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


From: Zhang, Yang Z
Subject: Re: [Qemu-devel] [PATCH 1/5] xen, gfx passthrough: basic graphics passthrough support
Date: Fri, 9 May 2014 07:27:43 +0000

Anthony PERARD wrote on 2014-03-22:
> On Fri, Feb 21, 2014 at 02:44:09PM +0800, Yang Zhang wrote:
>> From: Yang Zhang <address@hidden>
>> 
>> basic gfx passthrough support:
>> - add a vga type for gfx passthrough
>> - retrieve VGA bios from host 0xC0000, 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 <address@hidden>
>> 
>> Signed-off-by: Yang Zhang <address@hidden>
>> Cc: Weidong Han <address@hidden>

Hi all, 

Thanks for your comments. 

I am sorry for late reply. I have been busy working on other task so that I 
have no time to push this patch in the past two months. Now I and Tiejun will 
continue working on this and will send out the second version which is modified 
according your previous comments. Please help to review the second one again.

>> ---
>>  configure                    |    2 +- 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 
>>     |  164 ++++++++++++++++++++++++++++++++++++++++++ qemu-options.hx  
>>             |    9 +++ vl.c                         |    8 ++ 9 files
>>  changed, 203 insertions(+), 2 deletions(-)  create mode
>> 100644 hw/xen/xen_pt_graphics.c
>> 
>> diff --git a/configure b/configure
>> index 4648117..19525ab 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4608,7 +4608,7 @@ case "$target_name" in
>>      if test "$xen" = "yes" -a "$target_softmmu" = "yes" ; then
>>        echo "CONFIG_XEN=y" >> $config_target_mak
>>        if test "$xen_pci_passthrough" = yes; then
>> -        echo "CONFIG_XEN_PCI_PASSTHROUGH=y" >> "$config_target_mak" + 
>>       echo "CONFIG_XEN_PCI_PASSTHROUGH=y" >>
> "$config_host_mak"
> 
> Why do you need to move this option from config_target to config_host?
> 
>>        fi
>>      fi
>>      ;;
>> diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs index
>> ce640c6..350d337 100644 --- a/hw/xen/Makefile.objs +++
>> b/hw/xen/Makefile.objs @@ -3,4 +3,4 @@ common-obj-$(CONFIG_XEN_BACKEND)
>> += xen_backend.o xen_devconfig.o
>> 
>>  obj-$(CONFIG_XEN_I386) += xen_platform.o xen_apic.o xen_pvdevice.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..5a36902 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);
>>      }
>> +    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);
>>      }
>> +
>> +    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 (setup_vga_pt(&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..c04bbfd
>> 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 gfx_passthru;
>> +int register_vga_regions(XenHostPCIDevice *dev); int
>> +unregister_vga_regions(XenHostPCIDevice *dev); int
>> +setup_vga_pt(XenHostPCIDevice *dev);
> 
> I believe those function names need to be prefix with xen_pt_ (e.g.
> xen_pt_register_vga_regions).
> 
>>  #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..9ad8a74
>> --- /dev/null
>> +++ b/hw/xen/xen_pt_graphics.c
>> @@ -0,0 +1,164 @@
>> +/*
>> + * graphics passthrough
>> + */
>> +#include "xen_pt.h"
>> +#include "xen-host-pci-device.h"
>> +#include "hw/xen/xen_backend.h"
>> +
>> +/*
>> + * register VGA resources for the domain with assigned gfx  */ int
>> +register_vga_regions(XenHostPCIDevice *dev) {
>> +    int ret = 0;
>> +
>> +    if (!gfx_passthru || ((dev->class_code >> 0x8) != 0x0300)) {
> 
> Instead of 0x0300, you can use PCI_CLASS_DISPLAY_VGA. The same apply
> to the few other places.
> 
>> +        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 != 0) { +       
>> XEN_PT_ERR(NULL, "VGA region mapping failed\n"); +    } + +    return
>> ret; +} + +/* + * unregister VGA resources for the domain with assigned
>> gfx  */ +int unregister_vga_regions(XenHostPCIDevice *dev) { +    int
>> ret = 0; + +    if (!gfx_passthru || ((dev->class_code >> 0x8) !=
>> 0x0300)) { +        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 != 0) { +       
>> XEN_PT_ERR(NULL, "VGA region unmapping failed\n"); +    } + +    return
>> ret; +} + +static int get_vgabios(unsigned char *buf) { +    int fd; + 
>>   uint32_t bios_size = 0; +    uint32_t start = 0xC0000; +    uint16_t
>> magic = 0; + +    fd = open("/dev/mem", O_RDONLY); +    if (fd < 0) { +
>>        XEN_PT_ERR(NULL, "Can't open /dev/mem: %s\n", strerror(errno));
>> +        return 0; +    } + +    /* +     * Check if it a real bios
>> extension. +     * The magic number is 0xAA55. +     */ +    if (start
>> != lseek(fd, start, SEEK_SET)) { +        goto out; +    } +    if
>> (read(fd, &magic, 2) != 2) { +        goto out; +    } +    if (magic
>> != 0xAA55) { +        goto out; +    } + +    /* Find the size of the
>> rom extension */ +    if (start != lseek(fd, start, SEEK_SET)) { +     
>>   goto out; +    } +    if (lseek(fd, 2, SEEK_CUR) != (start + 2)) { + 
>>       goto out; +    } +    if (read(fd, &bios_size, 1) != 1) { +      
>>  goto out; +    } + +    /* This size is in 512 bytes */ +    bios_size
>> *= 512; + +    /* +     * Set the file to the begining of the rombios,
>> +     * to start the copy. +     */ +    if (start != lseek(fd, start,
>> SEEK_SET)) { +        goto out; +    } + +    if (bios_size != read(fd,
>> buf, bios_size)) { +        bios_size = 0; +    } + +out: +   
>> close(fd); +    return bios_size; +} + +int
>> setup_vga_pt(XenHostPCIDevice *dev) { +    unsigned char *bios = NULL;
>> +    int bios_size = 0; +    char *c = NULL; +    char checksum = 0; + 
>>   int rc = 0; + +    if (!gfx_passthru || ((dev->class_code >> 0x8) !=
>> 0x0300)) { +        return rc; +    } + +    bios = malloc(64 * 1024);
> 
> I think g_malloc should be used here, instead of malloc, and g_malloc
> always return an allocated buffer. (it never fail, or it don't return)
> 
>> +    /* Allocated 64K for the vga bios */
>> +    if (!bios) {
>> +        return -1;
>> +    }
>> +
>> +    bios_size = get_vgabios(bios);
>> +    if (bios_size == 0 || bios_size > 64 * 1024) {
>> +        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");
>> +    }
>> +
>> +    cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);
>> +out:
>> +    free(bios);
>> +    return rc;
>> +}
>> diff --git a/qemu-options.hx b/qemu-options.hx index
>> 56e5fdf..95de002
>> 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1034,6 +1034,15 @@ 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
>> address@hidden -gfx_passthru
>> address@hidden -gfx_passthru
>> +Enable Intel IGD passthrough by XEN ETEXI
>> +
> 
> Is this options really necessary?  If someone is passing-through a
> graphic card, he propably want to pass it through as a graphic card,
> without having to enable yet another option.
> 
>>  DEF("vga", HAS_ARG, QEMU_OPTION_vga,
>>      "-vga [std|cirrus|vmware|qxl|xenfb|none]\n"
>>      "                select video card type\n", QEMU_ARCH_ALL)
>> diff --git a/vl.c b/vl.c
>> index 316de54..8a91054 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -215,6 +215,9 @@ static bool tcg_allowed = true;  bool
>> xen_allowed; uint32_t xen_domid;  enum xen_mode xen_mode =
>> XEN_EMULATE;
>> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
>> +int gfx_passthru = 0;
>> +#endif
>>  static int tcg_tb_size;
>>  
>>  static int default_serial = 1;
>> @@ -3775,6 +3778,11 @@ int main(int argc, char **argv, char **envp)
>>                  }
>>                  configure_msg(opts);
>>                  break;
>> +#if defined(CONFIG_XEN_PCI_PASSTHROUGH)
>> +            case QEMU_OPTION_gfx_passthru:
>> +                gfx_passthru = 1;
>> +                break;
>> +#endif
>>              default:
>>                  os_parse_cmd_args(popt->index, optarg);
>>              }
>


Best regards,
Yang





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