[PATCH v5 12/16] KVM: x86/xen: register vcpu time info region

[David Woodhouse <dwmw2@infradead.org>]

From: Joao Martins <joao.m.martins@oracle.com>

Allow the Xen emulated guest the ability to register secondary
vcpu time information. On Xen guests this is used in order to be
mapped to userspace and hence allow vdso gettimeofday to work.

In doing so, move kvm_xen_set_pvclock_page() logic to
kvm_xen_update_vcpu_time() and have the former a top-level
function which updates primary vcpu time info (in struct vcpu_info)
and secondary one.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/x86.c              |  2 ++
 arch/x86/kvm/xen.c              | 26 ++++++++++++++++++++++++++
 include/uapi/linux/kvm.h        |  1 +
 4 files changed, 31 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 421d082d772d..cd65bd43fc5f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -524,7 +524,9 @@ struct kvm_vcpu_hv {
 struct kvm_vcpu_xen {
 	u64 hypercall_rip;
 	bool vcpu_info_set;
+	bool vcpu_time_info_set;
 	struct gfn_to_hva_cache vcpu_info_cache;
+	struct gfn_to_hva_cache vcpu_time_info_cache;
 };
 
 struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index af4490c20d63..1cf503d559eb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2735,6 +2735,8 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 	if (vcpu->xen.vcpu_info_set)
 		kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_info_cache,
 				       offsetof(struct compat_vcpu_info, time));
+	if (vcpu->xen.vcpu_time_info_set)
+		kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_time_info_cache, 0);
 	if (v == kvm_get_vcpu(v->kvm, 0))
 		kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
 	return 0;
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index d2055b60fdc1..1cca46effec8 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -95,6 +95,21 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 		kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
 		break;
 
+	case KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO:
+		v = kvm_get_vcpu_by_id(kvm, data->u.vcpu_attr.vcpu_id);
+		if (!v)
+			return -EINVAL;
+
+		r = kvm_gfn_to_hva_cache_init(kvm, &v->arch.xen.vcpu_time_info_cache,
+					      data->u.vcpu_attr.gpa,
+					      sizeof(struct pvclock_vcpu_time_info));
+		if (r)
+			return r;
+
+		v->arch.xen.vcpu_time_info_set = true;
+		kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
+		break;
+
 	default:
 		break;
 	}
@@ -131,6 +146,17 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 		}
 		break;
 
+	case KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO:
+		v = kvm_get_vcpu_by_id(kvm, data->u.vcpu_attr.vcpu_id);
+		if (!v)
+			return -EINVAL;
+
+		if (v->arch.xen.vcpu_time_info_set) {
+			data->u.vcpu_attr.gpa = v->arch.xen.vcpu_time_info_cache.gpa;
+			r = 0;
+		}
+		break;
+
 	default:
 		break;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5ab0063d109a..6e91c004ae68 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1607,6 +1607,7 @@ struct kvm_xen_hvm_attr {
 #define KVM_XEN_ATTR_TYPE_LONG_MODE		0x0
 #define KVM_XEN_ATTR_TYPE_SHARED_INFO		0x1
 #define KVM_XEN_ATTR_TYPE_VCPU_INFO		0x2
+#define KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO	0x3
 
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
-- 
2.29.2