Commit d0c94c49 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Restore PMU configuration on first run 



Restoring a guest with an active virtual PMU results in no perf
counters being instanciated on the host side. Not quite what
you'd expect from a restore.

In order to fix this, force a writeback of PMCR_EL0 on the first
run of a vcpu (using a new request so that it happens once the
vcpu has been loaded). This will in turn create all the host-side
counters that were missing.

Reported-by: default avatarJinank Jain <jinankj@amazon.de>
Tested-by: default avatarJinank Jain <jinankj@amazon.de>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/87wnrbylxv.wl-maz@kernel.org
Link: https://lore.kernel.org/r/b53dfcf9bbc4db7f96154b1cd5188d72b9766358.camel@amazon.de
parent 2a71fabf

arch/arm64/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ 
#define KVM_REQ_VCPU_RESET	KVM_ARCH_REQ(2)

#define KVM_REQ_RECORD_STEAL	KVM_ARCH_REQ(3)

#define KVM_REQ_RELOAD_GICv4	KVM_ARCH_REQ(4)

#define KVM_REQ_RELOAD_PMU	KVM_ARCH_REQ(5)



#define KVM_DIRTY_LOG_MANUAL_CAPS   (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \

				     KVM_DIRTY_LOG_INITIALLY_SET)

arch/arm64/kvm/arm.c

+4 −0
Original line number Diff line number Diff line
@@ -689,6 +689,10 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) 
			vgic_v4_load(vcpu);

			preempt_enable();

		}



		if (kvm_check_request(KVM_REQ_RELOAD_PMU, vcpu))

			kvm_pmu_handle_pmcr(vcpu,

					    __vcpu_sys_reg(vcpu, PMCR_EL0));

	}

}

arch/arm64/kvm/pmu-emul.c

+3 −0
Original line number Diff line number Diff line
@@ -851,6 +851,9 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu) 
		   return -EINVAL;

	}



	/* One-off reload of the PMU on first run */

	kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);



	return 0;

}