Re: [Qemu-devel] [v5][PATCH 1/5] xen, gfx passthrough: basic graphics passthrough support

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

On 2014/6/25 14:35, Michael S. Tsirkin wrote:
> On Wed, Jun 25, 2014 at 10:17:17AM +0800, Tiejun Chen wrote:
>> basic gfx passthrough support:
>> - add a vga type for gfx passthrough
>> - retrieve VGA bios from sysfs, then load it to guest at 0xC0000
>> - register/unregister legacy VGA I/O ports and MMIOs for passthrough GFX
>>
>> The original patch is from Weidong Han <weidong.han@intel.com>
>>
>> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
>> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
>> Cc: Weidong Han <weidong.han@intel.com>
>
> ROM loading code is duplicated from assigned_dev_load_option_rom.

Yes. Do you hint we need to split this?

> Would it be a problem for you to create a memory region holding
> the ROM?

Sorry, could you tell me what should do exactly?

> You won't need cpu_physical_memory_rw then, either, or need

How to make sure this is fixed at 0xc0000?

Thanks
Tiejun

> the VGA_BIOS_DEFAULT_SIZE hack.
>
>
>
>
>> ---
>> v5:
>>
>> * Just rebase.
>>
>> v4:
>>
>> * Fix some typos in the patch head description.
>> * Improve some comments.
>> * Given that xen_pt_register_vga_regions()/xen_pt_unregister_vga_regions()
>>    are called unconditionally, so we just return 0 there.
>> * Remove one spurious change.
>>
>> v3:
>>
>> * Fix some typos.
>> * Add more comments to make that readable.
>> * Improve some return paths.
>>
>> 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     | 232 +++++++++++++++++++++++++++++++++++++++++++
>>   qemu-options.hx              |   9 ++
>>   vl.c                         |  10 ++
>>   8 files changed, 272 insertions(+), 1 deletion(-)
>>   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..dac4238 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 passthrough GFX */
>> +    if (xen_pt_setup_vga(&s->real_device) < 0) {
>> +        XEN_PT_ERR(d, "Setup VGA BIOS of passthrough 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..461e526
>> --- /dev/null
>> +++ b/hw/xen/xen_pt_graphics.c
>> @@ -0,0 +1,232 @@
>> +/*
>> + * 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));
>> +}
>> +
>> +typedef struct VGARegion {
>> +    int type;           /* Memory or port I/O */
>> +    uint64_t guest_base_addr;
>> +    uint64_t machine_base_addr;
>> +    uint64_t size;    /* size of the region */
>> +    int rc;
>> +} VGARegion;
>> +
>> +#define IORESOURCE_IO           0x00000100
>> +#define IORESOURCE_MEM          0x00000200
>> +
>> +static struct VGARegion vga_args[] = {
>> +    {
>> +        .type = IORESOURCE_IO,
>> +        .guest_base_addr = 0x3B0,
>> +        .machine_base_addr = 0x3B0,
>> +        .size = 0xC,
>> +        .rc = -1,
>> +    },
>> +    {
>> +        .type = IORESOURCE_IO,
>> +        .guest_base_addr = 0x3C0,
>> +        .machine_base_addr = 0x3C0,
>> +        .size = 0x20,
>> +        .rc = -1,
>> +    },
>> +    {
>> +        .type = IORESOURCE_MEM,
>> +        .guest_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
>> +        .machine_base_addr = 0xa0000 >> XC_PAGE_SHIFT,
>> +        .size = 0x20,
>> +        .rc = -1,
>> +    },
>> +};
>> +
>> +/*
>> + * register VGA resources for the domain with assigned gfx
>> + */
>> +int xen_pt_register_vga_regions(XenHostPCIDevice *dev)
>> +{
>> +    int i = 0;
>> +
>> +    if (!is_vga_passthrough(dev)) {
>> +        return 0;
>> +    }
>> +
>> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
>> +        if (vga_args[i].type == IORESOURCE_IO) {
>> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_ADD_MAPPING);
>> +        } else {
>> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_ADD_MAPPING);
>> +        }
>> +
>> +        if (vga_args[i].rc) {
>> +            XEN_PT_ERR(NULL, "VGA %s mapping failed! (rc: %i)\n",
>> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
>> +                    vga_args[i].rc);
>> +            return vga_args[i].rc;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +/*
>> + * unregister VGA resources for the domain with assigned gfx
>> + */
>> +int xen_pt_unregister_vga_regions(XenHostPCIDevice *dev)
>> +{
>> +    int i = 0;
>> +
>> +    if (!is_vga_passthrough(dev)) {
>> +        return 0;
>> +    }
>> +
>> +    for (i = 0 ; i < ARRAY_SIZE(vga_args); i++) {
>> +        if (vga_args[i].type == IORESOURCE_IO) {
>> +            vga_args[i].rc = xc_domain_ioport_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
>> +        } else {
>> +            vga_args[i].rc = xc_domain_memory_mapping(xen_xc, xen_domid,
>> +                            vga_args[i].guest_base_addr,
>> +                            vga_args[i].machine_base_addr,
>> +                            vga_args[i].size, DPCI_REMOVE_MAPPING);
>> +        }
>> +
>> +        if (vga_args[i].rc) {
>> +            XEN_PT_ERR(NULL, "VGA %s unmapping failed! (rc: %i)\n",
>> +                    vga_args[i].type == IORESOURCE_IO ? "ioport" : "memory",
>> +                    vga_args[i].rc);
>> +            return vga_args[i].rc;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +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;
>> +    int ret = 0;
>> +
>> +    snprintf(rom_file, sizeof(rom_file),
>> +             "/sys/bus/pci/devices/%04x:%02x:%02x.%d/rom",
>> +             dev->domain, dev->bus, dev->dev,
>> +             dev->func);
>> +
>> +    if (stat(rom_file, &st)) {
>> +        return -ENODEV;
>> +    }
>> +
>> +    if (access(rom_file, F_OK)) {
>> +        XEN_PT_ERR(NULL, "pci-assign: Insufficient privileges for %s",
>> +                    rom_file);
>> +        return -ENODEV;
>> +    }
>> +
>> +    /* Write "1" to the ROM file to enable it */
>> +    fp = fopen(rom_file, "r+");
>> +    if (fp == NULL) {
>> +        return -EACCES;
>> +    }
>> +    val = 1;
>> +    if (fwrite(&val, 1, 1, fp) != 1) {
>> +        XEN_PT_LOG("%s\n", "Failed to enable pci-sysfs rom file");
>> +        ret = -EIO;
>> +        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)) {
>> +        XEN_PT_ERR(NULL, "VGA: can't get magic.\n");
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    if (magic != 0xAA55) {
>> +        XEN_PT_ERR(NULL, "VGA: wrong magic %x.\n", magic);
>> +        ret = -ENODEV;
>> +        goto close_rom;
>> +    }
>> +    fseek(fp, 0, SEEK_SET);
>> +
>> +    if (!fread(buf, 1, st.st_size, fp)) {
>> +        XEN_PT_ERR(NULL, "VGA: pci-assign: Cannot read from host %s", rom_file);
>> +        XEN_PT_LOG(NULL, "VGA: 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)) {
>> +        ret = -EIO;
>> +        XEN_PT_LOG("%s\n", "Failed to disable pci-sysfs rom file");
>> +    }
>> +    fclose(fp);
>> +    return ret;
>> +}
>> +
>> +/* 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) {
>> +        XEN_PT_ERR(NULL, "VGA: Error %d getting VBIOS!\n", bios_size);
>> +        if (bios_size < 0) {
>> +            XEN_PT_ERR(NULL, "VGA: Error (%s).\n", strerror(bios_size));
>> +        }
>> +        rc = -1;
>> +        goto out;
>> +    }
>> +
>> +    /* Adjust the bios checksum */
>
> It's easy to see that you do this here, but *why* do you do it?
> That's what the comment should explain.
> Do you see many ROMs with an invalid checksum
> in the field?
>
>> +    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 ff76ad4..1c77baa 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1066,6 +1066,15 @@ 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 a1686ef..c5b572d 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -1418,6 +1418,13 @@ static void configure_msg(QemuOpts *opts)
>>       enable_timestamp_msg = qemu_opt_get_bool(opts, "timestamp", true);
>>   }
>>
>> +/* 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;
>> +}
>> +
>>   /***********************************************************/
>>   /* USB devices */
>>
>> @@ -3945,6 +3952,9 @@ int main(int argc, char **argv, char **envp)
>>                       exit(1);
>>                   }
>>                   break;
>> +            case QEMU_OPTION_gfx_passthru:
>> +                xen_gfx_passthru(optarg);
>> +                break;
>>               default:
>>                   os_parse_cmd_args(popt->index, optarg);
>>               }
>> --
>> 1.9.1
>
>