LoongArch: KVM: Add PV steal time support in host side

Add ParaVirt steal time feature in host side, VM can search supported
features provided by KVM hypervisor, a feature KVM_FEATURE_STEAL_TIME
is added here. Like x86, steal time structure is saved in guest memory,
one hypercall function KVM_HCALL_FUNC_NOTIFY is added to notify KVM to
enable this feature.

One CPU attr ioctl command KVM_LOONGARCH_VCPU_PVTIME_CTRL is added to
save and restore the base address of steal time structure when a VM is
migrated.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 123 insertions, 2 deletions

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 815f54ba0241..bdfb1a910e27 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -31,6 +31,50 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
 		       sizeof(kvm_vcpu_stats_desc),
 };
 
+static void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
+{
+	u32 version;
+	u64 steal;
+	gpa_t gpa;
+	struct kvm_memslots *slots;
+	struct kvm_steal_time __user *st;
+	struct gfn_to_hva_cache *ghc;
+
+	ghc = &vcpu->arch.st.cache;
+	gpa = vcpu->arch.st.guest_addr;
+	if (!(gpa & KVM_STEAL_PHYS_VALID))
+		return;
+
+	gpa &= KVM_STEAL_PHYS_MASK;
+	slots = kvm_memslots(vcpu->kvm);
+	if (slots->generation != ghc->generation || gpa != ghc->gpa) {
+		if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st))) {
+			ghc->gpa = INVALID_GPA;
+			return;
+		}
+	}
+
+	st = (struct kvm_steal_time __user *)ghc->hva;
+	unsafe_get_user(version, &st->version, out);
+	if (version & 1)
+		version += 1; /* first time write, random junk */
+
+	version += 1;
+	unsafe_put_user(version, &st->version, out);
+	smp_wmb();
+
+	unsafe_get_user(steal, &st->steal, out);
+	steal += current->sched_info.run_delay - vcpu->arch.st.last_steal;
+	vcpu->arch.st.last_steal = current->sched_info.run_delay;
+	unsafe_put_user(steal, &st->steal, out);
+
+	smp_wmb();
+	version += 1;
+	unsafe_put_user(version, &st->version, out);
+out:
+	mark_page_dirty_in_slot(vcpu->kvm, ghc->memslot, gpa_to_gfn(ghc->gpa));
+}
+
 /*
  * kvm_check_requests - check and handle pending vCPU requests
  *
@@ -48,6 +92,9 @@ static int kvm_check_requests(struct kvm_vcpu *vcpu)
 	if (kvm_dirty_ring_check_request(vcpu))
 		return RESUME_HOST;
 
+	if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu))
+		kvm_update_stolen_time(vcpu);
+
 	return RESUME_GUEST;
 }
 
@@ -690,6 +737,16 @@ static int kvm_loongarch_cpucfg_has_attr(struct kvm_vcpu *vcpu,
 	return -ENXIO;
 }
 
+static int kvm_loongarch_pvtime_has_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	return 0;
+}
+
 static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
 				       struct kvm_device_attr *attr)
 {
@@ -699,6 +756,9 @@ static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
 	case KVM_LOONGARCH_VCPU_CPUCFG:
 		ret = kvm_loongarch_cpucfg_has_attr(vcpu, attr);
 		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_has_attr(vcpu, attr);
+		break;
 	default:
 		break;
 	}
@@ -706,7 +766,7 @@ static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
 	return ret;
 }
 
-static int kvm_loongarch_get_cpucfg_attr(struct kvm_vcpu *vcpu,
+static int kvm_loongarch_cpucfg_get_attr(struct kvm_vcpu *vcpu,
 					 struct kvm_device_attr *attr)
 {
 	int ret = 0;
@@ -722,6 +782,23 @@ static int kvm_loongarch_get_cpucfg_attr(struct kvm_vcpu *vcpu,
 	return ret;
 }
 
+static int kvm_loongarch_pvtime_get_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	u64 gpa;
+	u64 __user *user = (u64 __user *)attr->addr;
+
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	gpa = vcpu->arch.st.guest_addr;
+	if (put_user(gpa, user))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
 				       struct kvm_device_attr *attr)
 {
@@ -729,7 +806,10 @@ static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
 
 	switch (attr->group) {
 	case KVM_LOONGARCH_VCPU_CPUCFG:
-		ret = kvm_loongarch_get_cpucfg_attr(vcpu, attr);
+		ret = kvm_loongarch_cpucfg_get_attr(vcpu, attr);
+		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_get_attr(vcpu, attr);
 		break;
 	default:
 		break;
@@ -744,6 +824,43 @@ static int kvm_loongarch_cpucfg_set_attr(struct kvm_vcpu *vcpu,
 	return -ENXIO;
 }
 
+static int kvm_loongarch_pvtime_set_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	int idx, ret = 0;
+	u64 gpa, __user *user = (u64 __user *)attr->addr;
+	struct kvm *kvm = vcpu->kvm;
+
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	if (get_user(gpa, user))
+		return -EFAULT;
+
+	if (gpa & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
+		return -EINVAL;
+
+	if (!(gpa & KVM_STEAL_PHYS_VALID)) {
+		vcpu->arch.st.guest_addr = gpa;
+		return 0;
+	}
+
+	/* Check the address is in a valid memslot */
+	idx = srcu_read_lock(&kvm->srcu);
+	if (kvm_is_error_hva(gfn_to_hva(kvm, gpa >> PAGE_SHIFT)))
+		ret = -EINVAL;
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	if (!ret) {
+		vcpu->arch.st.guest_addr = gpa;
+		vcpu->arch.st.last_steal = current->sched_info.run_delay;
+		kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
+	}
+
+	return ret;
+}
+
 static int kvm_loongarch_vcpu_set_attr(struct kvm_vcpu *vcpu,
 				       struct kvm_device_attr *attr)
 {
@@ -753,6 +870,9 @@ static int kvm_loongarch_vcpu_set_attr(struct kvm_vcpu *vcpu,
 	case KVM_LOONGARCH_VCPU_CPUCFG:
 		ret = kvm_loongarch_cpucfg_set_attr(vcpu, attr);
 		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_set_attr(vcpu, attr);
+		break;
 	default:
 		break;
 	}
@@ -1113,6 +1233,7 @@ static int _kvm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	/* Control guest page CCA attribute */
 	change_csr_gcfg(CSR_GCFG_MATC_MASK, CSR_GCFG_MATC_ROOT);
+	kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
 
 	/* Don't bother restoring registers multiple times unless necessary */
 	if (vcpu->arch.aux_inuse & KVM_LARCH_HWCSR_USABLE)