linux-kernel - [PATCH 4/4] PCI: only enable pci realloc when SRIOV bar is not assigned

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Date:	Thu, 23 Feb 2012 19:23:32 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Ram Pai <linuxram@...ibm.com>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 4/4] PCI: only enable pci realloc when SRIOV bar is not assigned

If bios does not assign those BAR or wrong address, then kernel will
try to do pci realloc.

in that case, user still can use pci=realloc=off to override it.

-v2: According to Jesse, adding one CONFIG option for distribution to
     disable it or enable it.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 drivers/pci/Kconfig     |   10 ++++++++++
 drivers/pci/setup-bus.c |   28 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 37856f7..771a037 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -31,6 +31,16 @@ config PCI_DEBUG
 
 	  When in doubt, say N.
 
+config PCI_REALLOC_ENABLE_AUTO
+	bool "PCI Realloc Enable Auto"
+	depends on PCI
+	help
+	  Say Y here if you want the PCI core to detect if pci realloc
+	  need to be enabled. You can always use pci=realloc=on or
+	  pci=realloc=off to override it.
+
+	  When in doubt, say N.
+
 config PCI_STUB
 	tristate "PCI Stub driver"
 	depends on PCI
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index e21e1c2..c9214a1 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1294,6 +1294,31 @@ static bool __init pci_realloc_enabled(void)
 	return pci_realloc_enable >= user_enabled;
 }
 
+static void __init pci_realloc_detect(void)
+{
+#if defined(CONFIG_PCI_IOV) && defined(CONFIG_PCI_REALLOC_ENABLE_AUTO)
+	struct pci_dev *dev = NULL;
+
+	if (pci_realloc_enable != undefined)
+		return;
+
+	for_each_pci_dev(dev) {
+		int i;
+
+		for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
+			struct resource *r = &dev->resource[i];
+
+			/* Not assigned, or rejected by kernel ? */
+			if (r->flags && !r->start) {
+				pci_realloc_enable = auto_enabled;
+
+				return;
+			}
+		}
+	}
+#endif
+}
+
 /*
  * first try will not touch pci bridge res
  * second  and later try will clear small leaf bridge res
@@ -1315,6 +1340,7 @@ pci_assign_unassigned_resources(void)
 	int pci_try_num = 1;
 
 	/* don't realloc if asked to do so */
+	pci_realloc_detect();
 	if (pci_realloc_enabled()) {
 		int max_depth = pci_get_max_depth();
 
@@ -1349,6 +1375,8 @@ again:
 	if (tried_times >= pci_try_num) {
 		if (pci_realloc_enable == undefined)
 			printk(KERN_INFO "Some PCI device resources are unassigned, try booting with pci=realloc\n");
+		else if (pci_realloc_enable == auto_enabled)
+			printk(KERN_INFO "Automatically enabled pci realloc, if you have problem, try booting with pci=realloc=off\n");
 
 		free_list(&fail_head);
 		goto enable_and_dump;
-- 
1.7.7

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