From: David Woodhouse <dwmw@xxxxxxxxxxxx>
The primary console is special because the toolstack maps a page at a
fixed GFN and also allocates the guest-side event channel. Add support
for that in emulated mode, so that we can have a primary console.
Add a *very* rudimentary stub of foriegnmem ops for emulated mode, which
supports literally nothing except a single-page mapping of the console
page. This might as well have been a hack in the xen_console driver, but
this way at least the special-casing is kept within the Xen emulation
code, and it gives us a hook for a more complete implementation if/when
we ever do need one.
Now at last we can boot the Xen PV shim and run PV kernels in QEMU.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
hw/char/xen_console.c | 28 +++--
hw/i386/kvm/meson.build | 1 +
hw/i386/kvm/trace-events | 2 +
hw/i386/kvm/xen-stubs.c | 5 +
hw/i386/kvm/xen_gnttab.c | 32 +++++-
hw/i386/kvm/xen_primary_console.c | 167 ++++++++++++++++++++++++++++++
hw/i386/kvm/xen_primary_console.h | 22 ++++
hw/i386/kvm/xen_xenstore.c | 10 ++
target/i386/kvm/xen-emu.c | 23 +++-
9 files changed, 278 insertions(+), 12 deletions(-)
create mode 100644 hw/i386/kvm/xen_primary_console.c
create mode 100644 hw/i386/kvm/xen_primary_console.h
diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index f4c70709c7..8256b4b889 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -33,6 +33,7 @@
#include "hw/qdev-properties-system.h"
#include "hw/xen/interface/io/console.h"
#include "hw/xen/interface/io/xs_wire.h"
+#include "hw/i386/kvm/xen_primary_console.h"
#include "trace.h"
struct buffer {
@@ -335,14 +336,19 @@ static char *xen_console_get_name(XenDevice *xendev, Error **errp)
if (con->dev == -1) {
XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));
char fe_path[XENSTORE_ABS_PATH_MAX + 1];
+ int idx = (xen_mode == XEN_EMULATE) ? 0 : 1;
char *value;
- int idx = 1;
/* Theoretically we could go up to INT_MAX here but that's overkill */
while (idx < 100) {
- snprintf(fe_path, sizeof(fe_path),
- "/local/domain/%u/device/console/%u",
- xendev->frontend_id, idx);
+ if (!idx) {
+ snprintf(fe_path, sizeof(fe_path),
+ "/local/domain/%u/console", xendev->frontend_id);
+ } else {
+ snprintf(fe_path, sizeof(fe_path),
+ "/local/domain/%u/device/console/%u",
+ xendev->frontend_id, idx);
+ }
value = qemu_xen_xs_read(xenbus->xsh, XBT_NULL, fe_path, NULL);
if (!value) {
if (errno == ENOENT) {
@@ -397,11 +403,15 @@ static void xen_console_realize(XenDevice *xendev, Error **errp)
* be mapped directly as foreignmem (not a grant ref), and the guest port
* was allocated *for* the guest by the toolstack. The guest gets these
* through HVMOP_get_param and can use the console long before it's got
- * XenStore up and running. We cannot create those for a Xen guest.
+ * XenStore up and running. We cannot create those for a true Xen guest,
+ * but we can for Xen emulation.
*/
if (!con->dev) {
- if (xen_device_frontend_scanf(xendev, "ring-ref", "%u", &u) != 1 ||
- xen_device_frontend_scanf(xendev, "port", "%u", &u) != 1) {
+ if (xen_mode == XEN_EMULATE) {
+ xen_primary_console_create();
+ } else if (xen_device_frontend_scanf(xendev, "ring-ref", "%u", &u)
+ != 1 ||
+ xen_device_frontend_scanf(xendev, "port", "%u", &u) != 1) {
error_setg(errp, "cannot create primary Xen console");
return;
}
@@ -414,8 +424,8 @@ static void xen_console_realize(XenDevice *xendev, Error **errp)
xen_device_frontend_printf(xendev, "tty", "%s", cs->filename + 4);
}
- /* No normal PV driver initialization for the primary console */
- if (!con->dev) {
+ /* No normal PV driver initialization for the primary console under Xen */
+ if (!con->dev && xen_mode != XEN_EMULATE) {
xen_console_connect(xendev, errp);
}
}
diff --git a/hw/i386/kvm/meson.build b/hw/i386/kvm/meson.build
index ab143d6474..a4a2e23c06 100644
--- a/hw/i386/kvm/meson.build
+++ b/hw/i386/kvm/meson.build
@@ -9,6 +9,7 @@ i386_kvm_ss.add(when: 'CONFIG_XEN_EMU', if_true: files(
'xen_evtchn.c',
'xen_gnttab.c',
'xen_xenstore.c',
+ 'xen_primary_console.c',
'xenstore_impl.c',
))
diff --git a/hw/i386/kvm/trace-events b/hw/i386/kvm/trace-events
index e4c82de6f3..67bf7f174e 100644
--- a/hw/i386/kvm/trace-events
+++ b/hw/i386/kvm/trace-events
@@ -18,3 +18,5 @@ xenstore_watch(const char *path, const char *token) "path %s token %s"
xenstore_unwatch(const char *path, const char *token) "path %s token %s"
xenstore_reset_watches(void) ""
xenstore_watch_event(const char *path, const char *token) "path %s token %s"
+xen_primary_console_create(void) ""
+xen_primary_console_reset(int port) "port %u"
diff --git a/hw/i386/kvm/xen-stubs.c b/hw/i386/kvm/xen-stubs.c
index ae406e0b02..10068970fe 100644
--- a/hw/i386/kvm/xen-stubs.c
+++ b/hw/i386/kvm/xen-stubs.c
@@ -15,6 +15,7 @@
#include "qapi/qapi-commands-misc-target.h"
#include "xen_evtchn.h"
+#include "xen_primary_console.h"
void xen_evtchn_snoop_msi(PCIDevice *dev, bool is_msix, unsigned int vector,
uint64_t addr, uint32_t data, bool is_masked)
@@ -30,6 +31,10 @@ bool xen_evtchn_deliver_pirq_msi(uint64_t address, uint32_t data)
return false;
}
+void xen_primary_console_create(void)
+{
+}
+
#ifdef TARGET_I386
EvtchnInfoList *qmp_xen_event_list(Error **errp)
{
diff --git a/hw/i386/kvm/xen_gnttab.c b/hw/i386/kvm/xen_gnttab.c
index 839ec920a1..5519f7712f 100644
--- a/hw/i386/kvm/xen_gnttab.c
+++ b/hw/i386/kvm/xen_gnttab.c
@@ -25,6 +25,7 @@
#include "hw/xen/xen_backend_ops.h"
#include "xen_overlay.h"
#include "xen_gnttab.h"
+#include "xen_primary_console.h"
#include "sysemu/kvm.h"
#include "sysemu/kvm_xen.h"
@@ -38,6 +39,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(XenGnttabState, XEN_GNTTAB)
#define ENTRIES_PER_FRAME_V1 (XEN_PAGE_SIZE / sizeof(grant_entry_v1_t))
static struct gnttab_backend_ops emu_gnttab_backend_ops;
+static struct foreignmem_backend_ops emu_foreignmem_backend_ops;
struct XenGnttabState {
/*< private >*/
@@ -100,6 +102,7 @@ static void xen_gnttab_realize(DeviceState *dev, Error **errp)
s->map_track = g_new0(uint8_t, s->max_frames * ENTRIES_PER_FRAME_V1);
xen_gnttab_ops = &emu_gnttab_backend_ops;
+ xen_foreignmem_ops = &emu_foreignmem_backend_ops;
}
static int xen_gnttab_post_load(void *opaque, int version_id)
@@ -524,6 +527,29 @@ static struct gnttab_backend_ops emu_gnttab_backend_ops = {
.unmap = xen_be_gnttab_unmap,
};
+/* Dummy implementation of foreignmem; just enough for console */
+static void *xen_be_foreignmem_map(uint32_t dom, void *addr, int prot,
+ size_t pages, xen_pfn_t *pfns,
+ int *errs)
+{
+ if (dom == xen_domid && !addr && pages == 1 &&
+ pfns[0] == xen_primary_console_get_pfn()) {
+ return xen_primary_console_get_map();
+ }
+
+ return NULL;
+}
+
+static int xen_be_foreignmem_unmap(void *addr, size_t pages)
+{
+ return 0;
+}
+
+static struct foreignmem_backend_ops emu_foreignmem_backend_ops = {
+ .map = xen_be_foreignmem_map,
+ .unmap = xen_be_foreignmem_unmap,
+};
+
int xen_gnttab_reset(void)
{
XenGnttabState *s = xen_gnttab_singleton;
@@ -537,9 +563,13 @@ int xen_gnttab_reset(void)
s->nr_frames = 0;
memset(s->entries.v1, 0, XEN_PAGE_SIZE * s->max_frames);
-
s->entries.v1[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
s->entries.v1[GNTTAB_RESERVED_XENSTORE].frame = XEN_SPECIAL_PFN(XENSTORE);
+ if (xen_primary_console_get_pfn()) {
+ s->entries.v1[GNTTAB_RESERVED_CONSOLE].flags = GTF_permit_access;
+ s->entries.v1[GNTTAB_RESERVED_CONSOLE].frame = XEN_SPECIAL_PFN(CONSOLE);
+ }
+
return 0;
}
diff --git a/hw/i386/kvm/xen_primary_console.c b/hw/i386/kvm/xen_primary_console.c
new file mode 100644
index 0000000000..0aa1c16ad6
--- /dev/null
+++ b/hw/i386/kvm/xen_primary_console.c
@@ -0,0 +1,167 @@
+/*
+ * QEMU Xen emulation: Primary console support
+ *
+ * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Authors: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
+ *
+ * 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 "qapi/error.h"
+
+#include "hw/sysbus.h"
+#include "hw/xen/xen.h"
+#include "hw/xen/xen_backend_ops.h"
+#include "xen_evtchn.h"
+#include "xen_overlay.h"
+#include "xen_primary_console.h"
+
+#include "sysemu/kvm.h"
+#include "sysemu/kvm_xen.h"
+
+#include "trace.h"
+
+#include "hw/xen/interface/event_channel.h"
+#include "hw/xen/interface/grant_table.h"
+
+#define TYPE_XEN_PRIMARY_CONSOLE "xen-primary-console"
+OBJECT_DECLARE_SIMPLE_TYPE(XenPrimaryConsoleState, XEN_PRIMARY_CONSOLE)
+
+struct XenPrimaryConsoleState {
+ /*< private >*/
+ SysBusDevice busdev;
+ /*< public >*/
+
+ MemoryRegion console_page;
+ void *cp;
+
+ evtchn_port_t guest_port;
+ evtchn_port_t be_port;
+
+ struct xengntdev_handle *gt;
+ void *granted_xs;
+};
+
+struct XenPrimaryConsoleState *xen_primary_console_singleton;
+
+static void xen_primary_console_realize(DeviceState *dev, Error **errp)
+{
+ XenPrimaryConsoleState *s = XEN_PRIMARY_CONSOLE(dev);
+
+ if (xen_mode != XEN_EMULATE) {
+ error_setg(errp, "Xen primary console support is for Xen emulation");
+ return;
+ }
+
+ memory_region_init_ram(&s->console_page, OBJECT(dev), "xen:console_page",
+ XEN_PAGE_SIZE, &error_abort);
+ memory_region_set_enabled(&s->console_page, true);
+ s->cp = memory_region_get_ram_ptr(&s->console_page);
+ memset(s->cp, 0, XEN_PAGE_SIZE);
+
+ /* We can't map it this early as KVM isn't ready */
+ xen_primary_console_singleton = s;
+}
+
+static void xen_primary_console_class_init(ObjectClass *klass, void *data)
+{
+ DeviceClass *dc = DEVICE_CLASS(klass);
+
+ dc->realize = xen_primary_console_realize;
+}
+
+static const TypeInfo xen_primary_console_info = {
+ .name = TYPE_XEN_PRIMARY_CONSOLE,
+ .parent = TYPE_SYS_BUS_DEVICE,
+ .instance_size = sizeof(XenPrimaryConsoleState),
+ .class_init = xen_primary_console_class_init,
+};
+
+
+void xen_primary_console_create(void)
+{
+ DeviceState *dev = sysbus_create_simple(TYPE_XEN_PRIMARY_CONSOLE, -1, NULL);
+
+ trace_xen_primary_console_create();
+
+ xen_primary_console_singleton = XEN_PRIMARY_CONSOLE(dev);
+
+ /*
+ * Defer the init (xen_primary_console_reset()) until KVM is set up and the
+ * overlay page can be mapped.
+ */
+}
+
+static void xen_primary_console_register_types(void)
+{
+ type_register_static(&xen_primary_console_info);
+}
+
+type_init(xen_primary_console_register_types)
+
+uint16_t xen_primary_console_get_port(void)
+{
+ XenPrimaryConsoleState *s = xen_primary_console_singleton;
+ if (!s) {
+ return 0;
+ }
+ return s->guest_port;
+}
+
+uint64_t xen_primary_console_get_pfn(void)
+{
+ XenPrimaryConsoleState *s = xen_primary_console_singleton;
+ if (!s) {
+ return 0;
+ }
+ return XEN_SPECIAL_PFN(CONSOLE);
+}
+
+void *xen_primary_console_get_map(void)
+{
+ XenPrimaryConsoleState *s = xen_primary_console_singleton;
+ if (!s) {
+ return 0;
+ }
+ return s->cp;
+}
+
+static void alloc_guest_port(XenPrimaryConsoleState *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_primary_console_reset(void)
+{
+ XenPrimaryConsoleState *s = xen_primary_console_singleton;
+ if (!s) {
+ return 0;
+ }
+
+ if (!memory_region_is_mapped(&s->console_page)) {
+ uint64_t gpa = XEN_SPECIAL_PFN(CONSOLE) << TARGET_PAGE_BITS;
+ xen_overlay_do_map_page(&s->console_page, gpa);
+ }
+
+ alloc_guest_port(s);
+
+ trace_xen_primary_console_reset(s->guest_port);
+
+ s->gt = qemu_xen_gnttab_open();
+ uint32_t xs_gntref = GNTTAB_RESERVED_CONSOLE;
+ s->granted_xs = qemu_xen_gnttab_map_refs(s->gt, 1, xen_domid, &xs_gntref,
+ PROT_READ | PROT_WRITE);
+
+ return 0;
+}
diff --git a/hw/i386/kvm/xen_primary_console.h b/hw/i386/kvm/xen_primary_console.h
new file mode 100644
index 0000000000..dd4922f3f4
--- /dev/null
+++ b/hw/i386/kvm/xen_primary_console.h
@@ -0,0 +1,22 @@
+/*
+ * QEMU Xen emulation: Primary console support
+ *
+ * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Authors: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
+ *
+ * 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_PRIMARY_CONSOLE_H
+#define QEMU_XEN_PRIMARY_CONSOLE_H
+
+void xen_primary_console_create(void);
+int xen_primary_console_reset(void);
+
+uint16_t xen_primary_console_get_port(void);
+uint64_t xen_primary_console_get_pfn(void);
+void *xen_primary_console_get_map(void);
+
+#endif /* QEMU_XEN_PRIMARY_CONSOLE_H */
diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
index 61692d4489..2ee4916c64 100644
--- a/hw/i386/kvm/xen_xenstore.c
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -25,6 +25,7 @@
#include "hw/xen/xen_backend_ops.h"
#include "xen_overlay.h"
#include "xen_evtchn.h"
+#include "xen_primary_console.h"
#include "xen_xenstore.h"
#include "sysemu/kvm.h"
@@ -1434,6 +1435,7 @@ static void alloc_guest_port(XenXenstoreState *s)
int xen_xenstore_reset(void)
{
XenXenstoreState *s = xen_xenstore_singleton;
+ int console_port;
GList *perms;
int err;
@@ -1470,6 +1472,14 @@ int xen_xenstore_reset(void)
relpath_printf(s, perms, "store/ring-ref", "%lu",
XEN_SPECIAL_PFN(XENSTORE));
+ console_port = xen_primary_console_get_port();
+ if (console_port) {
+ relpath_printf(s, perms, "console/ring-ref", "%lu",
+ XEN_SPECIAL_PFN(CONSOLE));
+ relpath_printf(s, perms, "console/port", "%u", console_port);
+ relpath_printf(s, perms, "console/state", "%u", XenbusStateInitialised);
+ }
+
g_list_free_full(perms, g_free);
/*
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index 477e93cd92..9f57786e95 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_primary_console.h"
#include "hw/i386/kvm/xen_xenstore.h"
#include "hw/xen/interface/version.h"
@@ -182,7 +183,8 @@ int kvm_xen_init(KVMState *s, uint32_t hypercall_msr)
return ret;
}
- /* The page couldn't be overlaid until KVM was initialized */
+ /* The pages couldn't be overlaid until KVM was initialized */
+ xen_primary_console_reset();
xen_xenstore_reset();
return 0;
@@ -811,11 +813,23 @@ static bool handle_get_param(struct kvm_xen_exit *exit, X86CPU *cpu,
case HVM_PARAM_STORE_EVTCHN:
hp.value = xen_xenstore_get_port();
break;
+ case HVM_PARAM_CONSOLE_PFN:
+ hp.value = xen_primary_console_get_pfn();
+ if (!hp.value) {
+ err = -EINVAL;
+ }
+ break;
+ case HVM_PARAM_CONSOLE_EVTCHN:
+ hp.value = xen_primary_console_get_port();
+ if (!hp.value) {
+ err = -EINVAL;
+ }
+ break;
default:
return false;
}
- if (kvm_copy_to_gva(cs, arg, &hp, sizeof(hp))) {
+ if (!err && kvm_copy_to_gva(cs, arg, &hp, sizeof(hp))) {
err = -EFAULT;
}
out:
@@ -1426,6 +1440,11 @@ int kvm_xen_soft_reset(void)
return err;
}
+ err = xen_primary_console_reset();
+ if (err) {
+ return err;
+ }
+
err = xen_xenstore_reset();
if (err) {
return err;
--
2.40.1
