1 files changed, 193 insertions, 0 deletions
diff --git a/hw/i386/kvm/xen_primary_console.c b/hw/i386/kvm/xen_primary_console.c
new file mode 100644
index 0000000000..abe79f565b
--- /dev/null
+++ b/hw/i386/kvm/xen_primary_console.c
@@ -0,0 +1,193 @@
+/*
+ * QEMU Xen emulation: Primary console support
+ *
+ * Copyright © 2023 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 "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;
+}
+
+void xen_primary_console_set_be_port(uint16_t port)
+{
+    XenPrimaryConsoleState *s = xen_primary_console_singleton;
+    if (s) {
+        s->be_port = 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;
+    }
+}
+
+static void rebind_guest_port(XenPrimaryConsoleState *s)
+{
+    struct evtchn_bind_interdomain inter = {
+        .remote_dom = DOMID_QEMU,
+        .remote_port = s->be_port,
+    };
+
+    if (!xen_evtchn_bind_interdomain_op(&inter)) {
+        s->guest_port = inter.local_port;
+    }
+
+    s->be_port = 0;
+}
+
+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);
+    }
+
+    if (s->be_port) {
+        rebind_guest_port(s);
+    } else {
+        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;
+}