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centosplus kernel patch [bug#12818]
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From ac68351410df683a149e7eea09df178884cf2419 Mon Sep 17 00:00:00 2001
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From: Marcus Sundberg <marcus.sundberg@aptilo.com>
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Date: Mon, 13 Feb 2017 22:57:11 +0100
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Subject: [PATCH] [x86] perf: uncore: Avoid kernel panic on missing topology
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The uncore code is heavily dependent on the CPU topology mapping code,
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so if we do not even have a working topology for the boot CPU we just
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give up.
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This happens for example on HPE DL360 Gen9 servers with x2APIC enabled
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in the firmware settings, where the kernel only finds a single core.
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---
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 arch/x86/events/intel/uncore.c | 14 ++++++++++++++
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 1 file changed, 14 insertions(+)
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diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
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index 77ec6c0..88d79f6 100644
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--- a/arch/x86/events/intel/uncore.c
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+++ b/arch/x86/events/intel/uncore.c
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@@ -1394,6 +1394,20 @@ static int __init intel_uncore_init(void)
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 	if (is_kdump_kernel())
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 		return -ENODEV;
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+	/* Sanity check - do not even try to proceed if we have no
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+	   working topology mapping for the boot CPU. */
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+	if (rh_boot_cpu_data.logical_proc_id < 0 ||
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+	    topology_phys_to_logical_pkg(boot_cpu_data.phys_proc_id) < 0) {
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+		printk(KERN_ERR
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+		       "no mapping between physical and logical CPU, "
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+		       "boot CPU phys: %d, logical: %d/%d\n",
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+		       (int)boot_cpu_data.phys_proc_id,
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+		       (int)rh_boot_cpu_data.logical_proc_id,
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+		       (int)topology_phys_to_logical_pkg(
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+			       boot_cpu_data.phys_proc_id));
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+		return -ENODEV;
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+	}
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+
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 	max_packages = topology_max_packages();
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 	pret = uncore_pci_init();
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-- 
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2.5.0
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