<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/arch/x86/include, branch v3.14.4</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>x86, AVX-512: Enable AVX-512 States Context Switch</title>
<updated>2014-05-06T14:59:26+00:00</updated>
<author>
<name>Fenghua Yu</name>
<email>fenghua.yu@intel.com</email>
</author>
<published>2014-02-20T21:24:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5bc3ab30db9b6deee6a686596d13e0c20a52d13b'/>
<id>5bc3ab30db9b6deee6a686596d13e0c20a52d13b</id>
<content type='text'>
commit c2bc11f10a39527cd1bb252097b5525664560956 upstream.

This patch enables Opmask, ZMM_Hi256, and Hi16_ZMM AVX-512 states for
xstate context switch.

Signed-off-by: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Link: http://lkml.kernel.org/r/1392931491-33237-2-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c2bc11f10a39527cd1bb252097b5525664560956 upstream.

This patch enables Opmask, ZMM_Hi256, and Hi16_ZMM AVX-512 states for
xstate context switch.

Signed-off-by: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Link: http://lkml.kernel.org/r/1392931491-33237-2-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>x86, AVX-512: AVX-512 Feature Detection</title>
<updated>2014-05-06T14:59:26+00:00</updated>
<author>
<name>Fenghua Yu</name>
<email>fenghua.yu@intel.com</email>
</author>
<published>2014-02-20T21:24:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=05f4be82046529c44f01b42d905e57d1b2df4920'/>
<id>05f4be82046529c44f01b42d905e57d1b2df4920</id>
<content type='text'>
commit 8e5780fdeef7dc490b3f0b3a62704593721fa4f3 upstream.

AVX-512 is an extention of AVX2. Its spec can be found at:
http://download-software.intel.com/sites/default/files/managed/71/2e/319433-017.pdf

This patch detects AVX-512 features by CPUID.

Signed-off-by: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Link: http://lkml.kernel.org/r/1392931491-33237-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8e5780fdeef7dc490b3f0b3a62704593721fa4f3 upstream.

AVX-512 is an extention of AVX2. Its spec can be found at:
http://download-software.intel.com/sites/default/files/managed/71/2e/319433-017.pdf

This patch detects AVX-512 features by CPUID.

Signed-off-by: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Link: http://lkml.kernel.org/r/1392931491-33237-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>x86/efi: Make efi virtual runtime map passing more robust</title>
<updated>2014-04-14T13:50:02+00:00</updated>
<author>
<name>Borislav Petkov</name>
<email>bp@suse.de</email>
</author>
<published>2014-01-18T11:48:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=579d8f085b5745ea443a7e79b8283178f28981e0'/>
<id>579d8f085b5745ea443a7e79b8283178f28981e0</id>
<content type='text'>
commit b7b898ae0c0a82489511a1ce1b35f26215e6beb5 upstream.

Currently, running SetVirtualAddressMap() and passing the physical
address of the virtual map array was working only by a lucky coincidence
because the memory was present in the EFI page table too. Until Toshi
went and booted this on a big HP box - the krealloc() manner of resizing
the memmap we're doing did allocate from such physical addresses which
were not mapped anymore and boom:

http://lkml.kernel.org/r/1386806463.1791.295.camel@misato.fc.hp.com

One way to take care of that issue is to reimplement the krealloc thing
but with pages. We start with contiguous pages of order 1, i.e. 2 pages,
and when we deplete that memory (shouldn't happen all that often but you
know firmware) we realloc the next power-of-two pages.

Having the pages, it is much more handy and easy to map them into the
EFI page table with the already existing mapping code which we're using
for building the virtual mappings.

Thanks to Toshi Kani and Matt for the great debugging help.

Reported-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Tested-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b7b898ae0c0a82489511a1ce1b35f26215e6beb5 upstream.

Currently, running SetVirtualAddressMap() and passing the physical
address of the virtual map array was working only by a lucky coincidence
because the memory was present in the EFI page table too. Until Toshi
went and booted this on a big HP box - the krealloc() manner of resizing
the memmap we're doing did allocate from such physical addresses which
were not mapped anymore and boom:

http://lkml.kernel.org/r/1386806463.1791.295.camel@misato.fc.hp.com

One way to take care of that issue is to reimplement the krealloc thing
but with pages. We start with contiguous pages of order 1, i.e. 2 pages,
and when we deplete that memory (shouldn't happen all that often but you
know firmware) we realloc the next power-of-two pages.

Having the pages, it is much more handy and easy to map them into the
EFI page table with the already existing mapping code which we're using
for building the virtual mappings.

Thanks to Toshi Kani and Matt for the great debugging help.

Reported-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Tested-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, pageattr: Export page unmapping interface</title>
<updated>2014-04-14T13:50:02+00:00</updated>
<author>
<name>Borislav Petkov</name>
<email>bp@suse.de</email>
</author>
<published>2014-01-18T11:48:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6f48949f01c41782a3215a8fbff0997c5199d2c1'/>
<id>6f48949f01c41782a3215a8fbff0997c5199d2c1</id>
<content type='text'>
commit 42a5477251f0e0f33ad5f6a95c48d685ec03191e upstream.

We will use it in efi so expose it.

Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Tested-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 42a5477251f0e0f33ad5f6a95c48d685ec03191e upstream.

We will use it in efi so expose it.

Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Tested-by: Toshi Kani &lt;toshi.kani@hp.com&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>x86: fix boot on uniprocessor systems</title>
<updated>2014-03-28T20:56:58+00:00</updated>
<author>
<name>Artem Fetishev</name>
<email>artem_fetishev@epam.com</email>
</author>
<published>2014-03-28T20:33:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=825600c0f20e595daaa7a6dd8970f84fa2a2ee57'/>
<id>825600c0f20e595daaa7a6dd8970f84fa2a2ee57</id>
<content type='text'>
On x86 uniprocessor systems topology_physical_package_id() returns -1
which causes rapl_cpu_prepare() to leave rapl_pmu variable uninitialized
which leads to GPF in rapl_pmu_init().

See arch/x86/kernel/cpu/perf_event_intel_rapl.c.

It turns out that physical_package_id and core_id can actually be
retreived for uniprocessor systems too.  Enabling them also fixes
rapl_pmu code.

Signed-off-by: Artem Fetishev &lt;artem_fetishev@epam.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On x86 uniprocessor systems topology_physical_package_id() returns -1
which causes rapl_cpu_prepare() to leave rapl_pmu variable uninitialized
which leads to GPF in rapl_pmu_init().

See arch/x86/kernel/cpu/perf_event_intel_rapl.c.

It turns out that physical_package_id and core_id can actually be
retreived for uniprocessor systems too.  Enabling them also fixes
rapl_pmu code.

Signed-off-by: Artem Fetishev &lt;artem_fetishev@epam.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "xen: properly account for _PAGE_NUMA during xen pte translations"</title>
<updated>2014-03-25T11:11:42+00:00</updated>
<author>
<name>David Vrabel</name>
<email>david.vrabel@citrix.com</email>
</author>
<published>2014-03-25T10:38:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5926f87fdaad4be3ed10cec563bf357915e55a86'/>
<id>5926f87fdaad4be3ed10cec563bf357915e55a86</id>
<content type='text'>
This reverts commit a9c8e4beeeb64c22b84c803747487857fe424b68.

PTEs in Xen PV guests must contain machine addresses if _PAGE_PRESENT
is set and pseudo-physical addresses is _PAGE_PRESENT is clear.

This is because during a domain save/restore (migration) the page
table entries are "canonicalised" and uncanonicalised". i.e., MFNs are
converted to PFNs during domain save so that on a restore the page
table entries may be rewritten with the new MFNs on the destination.
This canonicalisation is only done for PTEs that are present.

This change resulted in writing PTEs with MFNs if _PAGE_PROTNONE (or
_PAGE_NUMA) was set but _PAGE_PRESENT was clear.  These PTEs would be
migrated as-is which would result in unexpected behaviour in the
destination domain.  Either a) the MFN would be translated to the
wrong PFN/page; b) setting the _PAGE_PRESENT bit would clear the PTE
because the MFN is no longer owned by the domain; or c) the present
bit would not get set.

Symptoms include "Bad page" reports when munmapping after migrating a
domain.

Signed-off-by: David Vrabel &lt;david.vrabel@citrix.com&gt;
Acked-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;        [3.12+]
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit a9c8e4beeeb64c22b84c803747487857fe424b68.

PTEs in Xen PV guests must contain machine addresses if _PAGE_PRESENT
is set and pseudo-physical addresses is _PAGE_PRESENT is clear.

This is because during a domain save/restore (migration) the page
table entries are "canonicalised" and uncanonicalised". i.e., MFNs are
converted to PFNs during domain save so that on a restore the page
table entries may be rewritten with the new MFNs on the destination.
This canonicalisation is only done for PTEs that are present.

This change resulted in writing PTEs with MFNs if _PAGE_PROTNONE (or
_PAGE_NUMA) was set but _PAGE_PRESENT was clear.  These PTEs would be
migrated as-is which would result in unexpected behaviour in the
destination domain.  Either a) the MFN would be translated to the
wrong PFN/page; b) setting the _PAGE_PRESENT bit would clear the PTE
because the MFN is no longer owned by the domain; or c) the present
bit would not get set.

Symptoms include "Bad page" reports when munmapping after migrating a
domain.

Signed-off-by: David Vrabel &lt;david.vrabel@citrix.com&gt;
Acked-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;        [3.12+]
</pre>
</div>
</content>
</entry>
<entry>
<title>x86: Remove CONFIG_X86_OOSTORE</title>
<updated>2014-03-11T17:16:18+00:00</updated>
<author>
<name>Dave Jones</name>
<email>davej@redhat.com</email>
</author>
<published>2014-03-10T23:32:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=09df7c4c8097ca4a11393b1edd4997d786daad52'/>
<id>09df7c4c8097ca4a11393b1edd4997d786daad52</id>
<content type='text'>
This was an optimization that made memcpy type benchmarks a little
faster on ancient (Circa 1998) IDT Winchip CPUs.  In real-life
workloads, it wasn't even noticable, and I doubt anyone is running
benchmarks on 16 year old silicon any more.

Given this code has likely seen very little use over the last decade,
let's just remove it.

Signed-off-by: Dave Jones &lt;davej@fedoraproject.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was an optimization that made memcpy type benchmarks a little
faster on ancient (Circa 1998) IDT Winchip CPUs.  In real-life
workloads, it wasn't even noticable, and I doubt anyone is running
benchmarks on 16 year old silicon any more.

Given this code has likely seen very little use over the last decade,
let's just remove it.

Signed-off-by: Dave Jones &lt;davej@fedoraproject.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'efi-urgent' into x86/urgent</title>
<updated>2014-03-04T23:50:06+00:00</updated>
<author>
<name>H. Peter Anvin</name>
<email>hpa@linux.intel.com</email>
</author>
<published>2014-03-04T23:49:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3c0b566334c9942c89927bd1b5ad2f32baab81fa'/>
<id>3c0b566334c9942c89927bd1b5ad2f32baab81fa</id>
<content type='text'>
 * Disable the new EFI 1:1 virtual mapping for SGI UV because using it
   causes a crash during boot - Borislav Petkov

Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
 * Disable the new EFI 1:1 virtual mapping for SGI UV because using it
   causes a crash during boot - Borislav Petkov

Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/efi: Quirk out SGI UV</title>
<updated>2014-03-04T23:43:33+00:00</updated>
<author>
<name>Borislav Petkov</name>
<email>bp@suse.de</email>
</author>
<published>2014-03-04T16:02:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a5d90c923bcfb9632d998ed06e9569216ad695f3'/>
<id>a5d90c923bcfb9632d998ed06e9569216ad695f3</id>
<content type='text'>
Alex reported hitting the following BUG after the EFI 1:1 virtual
mapping work was merged,

 kernel BUG at arch/x86/mm/init_64.c:351!
 invalid opcode: 0000 [#1] SMP
 Call Trace:
  [&lt;ffffffff818aa71d&gt;] init_extra_mapping_uc+0x13/0x15
  [&lt;ffffffff818a5e20&gt;] uv_system_init+0x22b/0x124b
  [&lt;ffffffff8108b886&gt;] ? clockevents_register_device+0x138/0x13d
  [&lt;ffffffff81028dbb&gt;] ? setup_APIC_timer+0xc5/0xc7
  [&lt;ffffffff8108b620&gt;] ? clockevent_delta2ns+0xb/0xd
  [&lt;ffffffff818a3a92&gt;] ? setup_boot_APIC_clock+0x4a8/0x4b7
  [&lt;ffffffff8153d955&gt;] ? printk+0x72/0x74
  [&lt;ffffffff818a1757&gt;] native_smp_prepare_cpus+0x389/0x3d6
  [&lt;ffffffff818957bc&gt;] kernel_init_freeable+0xb7/0x1fb
  [&lt;ffffffff81535530&gt;] ? rest_init+0x74/0x74
  [&lt;ffffffff81535539&gt;] kernel_init+0x9/0xff
  [&lt;ffffffff81541dfc&gt;] ret_from_fork+0x7c/0xb0
  [&lt;ffffffff81535530&gt;] ? rest_init+0x74/0x74

Getting this thing to work with the new mapping scheme would need more
work, so automatically switch to the old memmap layout for SGI UV.

Acked-by: Russ Anderson &lt;rja@sgi.com&gt;
Cc: Alex Thorlton &lt;athorlton@sgi.com
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Alex reported hitting the following BUG after the EFI 1:1 virtual
mapping work was merged,

 kernel BUG at arch/x86/mm/init_64.c:351!
 invalid opcode: 0000 [#1] SMP
 Call Trace:
  [&lt;ffffffff818aa71d&gt;] init_extra_mapping_uc+0x13/0x15
  [&lt;ffffffff818a5e20&gt;] uv_system_init+0x22b/0x124b
  [&lt;ffffffff8108b886&gt;] ? clockevents_register_device+0x138/0x13d
  [&lt;ffffffff81028dbb&gt;] ? setup_APIC_timer+0xc5/0xc7
  [&lt;ffffffff8108b620&gt;] ? clockevent_delta2ns+0xb/0xd
  [&lt;ffffffff818a3a92&gt;] ? setup_boot_APIC_clock+0x4a8/0x4b7
  [&lt;ffffffff8153d955&gt;] ? printk+0x72/0x74
  [&lt;ffffffff818a1757&gt;] native_smp_prepare_cpus+0x389/0x3d6
  [&lt;ffffffff818957bc&gt;] kernel_init_freeable+0xb7/0x1fb
  [&lt;ffffffff81535530&gt;] ? rest_init+0x74/0x74
  [&lt;ffffffff81535539&gt;] kernel_init+0x9/0xff
  [&lt;ffffffff81541dfc&gt;] ret_from_fork+0x7c/0xb0
  [&lt;ffffffff81535530&gt;] ? rest_init+0x74/0x74

Getting this thing to work with the new mapping scheme would need more
work, so automatically switch to the old memmap layout for SGI UV.

Acked-by: Russ Anderson &lt;rja@sgi.com&gt;
Cc: Alex Thorlton &lt;athorlton@sgi.com
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Matt Fleming &lt;matt.fleming@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, tsc: Fallback to normal calibration if fast MSR calibration fails</title>
<updated>2014-02-19T16:12:24+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2014-02-19T11:52:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5f0e030930d715920be4de638084aaf8653867e8'/>
<id>5f0e030930d715920be4de638084aaf8653867e8</id>
<content type='text'>
If we cannot calibrate TSC via MSR based calibration
try_msr_calibrate_tsc() stores zero to fast_calibrate and returns that
to the caller. This value gets then propagated further to clockevents
code resulting division by zero oops like the one below:

 divide error: 0000 [#1] PREEMPT SMP
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W    3.13.0+ #47
 task: ffff880075508000 ti: ffff880075506000 task.ti: ffff880075506000
 RIP: 0010:[&lt;ffffffff810aec14&gt;]  [&lt;ffffffff810aec14&gt;] clockevents_config.part.3+0x24/0xa0
 RSP: 0000:ffff880075507e58  EFLAGS: 00010246
 RAX: ffffffffffffffff RBX: ffff880079c0cd80 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffff
 RBP: ffff880075507e70 R08: 0000000000000001 R09: 00000000000000be
 R10: 00000000000000bd R11: 0000000000000003 R12: 000000000000b008
 R13: 0000000000000008 R14: 000000000000b010 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff880079c00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: ffff880079fff000 CR3: 0000000001c0b000 CR4: 00000000001006f0
 Stack:
  ffff880079c0cd80 000000000000b008 0000000000000008 ffff880075507e88
  ffffffff810aecb0 ffff880079c0cd80 ffff880075507e98 ffffffff81030168
  ffff880075507ed8 ffffffff81d1104f 00000000000000c3 0000000000000000
 Call Trace:
  [&lt;ffffffff810aecb0&gt;] clockevents_config_and_register+0x20/0x30
  [&lt;ffffffff81030168&gt;] setup_APIC_timer+0xc8/0xd0
  [&lt;ffffffff81d1104f&gt;] setup_boot_APIC_clock+0x4cc/0x4d8
  [&lt;ffffffff81d0f5de&gt;] native_smp_prepare_cpus+0x3dd/0x3f0
  [&lt;ffffffff81d02ee9&gt;] kernel_init_freeable+0xc3/0x205
  [&lt;ffffffff8177c910&gt;] ? rest_init+0x90/0x90
  [&lt;ffffffff8177c91e&gt;] kernel_init+0xe/0x120
  [&lt;ffffffff8178deec&gt;] ret_from_fork+0x7c/0xb0
  [&lt;ffffffff8177c910&gt;] ? rest_init+0x90/0x90

Prevent this from happening by:
 1) Modifying try_msr_calibrate_tsc() to return calibration value or zero
    if it fails.
 2) Check this return value in native_calibrate_tsc() and in case of zero
    fallback to use normal non-MSR based calibration.

[mw: Added subject and changelog]

Reported-and-tested-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Bin Gao &lt;bin.gao@linux.intel.com&gt;
Cc: One Thousand Gnomes &lt;gnomes@lxorguk.ukuu.org.uk&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Link: http://lkml.kernel.org/r/1392810750-18660-1-git-send-email-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If we cannot calibrate TSC via MSR based calibration
try_msr_calibrate_tsc() stores zero to fast_calibrate and returns that
to the caller. This value gets then propagated further to clockevents
code resulting division by zero oops like the one below:

 divide error: 0000 [#1] PREEMPT SMP
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W    3.13.0+ #47
 task: ffff880075508000 ti: ffff880075506000 task.ti: ffff880075506000
 RIP: 0010:[&lt;ffffffff810aec14&gt;]  [&lt;ffffffff810aec14&gt;] clockevents_config.part.3+0x24/0xa0
 RSP: 0000:ffff880075507e58  EFLAGS: 00010246
 RAX: ffffffffffffffff RBX: ffff880079c0cd80 RCX: 0000000000000000
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffff
 RBP: ffff880075507e70 R08: 0000000000000001 R09: 00000000000000be
 R10: 00000000000000bd R11: 0000000000000003 R12: 000000000000b008
 R13: 0000000000000008 R14: 000000000000b010 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff880079c00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: ffff880079fff000 CR3: 0000000001c0b000 CR4: 00000000001006f0
 Stack:
  ffff880079c0cd80 000000000000b008 0000000000000008 ffff880075507e88
  ffffffff810aecb0 ffff880079c0cd80 ffff880075507e98 ffffffff81030168
  ffff880075507ed8 ffffffff81d1104f 00000000000000c3 0000000000000000
 Call Trace:
  [&lt;ffffffff810aecb0&gt;] clockevents_config_and_register+0x20/0x30
  [&lt;ffffffff81030168&gt;] setup_APIC_timer+0xc8/0xd0
  [&lt;ffffffff81d1104f&gt;] setup_boot_APIC_clock+0x4cc/0x4d8
  [&lt;ffffffff81d0f5de&gt;] native_smp_prepare_cpus+0x3dd/0x3f0
  [&lt;ffffffff81d02ee9&gt;] kernel_init_freeable+0xc3/0x205
  [&lt;ffffffff8177c910&gt;] ? rest_init+0x90/0x90
  [&lt;ffffffff8177c91e&gt;] kernel_init+0xe/0x120
  [&lt;ffffffff8178deec&gt;] ret_from_fork+0x7c/0xb0
  [&lt;ffffffff8177c910&gt;] ? rest_init+0x90/0x90

Prevent this from happening by:
 1) Modifying try_msr_calibrate_tsc() to return calibration value or zero
    if it fails.
 2) Check this return value in native_calibrate_tsc() and in case of zero
    fallback to use normal non-MSR based calibration.

[mw: Added subject and changelog]

Reported-and-tested-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Bin Gao &lt;bin.gao@linux.intel.com&gt;
Cc: One Thousand Gnomes &lt;gnomes@lxorguk.ukuu.org.uk&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Link: http://lkml.kernel.org/r/1392810750-18660-1-git-send-email-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
</pre>
</div>
</content>
</entry>
</feed>
