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Re: [Xen-devel] [Qemu-devel] [RFC][PATCH 2/2] xen:i386:pc_piix: create isa bridge specific to IGD passthrough

On 2014/11/17 14:10, Michael S. Tsirkin wrote:

On Mon, Nov 17, 2014 at 10:47:56AM +0800, Chen, Tiejun wrote:

On 2014/11/5 22:09, Michael S. Tsirkin wrote:

On Wed, Nov 05, 2014 at 03:22:59PM +0800, Tiejun Chen wrote:

Currently IGD drivers always need to access PCH by 1f.0, and
PCH vendor/device id is used to identify the card.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
  hw/i386/pc_piix.c | 28 +++++++++++++++++++++++++++-
  1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index b559181..b19c7a9 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -50,7 +50,7 @@
  #include "cpu.h"
  #include "qemu/error-report.h"
  #ifdef CONFIG_XEN
-#  include <xen/hvm/hvm_info_table.h>
+#include <xen/hvm/hvm_info_table.h>
  #endif

  #define MAX_IDE_BUS 2
@@ -452,6 +452,31 @@ static void pc_init_isa(MachineState *machine)
  }

  #ifdef CONFIG_XEN
+static void xen_igd_passthrough_isa_bridge_create(PCIBus *bus)
+{
+    struct PCIDevice *dev;
+    Error *local_err = NULL;
+    uint16_t device_id = 0xffff;
+
+    /* Currently IGD drivers always need to access PCH by 1f.0. */
+    dev = pci_create_simple(bus, PCI_DEVFN(0x1f, 0),
+                            "xen-igd-passthrough-isa-bridge");
+
+    /* Identify PCH card with its own real vendor/device ids.
+     * Here that vendor id is always PCI_VENDOR_ID_INTEL.
+     */
+    if (dev) {
+        device_id = object_property_get_int(OBJECT(dev), "device-id",
+                                            &local_err);
+        if (!local_err && device_id != 0xffff) {
+            pci_config_set_device_id(dev->config, device_id);
+            return;
+        }
+    }
+
+    fprintf(stderr, "xen set xen-igd-passthrough-isa-bridge failed\n");
+}
+
  static void pc_xen_hvm_init(MachineState *machine)
  {
      PCIBus *bus;
@@ -461,6 +486,7 @@ static void pc_xen_hvm_init(MachineState *machine)
      bus = pci_find_primary_bus();
      if (bus != NULL) {
          pci_create_simple(bus, -1, "xen-platform");
+        xen_igd_passthrough_isa_bridge_create(bus);
      }
  }
  #endif


Can't we defer this step until the GPU is added?


Sounds great but I can't figure out where we can to do this exactly.


This way there won't be need to poke at host device
directly, you could get all info from dev->config
of the host device.


As I understand We have two steps here:

#1 At first I have to write something to check if we're registering 00:02.0
& IGD, right? But where? While registering each pci device?


In xen_pt_initfn.
Just check the device and vendor ID against the table you have.



Okay. Please see the follows which is just compiled:

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index c6466dc..f3ea313 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -632,6 +632,94 @@ static const MemoryListener xen_pt_io_listener = {
     .priority = 10,
 };

+typedef struct {
+    uint16_t gpu_device_id;
+    uint16_t pch_device_id;
+} XenIGDDeviceIDInfo;
+
+/* In real world different GPU should have different PCH. But actually
+ * the different PCH DIDs likely map to different PCH SKUs. We do the
+ * same thing for the GPU. For PCH, the different SKUs are going to be
+ * all the same silicon design and implementation, just different
+ * features turn on and off with fuses. The SW interfaces should be
+ * consistent across all SKUs in a given family (eg LPT). But just same
+ * features may not be supported.
+ *
+ * Most of these different PCH features probably don't matter to the
+ * Gfx driver, but obviously any difference in display port connections
+ * will so it should be fine with any PCH in case of passthrough.
+ *
+ * So currently use one PCH version, 0x8c4e, to cover all HSW(Haswell)
+ * scenarios, 0x9cc3 for BDW(Broadwell).
+ */
+static const XenIGDDeviceIDInfo xen_igd_combo_id_infos[] = {
+    /* HSW Classic */
+    {0x0402, 0x8c4e}, /* HSWGT1D, HSWD_w7 */
+    {0x0406, 0x8c4e}, /* HSWGT1M, HSWM_w7 */
+    {0x0412, 0x8c4e}, /* HSWGT2D, HSWD_w7 */
+    {0x0416, 0x8c4e}, /* HSWGT2M, HSWM_w7 */
+    {0x041E, 0x8c4e}, /* HSWGT15D, HSWD_w7 */
+    /* HSW ULT */
+    {0x0A06, 0x8c4e}, /* HSWGT1UT, HSWM_w7 */
+    {0x0A16, 0x8c4e}, /* HSWGT2UT, HSWM_w7 */
+    {0x0A26, 0x8c4e}, /* HSWGT3UT, HSWM_w7 */
+    {0x0A2E, 0x8c4e}, /* HSWGT3UT28W, HSWM_w7 */
+    {0x0A1E, 0x8c4e}, /* HSWGT2UX, HSWM_w7 */
+    {0x0A0E, 0x8c4e}, /* HSWGT1ULX, HSWM_w7 */
+    /* HSW CRW */
+    {0x0D26, 0x8c4e}, /* HSWGT3CW, HSWM_w7 */
+    {0x0D22, 0x8c4e}, /* HSWGT3CWDT, HSWD_w7 */
+    /* HSW Server */
+    {0x041A, 0x8c4e}, /* HSWSVGT2, HSWD_w7 */
+    /* HSW SRVR */
+    {0x040A, 0x8c4e}, /* HSWSVGT1, HSWD_w7 */
+    /* BSW */
+    {0x1606, 0x9cc3}, /* BDWULTGT1, BDWM_w7 */
+    {0x1616, 0x9cc3}, /* BDWULTGT2, BDWM_w7 */
+    {0x1626, 0x9cc3}, /* BDWULTGT3, BDWM_w7 */
+    {0x160E, 0x9cc3}, /* BDWULXGT1, BDWM_w7 */
+    {0x161E, 0x9cc3}, /* BDWULXGT2, BDWM_w7 */
+    {0x1602, 0x9cc3}, /* BDWHALOGT1, BDWM_w7 */
+    {0x1612, 0x9cc3}, /* BDWHALOGT2, BDWM_w7 */
+    {0x1622, 0x9cc3}, /* BDWHALOGT3, BDWM_w7 */
+    {0x162B, 0x9cc3}, /* BDWHALO28W, BDWM_w7 */
+    {0x162A, 0x9cc3}, /* BDWGT3WRKS, BDWM_w7 */
+    {0x162D, 0x9cc3}, /* BDWGT3SRVR, BDWM_w7 */
+};
+
+static void
+xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
+                                      XenHostPCIDevice *dev)
+{
+    struct PCIDevice *pci_dev;
+    int i, num;
+    uint16_t gpu_id = 0xffff, pch_id = 0xffff;
+    PCIDevice *d = &s->dev;
+
+    if (is_vga_passthrough(dev)) {
+        gpu_id = dev->device_id;
+        num = ARRAY_SIZE(xen_igd_combo_id_infos);
+        for (i = 0; i < num; i++)
+            if (gpu_id == xen_igd_combo_id_infos[i].gpu_device_id)
+                pch_id = xen_igd_combo_id_infos[i].pch_device_id;
+
+        /* Currently IGD drivers always need to access PCH by 1f.0. */
+        pci_dev = pci_create_simple(d->bus, PCI_DEVFN(0x1f, 0),
+                                    "xen-igd-passthrough-isa-bridge");
+
+        /*
+         * Identify PCH card with its own real vendor/device ids.
+         * Here that vendor id is always PCI_VENDOR_ID_INTEL.
+         */
+        if (pci_dev) {
+            pci_config_set_device_id(pci_dev->config, pch_id);
+            return;
+        }
+
+ fprintf(stderr, "xen set xen-igd-passthrough-isa-bridge failed!\n"); 
+    }
+}
+
 /* init */

 static int xen_pt_initfn(PCIDevice *d)
@@ -682,6 +770,9 @@ static int xen_pt_initfn(PCIDevice *d)
         return -1;
     }

+    /* Register ISA bridge for passthrough GFX. */
+    xen_igd_passthrough_isa_bridge_create(s, &s->real_device);
+
     /* reinitialize each config register to be emulated */
     if (xen_pt_config_init(s)) {
         XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");

Note I will introduce a inline function in another patch,

+static inline int is_vga_passthrough(XenHostPCIDevice *dev)
+{
+    return (xen_has_gfx_passthru && (dev->vendor_id == PCI_VENDOR_ID_INTEL)
+            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
+}

Thanks
Tiejun

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