* Re: [RFC v5.1 1/8] PCI: Introduce domain_nr in pci_host_bridge
2021-07-21 0:53 ` [RFC v5.1 1/8] PCI: Introduce domain_nr in pci_host_bridge Boqun Feng
@ 2021-07-22 15:53 ` Boqun Feng
0 siblings, 0 replies; 2+ messages in thread
From: Boqun Feng @ 2021-07-22 15:53 UTC (permalink / raw)
To: Bjorn Helgaas, Arnd Bergmann, Marc Zyngier, Lorenzo Pieralisi
Cc: Catalin Marinas, Will Deacon, K. Y. Srinivasan, Haiyang Zhang,
Stephen Hemminger, Wei Liu, Dexuan Cui, Lorenzo Pieralisi,
Rob Herring, Krzysztof Wilczyński, linux-arm-kernel,
linux-kernel, linux-hyperv, linux-pci, Sunil Muthuswamy,
Mike Rapoport
On Wed, Jul 21, 2021 at 08:53:36AM +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 <boqun.feng@gmail.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> 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..ba61f4e144aa 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()).
> +*/
Hmm.. I forgot to fix this part. Just fixed it locally. Apologies...
Lorenzo, how does the rest look to you? If you think they are good to
take then I can send a updated version of this patch #1 (version 5.2
maybe), otherwise (if you think more reviews are needed), I will wait
and resolve other feedbacks (if any) and put the updated patch #1 into
next iteration (maybe after next -rc is out). Thanks!
Just in case, this is the link for the whole series:
https://lore.kernel.org/lkml/20210720134429.511541-1-boqun.feng@gmail.com/
Regards,
Boqun
> +#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
>
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