<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/tools/testing/selftests/kvm/aarch64/debug-exceptions.c, branch for-next</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>KVM: arm64: selftests: Convert to kernel's ESR terminology</title>
<updated>2024-10-26T14:37:49+00:00</updated>
<author>
<name>Oliver Upton</name>
<email>oliver.upton@linux.dev</email>
</author>
<published>2024-10-25T20:31:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c660d334b3a54f22836955ca5255edd946771614'/>
<id>c660d334b3a54f22836955ca5255edd946771614</id>
<content type='text'>
Drop the KVM selftests specific flavoring of ESR in favor of the kernel
header.

Reviewed-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20241025203106.3529261-4-oliver.upton@linux.dev
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Drop the KVM selftests specific flavoring of ESR in favor of the kernel
header.

Reviewed-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20241025203106.3529261-4-oliver.upton@linux.dev
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Fix GUEST_PRINTF() format warnings in ARM code</title>
<updated>2024-02-12T20:41:49+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2024-02-02T23:46:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=06fdd894b473c6cc29c9b39b82e0941cefec4e51'/>
<id>06fdd894b473c6cc29c9b39b82e0941cefec4e51</id>
<content type='text'>
Fix a pile of -Wformat warnings in the KVM ARM selftests code, almost all
of which are benign "long" versus "long long" issues (selftests are 64-bit
only, and the guest printf code treats "ll" the same as "l").  The code
itself isn't problematic, but the warnings make it impossible to build ARM
selftests with -Werror, which does detect real issues from time to time.

Opportunistically have GUEST_ASSERT_BITMAP_REG() interpret set_expected,
which is a bool, as an unsigned decimal value, i.e. have it print '0' or
'1' instead of '0x0' or '0x1'.

Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Tested-by: Zenghui Yu &lt;yuzenghui@huawei.com&gt;
Link: https://lore.kernel.org/r/20240202234603.366925-1-seanjc@google.com
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix a pile of -Wformat warnings in the KVM ARM selftests code, almost all
of which are benign "long" versus "long long" issues (selftests are 64-bit
only, and the guest printf code treats "ll" the same as "l").  The code
itself isn't problematic, but the warnings make it impossible to build ARM
selftests with -Werror, which does detect real issues from time to time.

Opportunistically have GUEST_ASSERT_BITMAP_REG() interpret set_expected,
which is a bool, as an unsigned decimal value, i.e. have it print '0' or
'1' instead of '0x0' or '0x1'.

Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Tested-by: Zenghui Yu &lt;yuzenghui@huawei.com&gt;
Link: https://lore.kernel.org/r/20240202234603.366925-1-seanjc@google.com
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools headers arm64: Update sysreg.h with kernel sources</title>
<updated>2023-10-18T23:36:25+00:00</updated>
<author>
<name>Jing Zhang</name>
<email>jingzhangos@google.com</email>
</author>
<published>2023-10-11T19:57:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0359c946b13153bd57fac65f4f3600ba5673e3de'/>
<id>0359c946b13153bd57fac65f4f3600ba5673e3de</id>
<content type='text'>
The users of sysreg.h (perf, KVM selftests) are now generating the
necessary sysreg-defs.h; sync sysreg.h with the kernel sources and
fix the KVM selftests that use macros which suffered a rename.

Signed-off-by: Jing Zhang &lt;jingzhangos@google.com&gt;
Acked-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20231011195740.3349631-5-oliver.upton@linux.dev
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The users of sysreg.h (perf, KVM selftests) are now generating the
necessary sysreg-defs.h; sync sysreg.h with the kernel sources and
fix the KVM selftests that use macros which suffered a rename.

Signed-off-by: Jing Zhang &lt;jingzhangos@google.com&gt;
Acked-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20231011195740.3349631-5-oliver.upton@linux.dev
Signed-off-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Rip out old, param-based guest assert macros</title>
<updated>2023-08-02T21:43:16+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2023-07-29T00:36:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7ce7f8e754186f71ba7daffbc99543961a613bba'/>
<id>7ce7f8e754186f71ba7daffbc99543961a613bba</id>
<content type='text'>
Drop the param-based guest assert macros and enable the printf versions
for all selftests.  Note!  This change can affect tests even if they
don't use directly use guest asserts!  E.g. via library code, or due to
the compiler making different optimization decisions.

Link: https://lore.kernel.org/r/20230729003643.1053367-33-seanjc@google.com
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Drop the param-based guest assert macros and enable the printf versions
for all selftests.  Note!  This change can affect tests even if they
don't use directly use guest asserts!  E.g. via library code, or due to
the compiler making different optimization decisions.

Link: https://lore.kernel.org/r/20230729003643.1053367-33-seanjc@google.com
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Convert debug-exceptions to printf style GUEST_ASSERT</title>
<updated>2023-08-02T21:43:03+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2023-07-29T00:36:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bac9aeecc387a1436567b6e74f8257f7e8c4d194'/>
<id>bac9aeecc387a1436567b6e74f8257f7e8c4d194</id>
<content type='text'>
Convert ARM's debug exceptions  test to use printf-based GUEST_ASSERT().
Opportunistically Use GUEST_ASSERT_EQ() in guest_code_ss() so that the
expected vs. actual values get printed out.

Link: https://lore.kernel.org/r/20230729003643.1053367-12-seanjc@google.com
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Convert ARM's debug exceptions  test to use printf-based GUEST_ASSERT().
Opportunistically Use GUEST_ASSERT_EQ() in guest_code_ss() so that the
expected vs. actual values get printed out.

Link: https://lore.kernel.org/r/20230729003643.1053367-12-seanjc@google.com
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge remote-tracking branch 'kvm/queue' into HEAD</title>
<updated>2022-12-12T20:54:07+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-12-06T17:29:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9352e7470a1b4edd2fa9d235420ecc7bc3971bdc'/>
<id>9352e7470a1b4edd2fa9d235420ecc7bc3971bdc</id>
<content type='text'>
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

x86 fixes:

* 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 the MSR filter docs.

* 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

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 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().

* 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

Documentation:

* Remove deleted ioctls from documentation

* Various fixes
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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

x86 fixes:

* 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 the MSR filter docs.

* 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

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 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().

* 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

Documentation:

* Remove deleted ioctls from documentation

* Various fixes
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'kvmarm-6.2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD</title>
<updated>2022-12-09T08:12:12+00:00</updated>
<author>
<name>Paolo Bonzini</name>
<email>pbonzini@redhat.com</email>
</author>
<published>2022-12-06T17:27:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=eb5618911af0ac069d2313b289d4c19ca3379401'/>
<id>eb5618911af0ac069d2313b289d4c19ca3379401</id>
<content type='text'>
KVM/arm64 updates for 6.2

- 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.

- 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.

- Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
  stage-2 faults and access tracking. You name it, we got it, we
  probably broke it.

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

As a side effect, this tag also drags:

- The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
  series

- A shared branch with the arm64 tree that repaints all the system
  registers to match the ARM ARM's naming, and resulting in
  interesting conflicts
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
KVM/arm64 updates for 6.2

- 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.

- 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.

- Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
  stage-2 faults and access tracking. You name it, we got it, we
  probably broke it.

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

As a side effect, this tag also drags:

- The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
  series

- A shared branch with the arm64 tree that repaints all the system
  registers to match the ARM ARM's naming, and resulting in
  interesting conflicts
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: selftests: Enable single-step without a "full" ucall()</title>
<updated>2022-12-02T18:22:31+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2022-11-19T01:34:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ef16b2dff4d1c71eb32b306d400d4c0f3a383ba7'/>
<id>ef16b2dff4d1c71eb32b306d400d4c0f3a383ba7</id>
<content type='text'>
Add a new ucall hook, GUEST_UCALL_NONE(), to allow tests to make ucalls
without allocating a ucall struct, and use it to enable single-step
in ARM's debug-exceptions test.  Like the disable single-step path, the
enabling path also needs to ensure that no exclusive access sequences are
attempted after enabling single-step, as the exclusive monitor is cleared
on ERET from the debug exception taken to EL2.

The test currently "works" because clear_bit() isn't actually an atomic
operation... yet.

Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Message-Id: &lt;20221119013450.2643007-4-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>
Add a new ucall hook, GUEST_UCALL_NONE(), to allow tests to make ucalls
without allocating a ucall struct, and use it to enable single-step
in ARM's debug-exceptions test.  Like the disable single-step path, the
enabling path also needs to ensure that no exclusive access sequences are
attempted after enabling single-step, as the exclusive monitor is cleared
on ERET from the debug exception taken to EL2.

The test currently "works" because clear_bit() isn't actually an atomic
operation... yet.

Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Message-Id: &lt;20221119013450.2643007-4-seanjc@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Automatically do init_ucall() for non-barebones VMs</title>
<updated>2022-11-17T00:58:51+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2022-10-06T00:34:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=dc88244bf5488b04fb7bbe47d8d9c38ff8f7dbb4'/>
<id>dc88244bf5488b04fb7bbe47d8d9c38ff8f7dbb4</id>
<content type='text'>
Do init_ucall() automatically during VM creation to kill two (three?)
birds with one stone.

First, initializing ucall immediately after VM creations allows forcing
aarch64's MMIO ucall address to immediately follow memslot0.  This is
still somewhat fragile as tests could clobber the MMIO address with a
new memslot, but it's safe-ish since tests have to be conversative when
accounting for memslot0.  And this can be hardened in the future by
creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO
if the guest writes to a read-only memslot).  Add a TODO to document that
selftests can and should use a memslot for the ucall MMIO (doing so
requires yet more rework because tests assumes thay can use all memslots
except memslot0).

Second, initializing ucall for all VMs prepares for making ucall
initialization meaningful on all architectures.  aarch64 is currently the
only arch that needs to do any setup, but that will change in the future
by switching to a pool-based implementation (instead of the current
stack-based approach).

Lastly, defining the ucall MMIO address from common code will simplify
switching all architectures (except s390) to a common MMIO-based ucall
implementation (if there's ever sufficient motivation to do so).

Cc: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Reviewed-by: Andrew Jones &lt;andrew.jones@linux.dev&gt;
Tested-by: Peter Gonda &lt;pgonda@google.com&gt;
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Do init_ucall() automatically during VM creation to kill two (three?)
birds with one stone.

First, initializing ucall immediately after VM creations allows forcing
aarch64's MMIO ucall address to immediately follow memslot0.  This is
still somewhat fragile as tests could clobber the MMIO address with a
new memslot, but it's safe-ish since tests have to be conversative when
accounting for memslot0.  And this can be hardened in the future by
creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO
if the guest writes to a read-only memslot).  Add a TODO to document that
selftests can and should use a memslot for the ucall MMIO (doing so
requires yet more rework because tests assumes thay can use all memslots
except memslot0).

Second, initializing ucall for all VMs prepares for making ucall
initialization meaningful on all architectures.  aarch64 is currently the
only arch that needs to do any setup, but that will change in the future
by switching to a pool-based implementation (instead of the current
stack-based approach).

Lastly, defining the ucall MMIO address from common code will simplify
switching all architectures (except s390) to a common MMIO-based ucall
implementation (if there's ever sufficient motivation to do so).

Cc: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Reviewed-by: Andrew Jones &lt;andrew.jones@linux.dev&gt;
Tested-by: Peter Gonda &lt;pgonda@google.com&gt;
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: arm64: selftests: Disable single-step without relying on ucall()</title>
<updated>2022-11-17T00:58:14+00:00</updated>
<author>
<name>Sean Christopherson</name>
<email>seanjc@google.com</email>
</author>
<published>2022-11-17T00:23:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b3d937722de0e64eebe267451a0e3d5ed5107ef7'/>
<id>b3d937722de0e64eebe267451a0e3d5ed5107ef7</id>
<content type='text'>
Automatically disable single-step when the guest reaches the end of the
verified section instead of using an explicit ucall() to ask userspace to
disable single-step.  An upcoming change to implement a pool-based scheme
for ucall() will add an atomic operation (bit test and set) in the guest
ucall code, and if the compiler generate "old school" atomics, e.g.

  40e57c:       c85f7c20        ldxr    x0, [x1]
  40e580:       aa100011        orr     x17, x0, x16
  40e584:       c80ffc31        stlxr   w15, x17, [x1]
  40e588:       35ffffaf        cbnz    w15, 40e57c &lt;__aarch64_ldset8_sync+0x1c&gt;

the guest will hang as the local exclusive monitor is reset by eret,
i.e. the stlxr will always fail due to the debug exception taken to EL2.

Link: https://lore.kernel.org/all/20221006003409.649993-8-seanjc@google.com
Cc: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Link: https://lore.kernel.org/r/20221117002350.2178351-3-seanjc@google.com
Reviewed-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Automatically disable single-step when the guest reaches the end of the
verified section instead of using an explicit ucall() to ask userspace to
disable single-step.  An upcoming change to implement a pool-based scheme
for ucall() will add an atomic operation (bit test and set) in the guest
ucall code, and if the compiler generate "old school" atomics, e.g.

  40e57c:       c85f7c20        ldxr    x0, [x1]
  40e580:       aa100011        orr     x17, x0, x16
  40e584:       c80ffc31        stlxr   w15, x17, [x1]
  40e588:       35ffffaf        cbnz    w15, 40e57c &lt;__aarch64_ldset8_sync+0x1c&gt;

the guest will hang as the local exclusive monitor is reset by eret,
i.e. the stlxr will always fail due to the debug exception taken to EL2.

Link: https://lore.kernel.org/all/20221006003409.649993-8-seanjc@google.com
Cc: Oliver Upton &lt;oliver.upton@linux.dev&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Signed-off-by: Sean Christopherson &lt;seanjc@google.com&gt;
Link: https://lore.kernel.org/r/20221117002350.2178351-3-seanjc@google.com
Reviewed-by: Oliver Upton &lt;oliver.upton@linux.dev&gt;
</pre>
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