[PATCH v3 4/7] KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.

[Jue Wang <juew@google.com>]

This series adds the Corrected Machine Check Interrupt (CMCI) and
Uncorrectable Error No Action required (UCNA) emulation to KVM. The
former is implemented as a LVT CMCI vector. The emulation of UCNA share
the MCE emulation infrastructure.

CMCI emulation is only enabled when user space has opted in to enable
MCG_CMCI_P bit in MCG_CAP via KVM_X86_SETUP_MCE.

Signed-off-by: Jue Wang <juew@google.com>
---
 arch/x86/kvm/lapic.c | 40 +++++++++++++++++++++++++++++++++-------
 arch/x86/kvm/lapic.h |  3 ++-
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index c01f6ecb3d12..b451fbe8b394 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>
@@ -364,14 +365,26 @@ 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_is_cmci_supported(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.mcg_cap & MCG_CMCI_P;
+}
+
+static inline int kvm_apic_get_nr_lvt_entries(struct kvm_lapic *apic)
+{
+	return KVM_APIC_MAX_NR_LVT_ENTRIES - !kvm_is_cmci_supported(apic->vcpu);
+}
+
 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 | ((kvm_apic_get_nr_lvt_entries(apic) - 1) << 16);
+
 	/*
 	 * KVM emulates 82093AA datasheet (with in-kernel IOAPIC implementation)
 	 * which doesn't have EOI register; Some buggy OSes (e.g. Windows with
@@ -391,7 +404,8 @@ 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)
@@ -1406,6 +1420,9 @@ 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_is_cmci_supported(apic->vcpu))
+		valid_reg_mask |= APIC_REG_MASK(APIC_LVTCMCI);
+
 	/* ARBPRI is not valid on x2APIC */
 	if (!apic_x2apic_mode(apic))
 		valid_reg_mask |= APIC_REG_MASK(APIC_ARBPRI);
@@ -2038,12 +2055,10 @@ 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 < kvm_apic_get_nr_lvt_entries(apic); 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);
@@ -2093,6 +2108,17 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 		apic_update_lvtt(apic);
 		break;
 
+	case APIC_LVTCMCI:
+		if (!kvm_is_cmci_supported(apic->vcpu)) {
+			ret = 1;
+			break;
+		}
+		if (!kvm_apic_sw_enabled(apic))
+			val |= APIC_LVT_MASKED;
+		val &= apic_lvt_mask[LVT_CMCI];
+		kvm_lapic_set_reg(apic, APIC_LVTCMCI, val);
+		break;
+
 	case APIC_TMICT:
 		if (apic_lvtt_tscdeadline(apic))
 			break;
@@ -2341,7 +2367,7 @@ 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 < kvm_apic_get_nr_lvt_entries(apic); 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 7ba4c548853e..64ed18fe0fb4 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;
-- 
2.36.0.550.gb090851708-goog