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rkrcmarbonzini
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KVM: x86: use hardware-compatible format for APIC ID register
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 <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
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3 files changed

+52
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lines changed

arch/x86/kvm/lapic.c

Lines changed: 37 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -227,7 +227,7 @@ static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
227227
}
228228
}
229229

230-
static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
230+
static inline void kvm_apic_set_xapic_id(struct kvm_lapic *apic, u8 id)
231231
{
232232
kvm_lapic_set_reg(apic, APIC_ID, id << 24);
233233
recalculate_apic_map(apic->vcpu->kvm);
@@ -239,11 +239,11 @@ static inline void kvm_apic_set_ldr(struct kvm_lapic *apic, u32 id)
239239
recalculate_apic_map(apic->vcpu->kvm);
240240
}
241241

242-
static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u8 id)
242+
static inline void kvm_apic_set_x2apic_id(struct kvm_lapic *apic, u32 id)
243243
{
244244
u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
245245

246-
kvm_lapic_set_reg(apic, APIC_ID, id << 24);
246+
kvm_lapic_set_reg(apic, APIC_ID, id);
247247
kvm_lapic_set_reg(apic, APIC_LDR, ldr);
248248
recalculate_apic_map(apic->vcpu->kvm);
249249
}
@@ -1102,12 +1102,6 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset)
11021102
return 0;
11031103

11041104
switch (offset) {
1105-
case APIC_ID:
1106-
if (apic_x2apic_mode(apic))
1107-
val = kvm_apic_id(apic);
1108-
else
1109-
val = kvm_apic_id(apic) << 24;
1110-
break;
11111105
case APIC_ARBPRI:
11121106
apic_debug("Access APIC ARBPRI register which is for P6\n");
11131107
break;
@@ -1465,7 +1459,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
14651459
switch (reg) {
14661460
case APIC_ID: /* Local APIC ID */
14671461
if (!apic_x2apic_mode(apic))
1468-
kvm_apic_set_id(apic, val >> 24);
1462+
kvm_apic_set_xapic_id(apic, val >> 24);
14691463
else
14701464
ret = 1;
14711465
break;
@@ -1769,7 +1763,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
17691763
hrtimer_cancel(&apic->lapic_timer.timer);
17701764

17711765
if (!init_event)
1772-
kvm_apic_set_id(apic, vcpu->vcpu_id);
1766+
kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
17731767
kvm_apic_set_version(apic->vcpu);
17741768

17751769
for (i = 0; i < KVM_APIC_LVT_NUM; i++)
@@ -1990,17 +1984,43 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
19901984
return vector;
19911985
}
19921986

1993-
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
1994-
struct kvm_lapic_state *s)
1987+
static int kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
1988+
struct kvm_lapic_state *s, bool set)
1989+
{
1990+
if (apic_x2apic_mode(vcpu->arch.apic)) {
1991+
u32 *id = (u32 *)(s->regs + APIC_ID);
1992+
1993+
if (set)
1994+
*id >>= 24;
1995+
else
1996+
*id <<= 24;
1997+
}
1998+
1999+
return 0;
2000+
}
2001+
2002+
int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
2003+
{
2004+
memcpy(s->regs, vcpu->arch.apic->regs, sizeof(*s));
2005+
return kvm_apic_state_fixup(vcpu, s, false);
2006+
}
2007+
2008+
int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
19952009
{
19962010
struct kvm_lapic *apic = vcpu->arch.apic;
2011+
int r;
2012+
19972013

19982014
kvm_lapic_set_base(vcpu, vcpu->arch.apic_base);
19992015
/* set SPIV separately to get count of SW disabled APICs right */
20002016
apic_set_spiv(apic, *((u32 *)(s->regs + APIC_SPIV)));
2017+
2018+
r = kvm_apic_state_fixup(vcpu, s, true);
2019+
if (r)
2020+
return r;
20012021
memcpy(vcpu->arch.apic->regs, s->regs, sizeof *s);
2002-
/* call kvm_apic_set_id() to put apic into apic_map */
2003-
kvm_apic_set_id(apic, kvm_apic_id(apic));
2022+
2023+
recalculate_apic_map(vcpu->kvm);
20042024
kvm_apic_set_version(vcpu);
20052025

20062026
apic_update_ppr(apic);
@@ -2026,6 +2046,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
20262046
kvm_rtc_eoi_tracking_restore_one(vcpu);
20272047

20282048
vcpu->arch.apic_arb_prio = 0;
2049+
2050+
return 0;
20292051
}
20302052

20312053
void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)

arch/x86/kvm/lapic.h

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -81,8 +81,8 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
8181

8282
u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
8383
int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
84-
void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
85-
struct kvm_lapic_state *s);
84+
int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
85+
int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
8686
int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
8787

8888
u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
@@ -202,7 +202,13 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)
202202

203203
static inline u32 kvm_apic_id(struct kvm_lapic *apic)
204204
{
205-
return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;
205+
/* To avoid a race between apic_base and following APIC_ID update when
206+
* switching to x2apic_mode, the x2apic mode returns initial x2apic id.
207+
*/
208+
if (apic_x2apic_mode(apic))
209+
return apic->vcpu->vcpu_id;
210+
211+
return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
206212
}
207213

208214
bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);

arch/x86/kvm/x86.c

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2779,15 +2779,17 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
27792779
if (vcpu->arch.apicv_active)
27802780
kvm_x86_ops->sync_pir_to_irr(vcpu);
27812781

2782-
memcpy(s->regs, vcpu->arch.apic->regs, sizeof *s);
2783-
2784-
return 0;
2782+
return kvm_apic_get_state(vcpu, s);
27852783
}
27862784

27872785
static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
27882786
struct kvm_lapic_state *s)
27892787
{
2790-
kvm_apic_post_state_restore(vcpu, s);
2788+
int r;
2789+
2790+
r = kvm_apic_set_state(vcpu, s);
2791+
if (r)
2792+
return r;
27912793
update_cr8_intercept(vcpu);
27922794

27932795
return 0;

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