[PATCH v0 10/15] KVM: x86/xen: Add KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

In order to intercept hypercalls such as VCPUOP_set_singleshot_timer, we
need to be aware of the Xen CPU numbering.

This looks a lot like the Hyper-V handling of vpidx, for obvious reasons.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/x86.c              |  1 +
 arch/x86/kvm/xen.c              | 45 +++++++++++++++++++++++++++++++++
 arch/x86/kvm/xen.h              |  5 ++++
 include/uapi/linux/kvm.h        |  3 +++
 5 files changed, 55 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index dca0842d6926..3c58d0bf5f9b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -608,6 +608,7 @@ struct kvm_vcpu_xen {
 	u64 runstate_entry_time;
 	u64 runstate_times[4];
 	unsigned long evtchn_pending_sel;
+	u32 vcpu_id; /* The Xen / ACPI vCPU ID */
 };
 
 struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a54bd731cf41..2143c2652f8f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11141,6 +11141,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
 	vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
+	kvm_xen_init_vcpu(vcpu);
 	kvm_vcpu_mtrr_init(vcpu);
 	vcpu_load(vcpu);
 	kvm_set_tsc_khz(vcpu, max_tsc_khz);
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 3df44c996d66..8ee4bc648bcb 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -605,6 +605,15 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
 		r = 0;
 		break;
 
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID:
+		if (data->u.vcpu_id >= KVM_MAX_VCPUS)
+			r = -EINVAL;
+		else {
+			vcpu->arch.xen.vcpu_id = data->u.vcpu_id;
+			r = 0;
+		}
+		break;
+
 	default:
 		break;
 	}
@@ -680,6 +689,11 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
 		r = -EINVAL;
 		break;
 
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID:
+		data->u.vcpu_id = vcpu->arch.xen.vcpu_id;
+		r = 0;
+		break;
+
 	default:
 		break;
 	}
@@ -785,6 +799,32 @@ int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
 	return 0;
 }
 
+static struct kvm_vcpu *kvm_xen_vcpu_by_id(struct kvm *kvm, u32 vcpu_id,
+					   struct kvm_vcpu *vcpu)
+{
+	unsigned long i;
+
+	if (vcpu && vcpu->arch.xen.vcpu_id == vcpu_id)
+		return vcpu;
+
+	if (vcpu_id >= KVM_MAX_VCPUS)
+		return NULL;
+
+	/* Try the matching index first */
+	if (!vcpu || vcpu->vcpu_idx == vcpu_id) {
+		vcpu = kvm_get_vcpu(kvm, vcpu_id);
+
+		if (vcpu && vcpu->arch.xen.vcpu_id == vcpu_id)
+			return vcpu;
+	}
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		if (vcpu->arch.xen.vcpu_id == vcpu_id)
+			return vcpu;
+
+	return NULL;
+}
+
 static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
 {
 	kvm_rax_write(vcpu, result);
@@ -1358,6 +1398,11 @@ static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r)
 	return true;
 }
 
+void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.xen.vcpu_id = vcpu->vcpu_idx;
+}
+
 void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
 {
 	kvm_gfn_to_pfn_cache_destroy(vcpu->kvm,
diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 852286de574e..54d587aae85b 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -25,6 +25,7 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);
 int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);
 void kvm_xen_init_vm(struct kvm *kvm);
 void kvm_xen_destroy_vm(struct kvm *kvm);
+void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu);
 void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu);
 int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe,
 			    struct kvm *kvm);
@@ -75,6 +76,10 @@ static inline void kvm_xen_destroy_vm(struct kvm *kvm)
 {
 }
 
+static inline void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu)
+{
+}
+
 static inline void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
 {
 }
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index c0d6f49e3fd8..284645e1a872 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1739,6 +1739,7 @@ struct kvm_xen_vcpu_attr {
 			__u64 time_blocked;
 			__u64 time_offline;
 		} runstate;
+		__u32 vcpu_id;
 	} u;
 };
 
@@ -1749,6 +1750,8 @@ struct kvm_xen_vcpu_attr {
 #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT	0x3
 #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA	0x4
 #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST	0x5
+/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_EVTCHN_SEND */
+#define KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID		0x6
 
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {
-- 
2.33.1