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[Xen-devel] [v2][PATCH 3/8] xen, gfx passthrough: basic graphics passthrough support



basic gfx passthrough support:
- add a vga type for gfx passthrough
- retrieve VGA bios from sysfs, then load it to guest 0xC0000
- register/unregister legacy VGA I/O ports and MMIOs for passthroughed gfx

The original patch is from Weidong Han <weidong.han@xxxxxxxxx>

Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
Cc: Weidong Han <weidong.han@xxxxxxxxx>
---
v2:

* retrieve VGA bios from sysfs properly.
* redefine some function name.

 hw/xen/Makefile.objs         |   2 +-
 hw/xen/xen-host-pci-device.c |   5 ++
 hw/xen/xen-host-pci-device.h |   1 +
 hw/xen/xen_pt.c              |  10 +++
 hw/xen/xen_pt.h              |   4 +
 hw/xen/xen_pt_graphics.c     | 177 +++++++++++++++++++++++++++++++++++++++++++
 qemu-options.hx              |   9 +++
 vl.c                         |  11 ++-
 8 files changed, 217 insertions(+), 2 deletions(-)
 create mode 100644 hw/xen/xen_pt_graphics.c

diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
index a0ca0aa..77b7dae 100644
--- a/hw/xen/Makefile.objs
+++ b/hw/xen/Makefile.objs
@@ -2,4 +2,4 @@
 common-obj-$(CONFIG_XEN_BACKEND) += xen_backend.o xen_devconfig.o
 
 obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
-obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_msi.o
+obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o 
xen_pt_msi.o xen_pt_graphics.o
diff --git a/hw/xen/xen-host-pci-device.c b/hw/xen/xen-host-pci-device.c
index 743b37b..a54b7de 100644
--- a/hw/xen/xen-host-pci-device.c
+++ b/hw/xen/xen-host-pci-device.c
@@ -376,6 +376,11 @@ int xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t 
domain,
         goto error;
     }
     d->irq = v;
+    rc = xen_host_pci_get_hex_value(d, "class", &v);
+    if (rc) {
+        goto error;
+    }
+    d->class_code = v;
     d->is_virtfn = xen_host_pci_dev_is_virtfn(d);
 
     return 0;
diff --git a/hw/xen/xen-host-pci-device.h b/hw/xen/xen-host-pci-device.h
index c2486f0..f1e1c30 100644
--- a/hw/xen/xen-host-pci-device.h
+++ b/hw/xen/xen-host-pci-device.h
@@ -25,6 +25,7 @@ typedef struct XenHostPCIDevice {
 
     uint16_t vendor_id;
     uint16_t device_id;
+    uint32_t class_code;
     int irq;
 
     XenHostPCIIORegion io_regions[PCI_NUM_REGIONS - 1];
diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index be4220b..a0113ea 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -450,6 +450,7 @@ static int xen_pt_register_regions(XenPCIPassthroughState 
*s)
                    d->rom.size, d->rom.base_addr);
     }
 
+    xen_pt_register_vga_regions(d);
     return 0;
 }
 
@@ -470,6 +471,8 @@ static void 
xen_pt_unregister_regions(XenPCIPassthroughState *s)
     if (d->rom.base_addr && d->rom.size) {
         memory_region_destroy(&s->rom);
     }
+
+    xen_pt_unregister_vga_regions(d);
 }
 
 /* region mapping */
@@ -693,6 +696,13 @@ static int xen_pt_initfn(PCIDevice *d)
     /* Handle real device's MMIO/PIO BARs */
     xen_pt_register_regions(s);
 
+    /* Setup VGA bios for passthroughed gfx */
+    if (xen_pt_setup_vga(&s->real_device) < 0) {
+        XEN_PT_ERR(d, "Setup VGA BIOS of passthroughed gfx failed!\n");
+        xen_host_pci_device_put(&s->real_device);
+        return -1;
+    }
+
     /* reinitialize each config register to be emulated */
     if (xen_pt_config_init(s)) {
         XEN_PT_ERR(d, "PCI Config space initialisation failed.\n");
diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
index 942dc60..4d3a18d 100644
--- a/hw/xen/xen_pt.h
+++ b/hw/xen/xen_pt.h
@@ -298,5 +298,9 @@ static inline bool 
xen_pt_has_msix_mapping(XenPCIPassthroughState *s, int bar)
     return s->msix && s->msix->bar_index == bar;
 }
 
+extern int xen_has_gfx_passthru;
+int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev);
+int xen_pt_setup_vga(XenHostPCIDevice *dev);
 
 #endif /* !XEN_PT_H */
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
new file mode 100644
index 0000000..e1f0724
--- /dev/null
+++ b/hw/xen/xen_pt_graphics.c
@@ -0,0 +1,177 @@
+/*
+ * graphics passthrough
+ */
+#include "xen_pt.h"
+#include "xen-host-pci-device.h"
+#include "hw/xen/xen_backend.h"
+
+static int is_vga_passthrough(XenHostPCIDevice *dev)
+{
+    return (xen_has_gfx_passthru
+            && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
+}
+
+/*
+ * register VGA resources for the domain with assigned gfx
+ */
+int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
+{
+    int ret = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return ret;
+    }
+
+    ret |= xc_domain_ioport_mapping(xen_xc, xen_domid, 0x3B0,
+            0x3B0, 0xA, DPCI_ADD_MAPPING);
+
+    ret |= xc_domain_ioport_mapping(xen_xc, xen_domid, 0x3C0,
+            0x3C0, 0x20, DPCI_ADD_MAPPING);
+
+    ret |= xc_domain_memory_mapping(xen_xc, xen_domid,
+            0xa0000 >> XC_PAGE_SHIFT,
+            0xa0000 >> XC_PAGE_SHIFT,
+            0x20,
+            DPCI_ADD_MAPPING);
+
+    if (ret) {
+        XEN_PT_ERR(NULL, "VGA region mapping failed\n");
+    }
+
+    return ret;
+}
+
+/*
+ * unregister VGA resources for the domain with assigned gfx
+ */
+int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
+{
+    int ret = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return ret;
+    }
+
+    ret |= xc_domain_ioport_mapping(xen_xc, xen_domid, 0x3B0,
+            0x3B0, 0xC, DPCI_REMOVE_MAPPING);
+
+    ret |= xc_domain_ioport_mapping(xen_xc, xen_domid, 0x3C0,
+            0x3C0, 0x20, DPCI_REMOVE_MAPPING);
+
+    ret |= xc_domain_memory_mapping(xen_xc, xen_domid,
+            0xa0000 >> XC_PAGE_SHIFT,
+            0xa0000 >> XC_PAGE_SHIFT,
+            20,
+            DPCI_REMOVE_MAPPING);
+
+    if (ret) {
+        XEN_PT_ERR(NULL, "VGA region unmapping failed\n");
+    }
+
+    return ret;
+}
+
+static int get_vgabios(unsigned char *buf, XenHostPCIDevice *dev)
+{
+    char rom_file[64];
+    FILE *fp;
+    uint8_t val;
+    struct stat st;
+    uint16_t magic = 0;
+
+    snprintf(rom_file, sizeof(rom_file),
+             "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/rom",
+             dev->domain, dev->bus, dev->dev,
+             dev->func);
+
+    if (stat(rom_file, &st)) {
+        return -1;
+    }
+
+    if (access(rom_file, F_OK)) {
+        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
+                    rom_file);
+        return -1;
+    }
+
+    /* Write "1" to the ROM file to enable it */
+    fp = fopen(rom_file, "r+");
+    if (fp == NULL) {
+        return -1;
+    }
+    val = 1;
+    if (fwrite(&val, 1, 1, fp) != 1) {
+        goto close_rom;
+    }
+    fseek(fp, 0, SEEK_SET);
+
+    /*
+     * Check if it a real bios extension.
+     * The magic number is 0xAA55.
+     */
+    if (fread(&magic, sizeof(magic), 1, fp)) {
+        goto close_rom;
+    }
+
+    if (magic != 0xAA55) {
+        goto close_rom;
+    }
+    fseek(fp, 0, SEEK_SET);
+
+    if (!fread(buf, 1, st.st_size, fp)) {
+        XEN_PT_ERR(NULL, "pci-assign: Cannot read from host %s", rom_file);
+        XEN_PT_LOG(NULL, "Device option ROM contents are probably invalid "
+                     "(check dmesg).\nSkip option ROM probe with rombar=0, "
+                     "or load from file with romfile=\n");
+    }
+
+close_rom:
+    /* Write "0" to disable ROM */
+    fseek(fp, 0, SEEK_SET);
+    val = 0;
+    if (!fwrite(&val, 1, 1, fp)) {
+        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
+    }
+    fclose(fp);
+    return st.st_size;
+}
+
+/* Allocated 128K for the vga bios */
+#define VGA_BIOS_DEFAULT_SIZE (0x20000)
+
+int xen_pt_setup_vga(XenHostPCIDevice *dev)
+{
+    unsigned char *bios = NULL;
+    int bios_size = 0;
+    char *c = NULL;
+    char checksum = 0;
+    int rc = 0;
+
+    if (!is_vga_passthrough(dev)) {
+        return rc;
+    }
+
+    bios = g_malloc0(VGA_BIOS_DEFAULT_SIZE);
+
+    bios_size = get_vgabios(bios, dev);
+    if (bios_size == 0 || bios_size > VGA_BIOS_DEFAULT_SIZE) {
+        XEN_PT_ERR(NULL, "vga bios size (0x%x) is invalid!\n", bios_size);
+        rc = -1;
+        goto out;
+    }
+
+    /* Adjust the bios checksum */
+    for (c = (char *)bios; c < ((char *)bios + bios_size); c++) {
+        checksum += *c;
+    }
+    if (checksum) {
+        bios[bios_size - 1] -= checksum;
+        XEN_PT_LOG(NULL, "vga bios checksum is adjusted!\n");
+    }
+
+    /* Currently we fixed this address as a primary. */
+    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
+out:
+    g_free(bios);
+    return rc;
+}
diff --git a/qemu-options.hx b/qemu-options.hx
index 781af14..cece134 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1047,6 +1047,15 @@ STEXI
 Rotate graphical output some deg left (only PXA LCD).
 ETEXI
 
+DEF("gfx_passthru", 0, QEMU_OPTION_gfx_passthru,
+    "-gfx_passthru   enable Intel IGD passthrough by XEN\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -gfx_passthru
+@findex -gfx_passthru
+Enable Intel IGD passthrough by XEN
+ETEXI
+
 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
     "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|none]\n"
     "                select video card type\n", QEMU_ARCH_ALL)
diff --git a/vl.c b/vl.c
index 73e0661..c86e95f 100644
--- a/vl.c
+++ b/vl.c
@@ -1436,6 +1436,13 @@ static void smp_parse(QemuOpts *opts)
 
 }
 
+/* We still need this for compatibility with XEN. */
+int xen_has_gfx_passthru;
+static void xen_gfx_passthru(const char *optarg)
+{
+    xen_has_gfx_passthru = 1;
+}
+
 static void configure_realtime(QemuOpts *opts)
 {
     bool enable_mlock;
@@ -2988,7 +2995,6 @@ int main(int argc, char **argv, char **envp)
     const char *trace_file = NULL;
     const ram_addr_t default_ram_size = (ram_addr_t)DEFAULT_RAM_SIZE *
                                         1024 * 1024;
-
     atexit(qemu_run_exit_notifiers);
     error_set_progname(argv[0]);
     qemu_init_exec_dir(argv[0]);
@@ -3956,6 +3962,9 @@ int main(int argc, char **argv, char **envp)
                 }
                 configure_msg(opts);
                 break;
+            case QEMU_OPTION_gfx_passthru:
+                xen_gfx_passthru(optarg);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }
-- 
1.9.1


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