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KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to l…
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…apic.

This patch calculates the number of lvt entries as part of
KVM_X86_MCE_SETUP conditioned on the presence of MCG_CMCI_P bit in
MCG_CAP and stores result in kvm_lapic. It translats from APIC_LVTx
register to index in lapic_lvt_entry enum. It extends the APIC_LVTx
macro as well as other lapic write/reset handling etc to support
Corrected Machine Check Interrupt.

Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-5-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Jue Wang authored and Paolo Bonzini committed Jun 24, 2022
1 parent 987f625 commit 4b90356
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Showing 3 changed files with 39 additions and 16 deletions.
49 changes: 34 additions & 15 deletions arch/x86/kvm/lapic.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
#include <linux/math64.h>
#include <linux/slab.h>
#include <asm/processor.h>
#include <asm/mce.h>
#include <asm/msr.h>
#include <asm/page.h>
#include <asm/current.h>
Expand Down Expand Up @@ -399,14 +400,21 @@ static inline int apic_lvt_nmi_mode(u32 lvt_val)
return (lvt_val & (APIC_MODE_MASK | APIC_LVT_MASKED)) == APIC_DM_NMI;
}

static inline bool kvm_lapic_lvt_supported(struct kvm_lapic *apic, int lvt_index)
{
return apic->nr_lvt_entries > lvt_index;
}

void kvm_apic_set_version(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
u32 v = APIC_VERSION | ((KVM_APIC_MAX_NR_LVT_ENTRIES - 1) << 16);
u32 v = 0;

if (!lapic_in_kernel(vcpu))
return;

v = APIC_VERSION | ((apic->nr_lvt_entries - 1) << 16);

/*
* KVM emulates 82093AA datasheet (with in-kernel IOAPIC implementation)
* which doesn't have EOI register; Some buggy OSes (e.g. Windows with
Expand All @@ -426,7 +434,8 @@ static const unsigned int apic_lvt_mask[KVM_APIC_MAX_NR_LVT_ENTRIES] = {
[LVT_PERFORMANCE_COUNTER] = LVT_MASK | APIC_MODE_MASK,
[LVT_LINT0] = LINT_MASK,
[LVT_LINT1] = LINT_MASK,
[LVT_ERROR] = LVT_MASK
[LVT_ERROR] = LVT_MASK,
[LVT_CMCI] = LVT_MASK | APIC_MODE_MASK
};

static int find_highest_vector(void *bitmap)
Expand Down Expand Up @@ -1436,6 +1445,9 @@ static int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len,
APIC_REG_MASK(APIC_TMCCT) |
APIC_REG_MASK(APIC_TDCR);

if (kvm_lapic_lvt_supported(apic, LVT_CMCI))
valid_reg_mask |= APIC_REG_MASK(APIC_LVTCMCI);

/*
* ARBPRI and ICR2 are not valid in x2APIC mode. WARN if KVM reads ICR
* in x2APIC mode as it's an 8-byte register in x2APIC and needs to be
Expand Down Expand Up @@ -2044,6 +2056,16 @@ static void kvm_lapic_xapic_id_updated(struct kvm_lapic *apic)
kvm_set_apicv_inhibit(apic->vcpu->kvm, APICV_INHIBIT_REASON_APIC_ID_MODIFIED);
}

static int get_lvt_index(u32 reg)
{
if (reg == APIC_LVTCMCI)
return LVT_CMCI;
if (reg < APIC_LVTT || reg > APIC_LVTERR)
return -1;
return array_index_nospec(
(reg - APIC_LVTT) >> 4, KVM_APIC_MAX_NR_LVT_ENTRIES);
}

static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
{
int ret = 0;
Expand Down Expand Up @@ -2090,12 +2112,10 @@ static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
apic_set_spiv(apic, val & mask);
if (!(val & APIC_SPIV_APIC_ENABLED)) {
int i;
u32 lvt_val;

for (i = 0; i < KVM_APIC_MAX_NR_LVT_ENTRIES; i++) {
lvt_val = kvm_lapic_get_reg(apic, APIC_LVTx(i));
for (i = 0; i < apic->nr_lvt_entries; i++) {
kvm_lapic_set_reg(apic, APIC_LVTx(i),
lvt_val | APIC_LVT_MASKED);
kvm_lapic_get_reg(apic, APIC_LVTx(i)) | APIC_LVT_MASKED);
}
apic_update_lvtt(apic);
atomic_set(&apic->lapic_timer.pending, 0);
Expand Down Expand Up @@ -2124,16 +2144,15 @@ static int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
case APIC_LVTTHMR:
case APIC_LVTPC:
case APIC_LVT1:
case APIC_LVTERR: {
/* TODO: Check vector */
size_t size;
u32 index;

case APIC_LVTERR:
case APIC_LVTCMCI: {
u32 index = get_lvt_index(reg);
if (!kvm_lapic_lvt_supported(apic, index)) {
ret = 1;
break;
}
if (!kvm_apic_sw_enabled(apic))
val |= APIC_LVT_MASKED;
size = ARRAY_SIZE(apic_lvt_mask);
index = array_index_nospec(
(reg - APIC_LVTT) >> 4, size);
val &= apic_lvt_mask[index];
kvm_lapic_set_reg(apic, reg, val);
break;
Expand Down Expand Up @@ -2409,7 +2428,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
kvm_apic_set_xapic_id(apic, vcpu->vcpu_id);
kvm_apic_set_version(apic->vcpu);

for (i = 0; i < KVM_APIC_MAX_NR_LVT_ENTRIES; i++)
for (i = 0; i < apic->nr_lvt_entries; i++)
kvm_lapic_set_reg(apic, APIC_LVTx(i), APIC_LVT_MASKED);
apic_update_lvtt(apic);
if (kvm_vcpu_is_reset_bsp(vcpu) &&
Expand Down
4 changes: 3 additions & 1 deletion arch/x86/kvm/lapic.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,11 +35,12 @@ enum lapic_lvt_entry {
LVT_LINT0,
LVT_LINT1,
LVT_ERROR,
LVT_CMCI,

KVM_APIC_MAX_NR_LVT_ENTRIES,
};

#define APIC_LVTx(x) (APIC_LVTT + 0x10 * (x))
#define APIC_LVTx(x) ((x) == LVT_CMCI ? APIC_LVTCMCI : APIC_LVTT + 0x10 * (x))

struct kvm_timer {
struct hrtimer timer;
Expand Down Expand Up @@ -78,6 +79,7 @@ struct kvm_lapic {
struct gfn_to_hva_cache vapic_cache;
unsigned long pending_events;
unsigned int sipi_vector;
int nr_lvt_entries;
};

struct dest_map;
Expand Down
2 changes: 2 additions & 0 deletions arch/x86/kvm/x86.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4845,6 +4845,8 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
/* Init IA32_MCi_CTL to all 1s */
for (bank = 0; bank < bank_num; bank++)
vcpu->arch.mce_banks[bank*4] = ~(u64)0;
vcpu->arch.apic->nr_lvt_entries =
KVM_APIC_MAX_NR_LVT_ENTRIES - !(mcg_cap & MCG_CMCI_P);

static_call(kvm_x86_setup_mce)(vcpu);
out:
Expand Down

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