Re: SNB PCI root information

[Yinghai Lu <yinghai@kernel.org>]

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On Wed, Jun 20, 2012 at 7:37 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Wed, Jun 20, 2012 at 12:34 PM, Ingo Molnar <mingo@kernel.org> wrote:
>>> if the vendor provide _PXM, that _PXM should be right and be
>>> trusted.
>>>
>>> if the vendor does not provide _PXM, we can have command line
>>> to input it before user can get one updated BIOS from vendor.
>>
>> So how about an incorrect _PXM, or a slightly inefficient one?
>> Why shouldn't it be possible for the user to override it?
>
> Try to keep the code simple.
>
>>
>> I mean, if we create a parameter space that tweaks data then why
>> not make it complete and allow *all* firmware data to be
>> (optionally) modified, from the kernel boot line?
>
> that pxm/node for pci device should be consistent with srat table etc,
> so better solution is that BIOS keep them consistent.
>
> If BIOS provide _PXM for pci device, the _PXM should have more chance
> to be right.
>
> Anyway if you insist that it should cover that wrong case, let me
> check if it could be done simply.

please check -v3, and it will add 40 lines.

and -v2 is about 25 lines.

Thanks

Yinghai

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Subject: [PATCH] PCI, X86: busnum/node boot command line for pci dev node setting.

Some intel new sandybridge or newer two sockets system do support support numa
for pci devices. But BIOS does not provide _PXM under those root bus in DSDT.

Add boot command line, so user could have chance to input node info before
BIOS guys figure out to add _PXM.

Fold fix from Ulrich to use ";" instead of ",".
| The problem is the pci= parameter
| handling uses ',' to separate parameters and therefore the second PCI
| root information, separated by a comma, is interpreted as a new pci=
| parameter.

-v3: According to Bjorn and Ingo, change to use "user input first" policy
     so it could cover wrong _PXM case.

Reported-by: Ulrich Drepper <drepper@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 Documentation/kernel-parameters.txt |    5 +++++
 arch/x86/include/asm/pci_x86.h      |    3 +++
 arch/x86/pci/acpi.c                 |   22 +++++++++++++---------
 arch/x86/pci/common.c               |   28 ++++++++++++++++++++++++++++
 4 files changed, 49 insertions(+), 9 deletions(-)

Index: linux-2.6/Documentation/kernel-parameters.txt
===================================================================
--- linux-2.6.orig/Documentation/kernel-parameters.txt
+++ linux-2.6/Documentation/kernel-parameters.txt
@@ -2195,6 +2195,11 @@ bytes respectively. Such letter suffixes
 				only look for one device below a PCIe downstream
 				port.
 
+	busnum_node=    [X86] Set node for root bus.
+			Format:
+			<bus>:<node>[; ...]
+			Specifies node for bus, will override bios _PXM
+			or probed value from hostbridge.
 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
 			Management.
 		off	Disable ASPM.
Index: linux-2.6/arch/x86/pci/common.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/common.c
+++ linux-2.6/arch/x86/pci/common.c
@@ -494,6 +494,34 @@ int __init pcibios_init(void)
 	return 0;
 }
 
+int get_user_busnum_node(int busnum)
+{
+	int bus, node, count;
+	char *p;
+
+	p = strstr(boot_command_line, "busnum_node=");
+	if (!p)
+		return -1;
+
+	p += 12; /* strlen("busnum_node=") */
+	while (*p) {
+		count = 0;
+		if (sscanf(p, "%x:%x%n", &bus, &node, &count) != 2) {
+			printk(KERN_ERR "PCI: Can't parse busnum_node input: %s\n",
+					p);
+			break;
+		}
+		if (bus == busnum)
+			return node;
+		p += count;
+		if (*p != ';')
+			break;
+		p++;
+	}
+
+	return -1;
+}
+
 char * __devinit  pcibios_setup(char *str)
 {
 	if (!strcmp(str, "off")) {
Index: linux-2.6/arch/x86/include/asm/pci_x86.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/pci_x86.h
+++ linux-2.6/arch/x86/include/asm/pci_x86.h
@@ -46,6 +46,9 @@ enum pci_bf_sort_state {
 	pci_dmi_bf,
 };
 
+/* pci-common.c */
+int get_user_busnum_node(int busnum);
+
 /* pci-i386.c */
 
 void pcibios_resource_survey(void);
Index: linux-2.6/arch/x86/pci/acpi.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/acpi.c
+++ linux-2.6/arch/x86/pci/acpi.c
@@ -433,7 +433,7 @@ struct pci_bus * __devinit pci_acpi_scan
 	struct pci_sysdata *sd;
 	int node;
 #ifdef CONFIG_ACPI_NUMA
-	int pxm;
+	int pxm = -1;
 #endif
 
 	if (domain && !pci_domains_supported) {
@@ -443,16 +443,20 @@ struct pci_bus * __devinit pci_acpi_scan
 		return NULL;
 	}
 
-	node = -1;
+	node = get_user_busnum_node(busnum);
+	if (node == -1) {
 #ifdef CONFIG_ACPI_NUMA
-	pxm = acpi_get_pxm(device->handle);
-	if (pxm >= 0)
-		node = pxm_to_node(pxm);
-	if (node != -1)
-		set_mp_bus_to_node(busnum, node);
-	else
-#endif
+		pxm = acpi_get_pxm(device->handle);
+		if (pxm >= 0)
+			node = pxm_to_node(pxm);
+		if (node != -1)
+			set_mp_bus_to_node(busnum, node);
+		else
+			node = get_mp_bus_to_node(busnum);
+#else
 		node = get_mp_bus_to_node(busnum);
+#endif
+	}
 
 	if (node != -1 && !node_online(node))
 		node = -1;