From 70c130b1cfa5d59737379d2fa4b3c5c91bf36ca2 Mon Sep 17 00:00:00 2001 From: Bibo Mao Date: Sun, 9 Nov 2025 16:02:09 +0800 Subject: [PATCH] LoongArch: KVM: Restore guest PMU if it is enabled commit 5001bcf86edf2de02f025a0f789bcac37fa040e6 upstream. On LoongArch system, guest PMU hardware is shared by guest and host but 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, if it is enabled, PMU context for guest need switch on. Now KVM_REQ_PMU notification is set on vCPU context switch, but it is missing if there is no vCPU context switch while PMU is used by guest VM, so fix it. Cc: Fixes: f4e40ea9f78f ("LoongArch: KVM: Add PMU support for guest") Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman --- 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 b5439a10b765..fffea69191f7 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -127,6 +127,9 @@ 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 the 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); @@ -134,6 +137,8 @@ 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); }