hw/qxl: fix cpr

During normal migration, new QEMU creates and initializes memory regions,
then loads the preserved contents of the region from vmstate.

During CPR, memory regions are preserved in place, then the realize
method initializes the regions contents, losing the old contents.  To
fix, skip writes to the qxl memory regions during CPR load.

Reported-by: andrey.drobyshev@virtuozzo.com
Tested-by: andrey.drobyshev@virtuozzo.com
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-ID: <1741380954-341079-5-git-send-email-steven.sistare@oracle.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

hw/display/qxl.c

@@ -30,6 +30,7 @@
 #include "qemu/module.h"
 #include "hw/qdev-properties.h"
 #include "system/runstate.h"
+#include "migration/cpr.h"
 #include "migration/vmstate.h"
 #include "trace.h"
 
@@ -333,6 +334,10 @@ static void init_qxl_rom(PCIQXLDevice *d)
     uint32_t fb;
     int i, n;
 
+    if (cpr_is_incoming()) {
+        goto skip_init;
+    }
+
     memset(rom, 0, d->rom_size);
 
     rom->magic         = cpu_to_le32(QXL_ROM_MAGIC);
@@ -390,6 +395,7 @@ static void init_qxl_rom(PCIQXLDevice *d)
             sizeof(rom->client_monitors_config));
     }
 
+skip_init:
     d->shadow_rom = *rom;
     d->rom        = rom;
     d->modes      = modes;
@@ -403,6 +409,9 @@ static void init_qxl_ram(PCIQXLDevice *d)
 
     buf = d->vga.vram_ptr;
     d->ram = (QXLRam *)(buf + le32_to_cpu(d->shadow_rom.ram_header_offset));
+    if (cpr_is_incoming()) {
+        return;
+    }
     d->ram->magic       = cpu_to_le32(QXL_RAM_MAGIC);
     d->ram->int_pending = cpu_to_le32(0);
     d->ram->int_mask    = cpu_to_le32(0);
@@ -539,6 +548,10 @@ static void interface_set_compression_level(QXLInstance *sin, int level)
 
     trace_qxl_interface_set_compression_level(qxl->id, level);
     qxl->shadow_rom.compression_level = cpu_to_le32(level);
+    if (cpr_is_incoming()) {
+        assert(qxl->rom->compression_level == cpu_to_le32(level));
+        return;
+    }
     qxl->rom->compression_level = cpu_to_le32(level);
     qxl_rom_set_dirty(qxl);
 }
@@ -997,7 +1010,8 @@ static void interface_set_client_capabilities(QXLInstance *sin,
     }
 
     if (runstate_check(RUN_STATE_INMIGRATE) ||
-        runstate_check(RUN_STATE_POSTMIGRATE)) {
+        runstate_check(RUN_STATE_POSTMIGRATE) ||
+        cpr_is_incoming()) {
         return;
     }
 
@@ -1200,6 +1214,10 @@ static void qxl_reset_state(PCIQXLDevice *d)
 {
     QXLRom *rom = d->rom;
 
+    if (cpr_is_incoming()) {
+        return;
+    }
+
     qxl_check_state(d);
     d->shadow_rom.update_id = cpu_to_le32(0);
     *rom = d->shadow_rom;
@@ -1370,8 +1388,11 @@ static int qxl_add_memslot(PCIQXLDevice *d, uint32_t slot_id, uint64_t delta,
     memslot.virt_start = virt_start + (guest_start - pci_start);
     memslot.virt_end   = virt_start + (guest_end   - pci_start);
     memslot.addr_delta = memslot.virt_start - delta;
-    memslot.generation = d->rom->slot_generation = 0;
-    qxl_rom_set_dirty(d);
+    if (!cpr_is_incoming()) {
+        d->rom->slot_generation = 0;
+        qxl_rom_set_dirty(d);
+    }
+    memslot.generation = d->rom->slot_generation;
 
     qemu_spice_add_memslot(&d->ssd, &memslot, async);
     d->guest_slots[slot_id].mr = mr;