[linux] 04/05: [x86] xen: Fix APIC id mismatch warning on Intel (Closes: #853193)

[debian-kernel at lists.debian.org]

This is an automated email from the git hooks/post-receive script.

benh pushed a commit to branch sid
in repository linux.

commit 4e1df53c240ddbf17d7c5378ad8c5994d4763b68
Author: Ben Hutchings <ben at decadent.org.uk>
Date:   Fri Feb 17 02:42:17 2017 +0000

    [x86] xen: Fix APIC id mismatch warning on Intel (Closes: #853193)
---
 debian/changelog                                   |  1 +
 ...xen-fix-apic-id-mismatch-warning-on-intel.patch | 57 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 59 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index bde2abb..c20b2f0 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -257,6 +257,7 @@ linux (4.9.10-1) UNRELEASED; urgency=medium
   * udeb: Add bcache to md-modules (Closes: #718548)
   * [x86] platform: acer-wmi: setup accelerometer when machine has appropriate
     notify event (Closes: #853067)
+  * [x86] xen: Fix APIC id mismatch warning on Intel (Closes: #853193)
 
   [ Roger Shimizu ]
   * [armel] ARM: dts: orion5x-lschl: Fix model name
diff --git a/debian/patches/bugfix/x86/x86-xen-fix-apic-id-mismatch-warning-on-intel.patch b/debian/patches/bugfix/x86/x86-xen-fix-apic-id-mismatch-warning-on-intel.patch
new file mode 100644
index 0000000..93830d1
--- /dev/null
+++ b/debian/patches/bugfix/x86/x86-xen-fix-apic-id-mismatch-warning-on-intel.patch
@@ -0,0 +1,57 @@
+From: Mohit Gambhir <mohit.gambhir at oracle.com>
+Date: Thu, 26 Jan 2017 13:12:27 -0500
+Subject: x86/xen: Fix APIC id mismatch warning on Intel
+Origin: https://git.kernel.org/linus/cc272163ea554a97dac180fa8dd6cd54c2810bd1
+Bug-Debian: https://bugs.debian.org/853193
+
+This patch fixes the following warning message seen when booting the
+kernel as Dom0 with Xen on Intel machines.
+
+[0.003000] [Firmware Bug]: CPU1: APIC id mismatch. Firmware: 0 APIC: 1]
+
+The code generating the warning in validate_apic_and_package_id() matches
+cpu_data(cpu).apicid (initialized in init_intel()->
+detect_extended_topology() using cpuid) against the apicid returned from
+xen_apic_read(). Now, xen_apic_read() makes a hypercall to retrieve apicid
+for the boot  cpu but returns 0 otherwise. Hence the warning gets thrown
+for all but the boot cpu.
+
+The idea behind xen_apic_read() returning 0 for apicid is that the
+guests (even Dom0) should not need to know what physical processor their
+vcpus are running on. This is because we currently  do not have topology
+information in Xen and also because xen allows more vcpus than physical
+processors. However, boot cpu's apicid is required for loading
+xen-acpi-processor driver on AMD machines. Look at following patch for
+details:
+
+commit 558daa289a40 ("xen/apic: Return the APIC ID (and version) for CPU
+0.")
+
+So to get rid of the warning, this patch modifies
+xen_cpu_present_to_apicid() to return cpu_data(cpu).apicid instead of
+calling xen_apic_read().
+
+The warning is not seen on AMD machines because init_amd() populates
+cpu_data(cpu).apicid by calling hard_smp_processor_id()->xen_apic_read()
+as opposed to using apicid from cpuid as is done on Intel machines.
+
+Signed-off-by: Mohit Gambhir <mohit.gambhir at oracle.com>
+Reviewed-by: Juergen Gross <jgross at suse.com>
+Signed-off-by: Boris Ostrovsky <boris.ostrovsky at oracle.com>
+---
+ arch/x86/xen/apic.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
+index 44c88ad1841a..bcea81f36fc5 100644
+--- a/arch/x86/xen/apic.c
++++ b/arch/x86/xen/apic.c
+@@ -145,7 +145,7 @@ static void xen_silent_inquire(int apicid)
+ static int xen_cpu_present_to_apicid(int cpu)
+ {
+ 	if (cpu_present(cpu))
+-		return xen_get_apic_id(xen_apic_read(APIC_ID));
++		return cpu_data(cpu).apicid;
+ 	else
+ 		return BAD_APICID;
+ }
diff --git a/debian/patches/series b/debian/patches/series
index 4afea7e..be8372c 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -49,6 +49,7 @@ debian/fanotify-taint-on-use-of-fanotify_access_permissions.patch
 # Arch bug fixes
 bugfix/x86/asoc-intel-select-dw_dmac_core-since-it-s-mandatory.patch
 bugfix/x86/platform-x86-acer-wmi-setup-accelerometer-when-machi.patch
+bugfix/x86/x86-xen-fix-apic-id-mismatch-warning-on-intel.patch
 
 # Arch features
 features/mips/MIPS-increase-MAX-PHYSMEM-BITS-on-Loongson-3-only.patch

-- 
Alioth's /usr/local/bin/git-commit-notice on /srv/git.debian.org/git/kernel/linux.git