Hi,
Please find attached a kernel patch. This is based from a very old patch
that never made it into the kernel in 2014.
https://lkml.org/lkml/2014/10/20/295. I am not sure who else I should be
adding to the Signed-off-by section.
I have modified it and tested it, so that it works against kernel 5.1.10.
Summary below:
PCI: Introduce new device binding path using pci_dev.driver_override
In order to bind PCI slots to specific drivers use:
pci=driver[xxxx:xx:xx.x]=foo,driver[xxxx:xx:xx.x]=bar,...
The main use case for this is in relation to qemu passthrough
of a pci device using IOMMU and vfio-pci.
Example:
The host has two identical devices. E.g. 2 AMD Vega GPUs,
The user wishes to passthrough only one GPU.
This new feature allows the user to select which GPU to passthrough.
Signed-off-by: James Courtier-Dutton <ja...@superbug.co.uk>
commit bcb3011bb2e9906c669b249ab65312a03ecb041b
Author: James Courtier-Dutton <ja...@superbug.co.uk>
Date: Sat Jun 15 13:29:41 2019 +0100
PCI: Introduce new device binding path using pci_dev.driver_override
In order to bind PCI slots to specific drivers use:
pci=driver[xxxx:xx:xx.x]=foo,driver[xxxx:xx:xx.x]=bar,...
The main use case for this is in relation to qemu passthrough
of a pci device using IOMMU and vfio-pci.
Example:
The host has two identical devices. E.g. 2 AMD Vega GPUs,
The user wishes to passthrough only one GPU.
This new feature allows the user to select which GPU to passthrough.
Signed-off-by: James Courtier-Dutton <ja...@superbug.co.uk>
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7937f379d22..71df0fd19cc6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3439,6 +3439,10 @@
pcie_scan_all Scan all possible PCIe devices. Otherwise we
only look for one device below a PCIe downstream
port.
+ driver Provide an override to the devid<->driver mapping
+ for a specific slot.
+ Bind PCI slot 0001:02:03.4 to vfio-pci by:
+ driver[0001:02:03.4]=vfio-pci
big_root_window Try to add a big 64bit memory window to the PCIe
root complex on AMD CPUs. Some GFX hardware
can resize a BAR to allow access to all VRAM.
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 5cb40b2518f9..983f1d524a26 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -14,6 +14,8 @@
#include <linux/proc_fs.h>
#include <linux/slab.h>
+#include <asm/setup.h>
+
#include "pci.h"
void pci_add_resource_offset(struct list_head *resources, struct resource *res,
@@ -206,6 +208,116 @@ static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
return -ENOMEM;
}
+struct driver_override_entry {
+ u16 domain;
+ u8 bus;
+ u8 devfn;
+ char *driver_name;
+ struct list_head list;
+};
+
+static LIST_HEAD(driver_override_entries);
+
+static int pci_device_parse_driver_override(char *param, char *val,
+ const char *unused, void *unused2)
+{
+ unsigned int domain, bus, dev, fn;
+ char *buf;
+ struct driver_override_entry *entry;
+ int ret;
+
+ buf = kmalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
+ if (!buf)
+ goto err_buf;
+
+ while (val) {
+ char *k = strchr(val, ',');
+
+ if (k)
+ *k++ = 0;
+
+ if (strncmp(val, "driver", 6)) {
+ val = k;
+ continue;
+ }
+
+ memset(buf, 0, COMMAND_LINE_SIZE);
+ ret = sscanf(val + 6, "[%4x:%2x:%2x.%2x]=%s",
+ &domain, &bus, &dev, &fn, buf);
+ if (ret != 5) {
+ pr_warn("PCI: Invalid command line: %s\n", val);
+ val = k;
+ continue;
+ }
+
+ entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+ if (!entry)
+ goto err_entry;
+
+ INIT_LIST_HEAD(&entry->list);
+ entry->domain = domain;
+ entry->bus = bus;
+ entry->devfn = PCI_DEVFN(dev, fn);
+ entry->driver_name = kstrdup(buf, GFP_KERNEL);
+ if (!entry->driver_name)
+ goto err_driver_name;
+
+ pr_info("PCI: driver_override added for driver_name: %s to [%04x:%02x:%02x.%x]\n",
+ entry->driver_name, domain, bus, dev, fn);
+ list_add_tail(&entry->list, &driver_override_entries);
+ val = k;
+ }
+
+ kfree(buf);
+ return 0;
+
+err_driver_name:
+ kfree(entry);
+
+err_entry:
+ kfree(buf);
+
+err_buf:
+ pr_err("PCI: Out of memory while parsing command line: %s\n", val);
+ return -ENOMEM;
+}
+
+static void pci_device_setup_driver_override(struct pci_dev *dev)
+{
+ static int parse_done;
+ struct driver_override_entry *entry;
+
+ if (!parse_done) {
+ char *cmdline = kstrdup(saved_command_line, GFP_KERNEL);
+
+ if (!cmdline)
+ goto err_out_of_mem;
+
+ parse_args("pci", cmdline, NULL,
+ 0, 0, 0, NULL, &pci_device_parse_driver_override);
+ kfree(cmdline);
+ parse_done = 1;
+ }
+
+ list_for_each_entry(entry, &driver_override_entries, list) {
+ if (pci_domain_nr(dev->bus) != entry->domain ||
+ dev->bus->number != entry->bus ||
+ dev->devfn != entry->devfn)
+ continue;
+
+ dev->driver_override = kstrdup(entry->driver_name, GFP_KERNEL);
+ if (!dev->driver_override)
+ goto err_out_of_mem;
+
+ break;
+ }
+
+ return;
+
+err_out_of_mem:
+ pr_err("PCI: Out of memory while setting up driver override\n");
+}
+
/**
* pci_bus_alloc_resource - allocate a resource from a parent bus
* @bus: PCI bus
@@ -317,6 +429,7 @@ void pci_bus_add_device(struct pci_dev *dev)
*/
pcibios_bus_add_device(dev);
pci_fixup_device(pci_fixup_final, dev);
+ pci_device_setup_driver_override(dev);
pci_create_sysfs_dev_files(dev);
pci_proc_attach_device(dev);
pci_bridge_d3_update(dev);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 766f5779db92..7dd5d2dfeee1 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6261,6 +6261,8 @@ static int __init pci_setup(char *str)
pcie_bus_config = PCIE_BUS_PEER2PEER;
} else if (!strncmp(str, "pcie_scan_all", 13)) {
pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS);
+ } else if (!strncmp(str, "driver", 6)) {
+ /* lazy evaluation by the pci subsystem */
} else if (!strncmp(str, "disable_acs_redir=", 18)) {
disable_acs_redir_param = str + 18;
} else {
_______________________________________________
vfio-users mailing list
vfio-users@redhat.com
https://www.redhat.com/mailman/listinfo/vfio-users
