KVM: x86/xen: register shared_info page

We add a new ioctl, XEN_HVM_SHARED_INFO, to allow hypervisor
to know where the guest's shared info page is.

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 4fcb27a9fe36c3121725d3d8b46160b3736378b0..e48dac4f0359876b26bd4f0313d39212d5bde874 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -897,6 +897,8 @@ struct msr_bitmap_range {
 /* Xen emulation context */
 struct kvm_xen {
        bool long_mode;
+       bool shinfo_set;
+       struct gfn_to_hva_cache shinfo_cache;
 };
 
 enum kvm_irqchip_mode {

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 52cb9e4655421cd57424ff2a74025c322382b928..9dd9c42842b8f0caf40913a49af8a8e3ef5476da 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -13,9 +13,23 @@
 #include <linux/kvm_host.h>
 
 #include <trace/events/kvm.h>
+#include <xen/interface/xen.h>
 
 #include "trace.h"
 
+static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
+{
+       int ret;
+
+       ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
+                                       gfn_to_gpa(gfn), PAGE_SIZE);
+       if (ret)
+               return ret;
+
+       kvm->arch.xen.shinfo_set = true;
+       return 0;
+}
+
 int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 {
        int r = -ENOENT;
@@ -28,6 +42,11 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
                kvm->arch.xen.long_mode = !!data->u.long_mode;
                r = 0;
                break;
+
+       case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+               r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
+               break;
+
        default:
                break;
        }
@@ -44,6 +63,14 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
                data->u.long_mode = kvm->arch.xen.long_mode;
                r = 0;
                break;
+
+       case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+               if (kvm->arch.xen.shinfo_set) {
+                       data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);
+                       r = 0;
+               }
+               break;
+
        default:
                break;
        }

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index b7cf887c8e4da2907ff8cdc71c38c375848b7168..a47097b90fe86ceb990ebda169df1812e7e2ed36 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1591,11 +1591,15 @@ struct kvm_xen_hvm_attr {
 
        union {
                __u8 long_mode;
+               struct {
+                       __u64 gfn;
+               } shared_info;
                __u64 pad[4];
        } u;
 };
 
 #define KVM_XEN_ATTR_TYPE_LONG_MODE            0x0
+#define KVM_XEN_ATTR_TYPE_SHARED_INFO          0x1
 
 /* Secure Encrypted Virtualization command */
 enum sev_cmd_id {