[Qemu-devel] [v6][PATCH 08/10] xen, gfx passthrough: support Intel IGD passthrough with VT-D

[Tiejun Chen <tiejun.chen@intel.com>]

Some registers of Intel IGD are mapped in host bridge, so it needs to
passthrough these registers of physical host bridge to guest because
emulated host bridge in guest doesn't have these mappings.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
---
 hw/pci-host/piix.c       |  3 ++
 hw/xen/xen_pt.h          |  1 +
 hw/xen/xen_pt_graphics.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index 1468961..0a5a4c7 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -34,6 +34,7 @@
 #include "sysemu/sysemu.h"
 #include "hw/i386/ioapic.h"
 #include "qapi/visitor.h"
+#include "hw/xen/xen_pt.h"
 
 /*
  * I440FX chipset data sheet.
@@ -733,8 +734,10 @@ static void xen_igd_passthrough_i440fx_class_init(ObjectClass *klass,
                                                   void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
     dc->desc = "IGD PT XEN Host bridge";
+    k->config_read = xen_igd_pci_read;
 }
 
 static const TypeInfo xen_igd_passthrough_i440fx_info = {
diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
index 0aa5a93..94cde4a 100644
--- a/hw/xen/xen_pt.h
+++ b/hw/xen/xen_pt.h
@@ -5,6 +5,7 @@
 #include "hw/xen/xen_common.h"
 #include "hw/pci/pci.h"
 #include "xen-host-pci-device.h"
+uint32_t xen_igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len);
 
 void xen_pt_log(const PCIDevice *d, const char *f, ...) GCC_FMT_ATTR(2, 3);
 
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index 3232296..227089b 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -4,6 +4,7 @@
 #include "xen_pt.h"
 #include "xen-host-pci-device.h"
 #include "hw/xen/xen_backend.h"
+#include "hw/pci/pci_bus.h"
 
 typedef struct VGARegion {
     int type;           /* Memory or port I/O */
@@ -188,3 +189,74 @@ int xen_pt_setup_vga(XenPCIPassthroughState *s, XenHostPCIDevice *dev)
     cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
     return 0;
 }
+
+/*
+ * Currently we just pass this physical host bridge for IGD, 00:02.0.
+ *
+ * Here pci_dev is just that host bridge, so we have to get that real
+ * passthrough device by that given devfn to avoid other devices access.
+ */
+static int is_igd_passthrough(PCIDevice *pci_dev)
+{
+    PCIDevice *f = pci_dev->bus->devices[PCI_DEVFN(2, 0)];
+    if (pci_dev->bus->devices[PCI_DEVFN(2, 0)]) {
+        XenPCIPassthroughState *s = DO_UPCAST(XenPCIPassthroughState, dev, f);
+        return (is_igd_vga_passthrough(&s->real_device)
+                    && (s->real_device.vendor_id == PCI_VENDOR_ID_INTEL));
+    } else {
+        return 0;
+    }
+}
+
+uint32_t xen_igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len)
+{
+    XenHostPCIDevice dev;
+    uint32_t val;
+    int r;
+
+    /* IGD read/write is through the host bridge.
+     */
+    assert(pci_dev->devfn == 0x00);
+
+    if (!is_igd_passthrough(pci_dev)) {
+        goto read_default;
+    }
+
+    /* Just work for the i915 driver. */
+    switch (config_addr) {
+    case 0x08:        /* revision id */
+    case 0x2c:        /* sybsystem vendor id */
+    case 0x2e:        /* sybsystem id */
+    case 0x50:        /* SNB: processor graphics control register */
+    case 0x52:        /* processor graphics control register */
+    case 0xa0:        /* top of memory */
+    case 0xa4:        /* SNB: graphics base of stolen memory */
+    case 0xa8:        /* SNB: base of GTT stolen memory */
+        break;
+    default:
+        /* Just gets the emulated values. */
+        goto read_default;
+    }
+
+    /* Host read */
+    r = xen_host_pci_device_get(&dev, 0, 0, 0, 0);
+    if (r) {
+        goto err_out;
+    }
+
+    r = xen_host_pci_get_block(&dev, config_addr, (uint8_t *)&val, len);
+    if (r) {
+        goto err_out;
+    }
+
+    xen_host_pci_device_put(&dev);
+
+    return val;
+
+read_default:
+    return pci_default_read_config(pci_dev, config_addr, len);
+
+err_out:
+    XEN_PT_ERR(pci_dev, "Can't get pci_dev_host_bridge\n");
+    return -1;
+}
-- 
1.9.1