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KVM: x86: use hardware-compatible format for APIC ID register
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We currently always shift APIC ID as if APIC was in xAPIC mode.
x2APIC mode wants to use more bits and storing a hardware-compabible
value is the the sanest option.

KVM API to set the lapic expects that bottom 8 bits of APIC ID are in
top 8 bits of APIC_ID register, so the register needs to be shifted in
x2APIC mode.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@rkrcmar @bonzini
rkrcmar authored and bonzini committed Jul 14, 2016
1 parent 3159d36 commit a92e254
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Showing 3 changed files with 52 additions and 22 deletions.
52 changes: 37 additions & 15 deletions arch/x86/kvm/lapic.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -227,7 +227,7 @@ static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
}
}

static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
static inline void kvm_apic_set_xapic_id(struct kvm_lapic *apic, u8 id)
{
kvm_lapic_set_reg(apic, APIC_ID, id << 24);
recalculate_apic_map(apic->vcpu->kvm);
Expand All @@ -239,11 +239,11 @@ static inline void kvm_apic_set_ldr(struct kvm_lapic *apic, u32 id)
recalculate_apic_map(apic->vcpu->kvm);
}

static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u8 id)
static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u32 id)
{
u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));

kvm_lapic_set_reg(apic, APIC_ID, id << 24);
kvm_lapic_set_reg(apic, APIC_ID, id);
kvm_lapic_set_reg(apic, APIC_LDR, ldr);
recalculate_apic_map(apic->vcpu->kvm);
}
Expand Down Expand Up @@ -1102,12 +1102,6 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset)
return 0;

switch (offset) {
case APIC_ID:
if (apic_x2apic_mode(apic))
val = kvm_apic_id(apic);
else
val = kvm_apic_id(apic) << 24;
break;
case APIC_ARBPRI:
apic_debug("Access APIC ARBPRI register which is for P6\n");
break;
Expand Down Expand Up @@ -1465,7 +1459,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
switch (reg) {
case APIC_ID: /* Local APIC ID */
if (!apic_x2apic_mode(apic))
kvm_apic_set_id(apic, val >> 24);
kvm_apic_set_xapic_id(apic, val >> 24);
else
ret = 1;
break;
Expand Down Expand Up @@ -1769,7 +1763,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
hrtimer_cancel(&apic->lapic_timer.timer);

if (!init_event)
kvm_apic_set_id(apic, vcpu->vcpu_id);
kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
kvm_apic_set_version(apic->vcpu);

for (i = 0; i < KVM_APIC_LVT_NUM; i++)
Expand Down Expand Up @@ -1990,17 +1984,43 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
return vector;
}

void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s, bool set)
{
if (apic_x2apic_mode(vcpu->arch.apic)) {
u32 *id = (u32 *)(s->regs + APIC_ID);

if (set)
*id >>= 24;
else
*id <<= 24;
}

return 0;
}

int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
{
memcpy(s->regs, vcpu->arch.apic->regs, sizeof(*s));
return kvm_apic_state_fixup(vcpu, s, false);
}

int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
{
struct kvm_lapic *apic = vcpu->arch.apic;
int r;


kvm_lapic_set_base(vcpu, vcpu->arch.apic_base);
/* set SPIV separately to get count of SW disabled APICs right */
apic_set_spiv(apic, *((u32 *)(s->regs + APIC_SPIV)));

r = kvm_apic_state_fixup(vcpu, s, true);
if (r)
return r;
memcpy(vcpu->arch.apic->regs, s->regs, sizeof *s);
/* call kvm_apic_set_id() to put apic into apic_map */
kvm_apic_set_id(apic, kvm_apic_id(apic));

recalculate_apic_map(vcpu->kvm);
kvm_apic_set_version(vcpu);

apic_update_ppr(apic);
Expand All @@ -2026,6 +2046,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
kvm_rtc_eoi_tracking_restore_one(vcpu);

vcpu->arch.apic_arb_prio = 0;

return 0;
}

void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
Expand Down
12 changes: 9 additions & 3 deletions arch/x86/kvm/lapic.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -81,8 +81,8 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,

u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s);
int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);

u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
Expand Down Expand Up @@ -202,7 +202,13 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)

static inline u32 kvm_apic_id(struct kvm_lapic *apic)
{
return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;
/* To avoid a race between apic_base and following APIC_ID update when
* switching to x2apic_mode, the x2apic mode returns initial x2apic id.
*/
if (apic_x2apic_mode(apic))
return apic->vcpu->vcpu_id;

return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
}

bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
Expand Down
10 changes: 6 additions & 4 deletions arch/x86/kvm/x86.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2779,15 +2779,17 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
if (vcpu->arch.apicv_active)
kvm_x86_ops->sync_pir_to_irr(vcpu);

memcpy(s->regs, vcpu->arch.apic->regs, sizeof *s);

return 0;
return kvm_apic_get_state(vcpu, s);
}

static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
struct kvm_lapic_state *s)
{
kvm_apic_post_state_restore(vcpu, s);
int r;

r = kvm_apic_set_state(vcpu, s);
if (r)
return r;
update_cr8_intercept(vcpu);

return 0;
Expand Down

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