Re: [RFC v5 1/8] PCI: Introduce domain_nr in pci_host_bridge
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2021-07-20 22:51:31
Also in:
linux-arm-kernel, linux-pci, lkml
On Tue, Jul 20, 2021 at 09:44:22PM +0800, Boqun Feng wrote:
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. Signed-off-by: Boqun Feng <redacted>
Once all the issues are ironed out, Lorenzo should probably merge this since it's primarily Hyper-V stuff, but I'm OK with this part: Acked-by: Bjorn Helgaas <bhelgaas@google.com> But fix the comment issue below.
quoted hunk ↗ jump to hunk
--- drivers/pci/probe.c | 6 +++++- include/linux/pci.h | 10 ++++++++++ 2 files changed, 15 insertions(+), 1 deletion(-)diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 79177ac37880..60c50d4f156f 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c@@ -594,6 +594,7 @@ 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); }@@ -898,7 +899,10 @@ 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 540b377ca8f6..2c413a64d168 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h@@ -526,6 +526,15 @@ 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()). +*/
Fix comment indentation (follow style of other comments in this file). s/>domain_nr/->domain_nr/
quoted hunk ↗ jump to hunk
+#define PCI_DOMAIN_NR_NOT_SET (-1) + struct pci_host_bridge { struct device dev; struct pci_bus *bus; /* Root bus */@@ -533,6 +542,7 @@ 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 */-- 2.30.2