The new common domain number allocator can replace the custom allocator
in VMD.
Beyond some code reuse benefits it does close a potential race whereby
vmd_find_free_domain() collides with new PCI buses coming online with a
conflicting domain number. Such a race has not been observed in
practice, hence not tagging this change as a fix.
As VMD uses pci_create_root_bus() rather than pci_alloc_host_bridge() +
pci_scan_root_bus_bridge() it has no chance to set ->domain_nr in the
bridge so needs to manage freeing the domain number on its own.
Cc: Nirmal Patel <nirmal.patel@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/pci/controller/vmd.c | 33 ++++++++++-----------------------
1 file changed, 10 insertions(+), 23 deletions(-)
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 8df064b62a2f..f60244ff9ef8 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -565,22 +565,6 @@ static void vmd_detach_resources(struct vmd_dev *vmd)
vmd->dev->resource[VMD_MEMBAR2].child = NULL;
}
-/*
- * VMD domains start at 0x10000 to not clash with ACPI _SEG domains.
- * Per ACPI r6.0, sec 6.5.6, _SEG returns an integer, of which the lower
- * 16 bits are the PCI Segment Group (domain) number. Other bits are
- * currently reserved.
- */
-static int vmd_find_free_domain(void)
-{
- int domain = 0xffff;
- struct pci_bus *bus = NULL;
-
- while ((bus = pci_find_next_bus(bus)) != NULL)
- domain = max_t(int, domain, pci_domain_nr(bus));
- return domain + 1;
-}
-
static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
resource_size_t *offset1,
resource_size_t *offset2)
@@ -865,13 +849,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
.parent = res,
};
- sd->vmd_dev = vmd->dev;
- sd->domain = vmd_find_free_domain();
- if (sd->domain < 0)
- return sd->domain;
-
- sd->node = pcibus_to_node(vmd->dev->bus);
-
/*
* Currently MSI remapping must be enabled in guest passthrough mode
* due to some missing interrupt remapping plumbing. This is probably
@@ -903,9 +880,17 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
+ sd->vmd_dev = vmd->dev;
+ sd->domain = pci_bus_find_emul_domain_nr(PCI_DOMAIN_NR_NOT_SET);
+ if (sd->domain < 0)
+ return sd->domain;
+
+ sd->node = pcibus_to_node(vmd->dev->bus);
+
vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
&vmd_ops, sd, &resources);
if (!vmd->bus) {
+ pci_bus_release_emul_domain_nr(sd->domain);
pci_free_resource_list(&resources);
vmd_remove_irq_domain(vmd);
return -ENODEV;
@@ -998,6 +983,7 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
return -ENOMEM;
vmd->dev = dev;
+ vmd->sysdata.domain = PCI_DOMAIN_NR_NOT_SET;
vmd->instance = ida_alloc(&vmd_instance_ida, GFP_KERNEL);
if (vmd->instance < 0)
return vmd->instance;
@@ -1063,6 +1049,7 @@ static void vmd_remove(struct pci_dev *dev)
vmd_detach_resources(vmd);
vmd_remove_irq_domain(vmd);
ida_free(&vmd_instance_ida, vmd->instance);
+ pci_bus_release_emul_domain_nr(vmd->sysdata.domain);
}
static void vmd_shutdown(struct pci_dev *dev)
--
2.49.0
