Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu

[Neil Horman <nhorman@tuxdriver.com>]

Recently a kdump bug was discovered in which a system would hang inside
calibrate_delay during the booting of the kdump kernel.  This was caused by the
fact that the jiffies counter was not being incremented during timer
calibration.  The root cause of this problem was found to be a bios
misconfiguration of the hypertransport bus.  On system affected by this hang,
the bios had assigned APIC ids which used extended apic bits (more than the
nominal 4 bit ids's), but failed to configure bit 17 of the hypertransport
transaction config register, which indicated that the mask for the destination
field of interrupt packets accross the ht bus (see section 3.3.9 of
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26094.PDF).
If a crash occurs on a cpu with an APIC id that extends beyond 4 bits, it will
not recieve interrupts during the kdump kernel boot, and this hang will be the
result.  The fix is to add this patch, whcih add an early pci quirk check, to
forcibly enable this bit in the httcfg register.  This enables all cpus on a
system to receive interrupts, and allows kdump kernel bootup to procede
normally.

Regards
Neil


Signed-off-by: Neil Horman <nhorman@tuxdriver.com>


 early-quirks.c |   90 +++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 69 insertions(+), 21 deletions(-)


diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 88bb83e..c0d0c69 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -21,8 +21,36 @@
 #include <asm/gart.h>
 #endif
 
-static void __init via_bugs(void)
+static void __init fix_hypertransport_config(int num, int slot, int func)
 {
+	u32 htcfg;
+	/*
+	 *we found a hypertransport bus
+	 *make sure that are broadcasting
+	 *interrupts to all cpus on the ht bus
+	 *if we're using extended apic ids
+	 */
+	htcfg = read_pci_config(num, slot, func, 0x68);
+	if (htcfg & (1 << 18)) {	
+		printk(KERN_INFO "Detected use of extended apic ids on hypertransport bus\n");
+		if ((htcfg & (1 << 17)) == 0) {
+			printk(KERN_INFO "Enabling hypertransport extended apic interrupt broadcast\n");
+			printk(KERN_INFO "Note this is a bios bug, please contact your hw vendor\n");
+			htcfg |= (1 << 17);
+			write_pci_config(num, slot, func, 0x68, htcfg);
+		}
+	}
+
+	
+}
+
+static void __init via_bugs(int  num, int slot, int func)
+{
+	static int fix_applied = 0;
+
+	if (fix_applied++)
+		return;
+
 #ifdef CONFIG_GART_IOMMU
 	if ((end_pfn > MAX_DMA32_PFN ||  force_iommu) &&
 	    !gart_iommu_aperture_allowed) {
@@ -44,8 +72,13 @@ static int __init nvidia_hpet_check(struct acpi_table_header *header)
 #endif /* CONFIG_X86_IO_APIC */
 #endif /* CONFIG_ACPI */
 
-static void __init nvidia_bugs(void)
+static void __init nvidia_bugs(int num, int slot, int func)
 {
+	static int fix_applied = 0;
+
+	if (fix_applied++)
+		return;
+
 #ifdef CONFIG_ACPI
 #ifdef CONFIG_X86_IO_APIC
 	/*
@@ -72,8 +105,13 @@ static void __init nvidia_bugs(void)
 
 }
 
-static void __init ati_bugs(void)
+static void __init ati_bugs(int num, int slot, int func)
 {
+	static int fix_applied = 0;
+
+	if (fix_applied++)
+		return;
+
 #ifdef CONFIG_X86_IO_APIC
 	if (timer_over_8254 == 1) {
 		timer_over_8254 = 0;
@@ -84,14 +122,18 @@ static void __init ati_bugs(void)
 }
 
 struct chipset {
-	u16 vendor;
-	void (*f)(void);
+	u32 vendor;
+	u32 device;
+	u32 class;
+	u32 class_mask;
+	void (*f)(int num, int slot, int func);
 };
 
 static struct chipset early_qrk[] __initdata = {
-	{ PCI_VENDOR_ID_NVIDIA, nvidia_bugs },
-	{ PCI_VENDOR_ID_VIA, via_bugs },
-	{ PCI_VENDOR_ID_ATI, ati_bugs },
+	{ PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, nvidia_bugs },
+	{ PCI_VENDOR_ID_VIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, via_bugs },
+	{ PCI_VENDOR_ID_ATI, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, ati_bugs },
+	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB, PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, fix_hypertransport_config },
 	{}
 };
 
@@ -106,27 +148,33 @@ void __init early_quirks(void)
 	for (num = 0; num < 32; num++) {
 		for (slot = 0; slot < 32; slot++) {
 			for (func = 0; func < 8; func++) {
-				u32 class;
-				u32 vendor;
+				u16 class;
+				u16 vendor;
+				u16 device;
 				u8 type;
 				int i;
-				class = read_pci_config(num,slot,func,
+
+				class = read_pci_config_16(num,slot,func,
 							PCI_CLASS_REVISION);
-				if (class == 0xffffffff)
+				if (class == 0xffff)
 					break;
 
-				if ((class >> 16) != PCI_CLASS_BRIDGE_PCI)
-					continue;
-
-				vendor = read_pci_config(num, slot, func,
+				vendor = read_pci_config_16(num, slot, func,
 							 PCI_VENDOR_ID);
-				vendor &= 0xffff;
 
-				for (i = 0; early_qrk[i].f; i++)
-					if (early_qrk[i].vendor == vendor) {
-						early_qrk[i].f();
-						return;
+				device = read_pci_config_16(num, slot, func,
+							PCI_DEVICE_ID);
+
+				for(i=0;early_qrk[i].f != NULL;i++) {
+					if (((early_qrk[i].vendor == PCI_ANY_ID) ||
+					    (early_qrk[i].vendor == vendor)) &&
+					   ((early_qrk[i].device == PCI_ANY_ID) ||
+					    (early_qrk[i].device == device)) &&
+					   (!((early_qrk[i].class ^ class) & 
+					     early_qrk[i].class_mask))) {
+						early_qrk[i].f(num, slot, func);
 					}
+				}
 
 				type = read_pci_config_byte(num, slot, func,
 							    PCI_HEADER_TYPE);