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[RFC PATCH v5 51/52] hw/xen: Add xen_xenstore device for xenstore emulat
From: |
David Woodhouse |
Subject: |
[RFC PATCH v5 51/52] hw/xen: Add xen_xenstore device for xenstore emulation |
Date: |
Fri, 30 Dec 2022 12:12:34 +0000 |
From: David Woodhouse <dwmw@amazon.co.uk>
The hookup to event channel is a bit of a special case hack right now; as
we make this work for real PV driver back ends, that will be implemented
for the general case of Dom0 ports binding to DomU.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
hw/i386/kvm/meson.build | 1 +
hw/i386/kvm/xen_evtchn.c | 1 +
hw/i386/kvm/xen_xenstore.c | 248 +++++++++++++++++++++++++++++++++++++
hw/i386/kvm/xen_xenstore.h | 20 +++
hw/i386/pc.c | 2 +
target/i386/kvm/xen-emu.c | 12 ++
6 files changed, 284 insertions(+)
create mode 100644 hw/i386/kvm/xen_xenstore.c
create mode 100644 hw/i386/kvm/xen_xenstore.h
diff --git a/hw/i386/kvm/meson.build b/hw/i386/kvm/meson.build
index e02449e4d4..6d6981fced 100644
--- a/hw/i386/kvm/meson.build
+++ b/hw/i386/kvm/meson.build
@@ -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)
diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index c0f6ef9dff..0653cad3bb 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -31,6 +31,7 @@
#include "xen_evtchn.h"
#include "xen_overlay.h"
+#include "xen_xenstore.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_xen.h"
diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
new file mode 100644
index 0000000000..63530059fa
--- /dev/null
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -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 "standard-headers/xen/io/xs_wire.h"
+#include "standard-headers/xen/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(NULL, 0);
+ 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)) {
+ xen_overlay_map_page_locked(&s->xenstore_page,
+ XEN_SPECIAL_PFN(XENSTORE) <<
TARGET_PAGE_BITS);
+ }
+
+ 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;
+}
diff --git a/hw/i386/kvm/xen_xenstore.h b/hw/i386/kvm/xen_xenstore.h
new file mode 100644
index 0000000000..8c3768e075
--- /dev/null
+++ b/hw/i386/kvm/xen_xenstore.h
@@ -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 */
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 4f044bc7da..104f52b119 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -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"
@@ -1858,6 +1859,7 @@ 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;
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index 08db4c0d9b..cb119f43c0 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -28,6 +28,7 @@
#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 "standard-headers/xen/version.h"
#include "standard-headers/xen/sched.h"
@@ -153,6 +154,9 @@ 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;
}
@@ -731,6 +735,9 @@ 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;
}
@@ -1294,6 +1301,11 @@ static int kvm_xen_soft_reset(void)
return err;
}
+ err = xen_xenstore_reset();
+ if (err) {
+ return err;
+ }
+
return 0;
}
--
2.35.3
- [RFC PATCH v5 36/52] hw/xen: Implement EVTCHNOP_bind_interdomain, (continued)
- [RFC PATCH v5 36/52] hw/xen: Implement EVTCHNOP_bind_interdomain, David Woodhouse, 2022/12/30
- [RFC PATCH v5 43/52] hw/xen: Add xen_gnttab device for grant table emulation, David Woodhouse, 2022/12/30
- [RFC PATCH v5 19/52] i386/xen: implement HYPERVISOR_hvm_op, David Woodhouse, 2022/12/30
- [RFC PATCH v5 46/52] hw/xen: Implement GNTTABOP_query_size, David Woodhouse, 2022/12/30
- [RFC PATCH v5 34/52] hw/xen: Implement EVTCHNOP_send, David Woodhouse, 2022/12/30
- [RFC PATCH v5 13/52] i386/xen: Implement SCHEDOP_poll and SCHEDOP_yield, David Woodhouse, 2022/12/30
- [RFC PATCH v5 08/52] xen-platform: allow its creation with XEN_EMULATE mode, David Woodhouse, 2022/12/30
- [RFC PATCH v5 37/52] hw/xen: Implement EVTCHNOP_bind_vcpu, David Woodhouse, 2022/12/30
- [RFC PATCH v5 11/52] i386/xen: implement HYPERVISOR_xen_version, David Woodhouse, 2022/12/30
- [RFC PATCH v5 18/52] i386/xen: implement XENMEM_add_to_physmap_batch, David Woodhouse, 2022/12/30
- [RFC PATCH v5 51/52] hw/xen: Add xen_xenstore device for xenstore emulation,
David Woodhouse <=
- [RFC PATCH v5 03/52] xen: Add XEN_DISABLED mode and make it default, David Woodhouse, 2022/12/30
- [RFC PATCH v5 38/52] hw/xen: Implement EVTCHNOP_reset, David Woodhouse, 2022/12/30
- [RFC PATCH v5 29/52] hw/xen: Implement EVTCHNOP_status, David Woodhouse, 2022/12/30
- [RFC PATCH v5 30/52] hw/xen: Implement EVTCHNOP_close, David Woodhouse, 2022/12/30
- [RFC PATCH v5 15/52] i386/xen: add pc_machine_kvm_type to initialize XEN_EMULATE mode, David Woodhouse, 2022/12/30
- [RFC PATCH v5 12/52] i386/xen: implement HYPERVISOR_sched_op, SCHEDOP_shutdown, David Woodhouse, 2022/12/30
- [RFC PATCH v5 20/52] i386/xen: implement HYPERVISOR_vcpu_op, David Woodhouse, 2022/12/30
- [RFC PATCH v5 10/52] i386/xen: handle guest hypercalls, David Woodhouse, 2022/12/30
- [RFC PATCH v5 32/52] hw/xen: Implement EVTCHNOP_bind_virq, David Woodhouse, 2022/12/30
- [RFC PATCH v5 28/52] i386/xen: Add support for Xen event channel delivery to vCPU, David Woodhouse, 2022/12/30