lkml.org 
[lkml]   [2010]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [RFC PATCH 1/1] PCI: override BIOS/firmware resource allocation
Date
On Wednesday, September 08, 2010 12:59:58 am Ram Pai wrote:
> PCI: override BIOS/firmware resource allocation through command line parameters
>
> git commit 977d17bb1749517b353874ccdc9b85abc7a58c2a
> released and reallocated all resources when allocation of any
> resource of any type, ioport and memory, failed. This caused
> failure to reallocate fragile io port resources, as reported in
> https://bugzilla.kernel.org/show_bug.cgi?id=15960
>
> The problem was solved by reverting the commit, through
> git commit 769d9968e42c995eaaf61ac5583d998f32e0769a.
>
> However reverting the original patch fails MMIO resource allocation
> for SRIOV PCI-Bars on some platforms. Especially on platforms
> where the BIOS is unaware of SRIOV resource BARs.
>
> The following code, an idea proposed by Linus, allows the user
> to tailor the resource allocation for devices through kernel
> command line parameter. Details of the idea can be found at
> http://marc.info/?l=linux-kernel&m=127846075028242&w=2

This changelog doesn't really tell me why we want this patch.
I see it has something to do with BARs of SR-IOV devices, but
otherwise, it's just low-level details about past history.

What specific problem are you solving? Does this patch enable
us to assign resources to a device that previously had none?
A concrete example might help.

> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index f084af0..eec068f 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1961,6 +1961,21 @@ and is between 256 and 4096 characters. It is defined in the file
> PAGE_SIZE is used as alignment.
> PCI-PCI bridge can be specified, if resource
> windows need to be expanded.
> + override=[off, conflict, always, <device>]
> + off : Do not override BIOS/firmware allocations. This is the
> + default
> + conflict : override BIOS/firmware allocations if conflicting
> + or not allocated.
> + always : override all BIOS/firmware allocations
> + <device>: Format [<domain>:]<bus>:<slot>.<func>[; ...]
> + override BIOS/firmware allocations of specified
> + devices
> +
> + clear=<device>
> + <device>: Format [<domain>:]<bus>:<slot>.<func>[; ...]
> + release BIOS/firmware allocations of specified
> + devices. By default no allocations are cleared.

I object in principle to new kernel parameters that users might need
to use just to get their box to work. How would a user know that he
might need this option? Isn't it possible for the kernel to figure
that out automatically?

Bjorn

> ecrc= Enable/disable PCIe ECRC (transaction layer
> end-to-end CRC checking).
> bios: Use BIOS/firmware settings. This is the
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7fa3cbd..5676416 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2984,6 +2984,85 @@ void __weak pci_fixup_cardbus(struct pci_bus *bus)
> }
> EXPORT_SYMBOL(pci_fixup_cardbus);
>
> +#define RESOURCE_RELEASE_PARAM_SIZE COMMAND_LINE_SIZE
> +static char __initdata resource_release_param[RESOURCE_RELEASE_PARAM_SIZE];
> +int pci_override=PCI_OVERRIDE_OFF;
> +
> +/*
> + * Return success if 'dev' is listed as one of the devices
> + * through the kernel command line
> + * pci=[override|clear]=device[;device]*
> + */
> +int __init is_pci_reset_device(struct pci_dev *dev)
> +{
> + int seg, bus, slot, func, count;
> + char *p;
> +
> + p = resource_release_param;
> + while (*p) {
> + count = 0;
> + if (sscanf(p, "%x:%x:%x.%x%n",
> + &seg, &bus, &slot, &func, &count) != 4) {
> + seg = 0;
> + if (sscanf(p, "%x:%x.%x%n",
> + &bus, &slot, &func, &count) != 3) {
> + /* Invalid format */
> + printk(KERN_ERR "PCI: Can't parse resource_alignment parameter: %s\n",
> + p);
> + return 0;
> + }
> + }
> + p += count;
> + if (seg == pci_domain_nr(dev->bus) &&
> + bus == dev->bus->number &&
> + slot == PCI_SLOT(dev->devfn) &&
> + func == PCI_FUNC(dev->devfn)) {
> + return 1;
> + }
> + if (*p != ';') {
> + /* End of param or invalid format */
> + return 0;
> + }
> + p++;
> + }
> + return 0;
> +}
> +
> +
> +static void __init pci_override_setup(const char *str, int override)
> +{
> + if (override && !strncmp(str, "off", 3)) {
> +
> + pci_override = PCI_OVERRIDE_OFF;
> + printk(KERN_INFO "pci: do not override "
> + "BIOS/uEFI allocations\n");
> +
> + } else if (override && !strncmp(str, "conflict", 8)) {
> +
> + pci_override = PCI_OVERRIDE_CONFLICT;
> + printk(KERN_INFO "pci: reallocate BIOS/uEFI "
> + "allocated resources on conflicts\n");
> +
> + } else if (override && !strncmp(str, "always", 6)) {
> +
> + pci_override = PCI_OVERRIDE_ALWAYS;
> + printk(KERN_INFO "pci: override all BIOS/uEFI allocations\n");
> +
> + } else {
> + int count=strlen(str);
> +
> + pci_override = override ? PCI_OVERRIDE_DEVICE :
> + PCI_CLEAR_DEVICE;
> + if (count > RESOURCE_RELEASE_PARAM_SIZE - 1)
> + count = RESOURCE_RELEASE_PARAM_SIZE - 1;
> + strncpy(resource_release_param, str, count);
> + resource_release_param[count] = '\0';
> + printk(KERN_INFO "pci: %s BIOS/uEFI allocations for %s\n",
> + override ? "override" : "clear", resource_release_param);
> + }
> + return;
> +}
> +
> static int __init pci_setup(char *str)
> {
> while (str) {
> @@ -3010,6 +3089,10 @@ static int __init pci_setup(char *str)
> pci_hotplug_io_size = memparse(str + 9, &str);
> } else if (!strncmp(str, "hpmemsize=", 10)) {
> pci_hotplug_mem_size = memparse(str + 10, &str);
> + } else if (!strncmp(str, "override=", 9)) {
> + pci_override_setup(str + 9, 1);
> + } else if (!strncmp(str, "clear=", 6)) {
> + pci_override_setup(str + 6, 0);
> } else {
> printk(KERN_ERR "PCI: Unknown option `%s'\n",
> str);
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 66cb8f4..e215ee9 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -838,21 +838,195 @@ static void pci_bus_dump_resources(struct pci_bus *bus)
> }
> }
>
> +static void __init
> +__pci_dev_reset_resource(struct pci_dev *dev,
> + struct resource_list_x *fail_head)
> +{
> + int idx, start, end;
> + struct resource *r;
> + u16 class = dev->class >> 8;
> +
> + if (class == PCI_CLASS_BRIDGE_PCI) {
> + start=PCI_BRIDGE_RESOURCES;
> + end=PCI_BRIDGE_RESOURCE_END+1;
> + } else {
> + start=0;
> + end=PCI_NUM_RESOURCES;
> + }
> +
> + for (idx = start; idx < end; idx++) {
> + r = &dev->resource[idx];
> +
> + if (r->flags & IORESOURCE_PCI_FIXED)
> + continue;
> +
> + if ( idx == PCI_ROM_RESOURCE ||
> + r->flags & IORESOURCE_ROM_ENABLE)
> + continue;
> +
> + if (fail_head)
> + add_to_failed_list(fail_head, dev, r);
> +
> + /* keep the old size */
> + r->end = 0;
> + r->start = 0;
> + r->flags = 0;
> + }
> +}
> +
> +/*
> + * reset the resource requirement of the device tree under 'dev'.
> + * Capture and add each resource's original requirement to the list 'head'
> + */
> +static void __init
> +pci_dev_reset_resource(struct pci_dev *dev,
> + struct resource_list_x *head)
> +{
> + u16 class = dev->class >> 8;
> +
> + /* Don't touch classless devices or host bridges or ioapics. */
> + if (class == PCI_CLASS_NOT_DEFINED || class == PCI_CLASS_BRIDGE_HOST)
> + return;
> +
> + /* Don't touch ioapic devices already enabled by firmware */
> + if (class == PCI_CLASS_SYSTEM_PIC) {
> + u16 command;
> + pci_read_config_word(dev, PCI_COMMAND, &command);
> + if (command & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
> + return;
> + }
> +
> + if (class == PCI_CLASS_BRIDGE_PCI) {
> + struct pci_bus *bus = dev->subordinate;
> + if (bus) {
> + struct pci_dev *dev1;
> + list_for_each_entry(dev1, &bus->devices, bus_list)
> + pci_dev_reset_resource(dev1, head);
> + }
> + }
> + __pci_dev_reset_resource(dev, head);
> + return;
> +}
> +
> +
> +/*
> + * Reset the resource requirement of all devices under 'bus' that
> + * specified by the kernel parameter 'pci=[override|clear]=<device>[;<device>]*'
> + * Capture and add each resource's original requirement to the
> + * list 'head'
> + */
> +static void __init
> +pci_bus_reset_resource(struct pci_bus *bus,
> + struct resource_list_x *head)
> +{
> + struct pci_bus *b;
> + struct pci_dev *dev;
> +
> + if (bus->self && (pci_override == PCI_OVERRIDE_ALWAYS ||
> + is_pci_reset_device(bus->self))) {
> + pci_dev_reset_resource(bus->self, head);
> + return;
> + }
> +
> + list_for_each_entry(dev, &bus->devices, bus_list) {
> + if (is_pci_reset_device(dev)) {
> + pci_dev_reset_resource(dev, head);
> + continue;
> + }
> + if ((b = dev->subordinate))
> + pci_bus_reset_resource(b, head);
> + }
> + return;
> +}
> +
> +/*
> + * Release all the resources in the list 'head'.
> + */
> +static void __init
> +pci_release_resources(struct resource_list_x *head)
> +{
> + struct resource_list_x *list;
> + unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
> + IORESOURCE_PREFETCH;
> + enum release_type rel_type = whole_subtree;
> + /*
> + * Try to release leaf bridge's resources that doesn't fit resource of
> + * child device under that bridge
> + */
> + for (list = head->next; list;) {
> + struct pci_bus *bus = list->dev->bus;
> + pci_bus_release_bridge_resources(bus, list->flags & type_mask,
> + rel_type);
> + list = list->next;
> + }
> + /* restore size and flags */
> + for (list = head->next; list;) {
> + struct resource *res = list->res;
> +
> + res->start = list->start;
> + res->end = list->end;
> + res->flags = list->flags;
> + if (list->dev->subordinate)
> + res->flags = 0;
> +
> + list = list->next;
> + }
> + free_failed_list(head);
> +}
> +
> +
> void __init
> pci_assign_unassigned_resources(void)
> {
> struct pci_bus *bus;
> + int tried_times = 0;
> + struct resource_list_x head;
> +
> + head.next = NULL;
>
> - /* Depth first, calculate sizes and alignments of all
> - subordinate buses. */
> list_for_each_entry(bus, &pci_root_buses, node) {
> - pci_bus_size_bridges(bus);
> + if (pci_override == PCI_OVERRIDE_DEVICE ||
> + pci_override == PCI_OVERRIDE_ALWAYS) {
> + pci_bus_reset_resource(bus, &head);
> + pci_release_resources(&head);
> + } else if (pci_override == PCI_CLEAR_DEVICE) {
> + pci_bus_reset_resource(bus, NULL);
> + }
> }
> - /* Depth last, allocate resources and update the hardware. */
> - list_for_each_entry(bus, &pci_root_buses, node) {
> - pci_bus_assign_resources(bus);
> +
> + do { /* loop at most 2 times */
> + /* Depth first, calculate sizes and alignments of all
> + subordinate buses. */
> + list_for_each_entry(bus, &pci_root_buses, node) {
> + pci_bus_size_bridges(bus);
> + }
> +
> + /* Depth last, allocate resources and update the hardware. */
> + list_for_each_entry(bus, &pci_root_buses, node) {
> + __pci_bus_assign_resources(bus, &head);
> + }
> +
> + /* happily exit the loop if all devices are happy */
> + if (!head.next)
> + goto enable_and_dump;
> +
> + /* dont' care if any device complained, unless asked to care */
> + if (pci_override != PCI_OVERRIDE_CONFLICT) {
> + free_failed_list(&head);
> + goto enable_and_dump;
> + }
> +
> + printk(KERN_INFO "PCI: No. %d try to assign unassigned res\n",
> + tried_times);
> +
> + pci_release_resources(&head);
> +
> + } while (!tried_times++);
> +
> +enable_and_dump:
> + /* Depth last, update the hardware. */
> + list_for_each_entry(bus, &pci_root_buses, node)
> pci_enable_bridges(bus);
> - }
>
> /* dump the resource on buses */
> list_for_each_entry(bus, &pci_root_buses, node) {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index b1d1795..c001005 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1357,10 +1357,18 @@ extern u8 pci_cache_line_size;
> extern unsigned long pci_hotplug_io_size;
> extern unsigned long pci_hotplug_mem_size;
>
> +extern int pci_override;
> +#define PCI_OVERRIDE_OFF 1
> +#define PCI_OVERRIDE_CONFLICT 2
> +#define PCI_OVERRIDE_ALWAYS 3
> +#define PCI_OVERRIDE_DEVICE 4
> +#define PCI_CLEAR_DEVICE 5
> +
> int pcibios_add_platform_entries(struct pci_dev *dev);
> void pcibios_disable_device(struct pci_dev *dev);
> int pcibios_set_pcie_reset_state(struct pci_dev *dev,
> enum pcie_reset_state state);
> +int is_pci_reset_device(struct pci_dev *dev);
>
> #ifdef CONFIG_PCI_MMCONFIG
> extern void __init pci_mmcfg_early_init(void);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>


\
 
 \ /
  Last update: 2010-09-08 22:39    [from the cache]
©2003-2011 Jasper Spaans