[PATCH RFC 1/7] kvm: x86: emulate MSR_KVM_PV_TIMER_EN MSR

[Quan Xu]

From: Ben Luo <bn0418@xxxxxxxxx>

Guest enables pv timer functionality using this MSR

Signed-off-by: Yang Zhang <yang.zhang.wz@xxxxxxxxx>
Signed-off-by: Quan Xu <quan.xu0@xxxxxxxxx>
Signed-off-by: Ben Luo <bn0418@xxxxxxxxx>
---
 arch/x86/include/asm/kvm_host.h      |    5 +++++
 arch/x86/include/uapi/asm/kvm_para.h |    6 ++++++
 arch/x86/kvm/lapic.c                 |   22 ++++++++++++++++++++++
 arch/x86/kvm/lapic.h                 |    6 ++++++
 arch/x86/kvm/x86.c                   |    8 ++++++++
 5 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c73e493..641b4aa 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -684,6 +684,11 @@ struct kvm_vcpu_arch {
 		bool pv_unhalted;
 	} pv;
 
+	struct {
+		u64 msr_val;
+		struct gfn_to_hva_cache data;
+	} pv_timer;
+
 	int pending_ioapic_eoi;
 	int pending_external_vector;
 
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 554aa8f..3dd6116 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -41,6 +41,7 @@
 #define MSR_KVM_ASYNC_PF_EN 0x4b564d02
 #define MSR_KVM_STEAL_TIME  0x4b564d03
 #define MSR_KVM_PV_EOI_EN      0x4b564d04
+#define MSR_KVM_PV_TIMER_EN    0x4b564d05
 
 struct kvm_steal_time {
 	__u64 steal;
@@ -64,6 +65,11 @@ struct kvm_clock_pairing {
 #define KVM_STEAL_VALID_BITS ((-1ULL << (KVM_STEAL_ALIGNMENT_BITS + 1)))
 #define KVM_STEAL_RESERVED_MASK (((1 << KVM_STEAL_ALIGNMENT_BITS) - 1 ) << 1)
 
+struct pvtimer_vcpu_event_info {
+	__u64 expire_tsc;
+	__u64 next_sync_tsc;
+} __attribute__((__packed__));
+
 #define KVM_MAX_MMU_OP_BATCH           32
 
 #define KVM_ASYNC_PF_ENABLED			(1 << 0)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 36c90d6..55c9ba3 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1991,6 +1991,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 		kvm_lapic_set_base(vcpu,
 				vcpu->arch.apic_base | MSR_IA32_APICBASE_BSP);
 	vcpu->arch.pv_eoi.msr_val = 0;
+	vcpu->arch.pv_timer.msr_val = 0;
 	apic_update_ppr(apic);
 	if (vcpu->arch.apicv_active) {
 		kvm_x86_ops->apicv_post_state_restore(vcpu);
@@ -2478,6 +2479,27 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
 					 addr, sizeof(u8));
 }
 
+int kvm_lapic_enable_pv_timer(struct kvm_vcpu *vcpu, u64 data)
+{
+	u64 addr = data & ~KVM_MSR_ENABLED;
+	int ret;
+
+	if (!lapic_in_kernel(vcpu))
+		return 1;
+
+	if (!IS_ALIGNED(addr, 4))
+		return 1;
+
+	vcpu->arch.pv_timer.msr_val = data;
+	if (!pv_timer_enabled(vcpu))
+		return 0;
+
+	ret = kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_timer.data,
+				addr, sizeof(struct pvtimer_vcpu_event_info));
+
+	return ret;
+}
+
 void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 4b9935a..539a738 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -113,6 +113,7 @@ static inline bool kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu)
 }
 
 int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data);
+int kvm_lapic_enable_pv_timer(struct kvm_vcpu *vcpu, u64 data);
 void kvm_lapic_init(void);
 void kvm_lapic_exit(void);
 
@@ -207,6 +208,11 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)
 	return lapic_in_kernel(vcpu) && test_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
 }
 
+static inline bool pv_timer_enabled(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.pv_timer.msr_val & KVM_MSR_ENABLED;
+}
+
 bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
 
 void wait_lapic_expire(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 03869eb..5668774 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1025,6 +1025,7 @@ bool kvm_rdpmc(struct kvm_vcpu *vcpu)
 	HV_X64_MSR_STIMER0_CONFIG,
 	HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
 	MSR_KVM_PV_EOI_EN,
+	MSR_KVM_PV_TIMER_EN,
 
 	MSR_IA32_TSC_ADJUST,
 	MSR_IA32_TSCDEADLINE,
@@ -2279,6 +2280,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		if (kvm_lapic_enable_pv_eoi(vcpu, data))
 			return 1;
 		break;
+	case MSR_KVM_PV_TIMER_EN:
+		if (kvm_lapic_enable_pv_timer(vcpu, data))
+			return 1;
+		break;
 
 	case MSR_IA32_MCG_CTL:
 	case MSR_IA32_MCG_STATUS:
@@ -2510,6 +2515,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_KVM_PV_EOI_EN:
 		msr_info->data = vcpu->arch.pv_eoi.msr_val;
 		break;
+	case MSR_KVM_PV_TIMER_EN:
+		msr_info->data = vcpu->arch.pv_timer.msr_val;
+		break;
 	case MSR_IA32_P5_MC_ADDR:
 	case MSR_IA32_P5_MC_TYPE:
 	case MSR_IA32_MCG_CAP:
-- 
1.7.1