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LoongArch: KVM: Add FPU/LBT delay load support

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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 <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Bibo Mao 2026-02-06 09:28:00 +08:00 committed by Huacai Chen
parent b1388a9598
commit 382c38c9ec
3 changed files with 37 additions and 19 deletions
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2
arch/loongarch/include/asm/kvm_host.h
View File

@ -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;

21
arch/loongarch/kvm/exit.c
View File

@ -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;
}

33
arch/loongarch/kvm/vcpu.c
View File

@ -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;
}