58 lines
2.3 KiB
Diff
58 lines
2.3 KiB
Diff
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From: Mohit Gambhir <mohit.gambhir@oracle.com>
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Date: Thu, 26 Jan 2017 13:12:27 -0500
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Subject: x86/xen: Fix APIC id mismatch warning on Intel
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Origin: https://git.kernel.org/linus/cc272163ea554a97dac180fa8dd6cd54c2810bd1
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Bug-Debian: https://bugs.debian.org/853193
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This patch fixes the following warning message seen when booting the
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kernel as Dom0 with Xen on Intel machines.
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[0.003000] [Firmware Bug]: CPU1: APIC id mismatch. Firmware: 0 APIC: 1]
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The code generating the warning in validate_apic_and_package_id() matches
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cpu_data(cpu).apicid (initialized in init_intel()->
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detect_extended_topology() using cpuid) against the apicid returned from
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xen_apic_read(). Now, xen_apic_read() makes a hypercall to retrieve apicid
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for the boot cpu but returns 0 otherwise. Hence the warning gets thrown
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for all but the boot cpu.
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The idea behind xen_apic_read() returning 0 for apicid is that the
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guests (even Dom0) should not need to know what physical processor their
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vcpus are running on. This is because we currently do not have topology
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information in Xen and also because xen allows more vcpus than physical
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processors. However, boot cpu's apicid is required for loading
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xen-acpi-processor driver on AMD machines. Look at following patch for
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details:
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commit 558daa289a40 ("xen/apic: Return the APIC ID (and version) for CPU
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0.")
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So to get rid of the warning, this patch modifies
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xen_cpu_present_to_apicid() to return cpu_data(cpu).apicid instead of
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calling xen_apic_read().
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The warning is not seen on AMD machines because init_amd() populates
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cpu_data(cpu).apicid by calling hard_smp_processor_id()->xen_apic_read()
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as opposed to using apicid from cpuid as is done on Intel machines.
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Signed-off-by: Mohit Gambhir <mohit.gambhir@oracle.com>
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Reviewed-by: Juergen Gross <jgross@suse.com>
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Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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---
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arch/x86/xen/apic.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
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index 44c88ad1841a..bcea81f36fc5 100644
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--- a/arch/x86/xen/apic.c
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+++ b/arch/x86/xen/apic.c
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@@ -145,7 +145,7 @@ static void xen_silent_inquire(int apicid)
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static int xen_cpu_present_to_apicid(int cpu)
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{
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if (cpu_present(cpu))
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- return xen_get_apic_id(xen_apic_read(APIC_ID));
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+ return cpu_data(cpu).apicid;
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else
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return BAD_APICID;
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}
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