[RFC PATCH v3 04/38] i386/kvm: Add xen-version machine property and init KVM Xen support

[David Woodhouse]

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

This just initializes the basic Xen support in KVM for now.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 accel/kvm/kvm-all.c         |  1 +
 include/sysemu/kvm_int.h    |  1 +
 target/i386/kvm/kvm.c       | 53 +++++++++++++++++++++++++++++++++++++
 target/i386/kvm/meson.build |  2 ++
 target/i386/kvm/xen-emu.c   | 50 ++++++++++++++++++++++++++++++++++
 target/i386/kvm/xen-emu.h   | 19 +++++++++++++
 6 files changed, 126 insertions(+)
 create mode 100644 target/i386/kvm/xen-emu.c
 create mode 100644 target/i386/kvm/xen-emu.h

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index f99b0becd8..568bb09c09 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3620,6 +3620,7 @@ static void kvm_accel_instance_init(Object *obj)
     s->kvm_dirty_ring_size = 0;
     s->notify_vmexit = NOTIFY_VMEXIT_OPTION_RUN;
     s->notify_window = 0;
+    s->xen_version = 0;
 }
 
 /**
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index 3b4adcdc10..429cecbd04 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -110,6 +110,7 @@ struct KVMState
     struct KVMDirtyRingReaper reaper;
     NotifyVmexitOption notify_vmexit;
     uint32_t notify_window;
+    uint32_t xen_version;
 };
 
 void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a213209379..a98995d4d7 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -31,6 +31,7 @@
 #include "sysemu/runstate.h"
 #include "kvm_i386.h"
 #include "sev.h"
+#include "xen-emu.h"
 #include "hyperv.h"
 #include "hyperv-proto.h"
 
@@ -48,6 +49,8 @@
 #include "hw/i386/x86-iommu.h"
 #include "hw/i386/e820_memory_layout.h"
 
+#include "hw/xen/xen.h"
+
 #include "hw/pci/pci.h"
 #include "hw/pci/msi.h"
 #include "hw/pci/msix.h"
@@ -2513,6 +2516,18 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         }
     }
 
+    if (s->xen_version) {
+#ifdef CONFIG_XEN_EMU
+            ret = kvm_xen_init(s);
+            if (ret < 0) {
+                    return ret;
+            }
+#else
+            error_report("kvm: Xen support not enabled in qemu");
+            return -ENOTSUP;
+#endif
+    }
+
     ret = kvm_get_supported_msrs(s);
     if (ret < 0) {
         return ret;
@@ -5706,6 +5721,35 @@ static void kvm_arch_set_notify_window(Object *obj, 
Visitor *v,
     s->notify_window = value;
 }
 
+static void kvm_arch_get_xen_version(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    KVMState *s = KVM_STATE(obj);
+    uint32_t value = s->xen_version;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void kvm_arch_set_xen_version(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    KVMState *s = KVM_STATE(obj);
+    Error *error = NULL;
+    uint32_t value;
+
+    visit_type_uint32(v, name, &value, &error);
+    if (error) {
+        error_propagate(errp, error);
+        return;
+    }
+
+    s->xen_version = value;
+    if (value && xen_mode == XEN_DISABLED)
+            xen_mode = XEN_EMULATE;
+}
+
 void kvm_arch_accel_class_init(ObjectClass *oc)
 {
     object_class_property_add_enum(oc, "notify-vmexit", "NotifyVMexitOption",
@@ -5722,6 +5766,15 @@ void kvm_arch_accel_class_init(ObjectClass *oc)
     object_class_property_set_description(oc, "notify-window",
                                           "Clock cycles without an event 
window "
                                           "after which a notification VM exit 
occurs");
+
+    object_class_property_add(oc, "xen-version", "uint32",
+                              kvm_arch_get_xen_version,
+                              kvm_arch_set_xen_version,
+                              NULL, NULL);
+    object_class_property_set_description(oc, "xen-version",
+                                          "Xen version to be emulated "
+                                          "(in XENVER_version form "
+                                          "e.g. 0x4000a for 4.10)");
 }
 
 void kvm_set_max_apic_id(uint32_t max_apic_id)
diff --git a/target/i386/kvm/meson.build b/target/i386/kvm/meson.build
index 736df8b72e..322272091b 100644
--- a/target/i386/kvm/meson.build
+++ b/target/i386/kvm/meson.build
@@ -7,6 +7,8 @@ i386_softmmu_kvm_ss.add(files(
   'kvm-cpu.c',
 ))
 
+i386_softmmu_kvm_ss.add(when: 'CONFIG_XEN_EMU', if_true: files('xen-emu.c'))
+
 i386_softmmu_kvm_ss.add(when: 'CONFIG_SEV', if_false: files('sev-stub.c'))
 
 i386_softmmu_ss.add(when: 'CONFIG_HYPERV', if_true: files('hyperv.c'), 
if_false: files('hyperv-stub.c'))
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
new file mode 100644
index 0000000000..4bd2eeeb5a
--- /dev/null
+++ b/target/i386/kvm/xen-emu.c
@@ -0,0 +1,50 @@
+/*
+ * Xen HVM emulation support in KVM
+ *
+ * Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/kvm_int.h"
+#include "kvm/kvm_i386.h"
+#include "xen-emu.h"
+
+int kvm_xen_init(KVMState *s)
+{
+    const int required_caps = KVM_XEN_HVM_CONFIG_HYPERCALL_MSR |
+        KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL | KVM_XEN_HVM_CONFIG_SHARED_INFO;
+    struct kvm_xen_hvm_config cfg = {
+        .msr = XEN_HYPERCALL_MSR,
+        .flags = KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL,
+    };
+    int xen_caps, ret;
+
+    xen_caps = kvm_check_extension(s, KVM_CAP_XEN_HVM);
+    if (required_caps & ~xen_caps) {
+        error_report("kvm: Xen HVM guest support not present or insufficient");
+        return -ENOSYS;
+    }
+
+    if (xen_caps & KVM_XEN_HVM_CONFIG_EVTCHN_SEND) {
+        struct kvm_xen_hvm_attr ha = {
+            .type = KVM_XEN_ATTR_TYPE_XEN_VERSION,
+            .u.xen_version = s->xen_version,
+        };
+        (void)kvm_vm_ioctl(s, KVM_XEN_HVM_SET_ATTR, &ha);
+
+        cfg.flags |= KVM_XEN_HVM_CONFIG_EVTCHN_SEND;
+    }
+
+    ret = kvm_vm_ioctl(s, KVM_XEN_HVM_CONFIG, &cfg);
+    if (ret < 0) {
+        error_report("kvm: Failed to enable Xen HVM support: %s", 
strerror(-ret));
+        return ret;
+    }
+
+    return 0;
+}
diff --git a/target/i386/kvm/xen-emu.h b/target/i386/kvm/xen-emu.h
new file mode 100644
index 0000000000..4f31bd96cb
--- /dev/null
+++ b/target/i386/kvm/xen-emu.h
@@ -0,0 +1,19 @@
+/*
+ * Xen HVM emulation support in KVM
+ *
+ * Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_I386_KVM_XEN_EMU_H
+#define QEMU_I386_KVM_XEN_EMU_H
+
+#define XEN_HYPERCALL_MSR 0x40000000
+
+int kvm_xen_init(KVMState *s);
+
+#endif /* QEMU_I386_KVM_XEN_EMU_H */
-- 
2.35.3