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SubjectRe: [PATCH v4 3/4] PCI: Modify kernel parameters to differentiate between MMIO and MMIO_PREF sizes
On Wed, Apr 17, 2019 at 02:16:59PM +0000, Nicholas Johnson wrote:
> Add kernel parameter pci=hpmemprefsize=nn[KMG] to control MMIO_PREF
> size for PCI hotplug bridges.
>
> Change behaviour of pci=hpmemsize=nn[KMG] to only control MMIO size,
> rather than controlling both MMIO and MMIO_PREF sizes.

If I understand correctly, this patch as-is changes the behavior of
just specifying "pci=hpmemsize", and I think that will require some
users to change their boot configuration.

If the user doesn't specify "pci=hpmemprefsize", I think we might want
to preserve the existing behavior, i.e.,

- "pci=hpmemsize=XX" affects both MMIO and MMIO_PREF windows, as it
does today

- "pci=hpmemprefsize=XX" affects only MMIO_PREF window, use default
for MMIO window size

- "pci=hpmemsize=XX pci=hpmemprefsize=YY" sets MMIO window size to
XX and MMIO_PREF window size to YY

That way a user will not see any change in behavior unless he/she
actually uses the new kernel parameter.

> Update kernel-parameters documentation to reflect the above changes.
>
> Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
> ---
> .../admin-guide/kernel-parameters.txt | 5 +++-
> drivers/pci/pci.c | 12 ++++++---
> drivers/pci/setup-bus.c | 25 +++++++++++--------
> include/linux/pci.h | 3 ++-
> 4 files changed, 29 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 2b8ee90bb..f33b590c2 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3361,7 +3361,10 @@
> reserved for hotplug bridge's IO window.
> Default size is 256 bytes.
> hpmemsize=nn[KMG] The fixed amount of bus space which is
> - reserved for hotplug bridge's memory window.
> + reserved for hotplug bridge's MMIO window.
> + Default size is 2 megabytes.
> + hpmemprefsize=nn[KMG] The fixed amount of bus space which is
> + reserved for hotplug bridge's MMIO_PREF window.
> Default size is 2 megabytes.
> hpbussize=nn The minimum amount of additional bus numbers
> reserved for buses below a hotplug bridge.
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7c1b362f5..e0502831f 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -85,10 +85,12 @@ unsigned long pci_cardbus_io_size = DEFAULT_CARDBUS_IO_SIZE;
> unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
>
> #define DEFAULT_HOTPLUG_IO_SIZE (256)
> -#define DEFAULT_HOTPLUG_MEM_SIZE (2*1024*1024)
> +#define DEFAULT_HOTPLUG_MMIO_SIZE (2*1024*1024)
> +#define DEFAULT_HOTPLUG_MMIO_PREF_SIZE (2*1024*1024)
> /* pci=hpmemsize=nnM,hpiosize=nn can override this */
> unsigned long pci_hotplug_io_size = DEFAULT_HOTPLUG_IO_SIZE;
> -unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
> +unsigned long pci_hotplug_mmio_size = DEFAULT_HOTPLUG_MMIO_SIZE;
> +unsigned long pci_hotplug_mmio_pref_size = DEFAULT_HOTPLUG_MMIO_PREF_SIZE;
>
> #define DEFAULT_HOTPLUG_BUS_SIZE 1
> unsigned long pci_hotplug_bus_size = DEFAULT_HOTPLUG_BUS_SIZE;
> @@ -6245,7 +6247,11 @@ static int __init pci_setup(char *str)
> } else if (!strncmp(str, "hpiosize=", 9)) {
> pci_hotplug_io_size = memparse(str + 9, &str);
> } else if (!strncmp(str, "hpmemsize=", 10)) {
> - pci_hotplug_mem_size = memparse(str + 10, &str);
> + pci_hotplug_mmio_size =
> + memparse(str + 10, &str);
> + } else if (!strncmp(str, "hpmemprefsize=", 14)) {
> + pci_hotplug_mmio_pref_size =
> + memparse(str + 14, &str);
> } else if (!strncmp(str, "hpbussize=", 10)) {
> pci_hotplug_bus_size =
> simple_strtoul(str + 10, &str, 0);
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 5b9ee9945..95149165a 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1187,7 +1187,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> {
> struct pci_dev *dev;
> unsigned long mask, prefmask, type2 = 0, type3 = 0;
> - resource_size_t additional_mem_size = 0, additional_io_size = 0;
> + resource_size_t additional_io_size = 0, additional_mmio_size = 0,
> + additional_mmio_pref_size = 0;
> struct resource *b_res;
> int ret;
>
> @@ -1221,7 +1222,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> pci_bridge_check_ranges(bus);
> if (bus->self->is_hotplug_bridge) {
> additional_io_size = pci_hotplug_io_size;
> - additional_mem_size = pci_hotplug_mem_size;
> + additional_mmio_size = pci_hotplug_mmio_size;
> + additional_mmio_pref_size = pci_hotplug_mmio_pref_size;
> }
> /* Fall through */
> default:
> @@ -1239,9 +1241,9 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> if (b_res[2].flags & IORESOURCE_MEM_64) {
> prefmask |= IORESOURCE_MEM_64;
> ret = pbus_size_mem(bus, prefmask, prefmask,
> - prefmask, prefmask,
> - realloc_head ? 0 : additional_mem_size,
> - additional_mem_size, realloc_head);
> + prefmask, prefmask,
> + realloc_head ? 0 : additional_mmio_pref_size,
> + additional_mmio_pref_size, realloc_head);
>
> /*
> * If successful, all non-prefetchable resources
> @@ -1263,9 +1265,9 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> if (!type2) {
> prefmask &= ~IORESOURCE_MEM_64;
> ret = pbus_size_mem(bus, prefmask, prefmask,
> - prefmask, prefmask,
> - realloc_head ? 0 : additional_mem_size,
> - additional_mem_size, realloc_head);
> + prefmask, prefmask,
> + realloc_head ? 0 : additional_mmio_pref_size,
> + additional_mmio_pref_size, realloc_head);
>
> /*
> * If successful, only non-prefetchable resources
> @@ -1274,7 +1276,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> if (ret == 0)
> mask = prefmask;
> else
> - additional_mem_size += additional_mem_size;
> + additional_mmio_size +=
> + additional_mmio_pref_size;
>
> type2 = type3 = IORESOURCE_MEM;
> }
> @@ -1295,8 +1298,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
> * window.
> */
> pbus_size_mem(bus, mask, IORESOURCE_MEM, type2, type3,
> - realloc_head ? 0 : additional_mem_size,
> - additional_mem_size, realloc_head);
> + realloc_head ? 0 : additional_mmio_size,
> + additional_mmio_size, realloc_head);
> break;
> }
> }
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 77448215e..7ab8f5b88 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1964,7 +1964,8 @@ extern u8 pci_dfl_cache_line_size;
> extern u8 pci_cache_line_size;
>
> extern unsigned long pci_hotplug_io_size;
> -extern unsigned long pci_hotplug_mem_size;
> +extern unsigned long pci_hotplug_mmio_size;
> +extern unsigned long pci_hotplug_mmio_pref_size;
> extern unsigned long pci_hotplug_bus_size;
>
> /* Architecture-specific versions may override these (weak) */
> --
> 2.20.1
>

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