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Message-ID: <20211008213143.GA1373034@bhelgaas>
Date: Fri, 8 Oct 2021 16:31:43 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Xuesong Chen <xuesong.chen@...ux.alibaba.com>
Cc: catalin.marinas@....com, lorenzo.pieralisi@....com,
james.morse@....com, will@...nel.org, rafael@...nel.org,
tony.luck@...el.com, bp@...en8.de, mingo@...nel.org,
bhelgaas@...gle.com, mark.rutland@....com,
linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Jayachandran C <c.jayachandran@...il.com>,
Tomasz Nowicki <tn@...ihalf.com>
Subject: Re: [PATCH v2 1/2] PCI: MCFG: Consolidate the separate PCI MCFG
table entry list
[+cc Jayachandran, Tomasz; not sure if they're still around, but just
in case they have a comment on any reasons for keeping the
pci_mcfg_list list separate.]
On Fri, Oct 08, 2021 at 04:40:12PM +0800, Xuesong Chen wrote:
> The PCI MCFG entry list is discrete on x86 and other architectures like
> arm64 in current implementation, this list variable can be consolidated
> for unnecessary duplication and other purposes, for example, we can remove
> some of the 'arch' specific codes in the APEI/EINJ module and re-implement
> it in a more common arch-agnostic way.
This commit log could be more explicit about what's going on here.
>From deciphering the patch, I think it takes advantage of the fact
that struct pci_mmcfg_region and struct mcfg_entry contain basically
the same information, but pci_mmcfg_region contains a little extra
information (a struct resource, a virtual address, and a name).
To reduce the redundancy, it:
- Moves the "struct pci_mmcfg_region" definition from
arch/x86/include/asm/pci_x86.h to include/linux/pci.h, where it
can be shared across arches.
- Moves pci_mmcfg_list (a list of pci_mmcfg_region structs) from
arch/x86/pci/mmconfig-shared.c to drivers/pci/pci.c, where it can
be shared across arches.
- On x86 (which does not enable CONFIG_ACPI_MCFG), pci_mmcfg_list is
built in arch/x86/pci/mmconfig-shared.c as before.
- Removes the "struct mcfg_entry" from drivers/acpi/pci_mcfg.c.
- Replaces pci_mcfg_list (previously a list of mcfg_entry structs)
in drivers/acpi/pci_mcfg.c with the newly-shared pci_mmcfg_list (a
list of pci_mmcfg_region structs).
- On ARM64 (which does enable CONFIG_ACPI_MCFG), pci_mmcfg_list is
built in drivers/acpi/pci_mcfg.c.
Does that sound about right?
> Signed-off-by: Xuesong Chen <xuesong.chen@...ux.alibaba.com>
> ---
> arch/x86/include/asm/pci_x86.h | 17 +----------------
> arch/x86/pci/mmconfig-shared.c | 2 --
> drivers/acpi/pci_mcfg.c | 34 +++++++++++++---------------------
> drivers/pci/pci.c | 2 ++
> include/linux/pci.h | 17 +++++++++++++++++
> 5 files changed, 33 insertions(+), 39 deletions(-)
>
> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
> index 490411d..1f4257c 100644
> --- a/arch/x86/include/asm/pci_x86.h
> +++ b/arch/x86/include/asm/pci_x86.h
> @@ -146,20 +146,7 @@ static inline int __init pci_acpi_init(void)
> extern void pcibios_fixup_irqs(void);
>
> /* pci-mmconfig.c */
> -
> -/* "PCI MMCONFIG %04x [bus %02x-%02x]" */
> -#define PCI_MMCFG_RESOURCE_NAME_LEN (22 + 4 + 2 + 2)
> -
> -struct pci_mmcfg_region {
> - struct list_head list;
> - struct resource res;
> - u64 address;
> - char __iomem *virt;
> - u16 segment;
> - u8 start_bus;
> - u8 end_bus;
> - char name[PCI_MMCFG_RESOURCE_NAME_LEN];
> -};
> +struct pci_mmcfg_region;
>
> extern int __init pci_mmcfg_arch_init(void);
> extern void __init pci_mmcfg_arch_free(void);
> @@ -174,8 +161,6 @@ extern struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start,
>
> extern struct list_head pci_mmcfg_list;
>
> -#define PCI_MMCFG_BUS_OFFSET(bus) ((bus) << 20)
> -
> /*
> * On AMD Fam10h CPUs, all PCI MMIO configuration space accesses must use
> * %eax. No other source or target registers may be used. The following
> diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
> index 758cbfe..0b961fe6 100644
> --- a/arch/x86/pci/mmconfig-shared.c
> +++ b/arch/x86/pci/mmconfig-shared.c
> @@ -31,8 +31,6 @@
> static DEFINE_MUTEX(pci_mmcfg_lock);
> #define pci_mmcfg_lock_held() lock_is_held(&(pci_mmcfg_lock).dep_map)
>
> -LIST_HEAD(pci_mmcfg_list);
> -
> static void __init pci_mmconfig_remove(struct pci_mmcfg_region *cfg)
> {
> if (cfg->res.parent)
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index 53cab97..d9506b0 100644
> --- a/drivers/acpi/pci_mcfg.c
> +++ b/drivers/acpi/pci_mcfg.c
> @@ -13,14 +13,7 @@
> #include <linux/pci-acpi.h>
> #include <linux/pci-ecam.h>
>
> -/* Structure to hold entries from the MCFG table */
> -struct mcfg_entry {
> - struct list_head list;
> - phys_addr_t addr;
> - u16 segment;
> - u8 bus_start;
> - u8 bus_end;
> -};
> +extern struct list_head pci_mmcfg_list;
>
> #ifdef CONFIG_PCI_QUIRKS
> struct mcfg_fixup {
> @@ -214,16 +207,13 @@ static void pci_mcfg_apply_quirks(struct acpi_pci_root *root,
> #endif
> }
>
> -/* List to save MCFG entries */
> -static LIST_HEAD(pci_mcfg_list);
> -
> int pci_mcfg_lookup(struct acpi_pci_root *root, struct resource *cfgres,
> const struct pci_ecam_ops **ecam_ops)
> {
> const struct pci_ecam_ops *ops = &pci_generic_ecam_ops;
> struct resource *bus_res = &root->secondary;
> u16 seg = root->segment;
> - struct mcfg_entry *e;
> + struct pci_mmcfg_region *e;
> struct resource res;
>
> /* Use address from _CBA if present, otherwise lookup MCFG */
> @@ -233,10 +223,10 @@ int pci_mcfg_lookup(struct acpi_pci_root *root, struct resource *cfgres,
> /*
> * We expect the range in bus_res in the coverage of MCFG bus range.
> */
> - list_for_each_entry(e, &pci_mcfg_list, list) {
> - if (e->segment == seg && e->bus_start <= bus_res->start &&
> - e->bus_end >= bus_res->end) {
> - root->mcfg_addr = e->addr;
> + list_for_each_entry(e, &pci_mmcfg_list, list) {
> + if (e->segment == seg && e->start_bus <= bus_res->start &&
> + e->end_bus >= bus_res->end) {
> + root->mcfg_addr = e->address;
> }
>
> }
> @@ -268,7 +258,7 @@ static __init int pci_mcfg_parse(struct acpi_table_header *header)
> {
> struct acpi_table_mcfg *mcfg;
> struct acpi_mcfg_allocation *mptr;
> - struct mcfg_entry *e, *arr;
> + struct pci_mmcfg_region *e, *arr;
> int i, n;
>
> if (header->length < sizeof(struct acpi_table_mcfg))
> @@ -285,10 +275,12 @@ static __init int pci_mcfg_parse(struct acpi_table_header *header)
>
> for (i = 0, e = arr; i < n; i++, mptr++, e++) {
> e->segment = mptr->pci_segment;
> - e->addr = mptr->address;
> - e->bus_start = mptr->start_bus_number;
> - e->bus_end = mptr->end_bus_number;
> - list_add(&e->list, &pci_mcfg_list);
> + e->address = mptr->address;
> + e->start_bus = mptr->start_bus_number;
> + e->end_bus = mptr->end_bus_number;
> + e->res.start = e->address + PCI_MMCFG_BUS_OFFSET(e->start_bus);
> + e->res.end = e->address + PCI_MMCFG_BUS_OFFSET(e->end_bus + 1) - 1;
> + list_add(&e->list, &pci_mmcfg_list);
> }
>
> #ifdef CONFIG_PCI_QUIRKS
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index ce2ab62..899004e 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -47,6 +47,8 @@
> int pci_pci_problems;
> EXPORT_SYMBOL(pci_pci_problems);
>
> +LIST_HEAD(pci_mmcfg_list);
> +
> unsigned int pci_pm_d3hot_delay;
>
> static void pci_pme_list_scan(struct work_struct *work);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index cd8aa6f..71e4c06 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -55,6 +55,23 @@
> #define PCI_RESET_PROBE true
> #define PCI_RESET_DO_RESET false
>
> +#define PCI_MMCFG_BUS_OFFSET(bus) ((bus) << 20)
> +
> +/* "PCI MMCONFIG %04x [bus %02x-%02x]" */
> +#define PCI_MMCFG_RESOURCE_NAME_LEN (22 + 4 + 2 + 2)
> +
> +/* pci mcfg region */
> +struct pci_mmcfg_region {
> + struct list_head list;
> + struct resource res;
> + u64 address;
> + char __iomem *virt;
> + u16 segment;
> + u8 start_bus;
> + u8 end_bus;
> + char name[PCI_MMCFG_RESOURCE_NAME_LEN];
> +};
> +
> /*
> * The PCI interface treats multi-function devices as independent
> * devices. The slot/function address of each device is encoded
> --
> 1.8.3.1
>
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