<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/x86/kernel/cpu/cpu.h, branch v4.19</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'for-linus-4.19-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip</title>
<updated>2018-08-14T23:54:22+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-08-14T23:54:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=31130a16d459de809cd1c03eabc9567d094aae6a'/>
<id>31130a16d459de809cd1c03eabc9567d094aae6a</id>
<content type='text'>
Pull xen updates from Juergen Gross:

 - add dma-buf functionality to Xen grant table handling

 - fix for booting the kernel as Xen PVH dom0

 - fix for booting the kernel as a Xen PV guest with
   CONFIG_DEBUG_VIRTUAL enabled

 - other minor performance and style fixes

* tag 'for-linus-4.19-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: fix balloon initialization for PVH Dom0
  xen: don't use privcmd_call() from xen_mc_flush()
  xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits
  xen/biomerge: Use true and false for boolean values
  xen/gntdev: don't dereference a null gntdev_dmabuf on allocation failure
  xen/spinlock: Don't use pvqspinlock if only 1 vCPU
  xen/gntdev: Implement dma-buf import functionality
  xen/gntdev: Implement dma-buf export functionality
  xen/gntdev: Add initial support for dma-buf UAPI
  xen/gntdev: Make private routines/structures accessible
  xen/gntdev: Allow mappings for DMA buffers
  xen/grant-table: Allow allocating buffers suitable for DMA
  xen/balloon: Share common memory reservation routines
  xen/grant-table: Make set/clear page private code shared
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull xen updates from Juergen Gross:

 - add dma-buf functionality to Xen grant table handling

 - fix for booting the kernel as Xen PVH dom0

 - fix for booting the kernel as a Xen PV guest with
   CONFIG_DEBUG_VIRTUAL enabled

 - other minor performance and style fixes

* tag 'for-linus-4.19-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: fix balloon initialization for PVH Dom0
  xen: don't use privcmd_call() from xen_mc_flush()
  xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits
  xen/biomerge: Use true and false for boolean values
  xen/gntdev: don't dereference a null gntdev_dmabuf on allocation failure
  xen/spinlock: Don't use pvqspinlock if only 1 vCPU
  xen/gntdev: Implement dma-buf import functionality
  xen/gntdev: Implement dma-buf export functionality
  xen/gntdev: Add initial support for dma-buf UAPI
  xen/gntdev: Make private routines/structures accessible
  xen/gntdev: Allow mappings for DMA buffers
  xen/grant-table: Allow allocating buffers suitable for DMA
  xen/balloon: Share common memory reservation routines
  xen/grant-table: Make set/clear page private code shared
</pre>
</div>
</content>
</entry>
<entry>
<title>xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits</title>
<updated>2018-08-06T20:27:41+00:00</updated>
<author>
<name>M. Vefa Bicakci</name>
<email>m.v.b@runbox.com</email>
</author>
<published>2018-07-24T12:45:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=405c018a25fe464dc68057bbc8014a58f2bd4422'/>
<id>405c018a25fe464dc68057bbc8014a58f2bd4422</id>
<content type='text'>
Commit d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits
adjustment corruption") has moved the query and calculation of the
x86_virt_bits and x86_phys_bits fields of the cpuinfo_x86 struct
from the get_cpu_cap function to a new function named
get_cpu_address_sizes.

One of the call sites related to Xen PV VMs was unfortunately missed
in the aforementioned commit. This prevents successful boot-up of
kernel versions 4.17 and up in Xen PV VMs if CONFIG_DEBUG_VIRTUAL
is enabled, due to the following code path:

  enlighten_pv.c::xen_start_kernel
    mmu_pv.c::xen_reserve_special_pages
      page.h::__pa
        physaddr.c::__phys_addr
          physaddr.h::phys_addr_valid

phys_addr_valid uses boot_cpu_data.x86_phys_bits to validate physical
addresses. boot_cpu_data.x86_phys_bits is no longer populated before
the call to xen_reserve_special_pages due to the aforementioned commit
though, so the validation performed by phys_addr_valid fails, which
causes __phys_addr to trigger a BUG, preventing boot-up.

Signed-off-by: M. Vefa Bicakci &lt;m.v.b@runbox.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: "Kirill A. Shutemov" &lt;kirill.shutemov@linux.intel.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: Juergen Gross &lt;jgross@suse.com&gt;
Cc: xen-devel@lists.xenproject.org
Cc: x86@kernel.org
Cc: stable@vger.kernel.org # for v4.17 and up
Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Signed-off-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits
adjustment corruption") has moved the query and calculation of the
x86_virt_bits and x86_phys_bits fields of the cpuinfo_x86 struct
from the get_cpu_cap function to a new function named
get_cpu_address_sizes.

One of the call sites related to Xen PV VMs was unfortunately missed
in the aforementioned commit. This prevents successful boot-up of
kernel versions 4.17 and up in Xen PV VMs if CONFIG_DEBUG_VIRTUAL
is enabled, due to the following code path:

  enlighten_pv.c::xen_start_kernel
    mmu_pv.c::xen_reserve_special_pages
      page.h::__pa
        physaddr.c::__phys_addr
          physaddr.h::phys_addr_valid

phys_addr_valid uses boot_cpu_data.x86_phys_bits to validate physical
addresses. boot_cpu_data.x86_phys_bits is no longer populated before
the call to xen_reserve_special_pages due to the aforementioned commit
though, so the validation performed by phys_addr_valid fails, which
causes __phys_addr to trigger a BUG, preventing boot-up.

Signed-off-by: M. Vefa Bicakci &lt;m.v.b@runbox.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: "Kirill A. Shutemov" &lt;kirill.shutemov@linux.intel.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: Juergen Gross &lt;jgross@suse.com&gt;
Cc: xen-devel@lists.xenproject.org
Cc: x86@kernel.org
Cc: stable@vger.kernel.org # for v4.17 and up
Fixes: d94a155c59c9 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Signed-off-by: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/cpu/topology: Provide detect_extended_topology_early()</title>
<updated>2018-06-21T12:20:59+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2018-06-05T22:55:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=95f3d39ccf7aaea79d1ffdac1c887c2e100ec1b6'/>
<id>95f3d39ccf7aaea79d1ffdac1c887c2e100ec1b6</id>
<content type='text'>
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_extended_topology() cannot be called before
the APIC driver is selected, so split out the part which initializes
smp_num_siblings.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_extended_topology() cannot be called before
the APIC driver is selected, so split out the part which initializes
smp_num_siblings.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/cpu/common: Provide detect_ht_early()</title>
<updated>2018-06-21T12:20:59+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2018-06-05T22:53:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=545401f4448a807b963ff17b575e0a393e68b523'/>
<id>545401f4448a807b963ff17b575e0a393e68b523</id>
<content type='text'>
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_ht() cannot be called before the APIC driver
is selected, so split out the part which initializes smp_num_siblings.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_ht() cannot be called before the APIC driver
is selected, so split out the part which initializes smp_num_siblings.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2018-06-05T01:19:18+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-06-05T01:19:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5cef8c2a2289117b7f65de4313b7157578ec1a71'/>
<id>5cef8c2a2289117b7f65de4313b7157578ec1a71</id>
<content type='text'>
Pull x86 boot updates from Ingo Molnar:

 - Centaur CPU updates (David Wang)

 - AMD and other CPU topology enumeration improvements and fixes
   (Borislav Petkov, Thomas Gleixner, Suravee Suthikulpanit)

 - Continued 5-level paging work (Kirill A. Shutemov)

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Mark __pgtable_l5_enabled __initdata
  x86/mm: Mark p4d_offset() __always_inline
  x86/mm: Introduce the 'no5lvl' kernel parameter
  x86/mm: Stop pretending pgtable_l5_enabled is a variable
  x86/mm: Unify pgtable_l5_enabled usage in early boot code
  x86/boot/compressed/64: Fix trampoline page table address calculation
  x86/CPU: Move x86_cpuinfo::x86_max_cores assignment to detect_num_cpu_cores()
  x86/Centaur: Report correct CPU/cache topology
  x86/CPU: Move cpu_detect_cache_sizes() into init_intel_cacheinfo()
  x86/CPU: Make intel_num_cpu_cores() generic
  x86/CPU: Move cpu local function declarations to local header
  x86/CPU/AMD: Derive CPU topology from CPUID function 0xB when available
  x86/CPU: Modify detect_extended_topology() to return result
  x86/CPU/AMD: Calculate last level cache ID from number of sharing threads
  x86/CPU: Rename intel_cacheinfo.c to cacheinfo.c
  perf/events/amd/uncore: Fix amd_uncore_llc ID to use pre-defined cpu_llc_id
  x86/CPU/AMD: Have smp_num_siblings and cpu_llc_id always be present
  x86/Centaur: Initialize supported CPU features properly
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 boot updates from Ingo Molnar:

 - Centaur CPU updates (David Wang)

 - AMD and other CPU topology enumeration improvements and fixes
   (Borislav Petkov, Thomas Gleixner, Suravee Suthikulpanit)

 - Continued 5-level paging work (Kirill A. Shutemov)

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Mark __pgtable_l5_enabled __initdata
  x86/mm: Mark p4d_offset() __always_inline
  x86/mm: Introduce the 'no5lvl' kernel parameter
  x86/mm: Stop pretending pgtable_l5_enabled is a variable
  x86/mm: Unify pgtable_l5_enabled usage in early boot code
  x86/boot/compressed/64: Fix trampoline page table address calculation
  x86/CPU: Move x86_cpuinfo::x86_max_cores assignment to detect_num_cpu_cores()
  x86/Centaur: Report correct CPU/cache topology
  x86/CPU: Move cpu_detect_cache_sizes() into init_intel_cacheinfo()
  x86/CPU: Make intel_num_cpu_cores() generic
  x86/CPU: Move cpu local function declarations to local header
  x86/CPU/AMD: Derive CPU topology from CPUID function 0xB when available
  x86/CPU: Modify detect_extended_topology() to return result
  x86/CPU/AMD: Calculate last level cache ID from number of sharing threads
  x86/CPU: Rename intel_cacheinfo.c to cacheinfo.c
  perf/events/amd/uncore: Fix amd_uncore_llc ID to use pre-defined cpu_llc_id
  x86/CPU/AMD: Have smp_num_siblings and cpu_llc_id always be present
  x86/Centaur: Initialize supported CPU features properly
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/CPU: Move x86_cpuinfo::x86_max_cores assignment to detect_num_cpu_cores()</title>
<updated>2018-05-13T14:14:24+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2018-05-13T09:43:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9305bd6ca7b40fece04d7a7a02765e9e8349f146'/>
<id>9305bd6ca7b40fece04d7a7a02765e9e8349f146</id>
<content type='text'>
No point to have it at the call sites.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
No point to have it at the call sites.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>x86/CPU: Move cpu_detect_cache_sizes() into init_intel_cacheinfo()</title>
<updated>2018-05-13T14:14:24+00:00</updated>
<author>
<name>David Wang</name>
<email>davidwang@zhaoxin.com</email>
</author>
<published>2018-05-03T02:32:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=807e9bc8e2fe6b4907f9f77fd073f7ef5073af29'/>
<id>807e9bc8e2fe6b4907f9f77fd073f7ef5073af29</id>
<content type='text'>
There is no point in having the conditional cpu_detect_cache_sizes() call
at the callsite of init_intel_cacheinfo().

Move it into init_intel_cacheinfo() and make init_intel_cacheinfo() void.

[ tglx: Made the init_intel_cacheinfo() void as the return value was
  	pointless. Adjust changelog accordingly ]

Signed-off-by: David Wang &lt;davidwang@zhaoxin.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lukelin@viacpu.com
Cc: qiyuanwang@zhaoxin.com
Cc: gregkh@linuxfoundation.org
Cc: brucechang@via-alliance.com
Cc: timguo@zhaoxin.com
Cc: cooperyan@zhaoxin.com
Cc: hpa@zytor.com
Cc: benjaminpan@viatech.com
Link: https://lkml.kernel.org/r/1525314766-18910-3-git-send-email-davidwang@zhaoxin.com


</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is no point in having the conditional cpu_detect_cache_sizes() call
at the callsite of init_intel_cacheinfo().

Move it into init_intel_cacheinfo() and make init_intel_cacheinfo() void.

[ tglx: Made the init_intel_cacheinfo() void as the return value was
  	pointless. Adjust changelog accordingly ]

Signed-off-by: David Wang &lt;davidwang@zhaoxin.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lukelin@viacpu.com
Cc: qiyuanwang@zhaoxin.com
Cc: gregkh@linuxfoundation.org
Cc: brucechang@via-alliance.com
Cc: timguo@zhaoxin.com
Cc: cooperyan@zhaoxin.com
Cc: hpa@zytor.com
Cc: benjaminpan@viatech.com
Link: https://lkml.kernel.org/r/1525314766-18910-3-git-send-email-davidwang@zhaoxin.com


</pre>
</div>
</content>
</entry>
<entry>
<title>x86/CPU: Make intel_num_cpu_cores() generic</title>
<updated>2018-05-13T10:06:12+00:00</updated>
<author>
<name>David Wang</name>
<email>davidwang@zhaoxin.com</email>
</author>
<published>2018-05-03T02:32:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2cc61be60e37b1856a97ccbdcca3e86e593bf06a'/>
<id>2cc61be60e37b1856a97ccbdcca3e86e593bf06a</id>
<content type='text'>
intel_num_cpu_cores() is a static function in intel.c which can't be used
by other files. Define another function called detect_num_cpu_cores() in
common.c to replace this function so it can be reused.

Signed-off-by: David Wang &lt;davidwang@zhaoxin.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lukelin@viacpu.com
Cc: qiyuanwang@zhaoxin.com
Cc: gregkh@linuxfoundation.org
Cc: brucechang@via-alliance.com
Cc: timguo@zhaoxin.com
Cc: cooperyan@zhaoxin.com
Cc: hpa@zytor.com
Cc: benjaminpan@viatech.com
Link: https://lkml.kernel.org/r/1525314766-18910-2-git-send-email-davidwang@zhaoxin.com

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
intel_num_cpu_cores() is a static function in intel.c which can't be used
by other files. Define another function called detect_num_cpu_cores() in
common.c to replace this function so it can be reused.

Signed-off-by: David Wang &lt;davidwang@zhaoxin.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: lukelin@viacpu.com
Cc: qiyuanwang@zhaoxin.com
Cc: gregkh@linuxfoundation.org
Cc: brucechang@via-alliance.com
Cc: timguo@zhaoxin.com
Cc: cooperyan@zhaoxin.com
Cc: hpa@zytor.com
Cc: benjaminpan@viatech.com
Link: https://lkml.kernel.org/r/1525314766-18910-2-git-send-email-davidwang@zhaoxin.com

</pre>
</div>
</content>
</entry>
<entry>
<title>x86/CPU: Move cpu local function declarations to local header</title>
<updated>2018-05-13T10:06:12+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2018-05-13T09:29:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b5cf8707e6c9d85819b4bee3218ec560953149f7'/>
<id>b5cf8707e6c9d85819b4bee3218ec560953149f7</id>
<content type='text'>
No point in exposing all these functions globaly as they are strict local
to the cpu management code.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
No point in exposing all these functions globaly as they are strict local
to the cpu management code.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/bugs/intel: Set proper CPU features and setup RDS</title>
<updated>2018-05-03T11:55:48+00:00</updated>
<author>
<name>Konrad Rzeszutek Wilk</name>
<email>konrad.wilk@oracle.com</email>
</author>
<published>2018-04-26T02:04:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=772439717dbf703b39990be58d8d4e3e4ad0598a'/>
<id>772439717dbf703b39990be58d8d4e3e4ad0598a</id>
<content type='text'>
Intel CPUs expose methods to:

 - Detect whether RDS capability is available via CPUID.7.0.EDX[31],

 - The SPEC_CTRL MSR(0x48), bit 2 set to enable RDS.

 - MSR_IA32_ARCH_CAPABILITIES, Bit(4) no need to enable RRS.

With that in mind if spec_store_bypass_disable=[auto,on] is selected set at
boot-time the SPEC_CTRL MSR to enable RDS if the platform requires it.

Note that this does not fix the KVM case where the SPEC_CTRL is exposed to
guests which can muck with it, see patch titled :
 KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS.

And for the firmware (IBRS to be set), see patch titled:
 x86/spectre_v2: Read SPEC_CTRL MSR during boot and re-use reserved bits

[ tglx: Distangled it from the intel implementation and kept the call order ]

Signed-off-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Borislav Petkov &lt;bp@suse.de&gt;
Reviewed-by: Ingo Molnar &lt;mingo@kernel.org&gt;

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Intel CPUs expose methods to:

 - Detect whether RDS capability is available via CPUID.7.0.EDX[31],

 - The SPEC_CTRL MSR(0x48), bit 2 set to enable RDS.

 - MSR_IA32_ARCH_CAPABILITIES, Bit(4) no need to enable RRS.

With that in mind if spec_store_bypass_disable=[auto,on] is selected set at
boot-time the SPEC_CTRL MSR to enable RDS if the platform requires it.

Note that this does not fix the KVM case where the SPEC_CTRL is exposed to
guests which can muck with it, see patch titled :
 KVM/SVM/VMX/x86/spectre_v2: Support the combination of guest and host IBRS.

And for the firmware (IBRS to be set), see patch titled:
 x86/spectre_v2: Read SPEC_CTRL MSR during boot and re-use reserved bits

[ tglx: Distangled it from the intel implementation and kept the call order ]

Signed-off-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Reviewed-by: Borislav Petkov &lt;bp@suse.de&gt;
Reviewed-by: Ingo Molnar &lt;mingo@kernel.org&gt;

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