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KVM: Check for pending events before attempting injection
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Instead of blindly attempting to inject an event before each guest entry,
check for a possible event first in vcpu->requests.  Sites that can trigger
event injection are modified to set KVM_REQ_EVENT:

- interrupt, nmi window opening
- ppr updates
- i8259 output changes
- local apic irr changes
- rflags updates
- gif flag set
- event set on exit

This improves non-injecting entry performance, and sets the stage for
non-atomic injection.

Signed-off-by: Avi Kivity <avi@redhat.com>
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@avikivity
avikivity committed Oct 24, 2010
1 parent b0bc3ee commit 3842d13
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Showing 6 changed files with 58 additions and 12 deletions.
1 change: 1 addition & 0 deletions arch/x86/kvm/i8259.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ static void pic_unlock(struct kvm_pic *s)
if (!found)
return;

kvm_make_request(KVM_REQ_EVENT, found);
kvm_vcpu_kick(found);
}
}
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13 changes: 11 additions & 2 deletions arch/x86/kvm/lapic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -259,9 +259,10 @@ static inline int apic_find_highest_isr(struct kvm_lapic *apic)

static void apic_update_ppr(struct kvm_lapic *apic)
{
u32 tpr, isrv, ppr;
u32 tpr, isrv, ppr, old_ppr;
int isr;

old_ppr = apic_get_reg(apic, APIC_PROCPRI);
tpr = apic_get_reg(apic, APIC_TASKPRI);
isr = apic_find_highest_isr(apic);
isrv = (isr != -1) ? isr : 0;
Expand All @@ -274,7 +275,10 @@ static void apic_update_ppr(struct kvm_lapic *apic)
apic_debug("vlapic %p, ppr 0x%x, isr 0x%x, isrv 0x%x",
apic, ppr, isr, isrv);

apic_set_reg(apic, APIC_PROCPRI, ppr);
if (old_ppr != ppr) {
apic_set_reg(apic, APIC_PROCPRI, ppr);
kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
}
}

static void apic_set_tpr(struct kvm_lapic *apic, u32 tpr)
Expand Down Expand Up @@ -391,6 +395,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
break;
}

kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
break;

Expand All @@ -416,6 +421,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
"INIT on a runnable vcpu %d\n",
vcpu->vcpu_id);
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
} else {
apic_debug("Ignoring de-assert INIT to vcpu %d\n",
Expand All @@ -430,6 +436,7 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
result = 1;
vcpu->arch.sipi_vector = vector;
vcpu->arch.mp_state = KVM_MP_STATE_SIPI_RECEIVED;
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
}
break;
Expand Down Expand Up @@ -475,6 +482,7 @@ static void apic_set_eoi(struct kvm_lapic *apic)
trigger_mode = IOAPIC_EDGE_TRIG;
if (!(apic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI))
kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
}

static void apic_send_ipi(struct kvm_lapic *apic)
Expand Down Expand Up @@ -1152,6 +1160,7 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu)
update_divide_count(apic);
start_apic_timer(apic);
apic->irr_pending = true;
kvm_make_request(KVM_REQ_EVENT, vcpu);
}

void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
Expand Down
8 changes: 7 additions & 1 deletion arch/x86/kvm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2371,6 +2371,7 @@ static int stgi_interception(struct vcpu_svm *svm)

svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
skip_emulated_instruction(&svm->vcpu);
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);

enable_gif(svm);

Expand Down Expand Up @@ -2763,6 +2764,7 @@ static int interrupt_window_interception(struct vcpu_svm *svm)
{
struct kvm_run *kvm_run = svm->vcpu.run;

kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
svm_clear_vintr(svm);
svm->vmcb->control.int_ctl &= ~V_IRQ_MASK;
/*
Expand Down Expand Up @@ -3209,8 +3211,10 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)

svm->int3_injected = 0;

if (svm->vcpu.arch.hflags & HF_IRET_MASK)
if (svm->vcpu.arch.hflags & HF_IRET_MASK) {
svm->vcpu.arch.hflags &= ~(HF_NMI_MASK | HF_IRET_MASK);
kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
}

svm->vcpu.arch.nmi_injected = false;
kvm_clear_exception_queue(&svm->vcpu);
Expand All @@ -3219,6 +3223,8 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
if (!(exitintinfo & SVM_EXITINTINFO_VALID))
return;

kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);

vector = exitintinfo & SVM_EXITINTINFO_VEC_MASK;
type = exitintinfo & SVM_EXITINTINFO_TYPE_MASK;

Expand Down
6 changes: 6 additions & 0 deletions arch/x86/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3327,6 +3327,7 @@ static int handle_wrmsr(struct kvm_vcpu *vcpu)

static int handle_tpr_below_threshold(struct kvm_vcpu *vcpu)
{
kvm_make_request(KVM_REQ_EVENT, vcpu);
return 1;
}

Expand All @@ -3339,6 +3340,8 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu)
cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);

kvm_make_request(KVM_REQ_EVENT, vcpu);

++vcpu->stat.irq_window_exits;

/*
Expand Down Expand Up @@ -3595,6 +3598,7 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu)
cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;
vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
++vcpu->stat.nmi_window_exits;
kvm_make_request(KVM_REQ_EVENT, vcpu);

return 1;
}
Expand Down Expand Up @@ -3828,6 +3832,8 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
if (!idtv_info_valid)
return;

kvm_make_request(KVM_REQ_EVENT, &vmx->vcpu);

vector = idt_vectoring_info & VECTORING_INFO_VECTOR_MASK;
type = idt_vectoring_info & VECTORING_INFO_TYPE_MASK;

Expand Down
41 changes: 32 additions & 9 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,8 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
u32 prev_nr;
int class1, class2;

kvm_make_request(KVM_REQ_EVENT, vcpu);

if (!vcpu->arch.exception.pending) {
queue:
vcpu->arch.exception.pending = true;
Expand Down Expand Up @@ -356,6 +358,7 @@ void kvm_propagate_fault(struct kvm_vcpu *vcpu)

void kvm_inject_nmi(struct kvm_vcpu *vcpu)
{
kvm_make_request(KVM_REQ_EVENT, vcpu);
vcpu->arch.nmi_pending = 1;
}
EXPORT_SYMBOL_GPL(kvm_inject_nmi);
Expand Down Expand Up @@ -2418,6 +2421,7 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
return -ENXIO;

kvm_queue_interrupt(vcpu, irq->irq, false);
kvm_make_request(KVM_REQ_EVENT, vcpu);

return 0;
}
Expand Down Expand Up @@ -2571,6 +2575,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)
vcpu->arch.sipi_vector = events->sipi_vector;

kvm_make_request(KVM_REQ_EVENT, vcpu);

return 0;
}

Expand Down Expand Up @@ -4329,6 +4335,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,

toggle_interruptibility(vcpu, vcpu->arch.emulate_ctxt.interruptibility);
kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
kvm_make_request(KVM_REQ_EVENT, vcpu);
memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);

Expand Down Expand Up @@ -4998,6 +5005,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
int r;
bool req_int_win = !irqchip_in_kernel(vcpu->kvm) &&
vcpu->run->request_interrupt_window;
bool req_event;

if (vcpu->requests) {
if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu))
Expand Down Expand Up @@ -5045,8 +5053,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)

local_irq_disable();

req_event = kvm_check_request(KVM_REQ_EVENT, vcpu);

if (!atomic_read(&vcpu->guest_mode) || vcpu->requests
|| need_resched() || signal_pending(current)) {
if (req_event)
kvm_make_request(KVM_REQ_EVENT, vcpu);
atomic_set(&vcpu->guest_mode, 0);
smp_wmb();
local_irq_enable();
Expand All @@ -5055,17 +5067,19 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
goto out;
}

inject_pending_event(vcpu);
if (req_event || req_int_win) {
inject_pending_event(vcpu);

/* enable NMI/IRQ window open exits if needed */
if (vcpu->arch.nmi_pending)
kvm_x86_ops->enable_nmi_window(vcpu);
else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
kvm_x86_ops->enable_irq_window(vcpu);
/* enable NMI/IRQ window open exits if needed */
if (vcpu->arch.nmi_pending)
kvm_x86_ops->enable_nmi_window(vcpu);
else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
kvm_x86_ops->enable_irq_window(vcpu);

if (kvm_lapic_enabled(vcpu)) {
update_cr8_intercept(vcpu);
kvm_lapic_sync_to_vapic(vcpu);
if (kvm_lapic_enabled(vcpu)) {
update_cr8_intercept(vcpu);
kvm_lapic_sync_to_vapic(vcpu);
}
}

srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
Expand Down Expand Up @@ -5305,6 +5319,8 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)

vcpu->arch.exception.pending = false;

kvm_make_request(KVM_REQ_EVENT, vcpu);

return 0;
}

Expand Down Expand Up @@ -5368,6 +5384,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
vcpu->arch.mp_state = mp_state->mp_state;
kvm_make_request(KVM_REQ_EVENT, vcpu);
return 0;
}

Expand All @@ -5389,6 +5406,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,
memcpy(vcpu->arch.regs, c->regs, sizeof c->regs);
kvm_rip_write(vcpu, vcpu->arch.emulate_ctxt.eip);
kvm_x86_ops->set_rflags(vcpu, vcpu->arch.emulate_ctxt.eflags);
kvm_make_request(KVM_REQ_EVENT, vcpu);
return EMULATE_DONE;
}
EXPORT_SYMBOL_GPL(kvm_task_switch);
Expand Down Expand Up @@ -5459,6 +5477,8 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
!is_protmode(vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

kvm_make_request(KVM_REQ_EVENT, vcpu);

return 0;
}

Expand Down Expand Up @@ -5691,6 +5711,8 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
vcpu->arch.dr6 = DR6_FIXED_1;
vcpu->arch.dr7 = DR7_FIXED_1;

kvm_make_request(KVM_REQ_EVENT, vcpu);

return kvm_x86_ops->vcpu_reset(vcpu);
}

Expand Down Expand Up @@ -6001,6 +6023,7 @@ void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
kvm_is_linear_rip(vcpu, vcpu->arch.singlestep_rip))
rflags |= X86_EFLAGS_TF;
kvm_x86_ops->set_rflags(vcpu, rflags);
kvm_make_request(KVM_REQ_EVENT, vcpu);
}
EXPORT_SYMBOL_GPL(kvm_set_rflags);

Expand Down
1 change: 1 addition & 0 deletions include/linux/kvm_host.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@
#define KVM_REQ_KVMCLOCK_UPDATE 8
#define KVM_REQ_KICK 9
#define KVM_REQ_DEACTIVATE_FPU 10
#define KVM_REQ_EVENT 11

#define KVM_USERSPACE_IRQ_SOURCE_ID 0

Expand Down

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