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authorMax Gurtovoy <mgurtovoy@nvidia.com>2021-08-26 13:39:09 +0300
committerAlex Williamson <alex.williamson@redhat.com>2021-08-26 19:36:51 +0300
commitcc6711b0bf36de068b10490198d05ac168377989 (patch)
tree24e01ccccde5a2deabb8ba1cdce93b07d2a7cba9 /scripts/mod/file2alias.c
parent343b7258687ecfbb363bfda8833a7cf641aac524 (diff)
downloadlinux-cc6711b0bf36de068b10490198d05ac168377989.tar.xz
PCI / VFIO: Add 'override_only' support for VFIO PCI sub system
Expose an 'override_only' helper macro (i.e. PCI_DRIVER_OVERRIDE_DEVICE_VFIO) for VFIO PCI sub system and add the required code to prefix its matching entries with "vfio_" in modules.alias file. It allows VFIO device drivers to include match entries in the modules.alias file produced by kbuild that are not used for normal driver autoprobing and module autoloading. Drivers using these match entries can be connected to the PCI device manually, by userspace, using the existing driver_override sysfs. For example the resulting modules.alias may have: alias pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_core alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci In this example mlx5_core and mlx5_vfio_pci match to the same PCI device. The kernel will autoload and autobind to mlx5_core but the kernel and udev mechanisms will ignore mlx5_vfio_pci. When userspace wants to change a device to the VFIO subsystem it can implement a generic algorithm: 1) Identify the sysfs path to the device: /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0 2) Get the modalias string from the kernel: $ cat /sys/bus/pci/devices/0000:01:00.0/modalias pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00 3) Prefix it with vfio_: vfio_pci:v000015B3d00001021sv000015B3sd00000001bc02sc00i00 4) Search modules.alias for the above string and select the entry that has the fewest *'s: alias vfio_pci:v000015B3d00001021sv*sd*bc*sc*i* mlx5_vfio_pci 5) modprobe the matched module name: $ modprobe mlx5_vfio_pci 6) cat the matched module name to driver_override: echo mlx5_vfio_pci > /sys/bus/pci/devices/0000:01:00.0/driver_override 7) unbind device from original module echo 0000:01:00.0 > /sys/bus/pci/devices/0000:01:00.0/driver/unbind 8) probe PCI drivers (or explicitly bind to mlx5_vfio_pci) echo 0000:01:00.0 > /sys/bus/pci/drivers_probe The algorithm is independent of bus type. In future the other buses with VFIO device drivers, like platform and ACPI, can use this algorithm as well. This patch is the infrastructure to provide the information in the modules.alias to userspace. Convert the only VFIO pci_driver which results in one new line in the modules.alias: alias vfio_pci:v*d*sv*sd*bc*sc*i* vfio_pci Later series introduce additional HW specific VFIO PCI drivers, such as mlx5_vfio_pci. Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> # for pci.h Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Link: https://lore.kernel.org/r/20210826103912.128972-11-yishaih@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'scripts/mod/file2alias.c')
-rw-r--r--scripts/mod/file2alias.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 7c97fa8e36bc..49aba862073e 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -426,7 +426,7 @@ static int do_ieee1394_entry(const char *filename,
return 1;
}
-/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
+/* Looks like: pci:vNdNsvNsdNbcNscNiN or <prefix>_pci:vNdNsvNsdNbcNscNiN. */
static int do_pci_entry(const char *filename,
void *symval, char *alias)
{
@@ -440,8 +440,21 @@ static int do_pci_entry(const char *filename,
DEF_FIELD(symval, pci_device_id, subdevice);
DEF_FIELD(symval, pci_device_id, class);
DEF_FIELD(symval, pci_device_id, class_mask);
+ DEF_FIELD(symval, pci_device_id, override_only);
+
+ switch (override_only) {
+ case 0:
+ strcpy(alias, "pci:");
+ break;
+ case PCI_ID_F_VFIO_DRIVER_OVERRIDE:
+ strcpy(alias, "vfio_pci:");
+ break;
+ default:
+ warn("Unknown PCI driver_override alias %08X\n",
+ override_only);
+ return 0;
+ }
- strcpy(alias, "pci:");
ADD(alias, "v", vendor != PCI_ANY_ID, vendor);
ADD(alias, "d", device != PCI_ANY_ID, device);
ADD(alias, "sv", subvendor != PCI_ANY_ID, subvendor);