5.10-stable review patch. If anyone has any objections, please let me know.
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From: Boqun Feng boqun.feng@gmail.com
[ Upstream commit 15d82ca23c996d50062286d27ed6a42a8105c04a ]
Currently we retrieve the PCI domain number of the host bridge from the bus sysdata (or pci_config_window if PCI_DOMAINS_GENERIC=y). Actually we have the information at PCI host bridge probing time, and it makes sense that we store it into pci_host_bridge. One benefit of doing so is the requirement for supporting PCI on Hyper-V for ARM64, because the host bridge of Hyper-V doesn't have pci_config_window, whereas ARM64 is a PCI_DOMAINS_GENERIC=y arch, so we cannot retrieve the PCI domain number from pci_config_window on ARM64 Hyper-V guest.
As the preparation for ARM64 Hyper-V PCI support, we introduce the domain_nr in pci_host_bridge and a sentinel value to allow drivers to set domain numbers properly at probing time. Currently CONFIG_PCI_DOMAINS_GENERIC=y archs are only users of this newly-introduced field.
Link: https://lore.kernel.org/r/20210726180657.142727-2-boqun.feng@gmail.com Signed-off-by: Boqun Feng boqun.feng@gmail.com Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Acked-by: Bjorn Helgaas bhelgaas@google.com Stable-dep-of: 804443c1f278 ("PCI: Fix reference leak in pci_register_host_bridge()") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/probe.c | 6 +++++- include/linux/pci.h | 11 +++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 6439fc2e526c7..be7973e249cd7 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -595,6 +595,7 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge) bridge->native_pme = 1; bridge->native_ltr = 1; bridge->native_dpc = 1; + bridge->domain_nr = PCI_DOMAIN_NR_NOT_SET;
device_initialize(&bridge->dev); } @@ -899,7 +900,10 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) bus->ops = bridge->ops; bus->number = bus->busn_res.start = bridge->busnr; #ifdef CONFIG_PCI_DOMAINS_GENERIC - bus->domain_nr = pci_bus_find_domain_nr(bus, parent); + if (bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET) + bus->domain_nr = pci_bus_find_domain_nr(bus, parent); + else + bus->domain_nr = bridge->domain_nr; #endif
b = pci_find_bus(pci_domain_nr(bus), bridge->busnr); diff --git a/include/linux/pci.h b/include/linux/pci.h index 30bc462fb1964..a0fd1fe4189e4 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -538,6 +538,16 @@ static inline int pci_channel_offline(struct pci_dev *pdev) return (pdev->error_state != pci_channel_io_normal); }
+/* + * Currently in ACPI spec, for each PCI host bridge, PCI Segment + * Group number is limited to a 16-bit value, therefore (int)-1 is + * not a valid PCI domain number, and can be used as a sentinel + * value indicating ->domain_nr is not set by the driver (and + * CONFIG_PCI_DOMAINS_GENERIC=y archs will set it with + * pci_bus_find_domain_nr()). + */ +#define PCI_DOMAIN_NR_NOT_SET (-1) + struct pci_host_bridge { struct device dev; struct pci_bus *bus; /* Root bus */ @@ -545,6 +555,7 @@ struct pci_host_bridge { struct pci_ops *child_ops; void *sysdata; int busnr; + int domain_nr; struct list_head windows; /* resource_entry */ struct list_head dma_ranges; /* dma ranges resource list */ u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* Platform IRQ swizzler */