[PATCH v4 10/16] KVM: x86/xen: register vcpu info

[David Woodhouse <dwmw2@infradead.org>]

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

The vcpu info supersedes the per vcpu area of the shared info page and
the guest vcpus will use this instead.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/xen.c              | 30 ++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h        |  5 +++++
 3 files changed, 37 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e48dac4f0359..eabd0bf0035f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -523,6 +523,8 @@ struct kvm_vcpu_hv {
 /* Xen HVM per vcpu emulation context */
 struct kvm_vcpu_xen {
 	u64 hypercall_rip;
+	bool vcpu_info_set;
+	struct gfn_to_hva_cache vcpu_info_cache;
 };
 
 struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index e5117a611737..4bc72e0b9928 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -58,6 +58,7 @@ static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
 
 int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 {
+	struct kvm_vcpu *v;
 	int r = -ENOENT;
 
 	switch (data->type) {
@@ -73,6 +74,23 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 		r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
 		break;
 
+	case KVM_XEN_ATTR_TYPE_VCPU_INFO:
+		v = kvm_get_vcpu_by_id(kvm, data->u.vcpu_attr.vcpu_id);
+		if (!v)
+			return -EINVAL;
+
+		/* No compat necessary here. */
+		BUILD_BUG_ON(sizeof(struct vcpu_info) !=
+			     sizeof(struct compat_vcpu_info));
+		r = kvm_gfn_to_hva_cache_init(kvm, &v->arch.xen.vcpu_info_cache,
+					      data->u.vcpu_attr.gpa,
+					      sizeof(struct vcpu_info));
+		if (r)
+			return r;
+
+		v->arch.xen.vcpu_info_set = true;
+		break;
+
 	default:
 		break;
 	}
@@ -83,6 +101,7 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 {
 	int r = -ENOENT;
+	struct kvm_vcpu *v;
 
 	switch (data->type) {
 	case KVM_XEN_ATTR_TYPE_LONG_MODE:
@@ -97,6 +116,17 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 		}
 		break;
 
+	case KVM_XEN_ATTR_TYPE_VCPU_INFO:
+		v = kvm_get_vcpu_by_id(kvm, data->u.vcpu_attr.vcpu_id);
+		if (!v)
+			return -EINVAL;
+
+		if (v->arch.xen.vcpu_info_set) {
+			data->u.vcpu_attr.gpa = v->arch.xen.vcpu_info_cache.gpa;
+			r = 0;
+		}
+		break;
+
 	default:
 		break;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a47097b90fe8..6a5ff37874f4 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1594,12 +1594,17 @@ struct kvm_xen_hvm_attr {
 		struct {
 			__u64 gfn;
 		} shared_info;
+		struct {
+			__u32 vcpu_id;
+			__u64 gpa;
+		} vcpu_attr;
 		__u64 pad[4];
 	} u;
 };
 
 #define KVM_XEN_ATTR_TYPE_LONG_MODE		0x0
 #define KVM_XEN_ATTR_TYPE_SHARED_INFO		0x1
+#define KVM_XEN_ATTR_TYPE_VCPU_INFO		0x2
 
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
-- 
2.29.2