From: Bibo Mao Date: Fri, 6 Feb 2026 01:28:00 +0000 (+0800) Subject: LoongArch: KVM: Add FPU/LBT delay load support X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=382c38c9ec94fe87ffd6c9b456fa8ce67943cf1b;p=thirdparty%2Fkernel%2Fstable.git LoongArch: KVM: Add FPU/LBT delay load support FPU/LBT are lazy enabled with KVM hypervisor. After FPU/LBT enabled and loaded, vCPU can be preempted and FPU/LBT will be lost again, there will be unnecessary FPU/LBT exceptions, load and store stuff. Here delay the FPU/LBT load until the guest entry. Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen --- diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h index bced2d607849..4a7e816fae84 100644 --- a/arch/loongarch/include/asm/kvm_host.h +++ b/arch/loongarch/include/asm/kvm_host.h @@ -37,6 +37,7 @@ #define KVM_REQ_TLB_FLUSH_GPA KVM_ARCH_REQ(0) #define KVM_REQ_STEAL_UPDATE KVM_ARCH_REQ(1) #define KVM_REQ_PMU KVM_ARCH_REQ(2) +#define KVM_REQ_AUX_LOAD KVM_ARCH_REQ(3) #define KVM_GUESTDBG_SW_BP_MASK \ (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP) @@ -200,6 +201,7 @@ struct kvm_vcpu_arch { /* Which auxiliary state is loaded (KVM_LARCH_*) */ unsigned int aux_inuse; + unsigned int aux_ldtype; /* FPU state */ struct loongarch_fpu fpu FPU_ALIGN; diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c index 65ec10a7245a..da0ad89f2eb7 100644 --- a/arch/loongarch/kvm/exit.c +++ b/arch/loongarch/kvm/exit.c @@ -754,7 +754,8 @@ static int kvm_handle_fpu_disabled(struct kvm_vcpu *vcpu, int ecode) return RESUME_HOST; } - kvm_own_fpu(vcpu); + vcpu->arch.aux_ldtype = KVM_LARCH_FPU; + kvm_make_request(KVM_REQ_AUX_LOAD, vcpu); return RESUME_GUEST; } @@ -794,8 +795,10 @@ static int kvm_handle_lsx_disabled(struct kvm_vcpu *vcpu, int ecode) { if (!kvm_guest_has_lsx(&vcpu->arch)) kvm_queue_exception(vcpu, EXCCODE_INE, 0); - else - kvm_own_lsx(vcpu); + else { + vcpu->arch.aux_ldtype = KVM_LARCH_LSX; + kvm_make_request(KVM_REQ_AUX_LOAD, vcpu); + } return RESUME_GUEST; } @@ -812,8 +815,10 @@ static int kvm_handle_lasx_disabled(struct kvm_vcpu *vcpu, int ecode) { if (!kvm_guest_has_lasx(&vcpu->arch)) kvm_queue_exception(vcpu, EXCCODE_INE, 0); - else - kvm_own_lasx(vcpu); + else { + vcpu->arch.aux_ldtype = KVM_LARCH_LASX; + kvm_make_request(KVM_REQ_AUX_LOAD, vcpu); + } return RESUME_GUEST; } @@ -822,8 +827,10 @@ static int kvm_handle_lbt_disabled(struct kvm_vcpu *vcpu, int ecode) { if (!kvm_guest_has_lbt(&vcpu->arch)) kvm_queue_exception(vcpu, EXCCODE_INE, 0); - else - kvm_own_lbt(vcpu); + else { + vcpu->arch.aux_ldtype = KVM_LARCH_LBT; + kvm_make_request(KVM_REQ_AUX_LOAD, vcpu); + } return RESUME_GUEST; } diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c index 07c427a5e156..4f0d10f52b99 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -232,6 +232,27 @@ static void kvm_late_check_requests(struct kvm_vcpu *vcpu) kvm_flush_tlb_gpa(vcpu, vcpu->arch.flush_gpa); vcpu->arch.flush_gpa = INVALID_GPA; } + + if (kvm_check_request(KVM_REQ_AUX_LOAD, vcpu)) { + switch (vcpu->arch.aux_ldtype) { + case KVM_LARCH_FPU: + kvm_own_fpu(vcpu); + break; + case KVM_LARCH_LSX: + kvm_own_lsx(vcpu); + break; + case KVM_LARCH_LASX: + kvm_own_lasx(vcpu); + break; + case KVM_LARCH_LBT: + kvm_own_lbt(vcpu); + break; + default: + break; + } + + vcpu->arch.aux_ldtype = 0; + } } /* @@ -1304,13 +1325,11 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu) #ifdef CONFIG_CPU_HAS_LBT int kvm_own_lbt(struct kvm_vcpu *vcpu) { - preempt_disable(); if (!(vcpu->arch.aux_inuse & KVM_LARCH_LBT)) { set_csr_euen(CSR_EUEN_LBTEN); _restore_lbt(&vcpu->arch.lbt); vcpu->arch.aux_inuse |= KVM_LARCH_LBT; } - preempt_enable(); return 0; } @@ -1353,8 +1372,6 @@ static inline void kvm_check_fcsr_alive(struct kvm_vcpu *vcpu) { } /* Enable FPU and restore context */ void kvm_own_fpu(struct kvm_vcpu *vcpu) { - preempt_disable(); - /* * Enable FPU for guest * Set FR and FRE according to guest context @@ -1365,16 +1382,12 @@ void kvm_own_fpu(struct kvm_vcpu *vcpu) kvm_restore_fpu(&vcpu->arch.fpu); vcpu->arch.aux_inuse |= KVM_LARCH_FPU; trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_FPU); - - preempt_enable(); } #ifdef CONFIG_CPU_HAS_LSX /* Enable LSX and restore context */ int kvm_own_lsx(struct kvm_vcpu *vcpu) { - preempt_disable(); - /* Enable LSX for guest */ kvm_check_fcsr(vcpu, vcpu->arch.fpu.fcsr); set_csr_euen(CSR_EUEN_LSXEN | CSR_EUEN_FPEN); @@ -1396,7 +1409,6 @@ int kvm_own_lsx(struct kvm_vcpu *vcpu) trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_LSX); vcpu->arch.aux_inuse |= KVM_LARCH_LSX | KVM_LARCH_FPU; - preempt_enable(); return 0; } @@ -1406,8 +1418,6 @@ int kvm_own_lsx(struct kvm_vcpu *vcpu) /* Enable LASX and restore context */ int kvm_own_lasx(struct kvm_vcpu *vcpu) { - preempt_disable(); - kvm_check_fcsr(vcpu, vcpu->arch.fpu.fcsr); set_csr_euen(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN); switch (vcpu->arch.aux_inuse & (KVM_LARCH_FPU | KVM_LARCH_LSX)) { @@ -1429,7 +1439,6 @@ int kvm_own_lasx(struct kvm_vcpu *vcpu) trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_LASX); vcpu->arch.aux_inuse |= KVM_LARCH_LASX | KVM_LARCH_LSX | KVM_LARCH_FPU; - preempt_enable(); return 0; }