From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Turns out this is a fast path for PV guests because they use it to
trigger the event channel upcall. So letting it bounce all the way up
to userspace is not great.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/xen.c | 18 ++++++++++++++++++
include/uapi/linux/kvm.h | 3 ++-
3 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b0caf02d12fe..3aa9563dd1af 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1021,6 +1021,7 @@ struct msr_bitmap_range {
/* Xen emulation context */
struct kvm_xen {
+ u32 xen_version;
bool long_mode;
u8 upcall_vector;
struct gfn_to_pfn_cache shinfo_cache;
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index cc172ca83bbb..5f6c5840329e 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -18,6 +18,7 @@
#include <trace/events/kvm.h>
#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
+#include <xen/interface/version.h>
#include <xen/interface/event_channel.h>
#include <xen/interface/sched.h>
@@ -486,6 +487,12 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
r = kvm_xen_setattr_evtchn(kvm, data);
break;
+ case KVM_XEN_ATTR_TYPE_XEN_VERSION:
+ mutex_lock(&kvm->lock);
+ kvm->arch.xen.xen_version = data->u.xen_version;
+ mutex_unlock(&kvm->lock);
+ break;
+
default:
break;
}
@@ -518,6 +525,11 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
r = 0;
break;
+ case KVM_XEN_ATTR_TYPE_XEN_VERSION:
+ data->u.xen_version = kvm->arch.xen.xen_version;
+ r = 0;
+ break;
+
default:
break;
}
@@ -1082,6 +1094,12 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
params[3], params[4], params[5]);
switch (input) {
+ case __HYPERVISOR_xen_version:
+ if (params[0] == XENVER_version && vcpu->kvm->arch.xen.xen_version) {
+ r = vcpu->kvm->arch.xen.xen_version;
+ handled = true;
+ }
+ break;
case __HYPERVISOR_event_channel_op:
if (params[0] == EVTCHNOP_send)
handled = kvm_xen_hcall_evtchn_send(vcpu, params[1], &r);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 47d6b0f6d5ab..17784bcfcf75 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1700,7 +1700,7 @@ struct kvm_xen_hvm_attr {
__u32 padding[4];
} deliver;
} evtchn;
-
+ __u32 xen_version;
__u64 pad[8];
} u;
};
@@ -1711,6 +1711,7 @@ struct kvm_xen_hvm_attr {
#define KVM_XEN_ATTR_TYPE_UPCALL_VECTOR 0x2
/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_EVTCHN_SEND */
#define KVM_XEN_ATTR_TYPE_EVTCHN 0x3
+#define KVM_XEN_ATTR_TYPE_XEN_VERSION 0x4
/* Per-vCPU Xen attributes */
#define KVM_XEN_VCPU_GET_ATTR _IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr)
--
2.33.1
