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.
Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
Changes in v2:
- drop cmpxchg from INIT signaling
- rmb on SIPI processing
- reset sets all CPUs to 0xf000:0xfff0, RIP is fixed up on SIPI reception
arch/x86/include/asm/kvm_host.h | 3 +-
arch/x86/kvm/lapic.c | 48 +++++++++++++++++++++++++++-----
arch/x86/kvm/lapic.h | 11 +++++++
arch/x86/kvm/svm.c | 6 ----
arch/x86/kvm/vmx.c | 12 +-------
arch/x86/kvm/x86.c | 58 +++++++++++++++++++++++++-------------
6 files changed, 93 insertions(+), 45 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 348d859..ef7f4a5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 02b51dd..a8e9369 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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 */
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 1676d34..2c721b9 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -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
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 907e428..7219a40 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -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);
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f17cd2a..b73989d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b891ac3..a7e51ae 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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;
@@ -2823,10 +2821,9 @@ 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));
}
@@ -2857,8 +2854,9 @@ 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);
@@ -5713,6 +5711,12 @@ 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 */
@@ -5847,14 +5851,6 @@ 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) {
@@ -5871,8 +5867,8 @@ 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 =
@@ -5880,7 +5876,8 @@ 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;
@@ -6015,6 +6012,7 @@ 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;
@@ -6171,6 +6169,7 @@ 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;
}
@@ -6178,7 +6177,15 @@ 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;
}
@@ -6515,7 +6522,7 @@ 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;
@@ -6545,6 +6552,17 @@ 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;
@@ -6988,7 +7006,7 @@ 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));
--
1.7.3.4
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