[PATCH v6 4/4] PCI: Add pci=hpmemprefsize parameter to set MMIO_PREF size independently

Nicholas Johnson
2019-05-22T14:31:30Z

Add kernel parameter pci=hpmemprefsize=nn[KMG] to control MMIO_PREF size
for PCI hotplug bridges.

Change behaviour of pci=hpmemsize=nn[KMG] to not set MMIO_PREF size if
hpmempref has been specified, rather than controlling both MMIO and
MMIO_PREF sizes unconditionally.

Update kernel-parameters documentation to reflect the above changes.

The effect of the above changes is to allow for MMIO and MMIO_PREF to be
specified independently, whilst ensuring no changes in functionality are
noticed by the user if updating kernel version with hpmemsize specified.

Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
---
.../admin-guide/kernel-parameters.txt | 7 +++++-
drivers/pci/pci.c | 18 ++++++++++---
drivers/pci/setup-bus.c | 25 +++++++++++--------
include/linux/pci.h | 3 ++-
4 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 138f6664b..fdecff06c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3439,7 +3439,12 @@
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. If
+ hpmemprefsize is not specified, then the same
+ size is applied to hotplug bridge's MMIO_PREF
+ 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 8abc843b1..0e6292009 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;
@@ -6198,6 +6200,8 @@ EXPORT_SYMBOL(pci_fixup_cardbus);

static int __init pci_setup(char *str)
{
+ bool mmio_pref_specified = false;
+
while (str) {
char *k = strchr(str, ',');
if (k)
@@ -6232,7 +6236,15 @@ 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);
+ if (!mmio_pref_specified)
+ pci_hotplug_mmio_pref_size =
+ pci_hotplug_mmio_size;
+ } else if (!strncmp(str, "hpmemprefsize=", 14)) {
+ mmio_pref_specified = true;
+ 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 8e1bc7ee7..44c37dda9 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;
}
@@ -1294,8 +1297,8 @@ void __pci_bus_size_bridges(struct pci_bus *bus, struct list_head *realloc_head)
* prefetchable resource in a 64-bit prefetchable 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 4a5a84d7b..7015f0b0f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1972,7 +1972,8 @@ 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