<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/uapi/linux/kvm.h, branch v4.15.4</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>KVM: s390: wire up bpb feature</title>
<updated>2018-01-20T16:30:47+00:00</updated>
<author>
<name>Christian Borntraeger</name>
<email>borntraeger@de.ibm.com</email>
</author>
<published>2018-01-17T13:44:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=35b3fde6203b932b2b1a5b53b3d8808abc9c4f60'/>
<id>35b3fde6203b932b2b1a5b53b3d8808abc9c4f60</id>
<content type='text'>
The new firmware interfaces for branch prediction behaviour changes
are transparently available for the guest. Nevertheless, there is
new state attached that should be migrated and properly resetted.
Provide a mechanism for handling reset, migration and VSIE.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
[Changed capability number to 152. - Radim]
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The new firmware interfaces for branch prediction behaviour changes
are transparently available for the guest. Nevertheless, there is
new state attached that should be migrated and properly resetted.
Provide a mechanism for handling reset, migration and VSIE.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
[Changed capability number to 152. - Radim]
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S: Provide information about hardware/firmware CVE workarounds</title>
<updated>2018-01-19T04:17:01+00:00</updated>
<author>
<name>Paul Mackerras</name>
<email>paulus@ozlabs.org</email>
</author>
<published>2018-01-15T05:06:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3214d01f139b7544e870fc0b7fcce8da13c1cb51'/>
<id>3214d01f139b7544e870fc0b7fcce8da13c1cb51</id>
<content type='text'>
This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace
information about the underlying machine's level of vulnerability
to the recently announced vulnerabilities CVE-2017-5715,
CVE-2017-5753 and CVE-2017-5754, and whether the machine provides
instructions to assist software to work around the vulnerabilities.

The ioctl returns two u64 words describing characteristics of the
CPU and required software behaviour respectively, plus two mask
words which indicate which bits have been filled in by the kernel,
for extensibility.  The bit definitions are the same as for the
new H_GET_CPU_CHARACTERISTICS hypercall.

There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which
indicates whether the new ioctl is available.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This adds a new ioctl, KVM_PPC_GET_CPU_CHAR, that gives userspace
information about the underlying machine's level of vulnerability
to the recently announced vulnerabilities CVE-2017-5715,
CVE-2017-5753 and CVE-2017-5754, and whether the machine provides
instructions to assist software to work around the vulnerabilities.

The ioctl returns two u64 words describing characteristics of the
CPU and required software behaviour respectively, plus two mask
words which indicate which bits have been filled in by the kernel,
for extensibility.  The bit definitions are the same as for the
new H_GET_CPU_CHARACTERISTICS hypercall.

There is also a new capability, KVM_CAP_PPC_GET_CPU_CHAR, which
indicates whether the new ioctl is available.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: s390: mark irq_state.flags as non-usable</title>
<updated>2017-12-06T08:18:43+00:00</updated>
<author>
<name>Christian Borntraeger</name>
<email>borntraeger@de.ibm.com</email>
</author>
<published>2017-11-21T15:02:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bb64da9aba89765fee74b395967b18a7d6c364e9'/>
<id>bb64da9aba89765fee74b395967b18a7d6c364e9</id>
<content type='text'>
Old kernels did not check for zero in the irq_state.flags field and old
QEMUs did not zero the flag/reserved fields when calling
KVM_S390_*_IRQ_STATE.  Let's add comments to prevent future uses of
these fields.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: Thomas Huth &lt;thuth@redhat.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Old kernels did not check for zero in the irq_state.flags field and old
QEMUs did not zero the flag/reserved fields when calling
KVM_S390_*_IRQ_STATE.  Let's add comments to prevent future uses of
these fields.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: Thomas Huth &lt;thuth@redhat.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvm-4.15-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2017-11-16T21:00:24+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2017-11-16T21:00:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=974aa5630b318938273d7efe7a2cf031c7b927db'/>
<id>974aa5630b318938273d7efe7a2cf031c7b927db</id>
<content type='text'>
Pull KVM updates from Radim Krčmář:
 "First batch of KVM changes for 4.15

  Common:
   - Python 3 support in kvm_stat
   - Accounting of slabs to kmemcg

  ARM:
   - Optimized arch timer handling for KVM/ARM
   - Improvements to the VGIC ITS code and introduction of an ITS reset
     ioctl
   - Unification of the 32-bit fault injection logic
   - More exact external abort matching logic

  PPC:
   - Support for running hashed page table (HPT) MMU mode on a host that
     is using the radix MMU mode; single threaded mode on POWER 9 is
     added as a pre-requisite
   - Resolution of merge conflicts with the last second 4.14 HPT fixes
   - Fixes and cleanups

  s390:
   - Some initial preparation patches for exitless interrupts and crypto
   - New capability for AIS migration
   - Fixes

  x86:
   - Improved emulation of LAPIC timer mode changes, MCi_STATUS MSRs,
     and after-reset state
   - Refined dependencies for VMX features
   - Fixes for nested SMI injection
   - A lot of cleanups"

* tag 'kvm-4.15-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (89 commits)
  KVM: s390: provide a capability for AIS state migration
  KVM: s390: clear_io_irq() requests are not expected for adapter interrupts
  KVM: s390: abstract conversion between isc and enum irq_types
  KVM: s390: vsie: use common code functions for pinning
  KVM: s390: SIE considerations for AP Queue virtualization
  KVM: s390: document memory ordering for kvm_s390_vcpu_wakeup
  KVM: PPC: Book3S HV: Cosmetic post-merge cleanups
  KVM: arm/arm64: fix the incompatible matching for external abort
  KVM: arm/arm64: Unify 32bit fault injection
  KVM: arm/arm64: vgic-its: Implement KVM_DEV_ARM_ITS_CTRL_RESET
  KVM: arm/arm64: Document KVM_DEV_ARM_ITS_CTRL_RESET
  KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared
  KVM: arm/arm64: vgic-its: New helper functions to free the caches
  KVM: arm/arm64: vgic-its: Remove kvm_its_unmap_device
  arm/arm64: KVM: Load the timer state when enabling the timer
  KVM: arm/arm64: Rework kvm_timer_should_fire
  KVM: arm/arm64: Get rid of kvm_timer_flush_hwstate
  KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit
  KVM: arm/arm64: Move phys_timer_emulate function
  KVM: arm/arm64: Use kvm_arm_timer_set/get_reg for guest register traps
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull KVM updates from Radim Krčmář:
 "First batch of KVM changes for 4.15

  Common:
   - Python 3 support in kvm_stat
   - Accounting of slabs to kmemcg

  ARM:
   - Optimized arch timer handling for KVM/ARM
   - Improvements to the VGIC ITS code and introduction of an ITS reset
     ioctl
   - Unification of the 32-bit fault injection logic
   - More exact external abort matching logic

  PPC:
   - Support for running hashed page table (HPT) MMU mode on a host that
     is using the radix MMU mode; single threaded mode on POWER 9 is
     added as a pre-requisite
   - Resolution of merge conflicts with the last second 4.14 HPT fixes
   - Fixes and cleanups

  s390:
   - Some initial preparation patches for exitless interrupts and crypto
   - New capability for AIS migration
   - Fixes

  x86:
   - Improved emulation of LAPIC timer mode changes, MCi_STATUS MSRs,
     and after-reset state
   - Refined dependencies for VMX features
   - Fixes for nested SMI injection
   - A lot of cleanups"

* tag 'kvm-4.15-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (89 commits)
  KVM: s390: provide a capability for AIS state migration
  KVM: s390: clear_io_irq() requests are not expected for adapter interrupts
  KVM: s390: abstract conversion between isc and enum irq_types
  KVM: s390: vsie: use common code functions for pinning
  KVM: s390: SIE considerations for AP Queue virtualization
  KVM: s390: document memory ordering for kvm_s390_vcpu_wakeup
  KVM: PPC: Book3S HV: Cosmetic post-merge cleanups
  KVM: arm/arm64: fix the incompatible matching for external abort
  KVM: arm/arm64: Unify 32bit fault injection
  KVM: arm/arm64: vgic-its: Implement KVM_DEV_ARM_ITS_CTRL_RESET
  KVM: arm/arm64: Document KVM_DEV_ARM_ITS_CTRL_RESET
  KVM: arm/arm64: vgic-its: Free caches when GITS_BASER Valid bit is cleared
  KVM: arm/arm64: vgic-its: New helper functions to free the caches
  KVM: arm/arm64: vgic-its: Remove kvm_its_unmap_device
  arm/arm64: KVM: Load the timer state when enabling the timer
  KVM: arm/arm64: Rework kvm_timer_should_fire
  KVM: arm/arm64: Get rid of kvm_timer_flush_hwstate
  KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit
  KVM: arm/arm64: Move phys_timer_emulate function
  KVM: arm/arm64: Use kvm_arm_timer_set/get_reg for guest register traps
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: s390: provide a capability for AIS state migration</title>
<updated>2017-11-09T15:48:51+00:00</updated>
<author>
<name>Christian Borntraeger</name>
<email>borntraeger@de.ibm.com</email>
</author>
<published>2017-11-09T09:00:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=da9a1446d248f673a8560ce46251ff620214ab7b'/>
<id>da9a1446d248f673a8560ce46251ff620214ab7b</id>
<content type='text'>
The AIS capability was introduced in 4.12, while the interface to
migrate the state was added in 4.13. Unfortunately it is not possible
for userspace to detect the migration capability without creating a flic
kvm device. As in QEMU the cpu model detection runs on the "none"
machine this will result in cpu model issues regarding the "ais"
capability.

To get the "ais" capability properly let's add a new KVM capability that
tells userspace that AIS states can be migrated.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Halil Pasic &lt;pasic@linux.vnet.ibm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The AIS capability was introduced in 4.12, while the interface to
migrate the state was added in 4.13. Unfortunately it is not possible
for userspace to detect the migration capability without creating a flic
kvm device. As in QEMU the cpu model detection runs on the "none"
machine this will result in cpu model issues regarding the "ais"
capability.

To get the "ais" capability properly let's add a new KVM capability that
tells userspace that AIS states can be migrated.

Signed-off-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Reviewed-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Halil Pasic &lt;pasic@linux.vnet.ibm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>License cleanup: add SPDX license identifier to uapi header files with no license</title>
<updated>2017-11-02T10:19:54+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2017-11-01T14:08:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6f52b16c5b29b89d92c0e7236f4655dc8491ad70'/>
<id>6f52b16c5b29b89d92c0e7236f4655dc8491ad70</id>
<content type='text'>
Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2.  Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

   NOTE! This copyright does *not* cover user programs that use kernel
   services by normal system calls - this is merely considered normal use
   of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier.  The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception.  SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.  See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart &lt;kstewart@linuxfoundation.org&gt;
Reviewed-by: Philippe Ombredanne &lt;pombredanne@nexb.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.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>
Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2.  Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

   NOTE! This copyright does *not* cover user programs that use kernel
   services by normal system calls - this is merely considered normal use
   of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier.  The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception.  SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.  See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart &lt;kstewart@linuxfoundation.org&gt;
Reviewed-by: Philippe Ombredanne &lt;pombredanne@nexb.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: PPC: Book3S HV: Report storage key support to userspace</title>
<updated>2017-08-31T02:36:44+00:00</updated>
<author>
<name>Paul Mackerras</name>
<email>paulus@ozlabs.org</email>
</author>
<published>2017-08-25T09:53:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e3bfed1df379c18f20feb06427d952b766e2c00f'/>
<id>e3bfed1df379c18f20feb06427d952b766e2c00f</id>
<content type='text'>
This adds information about storage keys to the struct returned by
the KVM_PPC_GET_SMMU_INFO ioctl.  The new fields replace a pad field,
which was zeroed by previous kernel versions.  Thus userspace that
knows about the new fields will see zeroes when running on an older
kernel, indicating that storage keys are not supported.  The size of
the structure has not changed.

The number of keys is hard-coded for the CPUs supported by HV KVM,
which is just POWER7, POWER8 and POWER9.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Reviewed-by: David Gibson &lt;david@gibson.dropbear.id.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This adds information about storage keys to the struct returned by
the KVM_PPC_GET_SMMU_INFO ioctl.  The new fields replace a pad field,
which was zeroed by previous kernel versions.  Thus userspace that
knows about the new fields will see zeroes when running on an older
kernel, indicating that storage keys are not supported.  The size of
the structure has not changed.

The number of keys is hard-coded for the CPUs supported by HV KVM,
which is just POWER7, POWER8 and POWER9.

Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
Reviewed-by: David Gibson &lt;david@gibson.dropbear.id.au&gt;
Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kvm: x86: hyperv: make VP_INDEX managed by userspace</title>
<updated>2017-07-14T14:28:18+00:00</updated>
<author>
<name>Roman Kagan</name>
<email>rkagan@virtuozzo.com</email>
</author>
<published>2017-07-14T14:13:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d3457c877b14aaee8c52923eedf05a3b78af0476'/>
<id>d3457c877b14aaee8c52923eedf05a3b78af0476</id>
<content type='text'>
Hyper-V identifies vCPUs by Virtual Processor Index, which can be
queried via HV_X64_MSR_VP_INDEX msr.  It is defined by the spec as a
sequential number which can't exceed the maximum number of vCPUs per VM.
APIC ids can be sparse and thus aren't a valid replacement for VP
indices.

Current KVM uses its internal vcpu index as VP_INDEX.  However, to make
it predictable and persistent across VM migrations, the userspace has to
control the value of VP_INDEX.

This patch achieves that, by storing vp_index explicitly on vcpu, and
allowing HV_X64_MSR_VP_INDEX to be set from the host side.  For
compatibility it's initialized to KVM vcpu index.  Also a few variables
are renamed to make clear distinction betweed this Hyper-V vp_index and
KVM vcpu_id (== APIC id).  Besides, a new capability,
KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip
attempting msr writes where unsupported, to avoid spamming error logs.

Signed-off-by: Roman Kagan &lt;rkagan@virtuozzo.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Hyper-V identifies vCPUs by Virtual Processor Index, which can be
queried via HV_X64_MSR_VP_INDEX msr.  It is defined by the spec as a
sequential number which can't exceed the maximum number of vCPUs per VM.
APIC ids can be sparse and thus aren't a valid replacement for VP
indices.

Current KVM uses its internal vcpu index as VP_INDEX.  However, to make
it predictable and persistent across VM migrations, the userspace has to
control the value of VP_INDEX.

This patch achieves that, by storing vp_index explicitly on vcpu, and
allowing HV_X64_MSR_VP_INDEX to be set from the host side.  For
compatibility it's initialized to KVM vcpu index.  Also a few variables
are renamed to make clear distinction betweed this Hyper-V vp_index and
KVM vcpu_id (== APIC id).  Besides, a new capability,
KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip
attempting msr writes where unsupported, to avoid spamming error logs.

Signed-off-by: Roman Kagan &lt;rkagan@virtuozzo.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kvm: x86: hyperv: add KVM_CAP_HYPERV_SYNIC2</title>
<updated>2017-07-13T15:41:04+00:00</updated>
<author>
<name>Roman Kagan</name>
<email>rkagan@virtuozzo.com</email>
</author>
<published>2017-06-22T13:51:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=efc479e6900c22bad9a2b649d13405ed9cde2d53'/>
<id>efc479e6900c22bad9a2b649d13405ed9cde2d53</id>
<content type='text'>
There is a flaw in the Hyper-V SynIC implementation in KVM: when message
page or event flags page is enabled by setting the corresponding msr,
KVM zeroes it out.  This is problematic because on migration the
corresponding MSRs are loaded on the destination, so the content of
those pages is lost.

This went unnoticed so far because the only user of those pages was
in-KVM hyperv synic timers, which could continue working despite that
zeroing.

Newer QEMU uses those pages for Hyper-V VMBus implementation, and
zeroing them breaks the migration.

Besides, in newer QEMU the content of those pages is fully managed by
QEMU, so zeroing them is undesirable even when writing the MSRs from the
guest side.

To support this new scheme, introduce a new capability,
KVM_CAP_HYPERV_SYNIC2, which, when enabled, makes sure that the synic
pages aren't zeroed out in KVM.

Signed-off-by: Roman Kagan &lt;rkagan@virtuozzo.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is a flaw in the Hyper-V SynIC implementation in KVM: when message
page or event flags page is enabled by setting the corresponding msr,
KVM zeroes it out.  This is problematic because on migration the
corresponding MSRs are loaded on the destination, so the content of
those pages is lost.

This went unnoticed so far because the only user of those pages was
in-KVM hyperv synic timers, which could continue working despite that
zeroing.

Newer QEMU uses those pages for Hyper-V VMBus implementation, and
zeroing them breaks the migration.

Besides, in newer QEMU the content of those pages is fully managed by
QEMU, so zeroing them is undesirable even when writing the MSRs from the
guest side.

To support this new scheme, introduce a new capability,
KVM_CAP_HYPERV_SYNIC2, which, when enabled, makes sure that the synic
pages aren't zeroed out in KVM.

Signed-off-by: Roman Kagan &lt;rkagan@virtuozzo.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: s390: Fix KVM_S390_GET_CMMA_BITS ioctl definition</title>
<updated>2017-07-12T20:38:26+00:00</updated>
<author>
<name>Gleb Fotengauer-Malinovskiy</name>
<email>glebfm@altlinux.org</email>
</author>
<published>2017-07-10T21:22:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=949c033694864082db9b3f5304723a6d7407f8e2'/>
<id>949c033694864082db9b3f5304723a6d7407f8e2</id>
<content type='text'>
In case of KVM_S390_GET_CMMA_BITS, the kernel does not only read struct
kvm_s390_cmma_log passed from userspace (which constitutes _IOC_WRITE),
it also writes back a return value (which constitutes _IOC_READ) making
this an _IOWR ioctl instead of _IOW.

Fixes: 4036e387 ("KVM: s390: ioctls to get and set guest storage attributes")
Signed-off-by: Gleb Fotengauer-Malinovskiy &lt;glebfm@altlinux.org&gt;
Acked-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In case of KVM_S390_GET_CMMA_BITS, the kernel does not only read struct
kvm_s390_cmma_log passed from userspace (which constitutes _IOC_WRITE),
it also writes back a return value (which constitutes _IOC_READ) making
this an _IOWR ioctl instead of _IOW.

Fixes: 4036e387 ("KVM: s390: ioctls to get and set guest storage attributes")
Signed-off-by: Gleb Fotengauer-Malinovskiy &lt;glebfm@altlinux.org&gt;
Acked-by: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Signed-off-by: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
