On LoongArch system, guest PMU hardware is shared by guest and host and PMU interrupt is separated. PMU is pass-through to VM, and there is PMU context switch when exit to host and return to guest.

There is optimiation to check whether PMU is enabled by guest. If not, it is not necessary to return to guest. However it is enabled, PMU context for guest need switch on. Now KVM_REQ_PMU notification is set on vcpu context switch, however it is missing if there is no vcpu context switch and PMU is used by guest VM.

Fixes: f4e40ea9f78f ("LoongArch: KVM: Add PMU support for guest") Cc: stable@vger.kernel.org

Signed-off-by: Bibo Mao maobibo@loongson.cn --- arch/loongarch/kvm/vcpu.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c index 30e3b089a596..bf56ad29ac15 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -132,6 +132,9 @@ static void kvm_lose_pmu(struct kvm_vcpu *vcpu) * Clear KVM_LARCH_PMU if the guest is not using PMU CSRs when * exiting the guest, so that the next time trap into the guest. * We don't need to deal with PMU CSRs contexts. + * + * Otherwise set request bit KVM_REQ_PMU to restore guest PMU + * before entering guest VM */ val = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL0); val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL1); @@ -139,6 +142,8 @@ static void kvm_lose_pmu(struct kvm_vcpu *vcpu) val |= kvm_read_sw_gcsr(csr, LOONGARCH_CSR_PERFCTRL3); if (!(val & KVM_PMU_EVENT_ENABLED)) vcpu->arch.aux_inuse &= ~KVM_LARCH_PMU; + else + kvm_make_request(KVM_REQ_PMU, vcpu);

kvm_restore_host_pmu(vcpu); }