KVM: x86/xen: register vcpu time info region

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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 617c120d03a31b92c4ecb5807c413f059b3ea237..ec942528920922969a540d8c7acf1a05899e3f0b 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -525,6 +525,8 @@ struct kvm_vcpu_xen {
        u64 hypercall_rip;
        struct kvm_host_map vcpu_info_map;
        struct vcpu_info *vcpu_info;
+       struct kvm_host_map pv_time_map;
+       struct pvclock_vcpu_time_info *pv_time;
 };
 
 struct kvm_vcpu_arch {

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index e6cb727089040a6dc189acc92c31a9062b47aebf..81090f0052a3582294179091786a28deab33ea23 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -101,29 +101,10 @@ static void *xen_vcpu_info(struct kvm_vcpu *v)
        return hva;
 }
 
-void kvm_xen_setup_pvclock_page(struct kvm_vcpu *v)
+static void kvm_xen_update_vcpu_time(struct kvm_vcpu *v,
+                                    struct pvclock_vcpu_time_info *guest_hv_clock)
 {
        struct kvm_vcpu_arch *vcpu = &v->arch;
-       struct pvclock_vcpu_time_info *guest_hv_clock;
-       unsigned int offset;
-       void *hva;
-       int idx;
-
-       BUILD_BUG_ON(offsetof(struct shared_info, vcpu_info) != 0);
-       BUILD_BUG_ON(offsetof(struct compat_shared_info, vcpu_info) != 0);
-       BUILD_BUG_ON(sizeof(struct vcpu_info) != sizeof(struct compat_vcpu_info));
-       BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=
-                    offsetof(struct compat_vcpu_info, time));
-
-       idx = srcu_read_lock(&v->kvm->srcu);
-       hva = xen_vcpu_info(v);
-       if (!hva)
-               goto out;
-
-       offset = v->vcpu_id * sizeof(struct vcpu_info);
-       offset += offsetof(struct vcpu_info, time);
-
-       guest_hv_clock = hva + offset;
 
        if (guest_hv_clock->version & 1)
                ++guest_hv_clock->version;
@@ -150,8 +131,31 @@ void kvm_xen_setup_pvclock_page(struct kvm_vcpu *v)
        vcpu->hv_clock.version++;
 
        guest_hv_clock->version = vcpu->hv_clock.version;
+}
+
+void kvm_xen_setup_pvclock_page(struct kvm_vcpu *v)
+{
+       struct kvm_vcpu_xen *vcpu_xen = vcpu_to_xen_vcpu(v);
+       struct vcpu_info *vcpu_info;
+       struct pvclock_vcpu_time_info *pv_info;
+       int idx;
+
+       BUILD_BUG_ON(offsetof(struct shared_info, vcpu_info) != 0);
+       BUILD_BUG_ON(offsetof(struct compat_shared_info, vcpu_info) != 0);
+       BUILD_BUG_ON(sizeof(struct vcpu_info) != sizeof(struct compat_vcpu_info));
+       BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=
+                    offsetof(struct compat_vcpu_info, time));
+
+       idx = srcu_read_lock(&v->kvm->srcu);
+       vcpu_info = xen_vcpu_info(v);
+       if (likely(vcpu_info))
+               kvm_xen_update_vcpu_time(v, &vcpu_info->time);
+
+       /* Update secondary pvclock region if registered */
+       pv_info = READ_ONCE(vcpu_xen->pv_time);
+       if (pv_info)
+               kvm_xen_update_vcpu_time(v, pv_info);
 
- out:
        srcu_read_unlock(&v->kvm->srcu, idx);
 }
 
@@ -165,6 +169,13 @@ static int vcpu_attr_loc(struct kvm_vcpu *vcpu, u16 type,
                if (sz)
                        *sz = sizeof(struct vcpu_info);
                return 0;
+
+       case KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO:
+               *map = &vcpu->arch.xen.pv_time_map;
+               *hva = (void **)&vcpu->arch.xen.pv_time;
+               if (sz)
+                       *sz = sizeof(struct pvclock_vcpu_time_info);
+               return 0;
        }
        return -EINVAL;
 }
@@ -186,6 +197,7 @@ 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_TIME_INFO:
        case KVM_XEN_ATTR_TYPE_VCPU_INFO: {
                gpa_t gpa = data->u.vcpu_attr.gpa;
                struct kvm_host_map *map;
@@ -232,6 +244,7 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
                }
                break;
 
+       case KVM_XEN_ATTR_TYPE_VCPU_TIME_INFO:
        case KVM_XEN_ATTR_TYPE_VCPU_INFO: {
                struct kvm_host_map *map;
                struct kvm_vcpu *v;
@@ -401,6 +414,11 @@ void kvm_xen_vcpu_uninit(struct kvm_vcpu *vcpu)
                              NULL, true, false);
                vcpu_xen->vcpu_info = NULL;
        }
+       if (vcpu_xen->pv_time) {
+               kvm_unmap_gfn(vcpu->kvm, &vcpu_xen->pv_time_map,
+                             NULL, true, false);
+               vcpu_xen->pv_time = NULL;
+       }
 }
 
 void kvm_xen_destroy_vm(struct kvm *kvm)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 8dda080175b62425e44afe93e254d3898b9dd344..3ff3f72ac6b33838a3d786ed36ad5773f450d496 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1599,6 +1599,7 @@ 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 {