[Spice-devel] [PATCH v2] RFC: qxl: allow to specify head limit to qxl driver

[Frediano Ziglio]

This patch allow to limit number of heads using qxl driver. By default
qxl driver is not limited on any kind on head use so can decide to use
as much heads.

libvirt has this as a video card parameter (actually set to 1 but not
used). This parameter will allow to limit setting a use can do (which
could be confusing).

This patch rely on some change in spice-protocol which are not still
accepted. See
http://lists.freedesktop.org/archives/spice-devel/2015-June/020221.html.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 hw/display/qxl.c | 20 +++++++++++++++-----
 hw/display/qxl.h |  1 +
 2 files changed, 16 insertions(+), 5 deletions(-)

This version change the way limit is set. It came from Gerd Hoffmann
suggestion.

diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index b220e2d..678fde5 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -272,6 +272,10 @@ static void qxl_spice_monitors_config_async(PCIQXLDevice *qxl, int replay)
                     QXL_COOKIE_TYPE_POST_LOAD_MONITORS_CONFIG,
                     0));
     } else {
+        if (qxl->max_outputs) {
+            spice_qxl_set_monitors_config_limit(&qxl->ssd.qxl,
+                                                qxl->max_outputs);
+        }
         qxl->guest_monitors_config = qxl->ram->monitors_config;
         spice_qxl_monitors_config_async(&qxl->ssd.qxl,
                 qxl->ram->monitors_config,
@@ -992,6 +996,7 @@ static int interface_client_monitors_config(QXLInstance *sin,
     PCIQXLDevice *qxl = container_of(sin, PCIQXLDevice, ssd.qxl);
     QXLRom *rom = memory_region_get_ram_ptr(&qxl->rom_bar);
     int i;
+    unsigned max_outputs = ARRAY_SIZE(rom->client_monitors_config.heads);
 
     if (qxl->revision < 4) {
         trace_qxl_client_monitors_config_unsupported_by_device(qxl->id,
@@ -1014,17 +1019,21 @@ static int interface_client_monitors_config(QXLInstance *sin,
     if (!monitors_config) {
         return 1;
     }
+
+    /* limit number of outputs based on setting limit */
+    if (qxl->max_outputs && qxl->max_outputs <= max_outputs) {
+        max_outputs = qxl->max_outputs;
+    }
+
     memset(&rom->client_monitors_config, 0,
            sizeof(rom->client_monitors_config));
     rom->client_monitors_config.count = monitors_config->num_of_monitors;
     /* monitors_config->flags ignored */
-    if (rom->client_monitors_config.count >=
-            ARRAY_SIZE(rom->client_monitors_config.heads)) {
+    if (rom->client_monitors_config.count >= max_outputs) {
         trace_qxl_client_monitors_config_capped(qxl->id,
                                 monitors_config->num_of_monitors,
-                                ARRAY_SIZE(rom->client_monitors_config.heads));
-        rom->client_monitors_config.count =
-            ARRAY_SIZE(rom->client_monitors_config.heads);
+                                max_outputs);
+        rom->client_monitors_config.count = max_outputs;
     }
     for (i = 0 ; i < rom->client_monitors_config.count ; ++i) {
         VDAgentMonConfig *monitor = &monitors_config->monitors[i];
@@ -2278,6 +2287,7 @@ static Property qxl_properties[] = {
         DEFINE_PROP_UINT32("vram64_size_mb", PCIQXLDevice, vram_size_mb, -1),
         DEFINE_PROP_UINT32("vgamem_mb", PCIQXLDevice, vgamem_size_mb, 16),
         DEFINE_PROP_INT32("surfaces", PCIQXLDevice, ssd.num_surfaces, 1024),
+        DEFINE_PROP_UINT16("max_outputs", PCIQXLDevice, max_outputs, 0),
         DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/display/qxl.h b/hw/display/qxl.h
index deddd54..d045f59 100644
--- a/hw/display/qxl.h
+++ b/hw/display/qxl.h
@@ -99,6 +99,7 @@ typedef struct PCIQXLDevice {
     QXLModes           *modes;
     uint32_t           rom_size;
     MemoryRegion       rom_bar;
+    uint16_t           max_outputs;
 
     /* vram pci bar */
     uint32_t           vram_size;
-- 
2.1.0