From f84d8a785cd2309325476ae5e6a60170dac7c75a Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Date: Tue, 23 Jan 2018 18:09:33 +0100
Subject: [PATCH 3/3] qxl: add migration blocker to avoid pre-save assert
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: <20180123180933.26008-2-dgilbert@redhat.com>
Patchwork-id: 78698
O-Subject: [RHEL-7.5 qemu-kvm PATCH 1/1] qxl: add migration blocker to avoid pre-save assert
Bugzilla: 1536883
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Gerd Hoffmann <kraxel@redhat.com>

Cc: 1635339@bugs.launchpad.net
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20170410113131.2585-1-kraxel@redhat.com
(cherry picked from commit 86dbcdd9c7590d06db89ca256c5eaf0b4aba8858)
  dgilbert: Fixup change in migrate_add_blocker parameters

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/display/qxl.c | 27 +++++++++++++++++++++++++++
 hw/display/qxl.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index 0a755df..0625a76 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -26,6 +26,7 @@
 #include "qemu/atomic.h"
 #include "monitor/monitor.h"
 #include "sysemu/sysemu.h"
+#include "migration/migration.h"
 #include "trace.h"
 
 #include "qxl.h"
@@ -637,6 +638,26 @@ static int interface_get_command(QXLInstance *sin, struct QXLCommandExt *ext)
         qxl->guest_primary.commands++;
         qxl_track_command(qxl, ext);
         qxl_log_command(qxl, "cmd", ext);
+        {
+            /*
+             * Windows 8 drivers place qxl commands in the vram
+             * (instead of the ram) bar.  We can't live migrate such a
+             * guest, so add a migration blocker in case we detect
+             * this, to avoid triggering the assert in pre_save().
+             *
+             * https://cgit.freedesktop.org/spice/win32/qxl-wddm-dod/commit/?id=f6e099db39e7d0787f294d5fd0dce328b5210faa
+             */
+            void *msg = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id);
+            if (msg != NULL && (
+                    msg < (void *)qxl->vga.vram_ptr ||
+                    msg > ((void *)qxl->vga.vram_ptr + qxl->vga.vram_size))) {
+                if (!qxl->migration_blocker) {
+                    error_setg(&qxl->migration_blocker,
+                               "qxl: guest bug: command not in ram bar");
+                    migrate_add_blocker(qxl->migration_blocker);
+                }
+            }
+        }
         trace_qxl_ring_command_get(qxl->id, qxl_mode_to_string(qxl->mode));
         return true;
     default:
@@ -1215,6 +1236,12 @@ static void qxl_hard_reset(PCIQXLDevice *d, int loadvm)
     qemu_spice_create_host_memslot(&d->ssd);
     qxl_soft_reset(d);
 
+    if (d->migration_blocker) {
+        migrate_del_blocker(d->migration_blocker);
+        error_free(d->migration_blocker);
+        d->migration_blocker = NULL;
+    }
+
     if (startstop) {
         qemu_spice_display_start();
     }
diff --git a/hw/display/qxl.h b/hw/display/qxl.h
index f3f51e2..11cf2aa 100644
--- a/hw/display/qxl.h
+++ b/hw/display/qxl.h
@@ -36,6 +36,7 @@ typedef struct PCIQXLDevice {
     uint32_t           cmdlog;
 
     uint32_t           guest_bug;
+    Error              *migration_blocker;
 
     enum qxl_mode      mode;
     uint32_t           cmdflags;
-- 
1.8.3.1