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KVM: x86: Rework INIT and SIPI handling 

A VCPU sending INIT or SIPI to some other VCPU races for setting the
remote VCPU's mp_state. When we were unlucky, KVM_MP_STATE_INIT_RECEIVED
was overwritten by kvm_emulate_halt and, thus, got lost.

This introduces APIC events for those two signals, keeping them in
kvm_apic until kvm_apic_accept_events is run over the target vcpu
context. kvm_apic_has_events reports to kvm_arch_vcpu_runnable if there
are pending events, thus if vcpu blocking should end.

The patch comes with the side effect of effectively obsoleting
KVM_MP_STATE_SIPI_RECEIVED. We still accept it from user space, but
immediately translate it to KVM_MP_STATE_INIT_RECEIVED + KVM_APIC_SIPI.
The vcpu itself will no longer enter the KVM_MP_STATE_SIPI_RECEIVED
state. That also means we no longer exit to user space after receiving a
SIPI event.

Furthermore, we already reset the VCPU on INIT, only fixing up the code
segment later on when SIPI arrives. Moreover, we fix INIT handling for
the BSP: it never enter wait-for-SIPI but directly starts over on INIT.

Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Jan Kiszka 2013-03-13 12:42:34 +01:00 committed by Gleb Natapov
parent 5d21881432
commit 66450a21f9
6 changed files with 93 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/include/asm/kvm_host.h
View File

@ -345,7 +345,6 @@ struct kvm_vcpu_arch {
unsigned long apic_attention;
int32_t apic_arb_prio;
int mp_state;
int sipi_vector;
u64 ia32_misc_enable_msr;
bool tpr_access_reporting;
@ -819,6 +818,7 @@ int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu);
void kvm_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);
int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector, int seg);
void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, unsigned int vector);
int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
int reason, bool has_error_code, u32 error_code);
@ -1002,6 +1002,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v);
int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
void kvm_vcpu_reset(struct kvm_vcpu *vcpu);
void kvm_define_shared_msr(unsigned index, u32 msr);
void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);

48
arch/x86/kvm/lapic.c
View File

@ -731,7 +731,11 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
case APIC_DM_INIT:
if (!trig_mode || level) {
result = 1;
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
/* assumes that there are only KVM_APIC_INIT/SIPI */
apic->pending_events = (1UL << KVM_APIC_INIT);
/* make sure pending_events is visible before sending
* the request */
smp_wmb();
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
} else {
@ -743,13 +747,13 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
case APIC_DM_STARTUP:
apic_debug("SIPI to vcpu %d vector 0x%02x\n",
vcpu->vcpu_id, vector);
if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
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);
}
result = 1;
apic->sipi_vector = vector;
/* make sure sipi_vector is visible for the receiver */
smp_wmb();
set_bit(KVM_APIC_SIPI, &apic->pending_events);
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
break;
case APIC_DM_EXTINT:
@ -1860,6 +1864,34 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
addr);
}
void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
unsigned int sipi_vector;
if (!kvm_vcpu_has_lapic(vcpu))
return;
if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events)) {
kvm_lapic_reset(vcpu);
kvm_vcpu_reset(vcpu);
if (kvm_vcpu_is_bsp(apic->vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
else
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
}
if (test_and_clear_bit(KVM_APIC_SIPI, &apic->pending_events) &&
vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
/* evaluate pending_events before reading the vector */
smp_rmb();
sipi_vector = apic->sipi_vector;
pr_debug("vcpu %d received sipi with vector # %x\n",
vcpu->vcpu_id, sipi_vector);
kvm_vcpu_deliver_sipi_vector(vcpu, sipi_vector);
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
}
}
void kvm_lapic_init(void)
{
/* do not patch jump label more than once per second */

11
arch/x86/kvm/lapic.h
View File

@ -5,6 +5,9 @@
#include <linux/kvm_host.h>
#define KVM_APIC_INIT 0
#define KVM_APIC_SIPI 1
struct kvm_timer {
struct hrtimer timer;
s64 period; /* unit: ns */
@ -32,6 +35,8 @@ struct kvm_lapic {
void *regs;
gpa_t vapic_addr;
struct page *vapic_page;
unsigned long pending_events;
unsigned int sipi_vector;
};
int kvm_create_lapic(struct kvm_vcpu *vcpu);
void kvm_free_lapic(struct kvm_vcpu *vcpu);
@ -39,6 +44,7 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu);
int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu);
int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu);
int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu);
void kvm_apic_accept_events(struct kvm_vcpu *vcpu);
void kvm_lapic_reset(struct kvm_vcpu *vcpu);
u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu);
void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8);
@ -158,4 +164,9 @@ void kvm_calculate_eoi_exitmap(struct kvm_vcpu *vcpu,
struct kvm_lapic_irq *irq,
u64 *eoi_bitmap);
static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu)
{
return vcpu->arch.apic->pending_events;
}
#endif

6
arch/x86/kvm/svm.c
View File

@ -1199,12 +1199,6 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu)
init_vmcb(svm);
if (!kvm_vcpu_is_bsp(vcpu)) {
kvm_rip_write(vcpu, 0);
svm->vmcb->save.cs.base = svm->vcpu.arch.sipi_vector << 12;
svm->vmcb->save.cs.selector = svm->vcpu.arch.sipi_vector << 8;
}
kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
}

12
arch/x86/kvm/vmx.c
View File

@ -4119,12 +4119,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
vmx_segment_cache_clear(vmx);
seg_setup(VCPU_SREG_CS);
if (kvm_vcpu_is_bsp(&vmx->vcpu))
vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
else {
vmcs_write16(GUEST_CS_SELECTOR, vmx->vcpu.arch.sipi_vector << 8);
vmcs_writel(GUEST_CS_BASE, vmx->vcpu.arch.sipi_vector << 12);
}
vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
seg_setup(VCPU_SREG_DS);
seg_setup(VCPU_SREG_ES);
@ -4147,10 +4142,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu)
vmcs_writel(GUEST_SYSENTER_EIP, 0);
vmcs_writel(GUEST_RFLAGS, 0x02);
if (kvm_vcpu_is_bsp(&vmx->vcpu))
kvm_rip_write(vcpu, 0xfff0);
else
kvm_rip_write(vcpu, 0);
kvm_rip_write(vcpu, 0xfff0);
vmcs_writel(GUEST_GDTR_BASE, 0);
vmcs_write32(GUEST_GDTR_LIMIT, 0xffff);

58
arch/x86/kvm/x86.c
View File

@ -162,8 +162,6 @@ u64 __read_mostly host_xcr0;
static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt);
static void kvm_vcpu_reset(struct kvm_vcpu *vcpu);
static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu)
{
int i;
@ -2830,10 +2828,9 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
events->nmi.masked = kvm_x86_ops->get_nmi_mask(vcpu);
events->nmi.pad = 0;
events->sipi_vector = vcpu->arch.sipi_vector;
events->sipi_vector = 0; /* never valid when reporting to user space */
events->flags = (KVM_VCPUEVENT_VALID_NMI_PENDING
| KVM_VCPUEVENT_VALID_SIPI_VECTOR
| KVM_VCPUEVENT_VALID_SHADOW);
memset(&events->reserved, 0, sizeof(events->reserved));
}
@ -2864,8 +2861,9 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
vcpu->arch.nmi_pending = events->nmi.pending;
kvm_x86_ops->set_nmi_mask(vcpu, events->nmi.masked);
if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR)
vcpu->arch.sipi_vector = events->sipi_vector;
if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR &&
kvm_vcpu_has_lapic(vcpu))
vcpu->arch.apic->sipi_vector = events->sipi_vector;
kvm_make_request(KVM_REQ_EVENT, vcpu);
@ -5720,6 +5718,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
}
if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
kvm_apic_accept_events(vcpu);
if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
r = 1;
goto out;
}
inject_pending_event(vcpu);
/* enable NMI/IRQ window open exits if needed */
@ -5854,14 +5858,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
int r;
struct kvm *kvm = vcpu->kvm;
if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) {
pr_debug("vcpu %d received sipi with vector # %x\n",
vcpu->vcpu_id, vcpu->arch.sipi_vector);
kvm_lapic_reset(vcpu);
kvm_vcpu_reset(vcpu);
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
}
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
r = vapic_enter(vcpu);
if (r) {
@ -5878,8 +5874,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
kvm_vcpu_block(vcpu);
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
if (kvm_check_request(KVM_REQ_UNHALT, vcpu))
{
if (kvm_check_request(KVM_REQ_UNHALT, vcpu)) {
kvm_apic_accept_events(vcpu);
switch(vcpu->arch.mp_state) {
case KVM_MP_STATE_HALTED:
vcpu->arch.mp_state =
@ -5887,7 +5883,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
case KVM_MP_STATE_RUNNABLE:
vcpu->arch.apf.halted = false;
break;
case KVM_MP_STATE_SIPI_RECEIVED:
case KVM_MP_STATE_INIT_RECEIVED:
break;
default:
r = -EINTR;
break;
@ -6022,6 +6019,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) {
kvm_vcpu_block(vcpu);
kvm_apic_accept_events(vcpu);
clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
r = -EAGAIN;
goto out;
@ -6178,6 +6176,7 @@ int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state)
{
kvm_apic_accept_events(vcpu);
mp_state->mp_state = vcpu->arch.mp_state;
return 0;
}
@ -6185,7 +6184,15 @@ int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
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;
if (!kvm_vcpu_has_lapic(vcpu) &&
mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
return -EINVAL;
if (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED) {
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
set_bit(KVM_APIC_SIPI, &vcpu->arch.apic->pending_events);
} else
vcpu->arch.mp_state = mp_state->mp_state;
kvm_make_request(KVM_REQ_EVENT, vcpu);
return 0;
}
@ -6522,7 +6529,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
kvm_x86_ops->vcpu_free(vcpu);
}
static void kvm_vcpu_reset(struct kvm_vcpu *vcpu)
void kvm_vcpu_reset(struct kvm_vcpu *vcpu)
{
atomic_set(&vcpu->arch.nmi_queued, 0);
vcpu->arch.nmi_pending = 0;
@ -6552,6 +6559,17 @@ static void kvm_vcpu_reset(struct kvm_vcpu *vcpu)
kvm_x86_ops->vcpu_reset(vcpu);
}
void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, unsigned int vector)
{
struct kvm_segment cs;
kvm_get_segment(vcpu, &cs, VCPU_SREG_CS);
cs.selector = vector << 8;
cs.base = vector << 12;
kvm_set_segment(vcpu, &cs, VCPU_SREG_CS);
kvm_rip_write(vcpu, 0);
}
int kvm_arch_hardware_enable(void *garbage)
{
struct kvm *kvm;
@ -6995,7 +7013,7 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
!vcpu->arch.apf.halted)
|| !list_empty_careful(&vcpu->async_pf.done)
|| vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED
|| kvm_apic_has_events(vcpu)
|| atomic_read(&vcpu->arch.nmi_queued) ||
(kvm_arch_interrupt_allowed(vcpu) &&
kvm_cpu_has_interrupt(vcpu));