KVM: x86/xen: register shared_info page

Add KVM_XEN_ATTR_TYPE_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 016a005..00d1233 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -908,6 +908,8 @@ 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 55da739..924d4e8 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -13,25 +13,49 @@
 #include <linux/kvm_host.h>
 
 #include <trace/events/kvm.h>
+#include <xen/interface/xen.h>
 
 #include "trace.h"
 
 DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
 
+static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
+{
+       int ret;
+       int idx = srcu_read_lock(&kvm->srcu);
+
+       ret = kvm_gfn_to_hva_cache_init(kvm, &kvm->arch.xen.shinfo_cache,
+                                       gfn_to_gpa(gfn), PAGE_SIZE);
+       if (!ret) {
+               kvm->arch.xen.shinfo_set = true;
+       }
+
+       srcu_read_unlock(&kvm->srcu, idx);
+       return ret;
+}
+
 int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
 {
        int r = -ENOENT;
 
+       mutex_lock(&kvm->lock);
+
        mutex_unlock(&kvm->lock);
 
        switch (data->type) {
        case KVM_XEN_ATTR_TYPE_LONG_MODE:
-               if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode)
-                       return -EINVAL;
+               if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
+                       r = -EINVAL;
+               } else {
+                       kvm->arch.xen.long_mode = !!data->u.long_mode;
+                       r = 0;
+               }
+               break;
 
-               kvm->arch.xen.long_mode = !!data->u.long_mode;
-               r = 0;
+       case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+               r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
                break;
+
        default:
                break;
        }
@@ -51,6 +75,14 @@ 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 1164495..f57f6e7 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1595,11 +1595,15 @@ struct kvm_xen_hvm_attr {
        __u16 pad[3];
        union {
                __u8 long_mode;
+               struct {
+                       __u64 gfn;
+               } shared_info;
                __u64 pad[8];
        } 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 {