@@ -8,6 +8,7 @@ i386_kvm_ss.add(when: 'CONFIG_XEN_EMU', if_true: files(
'xen_overlay.c',
'xen_evtchn.c',
'xen_gnttab.c',
+ 'xen_xenstore.c',
))
i386_ss.add_all(when: 'CONFIG_KVM', if_true: i386_kvm_ss)
@@ -34,6 +34,7 @@
#include "xen_evtchn.h"
#include "xen_overlay.h"
+#include "xen_xenstore.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_xen.h"
new file mode 100644
@@ -0,0 +1,248 @@
+/*
+ * QEMU Xen emulation: Shared/overlay pages support
+ *
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Authors: David Woodhouse <dwmw2@infradead.org>
+ *
+ * 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 "qemu/host-utils.h"
+#include "qemu/module.h"
+#include "qemu/main-loop.h"
+#include "qemu/cutils.h"
+#include "qapi/error.h"
+#include "qom/object.h"
+#include "migration/vmstate.h"
+
+#include "hw/sysbus.h"
+#include "hw/xen/xen.h"
+#include "xen_overlay.h"
+#include "xen_evtchn.h"
+#include "xen_xenstore.h"
+
+#include "sysemu/kvm.h"
+#include "sysemu/kvm_xen.h"
+
+#include "hw/xen/interface/io/xs_wire.h"
+#include "hw/xen/interface/event_channel.h"
+
+#define TYPE_XEN_XENSTORE "xen-xenstore"
+OBJECT_DECLARE_SIMPLE_TYPE(XenXenstoreState, XEN_XENSTORE)
+
+#define XEN_PAGE_SHIFT 12
+#define XEN_PAGE_SIZE (1ULL << XEN_PAGE_SHIFT)
+
+#define ENTRIES_PER_FRAME_V1 (XEN_PAGE_SIZE / sizeof(grant_entry_v1_t))
+#define ENTRIES_PER_FRAME_V2 (XEN_PAGE_SIZE / sizeof(grant_entry_v2_t))
+
+#define XENSTORE_HEADER_SIZE ((unsigned int)sizeof(struct xsd_sockmsg))
+
+struct XenXenstoreState {
+ /*< private >*/
+ SysBusDevice busdev;
+ /*< public >*/
+
+ MemoryRegion xenstore_page;
+ struct xenstore_domain_interface *xs;
+ uint8_t req_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX];
+ uint8_t rsp_data[XENSTORE_HEADER_SIZE + XENSTORE_PAYLOAD_MAX];
+ uint32_t req_offset;
+ uint32_t rsp_offset;
+ bool rsp_pending;
+ bool fatal_error;
+
+ evtchn_port_t guest_port;
+ evtchn_port_t be_port;
+ struct xenevtchn_handle *eh;
+};
+
+struct XenXenstoreState *xen_xenstore_singleton;
+
+static void xen_xenstore_event(void *opaque);
+
+static void xen_xenstore_realize(DeviceState *dev, Error **errp)
+{
+ XenXenstoreState *s = XEN_XENSTORE(dev);
+
+ if (xen_mode != XEN_EMULATE) {
+ error_setg(errp, "Xen xenstore support is for Xen emulation");
+ return;
+ }
+ memory_region_init_ram(&s->xenstore_page, OBJECT(dev), "xen:xenstore_page",
+ XEN_PAGE_SIZE, &error_abort);
+ memory_region_set_enabled(&s->xenstore_page, true);
+ s->xs = memory_region_get_ram_ptr(&s->xenstore_page);
+ memset(s->xs, 0, XEN_PAGE_SIZE);
+
+ /* We can't map it this early as KVM isn't ready */
+ xen_xenstore_singleton = s;
+
+ s->eh = xen_be_evtchn_open();
+ if (!s->eh) {
+ error_setg(errp, "Xenstore evtchn port init failed");
+ return;
+ }
+ aio_set_fd_handler(qemu_get_aio_context(), xen_be_evtchn_fd(s->eh), true,
+ xen_xenstore_event, NULL, NULL, NULL, s);
+}
+
+static bool xen_xenstore_is_needed(void *opaque)
+{
+ return xen_mode == XEN_EMULATE;
+}
+
+static int xen_xenstore_pre_save(void *opaque)
+{
+ XenXenstoreState *s = opaque;
+
+ if (s->eh) {
+ s->guest_port = xen_be_evtchn_get_guest_port(s->eh);
+ }
+ return 0;
+}
+
+static int xen_xenstore_post_load(void *opaque, int ver)
+{
+ XenXenstoreState *s = opaque;
+
+ /*
+ * As qemu/dom0, rebind to the guest's port. The Windows drivers may
+ * unbind the XenStore evtchn and rebind to it, having obtained the
+ * "remote" port through EVTCHNOP_status. In the case that migration
+ * occurs while it's unbound, the "remote" port needs to be the same
+ * as before so that the guest can find it, but should remain unbound.
+ */
+ if (s->guest_port) {
+ int be_port = xen_be_evtchn_bind_interdomain(s->eh, xen_domid, s->guest_port);
+ if (be_port < 0) {
+ return be_port;
+ }
+ s->be_port = be_port;
+ }
+ return 0;
+}
+
+static const VMStateDescription xen_xenstore_vmstate = {
+ .name = "xen_xenstore",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .needed = xen_xenstore_is_needed,
+ .pre_save = xen_xenstore_pre_save,
+ .post_load = xen_xenstore_post_load,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT8_ARRAY(req_data, XenXenstoreState, sizeof_field(XenXenstoreState, req_data)),
+ VMSTATE_UINT8_ARRAY(rsp_data, XenXenstoreState, sizeof_field(XenXenstoreState, rsp_data)),
+ VMSTATE_UINT32(req_offset, XenXenstoreState),
+ VMSTATE_UINT32(rsp_offset, XenXenstoreState),
+ VMSTATE_BOOL(rsp_pending, XenXenstoreState),
+ VMSTATE_UINT32(guest_port, XenXenstoreState),
+ VMSTATE_BOOL(fatal_error, XenXenstoreState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static void xen_xenstore_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+
+ dc->realize = xen_xenstore_realize;
+ dc->vmsd = &xen_xenstore_vmstate;
+}
+
+static const TypeInfo xen_xenstore_info = {
+ .name = TYPE_XEN_XENSTORE,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(XenXenstoreState),
+ .class_init = xen_xenstore_class_init,
+};
+
+void xen_xenstore_create(void)
+{
+ xen_xenstore_singleton = XEN_XENSTORE(sysbus_create_simple(TYPE_XEN_XENSTORE,
+ -1, NULL));
+
+ /*
+ * Defer the init (xen_xenstore_reset()) until KVM is set up and the
+ * overlay page can be mapped.
+ */
+}
+
+static void xen_xenstore_register_types(void)
+{
+ type_register_static(&xen_xenstore_info);
+}
+
+type_init(xen_xenstore_register_types)
+
+uint16_t xen_xenstore_get_port(void)
+{
+ XenXenstoreState *s = xen_xenstore_singleton;
+ if (!s) {
+ return 0;
+ }
+ return s->guest_port;
+}
+
+static void xen_xenstore_event(void *opaque)
+{
+ XenXenstoreState *s = opaque;
+ evtchn_port_t port = xen_be_evtchn_pending(s->eh);
+ if (port != s->be_port) {
+ return;
+ }
+ printf("xenstore event\n");
+ /* We know this is a no-op. */
+ xen_be_evtchn_unmask(s->eh, port);
+ qemu_hexdump(stdout, "", s->xs, sizeof(*s->xs));
+ xen_be_evtchn_notify(s->eh, s->be_port);
+}
+
+static void alloc_guest_port(XenXenstoreState *s)
+{
+ struct evtchn_alloc_unbound alloc = {
+ .dom = DOMID_SELF,
+ .remote_dom = DOMID_QEMU,
+ };
+
+ if (!xen_evtchn_alloc_unbound_op(&alloc)) {
+ s->guest_port = alloc.port;
+ }
+}
+
+int xen_xenstore_reset(void)
+{
+ XenXenstoreState *s = xen_xenstore_singleton;
+ int err;
+
+ if (!s) {
+ return -ENOTSUP;
+ }
+
+ s->req_offset = s->rsp_offset = 0;
+ s->rsp_pending = false;
+
+ if (!memory_region_is_mapped(&s->xenstore_page)) {
+ uint64_t gpa = XEN_SPECIAL_PFN(XENSTORE) << TARGET_PAGE_BITS;
+ xen_overlay_do_map_page(&s->xenstore_page, gpa);
+ }
+
+ alloc_guest_port(s);
+
+ /*
+ * As qemu/dom0, bind to the guest's port. For incoming migration, this
+ * will be unbound as the guest's evtchn table is overwritten. We then
+ * rebind to the correct guest port in xen_xenstore_post_load().
+ */
+ err = xen_be_evtchn_bind_interdomain(s->eh, xen_domid, s->guest_port);
+ if (err < 0) {
+ return err;
+ }
+ s->be_port = err;
+
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,20 @@
+/*
+ * QEMU Xen emulation: Xenstore emulation
+ *
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Authors: David Woodhouse <dwmw2@infradead.org>
+ *
+ * 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_XEN_XENSTORE_H
+#define QEMU_XEN_XENSTORE_H
+
+void xen_xenstore_create(void);
+int xen_xenstore_reset(void);
+
+uint16_t xen_xenstore_get_port(void);
+
+#endif /* QEMU_XEN_XENSTORE_H */
@@ -92,6 +92,7 @@
#include "hw/i386/kvm/xen_overlay.h"
#include "hw/i386/kvm/xen_evtchn.h"
#include "hw/i386/kvm/xen_gnttab.h"
+#include "hw/i386/kvm/xen_xenstore.h"
#include "hw/mem/memory-device.h"
#include "sysemu/replay.h"
#include "target/i386/cpu.h"
@@ -1860,6 +1861,7 @@ int pc_machine_kvm_type(MachineState *machine, const char *kvm_type)
xen_overlay_create();
xen_evtchn_create();
xen_gnttab_create();
+ xen_xenstore_create();
}
#endif
return 0;
@@ -27,6 +27,7 @@
#include "hw/i386/kvm/xen_overlay.h"
#include "hw/i386/kvm/xen_evtchn.h"
#include "hw/i386/kvm/xen_gnttab.h"
+#include "hw/i386/kvm/xen_xenstore.h"
#include "hw/xen/interface/version.h"
#include "hw/xen/interface/sched.h"
@@ -179,6 +180,9 @@ int kvm_xen_init(KVMState *s, uint32_t hypercall_msr)
return ret;
}
+ /* The page couldn't be overlaid until KVM was initialized */
+ xen_xenstore_reset();
+
return 0;
}
@@ -786,6 +790,9 @@ static bool handle_get_param(struct kvm_xen_exit *exit, X86CPU *cpu,
case HVM_PARAM_STORE_PFN:
hp.value = XEN_SPECIAL_PFN(XENSTORE);
break;
+ case HVM_PARAM_STORE_EVTCHN:
+ hp.value = xen_xenstore_get_port();
+ break;
default:
return false;
}
@@ -1361,6 +1368,11 @@ int kvm_xen_soft_reset(void)
return err;
}
+ err = xen_xenstore_reset();
+ if (err) {
+ return err;
+ }
+
return 0;
}