[PATCH v5 4/8] KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.

Jue Wang
2022-06-10T17:11:55Z

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>
---
arch/x86/kvm/lapic.c | 48 ++++++++++++++++++++++++++++++--------------
arch/x86/kvm/lapic.h | 4 +++-
arch/x86/kvm/x86.c | 2 ++
3 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index db12d2ef1aef..8537b66cc646 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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>
@@ -398,14 +399,21 @@ 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
@@ -425,7 +433,8 @@ 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)
@@ -1445,6 +1454,9 @@ 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
@@ -2039,6 +2051,15 @@ static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
}
}

+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;
@@ -2083,12 +2104,10 @@ 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);
@@ -2117,16 +2136,15 @@ 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;
@@ -2383,7 +2401,7 @@ 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) &&
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 2d197ed0b8ce..0fcafc76a3ce 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -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;
@@ -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;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4790f0d7d40b..a08693808729 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4772,6 +4772,8 @@ 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:
--
2.36.1.255.ge46751e96f-goog