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

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 accel/kvm/kvm-all.c       |  1 +
 include/sysemu/kvm_int.h  |  1 +
 include/sysemu/kvm_xen.h  |  1 +
 target/i386/kvm/kvm.c     | 34 ++++++++++++++++++++++++++++++++++
 target/i386/kvm/xen-emu.c |  6 ++++++
 5 files changed, 43 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index ca1efac278..9c0c964296 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3704,6 +3704,7 @@ static void kvm_accel_instance_init(Object *obj)
     s->notify_vmexit = NOTIFY_VMEXIT_OPTION_RUN;
     s->notify_window = 0;
     s->xen_version = 0;
+    s->xen_gnttab_max_frames = 64;
 }
 
 /**
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index 7f945bc763..39ce4d36f6 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -120,6 +120,7 @@ struct KVMState
     uint32_t notify_window;
     uint32_t xen_version;
     uint32_t xen_caps;
+    uint16_t xen_gnttab_max_frames;
 };
 
 void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
diff --git a/include/sysemu/kvm_xen.h b/include/sysemu/kvm_xen.h
index 1edff29541..7fee28dec7 100644
--- a/include/sysemu/kvm_xen.h
+++ b/include/sysemu/kvm_xen.h
@@ -25,6 +25,7 @@ void *kvm_xen_get_vcpu_info_hva(uint32_t vcpu_id);
 void kvm_xen_inject_vcpu_callback_vector(uint32_t vcpu_id, int type);
 void kvm_xen_set_callback_asserted(void);
 int kvm_xen_set_vcpu_virq(uint32_t vcpu_id, uint16_t virq, uint16_t port);
+uint16_t kvm_xen_get_gnttab_max_frames(void);
 
 #define kvm_xen_has_cap(cap) (!!(kvm_xen_get_caps() &           \
                                  KVM_XEN_HVM_CONFIG_ ## cap))
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index ae8962f1af..9ff964c849 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -5865,6 +5865,33 @@ static void kvm_arch_set_xen_version(Object *obj, Visitor *v,
     }
 }
 
+static void kvm_arch_get_xen_gnttab_max_frames(Object *obj, Visitor *v,
+                                               const char *name, void *opaque,
+                                               Error **errp)
+{
+    KVMState *s = KVM_STATE(obj);
+    uint16_t value = s->xen_gnttab_max_frames;
+
+    visit_type_uint16(v, name, &value, errp);
+}
+
+static void kvm_arch_set_xen_gnttab_max_frames(Object *obj, Visitor *v,
+                                               const char *name, void *opaque,
+                                               Error **errp)
+{
+    KVMState *s = KVM_STATE(obj);
+    Error *error = NULL;
+    uint16_t value;
+
+    visit_type_uint16(v, name, &value, &error);
+    if (error) {
+        error_propagate(errp, error);
+        return;
+    }
+
+    s->xen_gnttab_max_frames = value;
+}
+
 void kvm_arch_accel_class_init(ObjectClass *oc)
 {
     object_class_property_add_enum(oc, "notify-vmexit", "NotifyVMexitOption",
@@ -5890,6 +5917,13 @@ void kvm_arch_accel_class_init(ObjectClass *oc)
                                           "Xen version to be emulated "
                                           "(in XENVER_version form "
                                           "e.g. 0x4000a for 4.10)");
+
+    object_class_property_add(oc, "xen-gnttab-max-frames", "uint16",
+                              kvm_arch_get_xen_gnttab_max_frames,
+                              kvm_arch_set_xen_gnttab_max_frames,
+                              NULL, NULL);
+    object_class_property_set_description(oc, "xen-gnttab-max-frames",
+                                          "Maximum number of grant table frames");
 }
 
 void kvm_set_max_apic_id(uint32_t max_apic_id)
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index ba83b45b62..121c037eca 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -1235,6 +1235,12 @@ int kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
     return 0;
 }
 
+uint16_t kvm_xen_get_gnttab_max_frames(void)
+{
+    KVMState *s = KVM_STATE(current_accel());
+    return s->xen_gnttab_max_frames;
+}
+
 int kvm_put_xen_state(CPUState *cs)
 {
     X86CPU *cpu = X86_CPU(cs);
-- 
2.39.0