[PATCH i-g-t] lib/igt_sriov_device: Replace libpciaccess with direct sysfs interaction
Laguna, Lukasz
lukasz.laguna at intel.com
Tue Jul 2 08:31:25 UTC 2024
On 6/27/2024 16:51, Marcin Bernatowicz wrote:
> Previously, libpciaccess was used to fetch PCI device information for
> VFs in SR-IOV, which does not refresh the PCI bus state after the initial
> scan. This can lead to outdated PCI information in dynamic SR-IOV
> environments where VFs are dynamically managed.
>
> The new implementation directly interacts with sysfs to resolve the PCI
> slot address of a VF, ensuring access to the most current state of the
> PCI bus. This change removes the dependency on libpciaccess and uses
> __igt_sriov_get_vf_pci_slot_alloc to fetch the PCI slot addresses
> directly from sysfs based on VF numbers.
>
> Reported-by: Michal Wajdeczko<michal.wajdeczko at intel.com>
> Closes:https://intel-gfx-ci.01.org/tree/intel-xe/xe-pw-135423v1/shard-adlp-9/igt@sriov_basic@bind-unbind-vf@vf-2.html
> Cc: Michal Wajdeczko<michal.wajdeczko at intel.com>
> Cc: Lukasz Laguna<lukasz.laguna at intel.com>
> Cc: Kamil Konieczny<kamil.konieczny at linux.intel.com>
> Signed-off-by: Marcin Bernatowicz<marcin.bernatowicz at linux.intel.com>
> ---
> lib/igt_sriov_device.c | 46 +++++++++++++++++++++++++++++++++++-------
> 1 file changed, 39 insertions(+), 7 deletions(-)
>
> diff --git a/lib/igt_sriov_device.c b/lib/igt_sriov_device.c
> index a0ef05d5c..416d8f4aa 100644
> --- a/lib/igt_sriov_device.c
> +++ b/lib/igt_sriov_device.c
> @@ -297,26 +297,58 @@ bool igt_sriov_is_vf_drm_driver_probed(int pf, unsigned int vf_num)
> return ret;
> }
>
> +/*
> + * __igt_sriov_get_vf_pci_slot_alloc:
> + * @pf_sysfs: sysfs directory file descriptor
> + * @vf_num: VF number (1-based)
> + *
> + * Resolve symbolic link from virtfnX to obtain the PCI slot address.
> + * Returns a dynamically allocated string containing the PCI slot address,
> + * or NULL if the link cannot be resolved.
> + * The caller is responsible for freeing the returned memory.
> + */
> +static char *__igt_sriov_get_vf_pci_slot_alloc(int pf_sysfs, unsigned int vf_num)
> +{
> + char dir_path[PATH_MAX];
> + char path[PATH_MAX];
> + char *pci_slot_addr;
> + int len;
> +
> + /* Adjust for 0-based index as vf_num is 1-based */
> + if (vf_num)
> + snprintf(dir_path, sizeof(dir_path), "device/virtfn%u",
> + vf_num - 1);
> + else
> + snprintf(dir_path, sizeof(dir_path), "device");
> +
> + len = readlinkat(pf_sysfs, dir_path, path, sizeof(path));
> + if (len <= 0)
> + return NULL;
> +
> + path[len] = '\0';
> + pci_slot_addr = strrchr(path, '/') + 1;
> +
> + return pci_slot_addr ? strdup(pci_slot_addr) : NULL;
> +}
> +
> static bool __igt_sriov_bind_vf_drm_driver(int pf, unsigned int vf_num, bool bind)
> {
> - struct pci_device *pci_dev;
> - char pci_slot[14];
> + char *pci_slot;
> int sysfs;
> bool ret;
>
> igt_assert(vf_num > 0);
>
> - pci_dev = __igt_device_get_pci_device(pf, vf_num);
> - igt_assert_f(pci_dev, "No PCI device for given VF number: %d\n", vf_num);
> - sprintf(pci_slot, "%04x:%02x:%02x.%x",
> - pci_dev->domain_16, pci_dev->bus, pci_dev->dev, pci_dev->func);
> -
> sysfs = igt_sysfs_open(pf);
> igt_assert_fd(sysfs);
>
> + pci_slot = __igt_sriov_get_vf_pci_slot_alloc(sysfs, vf_num);
> + igt_assert(pci_slot);
> +
> igt_debug("vf_num: %u, pci_slot: %s\n", vf_num, pci_slot);
> ret = igt_sysfs_set(sysfs, bind ? "device/driver/bind" : "device/driver/unbind", pci_slot);
>
> + free(pci_slot);
> close(sysfs);
>
> return ret;
Reviewed-by: Lukasz Laguna <lukasz.laguna at intel.com
<mailto:lukasz.laguna at intel.com>>
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