From: Roger Pau Monne roger.pau@citrix.com
[ Upstream commit 5ccf1b8ae76ddf348e02a0d1564ff9baf8b6c415 ]
The current hypercall interface for doing PCI device operations always uses a segment field that has a 16 bit width. However on Linux there are buses like VMD that hook up devices into the PCI hierarchy at segment >= 0x10000, after the maximum possible segment enumerated in ACPI.
Attempting to register or manage those devices with Xen would result in errors at best, or overlaps with existing devices living on the truncated equivalent segment values. Note also that the VMD segment numbers are arbitrarily assigned by the OS, and hence there would need to be some negotiation between Xen and the OS to agree on how to enumerate VMD segments and devices behind them.
Skip notifying Xen about those devices. Given how VMD bridges can multiplex interrupts on behalf of devices behind them there's no need for Xen to be aware of such devices for them to be usable by Linux.
Signed-off-by: Roger Pau Monné roger.pau@citrix.com Acked-by: Juergen Gross jgross@suse.com Message-ID: 20250219092059.90850-2-roger.pau@citrix.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/pci.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c index 416f231809cb6..bfe07adb3e3a6 100644 --- a/drivers/xen/pci.c +++ b/drivers/xen/pci.c @@ -43,6 +43,18 @@ static int xen_add_device(struct device *dev) pci_mcfg_reserved = true; } #endif + + if (pci_domain_nr(pci_dev->bus) >> 16) { + /* + * The hypercall interface is limited to 16bit PCI segment + * values, do not attempt to register devices with Xen in + * segments greater or equal than 0x10000. + */ + dev_info(dev, + "not registering with Xen: invalid PCI segment\n"); + return 0; + } + if (pci_seg_supported) { DEFINE_RAW_FLEX(struct physdev_pci_device_add, add, optarr, 1);
@@ -149,6 +161,16 @@ static int xen_remove_device(struct device *dev) int r; struct pci_dev *pci_dev = to_pci_dev(dev);
+ if (pci_domain_nr(pci_dev->bus) >> 16) { + /* + * The hypercall interface is limited to 16bit PCI segment + * values. + */ + dev_info(dev, + "not unregistering with Xen: invalid PCI segment\n"); + return 0; + } + if (pci_seg_supported) { struct physdev_pci_device device = { .seg = pci_domain_nr(pci_dev->bus), @@ -182,6 +204,16 @@ int xen_reset_device(const struct pci_dev *dev) .flags = PCI_DEVICE_RESET_FLR, };
+ if (pci_domain_nr(dev->bus) >> 16) { + /* + * The hypercall interface is limited to 16bit PCI segment + * values. + */ + dev_info(&dev->dev, + "unable to notify Xen of device reset: invalid PCI segment\n"); + return 0; + } + return HYPERVISOR_physdev_op(PHYSDEVOP_pci_device_reset, &device); } EXPORT_SYMBOL_GPL(xen_reset_device);