cpu = -1;



	kvm_arm_set_running_vcpu(NULL);
@@ -633,7 +632,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) 
		 * non-preemptible context.

		 */

		preempt_disable();



		kvm_pmu_flush_hwstate(vcpu);



		kvm_timer_flush_hwstate(vcpu);

		kvm_vgic_flush_hwstate(vcpu);

arch/arm64/include/asm/kvm_asm.h

+2 −0
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ extern void __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu); 
extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);



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);



extern u32 __kvm_get_mdcr_el2(void);

include/kvm/arm_vgic.h

+3 −0
Original line number Diff line number Diff line
@@ -306,6 +306,9 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq); 


int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);



void kvm_vgic_load(struct kvm_vcpu *vcpu);

void kvm_vgic_put(struct kvm_vcpu *vcpu);



#define irqchip_in_kernel(k)	(!!((k)->arch.vgic.in_kernel))

#define vgic_initialized(k)	((k)->arch.vgic.initialized)

#define vgic_ready(k)		((k)->arch.vgic.ready)

virt/kvm/arm/hyp/vgic-v2-sr.c

+0 −3
Original line number Diff line number Diff line
@@ -114,8 +114,6 @@ void __hyp_text __vgic_v2_save_state(struct kvm_vcpu *vcpu) 
	if (!base)

		return;



	cpu_if->vgic_vmcr = readl_relaxed(base + GICH_VMCR);



	if (vcpu->arch.vgic_cpu.live_lrs) {

		cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
@@ -165,7 +163,6 @@ void __hyp_text __vgic_v2_restore_state(struct kvm_vcpu *vcpu) 
		}

	}



	writel_relaxed(cpu_if->vgic_vmcr, base + GICH_VMCR);

	vcpu->arch.vgic_cpu.live_lrs = live_lrs;

}