<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/x86/kernel/kvm.c, branch v6.2</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' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2022-12-15T19:12:21+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-12-15T19:12:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8fa590bf344816c925810331eea8387627bbeb40'/>
<id>8fa590bf344816c925810331eea8387627bbeb40</id>
<content type='text'>
Pull kvm updates from Paolo Bonzini:
 "ARM64:

   - Enable the per-vcpu dirty-ring tracking mechanism, together with an
     option to keep the good old dirty log around for pages that are
     dirtied by something other than a vcpu.

   - Switch to the relaxed parallel fault handling, using RCU to delay
     page table reclaim and giving better performance under load.

   - Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
     option, which multi-process VMMs such as crosvm rely on (see merge
     commit 382b5b87a97d: "Fix a number of issues with MTE, such as
     races on the tags being initialised vs the PG_mte_tagged flag as
     well as the lack of support for VM_SHARED when KVM is involved.
     Patches from Catalin Marinas and Peter Collingbourne").

   - Merge the pKVM shadow vcpu state tracking that allows the
     hypervisor to have its own view of a vcpu, keeping that state
     private.

   - Add support for the PMUv3p5 architecture revision, bringing support
     for 64bit counters on systems that support it, and fix the
     no-quite-compliant CHAIN-ed counter support for the machines that
     actually exist out there.

   - Fix a handful of minor issues around 52bit VA/PA support (64kB
     pages only) as a prefix of the oncoming support for 4kB and 16kB
     pages.

   - Pick a small set of documentation and spelling fixes, because no
     good merge window would be complete without those.

  s390:

   - Second batch of the lazy destroy patches

   - First batch of KVM changes for kernel virtual != physical address
     support

   - Removal of a unused function

  x86:

   - Allow compiling out SMM support

   - Cleanup and documentation of SMM state save area format

   - Preserve interrupt shadow in SMM state save area

   - Respond to generic signals during slow page faults

   - Fixes and optimizations for the non-executable huge page errata
     fix.

   - Reprogram all performance counters on PMU filter change

   - Cleanups to Hyper-V emulation and tests

   - Process Hyper-V TLB flushes from a nested guest (i.e. from a L2
     guest running on top of a L1 Hyper-V hypervisor)

   - Advertise several new Intel features

   - x86 Xen-for-KVM:

      - Allow the Xen runstate information to cross a page boundary

      - Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured

      - Add support for 32-bit guests in SCHEDOP_poll

   - Notable x86 fixes and cleanups:

      - One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

      - Reinstate IBPB on emulated VM-Exit that was incorrectly dropped
        a few years back when eliminating unnecessary barriers when
        switching between vmcs01 and vmcs02.

      - Clean up vmread_error_trampoline() to make it more obvious that
        params must be passed on the stack, even for x86-64.

      - Let userspace set all supported bits in MSR_IA32_FEAT_CTL
        irrespective of the current guest CPUID.

      - Fudge around a race with TSC refinement that results in KVM
        incorrectly thinking a guest needs TSC scaling when running on a
        CPU with a constant TSC, but no hardware-enumerated TSC
        frequency.

      - Advertise (on AMD) that the SMM_CTL MSR is not supported

      - Remove unnecessary exports

  Generic:

   - Support for responding to signals during page faults; introduces
     new FOLL_INTERRUPTIBLE flag that was reviewed by mm folks

  Selftests:

   - Fix an inverted check in the access tracking perf test, and restore
     support for asserting that there aren't too many idle pages when
     running on bare metal.

   - Fix build errors that occur in certain setups (unsure exactly what
     is unique about the problematic setup) due to glibc overriding
     static_assert() to a variant that requires a custom message.

   - Introduce actual atomics for clear/set_bit() in selftests

   - Add support for pinning vCPUs in dirty_log_perf_test.

   - Rename the so called "perf_util" framework to "memstress".

   - Add a lightweight psuedo RNG for guest use, and use it to randomize
     the access pattern and write vs. read percentage in the memstress
     tests.

   - Add a common ucall implementation; code dedup and pre-work for
     running SEV (and beyond) guests in selftests.

   - Provide a common constructor and arch hook, which will eventually
     be used by x86 to automatically select the right hypercall (AMD vs.
     Intel).

   - A bunch of added/enabled/fixed selftests for ARM64, covering
     memslots, breakpoints, stage-2 faults and access tracking.

   - x86-specific selftest changes:

      - Clean up x86's page table management.

      - Clean up and enhance the "smaller maxphyaddr" test, and add a
        related test to cover generic emulation failure.

      - Clean up the nEPT support checks.

      - Add X86_PROPERTY_* framework to retrieve multi-bit CPUID values.

      - Fix an ordering issue in the AMX test introduced by recent
        conversions to use kvm_cpu_has(), and harden the code to guard
        against similar bugs in the future. Anything that tiggers
        caching of KVM's supported CPUID, kvm_cpu_has() in this case,
        effectively hides opt-in XSAVE features if the caching occurs
        before the test opts in via prctl().

  Documentation:

   - Remove deleted ioctls from documentation

   - Clean up the docs for the x86 MSR filter.

   - Various fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (361 commits)
  KVM: x86: Add proper ReST tables for userspace MSR exits/flags
  KVM: selftests: Allocate ucall pool from MEM_REGION_DATA
  KVM: arm64: selftests: Align VA space allocator with TTBR0
  KVM: arm64: Fix benign bug with incorrect use of VA_BITS
  KVM: arm64: PMU: Fix period computation for 64bit counters with 32bit overflow
  KVM: x86: Advertise that the SMM_CTL MSR is not supported
  KVM: x86: remove unnecessary exports
  KVM: selftests: Fix spelling mistake "probabalistic" -&gt; "probabilistic"
  tools: KVM: selftests: Convert clear/set_bit() to actual atomics
  tools: Drop "atomic_" prefix from atomic test_and_set_bit()
  tools: Drop conflicting non-atomic test_and_{clear,set}_bit() helpers
  KVM: selftests: Use non-atomic clear/set bit helpers in KVM tests
  perf tools: Use dedicated non-atomic clear/set bit helpers
  tools: Take @bit as an "unsigned long" in {clear,set}_bit() helpers
  KVM: arm64: selftests: Enable single-step without a "full" ucall()
  KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself
  KVM: Remove stale comment about KVM_REQ_UNHALT
  KVM: Add missing arch for KVM_CREATE_DEVICE and KVM_{SET,GET}_DEVICE_ATTR
  KVM: Reference to kvm_userspace_memory_region in doc and comments
  KVM: Delete all references to removed KVM_SET_MEMORY_ALIAS ioctl
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull kvm updates from Paolo Bonzini:
 "ARM64:

   - Enable the per-vcpu dirty-ring tracking mechanism, together with an
     option to keep the good old dirty log around for pages that are
     dirtied by something other than a vcpu.

   - Switch to the relaxed parallel fault handling, using RCU to delay
     page table reclaim and giving better performance under load.

   - Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
     option, which multi-process VMMs such as crosvm rely on (see merge
     commit 382b5b87a97d: "Fix a number of issues with MTE, such as
     races on the tags being initialised vs the PG_mte_tagged flag as
     well as the lack of support for VM_SHARED when KVM is involved.
     Patches from Catalin Marinas and Peter Collingbourne").

   - Merge the pKVM shadow vcpu state tracking that allows the
     hypervisor to have its own view of a vcpu, keeping that state
     private.

   - Add support for the PMUv3p5 architecture revision, bringing support
     for 64bit counters on systems that support it, and fix the
     no-quite-compliant CHAIN-ed counter support for the machines that
     actually exist out there.

   - Fix a handful of minor issues around 52bit VA/PA support (64kB
     pages only) as a prefix of the oncoming support for 4kB and 16kB
     pages.

   - Pick a small set of documentation and spelling fixes, because no
     good merge window would be complete without those.

  s390:

   - Second batch of the lazy destroy patches

   - First batch of KVM changes for kernel virtual != physical address
     support

   - Removal of a unused function

  x86:

   - Allow compiling out SMM support

   - Cleanup and documentation of SMM state save area format

   - Preserve interrupt shadow in SMM state save area

   - Respond to generic signals during slow page faults

   - Fixes and optimizations for the non-executable huge page errata
     fix.

   - Reprogram all performance counters on PMU filter change

   - Cleanups to Hyper-V emulation and tests

   - Process Hyper-V TLB flushes from a nested guest (i.e. from a L2
     guest running on top of a L1 Hyper-V hypervisor)

   - Advertise several new Intel features

   - x86 Xen-for-KVM:

      - Allow the Xen runstate information to cross a page boundary

      - Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured

      - Add support for 32-bit guests in SCHEDOP_poll

   - Notable x86 fixes and cleanups:

      - One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).

      - Reinstate IBPB on emulated VM-Exit that was incorrectly dropped
        a few years back when eliminating unnecessary barriers when
        switching between vmcs01 and vmcs02.

      - Clean up vmread_error_trampoline() to make it more obvious that
        params must be passed on the stack, even for x86-64.

      - Let userspace set all supported bits in MSR_IA32_FEAT_CTL
        irrespective of the current guest CPUID.

      - Fudge around a race with TSC refinement that results in KVM
        incorrectly thinking a guest needs TSC scaling when running on a
        CPU with a constant TSC, but no hardware-enumerated TSC
        frequency.

      - Advertise (on AMD) that the SMM_CTL MSR is not supported

      - Remove unnecessary exports

  Generic:

   - Support for responding to signals during page faults; introduces
     new FOLL_INTERRUPTIBLE flag that was reviewed by mm folks

  Selftests:

   - Fix an inverted check in the access tracking perf test, and restore
     support for asserting that there aren't too many idle pages when
     running on bare metal.

   - Fix build errors that occur in certain setups (unsure exactly what
     is unique about the problematic setup) due to glibc overriding
     static_assert() to a variant that requires a custom message.

   - Introduce actual atomics for clear/set_bit() in selftests

   - Add support for pinning vCPUs in dirty_log_perf_test.

   - Rename the so called "perf_util" framework to "memstress".

   - Add a lightweight psuedo RNG for guest use, and use it to randomize
     the access pattern and write vs. read percentage in the memstress
     tests.

   - Add a common ucall implementation; code dedup and pre-work for
     running SEV (and beyond) guests in selftests.

   - Provide a common constructor and arch hook, which will eventually
     be used by x86 to automatically select the right hypercall (AMD vs.
     Intel).

   - A bunch of added/enabled/fixed selftests for ARM64, covering
     memslots, breakpoints, stage-2 faults and access tracking.

   - x86-specific selftest changes:

      - Clean up x86's page table management.

      - Clean up and enhance the "smaller maxphyaddr" test, and add a
        related test to cover generic emulation failure.

      - Clean up the nEPT support checks.

      - Add X86_PROPERTY_* framework to retrieve multi-bit CPUID values.

      - Fix an ordering issue in the AMX test introduced by recent
        conversions to use kvm_cpu_has(), and harden the code to guard
        against similar bugs in the future. Anything that tiggers
        caching of KVM's supported CPUID, kvm_cpu_has() in this case,
        effectively hides opt-in XSAVE features if the caching occurs
        before the test opts in via prctl().

  Documentation:

   - Remove deleted ioctls from documentation

   - Clean up the docs for the x86 MSR filter.

   - Various fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (361 commits)
  KVM: x86: Add proper ReST tables for userspace MSR exits/flags
  KVM: selftests: Allocate ucall pool from MEM_REGION_DATA
  KVM: arm64: selftests: Align VA space allocator with TTBR0
  KVM: arm64: Fix benign bug with incorrect use of VA_BITS
  KVM: arm64: PMU: Fix period computation for 64bit counters with 32bit overflow
  KVM: x86: Advertise that the SMM_CTL MSR is not supported
  KVM: x86: remove unnecessary exports
  KVM: selftests: Fix spelling mistake "probabalistic" -&gt; "probabilistic"
  tools: KVM: selftests: Convert clear/set_bit() to actual atomics
  tools: Drop "atomic_" prefix from atomic test_and_set_bit()
  tools: Drop conflicting non-atomic test_and_{clear,set}_bit() helpers
  KVM: selftests: Use non-atomic clear/set bit helpers in KVM tests
  perf tools: Use dedicated non-atomic clear/set bit helpers
  tools: Take @bit as an "unsigned long" in {clear,set}_bit() helpers
  KVM: arm64: selftests: Enable single-step without a "full" ucall()
  KVM: x86: fix APICv/x2AVIC disabled when vm reboot by itself
  KVM: Remove stale comment about KVM_REQ_UNHALT
  KVM: Add missing arch for KVM_CREATE_DEVICE and KVM_{SET,GET}_DEVICE_ATTR
  KVM: Reference to kvm_userspace_memory_region in doc and comments
  KVM: Delete all references to removed KVM_SET_MEMORY_ALIAS ioctl
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/paravirt: Use common macro for creating simple asm paravirt functions</title>
<updated>2022-11-24T12:56:44+00:00</updated>
<author>
<name>Juergen Gross</name>
<email>jgross@suse.com</email>
</author>
<published>2022-11-09T13:44:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f1a033cc6b9eb6d80322008422df3c87aa5d47a0'/>
<id>f1a033cc6b9eb6d80322008422df3c87aa5d47a0</id>
<content type='text'>
There are some paravirt assembler functions which are sharing a common
pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them.

Note that this macro is including explicit alignment of the generated
functions, leading to __raw_callee_save___kvm_vcpu_is_preempted(),
_paravirt_nop() and paravirt_ret0() to be aligned at 4 byte boundaries
now.

The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as
it is included in paravirt_types.h already.

Signed-off-by: Juergen Gross &lt;jgross@suse.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Srivatsa S. Bhat (VMware) &lt;srivatsa@csail.mit.edu&gt;
Link: https://lkml.kernel.org/r/20221109134418.6516-1-jgross@suse.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There are some paravirt assembler functions which are sharing a common
pattern. Introduce a macro DEFINE_PARAVIRT_ASM() for creating them.

Note that this macro is including explicit alignment of the generated
functions, leading to __raw_callee_save___kvm_vcpu_is_preempted(),
_paravirt_nop() and paravirt_ret0() to be aligned at 4 byte boundaries
now.

The explicit _paravirt_nop() prototype in paravirt.c isn't needed, as
it is included in paravirt_types.h already.

Signed-off-by: Juergen Gross &lt;jgross@suse.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Srivatsa S. Bhat (VMware) &lt;srivatsa@csail.mit.edu&gt;
Link: https://lkml.kernel.org/r/20221109134418.6516-1-jgross@suse.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/kvm: Remove unused virt to phys translation in kvm_guest_cpu_init()</title>
<updated>2022-11-09T17:31:15+00:00</updated>
<author>
<name>Rafael Mendonca</name>
<email>rafaelmendsr@gmail.com</email>
</author>
<published>2022-10-21T02:01:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=00009406f0dbc53b95b9062c0cc297d6893ff394'/>
<id>00009406f0dbc53b95b9062c0cc297d6893ff394</id>
<content type='text'>
Presumably, this was introduced due to a conflict resolution with
commit ef68017eb570 ("x86/kvm: Handle async page faults directly through
do_page_fault()"), given that the last posted version [1] of the blamed
commit was not based on the aforementioned commit.

[1] https://lore.kernel.org/kvm/20200525144125.143875-9-vkuznets@redhat.com/

Fixes: b1d405751cd5 ("KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery")
Signed-off-by: Rafael Mendonca &lt;rafaelmendsr@gmail.com&gt;
Message-Id: &lt;20221021020113.922027-1-rafaelmendsr@gmail.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Presumably, this was introduced due to a conflict resolution with
commit ef68017eb570 ("x86/kvm: Handle async page faults directly through
do_page_fault()"), given that the last posted version [1] of the blamed
commit was not based on the aforementioned commit.

[1] https://lore.kernel.org/kvm/20200525144125.143875-9-vkuznets@redhat.com/

Fixes: b1d405751cd5 ("KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery")
Signed-off-by: Rafael Mendonca &lt;rafaelmendsr@gmail.com&gt;
Message-Id: &lt;20221021020113.922027-1-rafaelmendsr@gmail.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/paravirt: Properly align PV functions</title>
<updated>2022-10-17T14:40:59+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2022-09-15T11:10:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1d293758e548aa6ff65e4dd3f5a9bc2a34b38ce3'/>
<id>1d293758e548aa6ff65e4dd3f5a9bc2a34b38ce3</id>
<content type='text'>
Ensure inline asm functions are consistently aligned with compiler
generated and SYM_FUNC_START*() functions.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Juergen Gross &lt;jgross@suse.com&gt;
Link: https://lore.kernel.org/r/20220915111144.038540008@infradead.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Ensure inline asm functions are consistently aligned with compiler
generated and SYM_FUNC_START*() functions.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Reviewed-by: Juergen Gross &lt;jgross@suse.com&gt;
Link: https://lore.kernel.org/r/20220915111144.038540008@infradead.org
</pre>
</div>
</content>
</entry>
<entry>
<title>x86: kvm: remove NULL check before kfree</title>
<updated>2022-06-20T10:22:04+00:00</updated>
<author>
<name>Dongliang Mu</name>
<email>mudongliangabcd@gmail.com</email>
</author>
<published>2022-06-14T13:34:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=e20918f6d11253d62b110e8d16b17cc9bf82d832'/>
<id>e20918f6d11253d62b110e8d16b17cc9bf82d832</id>
<content type='text'>
kfree can handle NULL pointer as its argument.
According to coccinelle isnullfree check, remove NULL check
before kfree operation.

Signed-off-by: Dongliang Mu &lt;mudongliangabcd@gmail.com&gt;
Message-Id: &lt;20220614133458.147314-1-dzm91@hust.edu.cn&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
kfree can handle NULL pointer as its argument.
According to coccinelle isnullfree check, remove NULL check
before kfree operation.

Signed-off-by: Dongliang Mu &lt;mudongliangabcd@gmail.com&gt;
Message-Id: &lt;20220614133458.147314-1-dzm91@hust.edu.cn&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, kvm: use correct GFP flags for preemption disabled</title>
<updated>2022-05-25T09:13:40+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-05-24T13:43:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=baec4f5a018fe2d708fc1022330dba04b38b5fe3'/>
<id>baec4f5a018fe2d708fc1022330dba04b38b5fe3</id>
<content type='text'>
Commit ddd7ed842627 ("x86/kvm: Alloc dummy async #PF token outside of
raw spinlock") leads to the following Smatch static checker warning:

	arch/x86/kernel/kvm.c:212 kvm_async_pf_task_wake()
	warn: sleeping in atomic context

arch/x86/kernel/kvm.c
    202         raw_spin_lock(&amp;b-&gt;lock);
    203         n = _find_apf_task(b, token);
    204         if (!n) {
    205                 /*
    206                  * Async #PF not yet handled, add a dummy entry for the token.
    207                  * Allocating the token must be down outside of the raw lock
    208                  * as the allocator is preemptible on PREEMPT_RT kernels.
    209                  */
    210                 if (!dummy) {
    211                         raw_spin_unlock(&amp;b-&gt;lock);
--&gt; 212                         dummy = kzalloc(sizeof(*dummy), GFP_KERNEL);
                                                                ^^^^^^^^^^
Smatch thinks the caller has preempt disabled.  The `smdb.py preempt
kvm_async_pf_task_wake` output call tree is:

sysvec_kvm_asyncpf_interrupt() &lt;- disables preempt
-&gt; __sysvec_kvm_asyncpf_interrupt()
   -&gt; kvm_async_pf_task_wake()

The caller is this:

arch/x86/kernel/kvm.c
   290        DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
   291        {
   292                struct pt_regs *old_regs = set_irq_regs(regs);
   293                u32 token;
   294
   295                ack_APIC_irq();
   296
   297                inc_irq_stat(irq_hv_callback_count);
   298
   299                if (__this_cpu_read(apf_reason.enabled)) {
   300                        token = __this_cpu_read(apf_reason.token);
   301                        kvm_async_pf_task_wake(token);
   302                        __this_cpu_write(apf_reason.token, 0);
   303                        wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
   304                }
   305
   306                set_irq_regs(old_regs);
   307        }

The DEFINE_IDTENTRY_SYSVEC() is a wrapper that calls this function
from the call_on_irqstack_cond().  It's inside the call_on_irqstack_cond()
where preempt is disabled (unless it's already disabled).  The
irq_enter/exit_rcu() functions disable/enable preempt.

Reported-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit ddd7ed842627 ("x86/kvm: Alloc dummy async #PF token outside of
raw spinlock") leads to the following Smatch static checker warning:

	arch/x86/kernel/kvm.c:212 kvm_async_pf_task_wake()
	warn: sleeping in atomic context

arch/x86/kernel/kvm.c
    202         raw_spin_lock(&amp;b-&gt;lock);
    203         n = _find_apf_task(b, token);
    204         if (!n) {
    205                 /*
    206                  * Async #PF not yet handled, add a dummy entry for the token.
    207                  * Allocating the token must be down outside of the raw lock
    208                  * as the allocator is preemptible on PREEMPT_RT kernels.
    209                  */
    210                 if (!dummy) {
    211                         raw_spin_unlock(&amp;b-&gt;lock);
--&gt; 212                         dummy = kzalloc(sizeof(*dummy), GFP_KERNEL);
                                                                ^^^^^^^^^^
Smatch thinks the caller has preempt disabled.  The `smdb.py preempt
kvm_async_pf_task_wake` output call tree is:

sysvec_kvm_asyncpf_interrupt() &lt;- disables preempt
-&gt; __sysvec_kvm_asyncpf_interrupt()
   -&gt; kvm_async_pf_task_wake()

The caller is this:

arch/x86/kernel/kvm.c
   290        DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
   291        {
   292                struct pt_regs *old_regs = set_irq_regs(regs);
   293                u32 token;
   294
   295                ack_APIC_irq();
   296
   297                inc_irq_stat(irq_hv_callback_count);
   298
   299                if (__this_cpu_read(apf_reason.enabled)) {
   300                        token = __this_cpu_read(apf_reason.token);
   301                        kvm_async_pf_task_wake(token);
   302                        __this_cpu_write(apf_reason.token, 0);
   303                        wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
   304                }
   305
   306                set_irq_regs(old_regs);
   307        }

The DEFINE_IDTENTRY_SYSVEC() is a wrapper that calls this function
from the call_on_irqstack_cond().  It's inside the call_on_irqstack_cond()
where preempt is disabled (unless it's already disabled).  The
irq_enter/exit_rcu() functions disable/enable preempt.

Reported-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/kvm: Alloc dummy async #PF token outside of raw spinlock</title>
<updated>2022-05-25T09:12:34+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2022-05-19T14:57:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0547758a6de3cc71a0cfdd031a3621a30db6a68b'/>
<id>0547758a6de3cc71a0cfdd031a3621a30db6a68b</id>
<content type='text'>
Drop the raw spinlock in kvm_async_pf_task_wake() before allocating the
the dummy async #PF token, the allocator is preemptible on PREEMPT_RT
kernels and must not be called from truly atomic contexts.

Opportunistically document why it's ok to loop on allocation failure,
i.e. why the function won't get stuck in an infinite loop.

Reported-by: Yajun Deng &lt;yajun.deng@linux.dev&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Drop the raw spinlock in kvm_async_pf_task_wake() before allocating the
the dummy async #PF token, the allocator is preemptible on PREEMPT_RT
kernels and must not be called from truly atomic contexts.

Opportunistically document why it's ok to loop on allocation failure,
i.e. why the function won't get stuck in an infinite loop.

Reported-by: Yajun Deng &lt;yajun.deng@linux.dev&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvmarm-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD</title>
<updated>2022-05-25T09:09:23+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-05-20T11:16:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=47e8eec83262083c7da220446551eaad614218ea'/>
<id>47e8eec83262083c7da220446551eaad614218ea</id>
<content type='text'>
KVM/arm64 updates for 5.19

- Add support for the ARMv8.6 WFxT extension

- Guard pages for the EL2 stacks

- Trap and emulate AArch32 ID registers to hide unsupported features

- Ability to select and save/restore the set of hypercalls exposed
  to the guest

- Support for PSCI-initiated suspend in collaboration with userspace

- GICv3 register-based LPI invalidation support

- Move host PMU event merging into the vcpu data structure

- GICv3 ITS save/restore fixes

- The usual set of small-scale cleanups and fixes

[Due to the conflict, KVM_SYSTEM_EVENT_SEV_TERM is relocated
 from 4 to 6. - Paolo]
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM/arm64 updates for 5.19

- Add support for the ARMv8.6 WFxT extension

- Guard pages for the EL2 stacks

- Trap and emulate AArch32 ID registers to hide unsupported features

- Ability to select and save/restore the set of hypercalls exposed
  to the guest

- Support for PSCI-initiated suspend in collaboration with userspace

- GICv3 register-based LPI invalidation support

- Move host PMU event merging into the vcpu data structure

- GICv3 ITS save/restore fixes

- The usual set of small-scale cleanups and fixes

[Due to the conflict, KVM_SYSTEM_EVENT_SEV_TERM is relocated
 from 4 to 6. - Paolo]
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/kvm: Preserve BSP MSR_KVM_POLL_CONTROL across suspend/resume</title>
<updated>2022-04-21T17:16:14+00:00</updated>
<author>
<name>Wanpeng Li</name>
<email>wanpengli@tencent.com</email>
</author>
<published>2022-04-18T07:42:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0361bdfddca20c8855ea3bdbbbc9c999912b10ff'/>
<id>0361bdfddca20c8855ea3bdbbbc9c999912b10ff</id>
<content type='text'>
MSR_KVM_POLL_CONTROL is cleared on reset, thus reverting guests to
host-side polling after suspend/resume.  Non-bootstrap CPUs are
restored correctly by the haltpoll driver because they are hot-unplugged
during suspend and hot-plugged during resume; however, the BSP
is not hotpluggable and remains in host-sde polling mode after
the guest resume.  The makes the guest pay for the cost of vmexits
every time the guest enters idle.

Fix it by recording BSP's haltpoll state and resuming it during guest
resume.

Cc: Marcelo Tosatti &lt;mtosatti@redhat.com&gt;
Signed-off-by: Wanpeng Li &lt;wanpengli@tencent.com&gt;
Message-Id: &lt;1650267752-46796-1-git-send-email-wanpengli@tencent.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
MSR_KVM_POLL_CONTROL is cleared on reset, thus reverting guests to
host-side polling after suspend/resume.  Non-bootstrap CPUs are
restored correctly by the haltpoll driver because they are hot-unplugged
during suspend and hot-plugged during resume; however, the BSP
is not hotpluggable and remains in host-sde polling mode after
the guest resume.  The makes the guest pay for the cost of vmexits
every time the guest enters idle.

Fix it by recording BSP's haltpoll state and resuming it during guest
resume.

Cc: Marcelo Tosatti &lt;mtosatti@redhat.com&gt;
Signed-off-by: Wanpeng Li &lt;wanpengli@tencent.com&gt;
Message-Id: &lt;1650267752-46796-1-git-send-email-wanpengli@tencent.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'kvm-older-features' into HEAD</title>
<updated>2022-04-13T17:37:17+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-04-08T16:43:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a4cfff3f0f8c07f1f7873a82bdeb3995807dac8c'/>
<id>a4cfff3f0f8c07f1f7873a82bdeb3995807dac8c</id>
<content type='text'>
Merge branch for features that did not make it into 5.18:

* New ioctls to get/set TSC frequency for a whole VM

* Allow userspace to opt out of hypercall patching

Nested virtualization improvements for AMD:

* Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
  nested vGIF)

* Allow AVIC to co-exist with a nested guest running

* Fixes for LBR virtualizations when a nested guest is running,
  and nested LBR virtualization support

* PAUSE filtering for nested hypervisors

Guest support:

* Decoupling of vcpu_is_preempted from PV spinlocks

Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Merge branch for features that did not make it into 5.18:

* New ioctls to get/set TSC frequency for a whole VM

* Allow userspace to opt out of hypercall patching

Nested virtualization improvements for AMD:

* Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE,
  nested vGIF)

* Allow AVIC to co-exist with a nested guest running

* Fixes for LBR virtualizations when a nested guest is running,
  and nested LBR virtualization support

* PAUSE filtering for nested hypervisors

Guest support:

* Decoupling of vcpu_is_preempted from PV spinlocks

Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
