hv: TLFS: Add tsc_offset support for reference time

TLFS spec defines that when a VM is created, the value of
HV_X64_MSR_TIME_REF_COUNT is set to zero. Now tsc_offset is not
supported properly, so guest get a drifted reference time.

This patch implements tsc_offset. tsc_scale and tsc_offset
are calculated when a VM is launched and are saved in
struct acrn_hyperv of struct acrn_vm.

Tracked-On: #5956
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/arch/x86/guest/hyperv.c

@@ -56,41 +56,11 @@ u64_mul_u64_shr64(uint64_t a, uint64_t b)
 	return ret;
 }
 
-static inline void
-hyperv_get_tsc_scale_offset(struct acrn_vm *vm, uint64_t *scale, uint64_t *offset)
-{
-	if (vm->arch_vm.hyperv.tsc_scale == 0UL) {
-		/*
-		 * The partition reference time is computed by the following formula:
-		 * ReferenceTime = ((VirtualTsc * TscScale) >> 64) + TscOffset
-		 * ReferenceTime is in 100ns units
-		 *
-		 * ReferenceTime =
-		 *     VirtualTsc / (get_tsc_khz() * 1000) * 1000000000 / 100
-		 *     + TscOffset
-		 */
-
-		uint64_t ret, khz = get_tsc_khz();
-
-		/* ret = (10000U << 64U) / get_tsc_khz() */
-		ret = u64_shl64_div_u64(10000U, khz);
-
-		dev_dbg(DBG_LEVEL_HYPERV, "%s, ret = 0x%lx", __func__, ret);
-
-		vm->arch_vm.hyperv.tsc_scale = ret;
-		vm->arch_vm.hyperv.tsc_offset = 0UL;
-	}
-
-	*scale = vm->arch_vm.hyperv.tsc_scale;
-	*offset = vm->arch_vm.hyperv.tsc_offset;
-}
-
 static void
 hyperv_setup_tsc_page(const struct acrn_vcpu *vcpu, uint64_t val)
 {
 	union hyperv_ref_tsc_page_msr *ref_tsc_page = &vcpu->vm->arch_vm.hyperv.ref_tsc_page;
 	struct HV_REFERENCE_TSC_PAGE *p;
-	uint64_t tsc_scale, tsc_offset;
 	uint32_t tsc_seq;
 
 	ref_tsc_page->val64 = val;
@@ -98,10 +68,9 @@ hyperv_setup_tsc_page(const struct acrn_vcpu *vcpu, uint64_t val)
 	if (ref_tsc_page->enabled == 1U) {
 		p = (struct HV_REFERENCE_TSC_PAGE *)gpa2hva(vcpu->vm, ref_tsc_page->gpfn << PAGE_SHIFT);
 		if (p != NULL) {
-			hyperv_get_tsc_scale_offset(vcpu->vm, &tsc_scale, &tsc_offset);
 			stac();
-			p->tsc_scale = tsc_scale;
+			p->tsc_scale = vcpu->vm->arch_vm.hyperv.tsc_scale;
-			p->tsc_offset = tsc_offset;
+			p->tsc_offset = vcpu->vm->arch_vm.hyperv.tsc_offset;
 			cpu_write_memory_barrier();
 			tsc_seq = p->tsc_sequence + 1U;
 			if ((tsc_seq == 0xFFFFFFFFU) || (tsc_seq == 0U)) {
@@ -114,19 +83,19 @@ hyperv_setup_tsc_page(const struct acrn_vcpu *vcpu, uint64_t val)
 }
 
 static inline uint64_t
-hyperv_get_ref_count(struct acrn_vm *vm)
+hyperv_scale_tsc(uint64_t scale)
 {
-	uint64_t tsc, tsc_scale, tsc_offset, ret;
+	uint64_t tsc;
 
-	/* currently only "use tsc offsetting" is set to 1 */
 	tsc = rdtsc() + exec_vmread64(VMX_TSC_OFFSET_FULL);
 
-	hyperv_get_tsc_scale_offset(vm, &tsc_scale, &tsc_offset);
+	return u64_mul_u64_shr64(tsc, scale);
+}
 
-	/* ret = ((tsc * tsc_scale) >> 64) + tsc_offset */
+static inline uint64_t
-	ret = u64_mul_u64_shr64(tsc, tsc_scale) + tsc_offset;
+hyperv_get_ReferenceTime(struct acrn_vm *vm)
-
+{
-	return ret;
+	return hyperv_scale_tsc(vm->arch_vm.hyperv.tsc_scale) - vm->arch_vm.hyperv.tsc_offset;
 }
 
 static void
@@ -227,7 +196,7 @@ hyperv_rdmsr(struct acrn_vcpu *vcpu, uint32_t msr, uint64_t *rval)
 		*rval = vcpu->vcpu_id;
 		break;
 	case HV_X64_MSR_TIME_REF_COUNT:
-		*rval = hyperv_get_ref_count(vcpu->vm);
+		*rval = hyperv_get_ReferenceTime(vcpu->vm);
 		break;
 	case HV_X64_MSR_REFERENCE_TSC:
 		*rval = vcpu->vm->arch_vm.hyperv.ref_tsc_page.val64;
@@ -244,6 +213,33 @@ hyperv_rdmsr(struct acrn_vcpu *vcpu, uint32_t msr, uint64_t *rval)
 	return ret;
 }
 
+void
+hyperv_init_time(struct acrn_vm *vm)
+{
+	uint64_t tsc_scale, tsc_khz = get_tsc_khz();
+	uint64_t tsc_offset;
+
+	/*
+	 * The partition reference time is computed by the following formula:
+	 * ReferenceTime = ((VirtualTsc * TscScale) >> 64) + TscOffset
+	 * ReferenceTime is in 100ns units
+	 *
+	 * ReferenceTime =
+	 *     VirtualTsc / (get_tsc_khz() * 1000) * 1000000000 / 100
+	 *     + TscOffset
+	 *
+	 * TscScale = (10000U << 64U) / get_tsc_khz()
+	 */
+	tsc_scale = u64_shl64_div_u64(10000U, tsc_khz);
+	tsc_offset = hyperv_scale_tsc(tsc_scale);
+
+	vm->arch_vm.hyperv.tsc_scale = tsc_scale;
+	vm->arch_vm.hyperv.tsc_offset = tsc_offset;
+
+	dev_dbg(DBG_LEVEL_HYPERV, "%s, tsc_scale = 0x%lx, tsc_offset = %ld",
+		__func__, tsc_scale, tsc_offset);
+}
+
 void
 hyperv_init_vcpuid_entry(uint32_t leaf, uint32_t subleaf, uint32_t flags,
 			 struct vcpuid_entry *entry)

hypervisor/arch/x86/guest/vcpu.c

@@ -643,6 +643,12 @@ int32_t run_vcpu(struct acrn_vcpu *vcpu)
 		 */
 		flush_vpid_global();
 
+#ifdef CONFIG_HYPERV_ENABLED
+		if (is_vcpu_bsp(vcpu)) {
+			hyperv_init_time(vcpu->vm);
+		}
+#endif
+
 		/* Set vcpu launched */
 		vcpu->launched = true;
 

hypervisor/include/arch/x86/guest/hyperv.h

@@ -59,7 +59,7 @@ struct acrn_hyperv {
 
 int32_t hyperv_wrmsr(struct acrn_vcpu *vcpu, uint32_t msr, uint64_t wval);
 int32_t hyperv_rdmsr(struct acrn_vcpu *vcpu, uint32_t msr, uint64_t *rval);
+void hyperv_init_time(struct acrn_vm *vm);
 void hyperv_init_vcpuid_entry(uint32_t leaf, uint32_t subleaf, uint32_t flags,
 	struct vcpuid_entry *entry);
-
 #endif