[PATCH libdrm] libdrm: Fix issue about differrent domainID but same BDF

[Alex Deucher]

Adding dri-devel.

On Thu, Feb 14, 2019 at 2:53 AM Emily Deng <Emily.Deng at amd.com> wrote:
>
> For multiple GPUs which has the same BDF, but has different domain ID,
> the drmOpenByBusid will return the wrong fd when startx.
>
> The reproduce sequence as below:
> 1. Call drmOpenByBusid to open Card0, then will return the right fd0, and the
> fd0 is master privilege;
> 2. Call drmOpenByBusid to open Card1. In function drmOpenByBusid, it will
> open Card0 first, this time, the fd1 for opening Card0 is not master
> privilege, and will call drmSetInterfaceVersion to identify the
> domain ID feature, as the fd1 is not master privilege, then drmSetInterfaceVersion
> will fail, and then won't compare domain ID, then return the wrong fd for Card1.
>
> Solution:
> First loop search the best match fd about drm 1.4.
>
> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
> ---
>  xf86drm.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/xf86drm.c b/xf86drm.c
> index 336d64d..b60e029 100644
> --- a/xf86drm.c
> +++ b/xf86drm.c
> @@ -584,11 +584,34 @@ static int drmOpenByBusid(const char *busid, int type)
>      if (base < 0)
>          return -1;
>
> +    /* We need to try for 1.4 first for proper PCI domain support */
>      drmMsg("drmOpenByBusid: Searching for BusID %s\n", busid);
>      for (i = base; i < base + DRM_MAX_MINOR; i++) {
>          fd = drmOpenMinor(i, 1, type);
>          drmMsg("drmOpenByBusid: drmOpenMinor returns %d\n", fd);
>          if (fd >= 0) {
> +            sv.drm_di_major = 1;
> +            sv.drm_di_minor = 4;
> +            sv.drm_dd_major = -1;        /* Don't care */
> +            sv.drm_dd_minor = -1;        /* Don't care */
> +            if (!drmSetInterfaceVersion(fd, &sv)) {
> +                buf = drmGetBusid(fd);
> +                drmMsg("drmOpenByBusid: drmGetBusid reports %s\n", buf);
> +                if (buf && drmMatchBusID(buf, busid, 1)) {
> +                    drmFreeBusid(buf);
> +                    return fd;
> +                }
> +                if (buf)
> +                    drmFreeBusid(buf);
> +            }
> +            close(fd);
> +        }
> +    }
> +
> +   for (i = base; i < base + DRM_MAX_MINOR; i++) {
> +        fd = drmOpenMinor(i, 1, type);
> +        drmMsg("drmOpenByBusid: drmOpenMinor returns %d\n", fd);
> +        if (fd >= 0) {
>              /* We need to try for 1.4 first for proper PCI domain support
>               * and if that fails, we know the kernel is busted
>               */
> --
> 2.7.4
>
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