<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/tools/testing/selftests/kvm, branch linux-5.14.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>KVM: selftests: Fix nested SVM tests when built with clang</title>
<updated>2021-11-17T10:04:13+00:00</updated>
<author>
<name>Jim Mattson</name>
<email>jmattson@google.com</email>
</author>
<published>2021-09-30T00:36:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f0c9660943860a295adba5958f3469ac6e1f0a38'/>
<id>f0c9660943860a295adba5958f3469ac6e1f0a38</id>
<content type='text'>
[ Upstream commit ed290e1c20da19fa100a3e0f421aa31b65984960 ]

Though gcc conveniently compiles a simple memset to "rep stos," clang
prefers to call the libc version of memset. If a test is dynamically
linked, the libc memset isn't available in L1 (nor is the PLT or the
GOT, for that matter). Even if the test is statically linked, the libc
memset may choose to use some CPU features, like AVX, which may not be
enabled in L1. Note that __builtin_memset doesn't solve the problem,
because (a) the compiler is free to call memset anyway, and (b)
__builtin_memset may also choose to use features like AVX, which may
not be available in L1.

To avoid a myriad of problems, use an explicit "rep stos" to clear the
VMCB in generic_svm_setup(), which is called both from L0 and L1.

Reported-by: Ricardo Koller &lt;ricarkol@google.com&gt;
Signed-off-by: Jim Mattson &lt;jmattson@google.com&gt;
Fixes: 20ba262f8631a ("selftests: KVM: AMD Nested test infrastructure")
Message-Id: &lt;20210930003649.4026553-1-jmattson@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit ed290e1c20da19fa100a3e0f421aa31b65984960 ]

Though gcc conveniently compiles a simple memset to "rep stos," clang
prefers to call the libc version of memset. If a test is dynamically
linked, the libc memset isn't available in L1 (nor is the PLT or the
GOT, for that matter). Even if the test is statically linked, the libc
memset may choose to use some CPU features, like AVX, which may not be
enabled in L1. Note that __builtin_memset doesn't solve the problem,
because (a) the compiler is free to call memset anyway, and (b)
__builtin_memset may also choose to use features like AVX, which may
not be available in L1.

To avoid a myriad of problems, use an explicit "rep stos" to clear the
VMCB in generic_svm_setup(), which is called both from L0 and L1.

Reported-by: Ricardo Koller &lt;ricarkol@google.com&gt;
Signed-off-by: Jim Mattson &lt;jmattson@google.com&gt;
Fixes: 20ba262f8631a ("selftests: KVM: AMD Nested test infrastructure")
Message-Id: &lt;20210930003649.4026553-1-jmattson@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests: kvm: fix mismatched fclose() after popen()</title>
<updated>2021-11-17T10:03:53+00:00</updated>
<author>
<name>Shuah Khan</name>
<email>skhan@linuxfoundation.org</email>
</author>
<published>2021-10-21T17:56:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=65b5763eef821dd570667c8b20f5a2b972aace38'/>
<id>65b5763eef821dd570667c8b20f5a2b972aace38</id>
<content type='text'>
[ Upstream commit c3867ab5924b7a9a0b4a117902a08669d8be7c21 ]

get_warnings_count() does fclose() using File * returned from popen().
Fix it to call pclose() as it should.

tools/testing/selftests/kvm/x86_64/mmio_warning_test
x86_64/mmio_warning_test.c: In function ‘get_warnings_count’:
x86_64/mmio_warning_test.c:87:9: warning: ‘fclose’ called on pointer returned from a mismatched allocation function [-Wmismatched-dealloc]
   87 |         fclose(f);
      |         ^~~~~~~~~
x86_64/mmio_warning_test.c:84:13: note: returned from ‘popen’
   84 |         f = popen("dmesg | grep \"WARNING:\" | wc -l", "r");
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit c3867ab5924b7a9a0b4a117902a08669d8be7c21 ]

get_warnings_count() does fclose() using File * returned from popen().
Fix it to call pclose() as it should.

tools/testing/selftests/kvm/x86_64/mmio_warning_test
x86_64/mmio_warning_test.c: In function ‘get_warnings_count’:
x86_64/mmio_warning_test.c:87:9: warning: ‘fclose’ called on pointer returned from a mismatched allocation function [-Wmismatched-dealloc]
   87 |         fclose(f);
      |         ^~~~~~~~~
x86_64/mmio_warning_test.c:84:13: note: returned from ‘popen’
   84 |         f = popen("dmesg | grep \"WARNING:\" | wc -l", "r");
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests: KVM: Align SMCCC call with the spec in steal_time</title>
<updated>2021-10-09T13:02:41+00:00</updated>
<author>
<name>Oliver Upton</name>
<email>oupton@google.com</email>
</author>
<published>2021-09-21T17:11:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=11e4acd09e3fda3233225a131c2121684209720f'/>
<id>11e4acd09e3fda3233225a131c2121684209720f</id>
<content type='text'>
[ Upstream commit 01f91acb55be7aac3950b89c458bcea9ef6e4f49 ]

The SMC64 calling convention passes a function identifier in w0 and its
parameters in x1-x17. Given this, there are two deviations in the
SMC64 call performed by the steal_time test: the function identifier is
assigned to a 64 bit register and the parameter is only 32 bits wide.

Align the call with the SMCCC by using a 32 bit register to handle the
function identifier and increasing the parameter width to 64 bits.

Suggested-by: Andrew Jones &lt;drjones@redhat.com&gt;
Signed-off-by: Oliver Upton &lt;oupton@google.com&gt;
Reviewed-by: Andrew Jones &lt;drjones@redhat.com&gt;
Message-Id: &lt;20210921171121.2148982-3-oupton@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 01f91acb55be7aac3950b89c458bcea9ef6e4f49 ]

The SMC64 calling convention passes a function identifier in w0 and its
parameters in x1-x17. Given this, there are two deviations in the
SMC64 call performed by the steal_time test: the function identifier is
assigned to a 64 bit register and the parameter is only 32 bits wide.

Align the call with the SMCCC by using a 32 bit register to handle the
function identifier and increasing the parameter width to 64 bits.

Suggested-by: Andrew Jones &lt;drjones@redhat.com&gt;
Signed-off-by: Oliver Upton &lt;oupton@google.com&gt;
Reviewed-by: Andrew Jones &lt;drjones@redhat.com&gt;
Message-Id: &lt;20210921171121.2148982-3-oupton@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests: kvm: fix get_run_delay() ignoring fscanf() return warn</title>
<updated>2021-10-09T13:02:40+00:00</updated>
<author>
<name>Shuah Khan</name>
<email>skhan@linuxfoundation.org</email>
</author>
<published>2021-09-15T21:28:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=95342046ba4e885eaaa042fabafec4e7a7c8d742'/>
<id>95342046ba4e885eaaa042fabafec4e7a7c8d742</id>
<content type='text'>
[ Upstream commit f5013d412a43662b63f3d5f3a804d63213acd471 ]

Fix get_run_delay() to check fscanf() return value to get rid of the
following warning. When fscanf() fails return MIN_RUN_DELAY_NS from
get_run_delay(). Move MIN_RUN_DELAY_NS from steal_time.c to test_util.h
so get_run_delay() and steal_time.c can use it.

lib/test_util.c: In function ‘get_run_delay’:
lib/test_util.c:316:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  316 |  fscanf(fp, "%ld %ld ", &amp;val[0], &amp;val[1]);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit f5013d412a43662b63f3d5f3a804d63213acd471 ]

Fix get_run_delay() to check fscanf() return value to get rid of the
following warning. When fscanf() fails return MIN_RUN_DELAY_NS from
get_run_delay(). Move MIN_RUN_DELAY_NS from steal_time.c to test_util.h
so get_run_delay() and steal_time.c can use it.

lib/test_util.c: In function ‘get_run_delay’:
lib/test_util.c:316:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  316 |  fscanf(fp, "%ld %ld ", &amp;val[0], &amp;val[1]);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests: kvm: move get_run_delay() into lib/test_util</title>
<updated>2021-10-09T13:02:40+00:00</updated>
<author>
<name>Shuah Khan</name>
<email>skhan@linuxfoundation.org</email>
</author>
<published>2021-09-15T21:28:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=80b7cc21401b9eb4cf4e4ecc1258877bd5419d58'/>
<id>80b7cc21401b9eb4cf4e4ecc1258877bd5419d58</id>
<content type='text'>
[ Upstream commit 20175d5eac5bb94a7a3719ef275337fc9abf26ac ]

get_run_delay() is defined static in xen_shinfo_test and steal_time test.
Move it to lib and remove code duplication.

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 20175d5eac5bb94a7a3719ef275337fc9abf26ac ]

get_run_delay() is defined static in xen_shinfo_test and steal_time test.
Move it to lib and remove code duplication.

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests:kvm: fix get_trans_hugepagesz() ignoring fscanf() return warn</title>
<updated>2021-10-09T13:02:40+00:00</updated>
<author>
<name>Shuah Khan</name>
<email>skhan@linuxfoundation.org</email>
</author>
<published>2021-09-15T21:28:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b6d7e8c09c4086d51e277cd00f136448750364ef'/>
<id>b6d7e8c09c4086d51e277cd00f136448750364ef</id>
<content type='text'>
[ Upstream commit 3a4f0cc693cd3d80e66a255f0bff0e2c0461eef1 ]

Fix get_trans_hugepagesz() to check fscanf() return value to get rid
of the following warning:

lib/test_util.c: In function ‘get_trans_hugepagesz’:
lib/test_util.c:138:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  138 |  fscanf(f, "%ld", &amp;size);
      |  ^~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3a4f0cc693cd3d80e66a255f0bff0e2c0461eef1 ]

Fix get_trans_hugepagesz() to check fscanf() return value to get rid
of the following warning:

lib/test_util.c: In function ‘get_trans_hugepagesz’:
lib/test_util.c:138:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  138 |  fscanf(f, "%ld", &amp;size);
      |  ^~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>selftests:kvm: fix get_warnings_count() ignoring fscanf() return warn</title>
<updated>2021-10-09T13:02:40+00:00</updated>
<author>
<name>Shuah Khan</name>
<email>skhan@linuxfoundation.org</email>
</author>
<published>2021-09-15T21:28:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b664df7bb40ae9328bd5e7937338f8f229ea7cb2'/>
<id>b664df7bb40ae9328bd5e7937338f8f229ea7cb2</id>
<content type='text'>
[ Upstream commit 39a71f712d8a13728febd8f3cb3f6db7e1fa7221 ]

Fix get_warnings_count() to check fscanf() return value to get rid
of the following warning:

x86_64/mmio_warning_test.c: In function ‘get_warnings_count’:
x86_64/mmio_warning_test.c:85:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   85 |  fscanf(f, "%d", &amp;warnings);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 39a71f712d8a13728febd8f3cb3f6db7e1fa7221 ]

Fix get_warnings_count() to check fscanf() return value to get rid
of the following warning:

x86_64/mmio_warning_test.c: In function ‘get_warnings_count’:
x86_64/mmio_warning_test.c:85:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   85 |  fscanf(f, "%d", &amp;warnings);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Acked-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: fix hyperv_clock test</title>
<updated>2021-08-04T13:43:03+00:00</updated>
<author>
<name>Maxim Levitsky</name>
<email>mlevitsk@redhat.com</email>
</author>
<published>2021-08-04T11:20:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=13c2c3cfe01952575b1dd5e24d450fcccff93bc0'/>
<id>13c2c3cfe01952575b1dd5e24d450fcccff93bc0</id>
<content type='text'>
The test was mistakenly using addr_gpa2hva on a gva and that happened
to work accidentally.  Commit 106a2e766eae ("KVM: selftests: Lower the
min virtual address for misc page allocations") revealed this bug.

Fixes: 2c7f76b4c42b ("selftests: kvm: Add basic Hyper-V clocksources tests", 2021-03-18)
Signed-off-by: Maxim Levitsky &lt;mlevitsk@redhat.com&gt;
Message-Id: &lt;20210804112057.409498-1-mlevitsk@redhat.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>
The test was mistakenly using addr_gpa2hva on a gva and that happened
to work accidentally.  Commit 106a2e766eae ("KVM: selftests: Lower the
min virtual address for misc page allocations") revealed this bug.

Fixes: 2c7f76b4c42b ("selftests: kvm: Add basic Hyper-V clocksources tests", 2021-03-18)
Signed-off-by: Maxim Levitsky &lt;mlevitsk@redhat.com&gt;
Message-Id: &lt;20210804112057.409498-1-mlevitsk@redhat.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Test access to XMM fast hypercalls</title>
<updated>2021-08-03T10:16:40+00:00</updated>
<author>
<name>Vitaly Kuznetsov</name>
<email>vkuznets@redhat.com</email>
</author>
<published>2021-07-30T12:26:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2476b5a1b16ced78a80629da8ff87538d5c95073'/>
<id>2476b5a1b16ced78a80629da8ff87538d5c95073</id>
<content type='text'>
Check that #UD is raised if bit 16 is clear in
HYPERV_CPUID_FEATURES.EDX and an 'XMM fast' hypercall is issued.

Signed-off-by: Vitaly Kuznetsov &lt;vkuznets@redhat.com&gt;
Reviewed-by: Siddharth Chandrasekaran &lt;sidcha@amazon.de&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Message-Id: &lt;20210730122625.112848-5-vkuznets@redhat.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>
Check that #UD is raised if bit 16 is clear in
HYPERV_CPUID_FEATURES.EDX and an 'XMM fast' hypercall is issued.

Signed-off-by: Vitaly Kuznetsov &lt;vkuznets@redhat.com&gt;
Reviewed-by: Siddharth Chandrasekaran &lt;sidcha@amazon.de&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Message-Id: &lt;20210730122625.112848-5-vkuznets@redhat.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: selftests: Introduce access_tracking_perf_test</title>
<updated>2021-07-27T20:59:00+00:00</updated>
<author>
<name>David Matlack</name>
<email>dmatlack@google.com</email>
</author>
<published>2021-07-13T22:09:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c33e05d9b067433252b1008d2f37bf64e11151f1'/>
<id>c33e05d9b067433252b1008d2f37bf64e11151f1</id>
<content type='text'>
This test measures the performance effects of KVM's access tracking.
Access tracking is driven by the MMU notifiers test_young, clear_young,
and clear_flush_young. These notifiers do not have a direct userspace
API, however the clear_young notifier can be triggered by marking a
pages as idle in /sys/kernel/mm/page_idle/bitmap. This test leverages
that mechanism to enable access tracking on guest memory.

To measure performance this test runs a VM with a configurable number of
vCPUs that each touch every page in disjoint regions of memory.
Performance is measured in the time it takes all vCPUs to finish
touching their predefined region.

Example invocation:

  $ ./access_tracking_perf_test -v 8
  Testing guest mode: PA-bits:ANY, VA-bits:48,  4K pages
  guest physical test memory offset: 0xffdfffff000

  Populating memory             : 1.337752570s
  Writing to populated memory   : 0.010177640s
  Reading from populated memory : 0.009548239s
  Mark memory idle              : 23.973131748s
  Writing to idle memory        : 0.063584496s
  Mark memory idle              : 24.924652964s
  Reading from idle memory      : 0.062042814s

Breaking down the results:

 * "Populating memory": The time it takes for all vCPUs to perform the
   first write to every page in their region.

 * "Writing to populated memory" / "Reading from populated memory": The
   time it takes for all vCPUs to write and read to every page in their
   region after it has been populated. This serves as a control for the
   later results.

 * "Mark memory idle": The time it takes for every vCPU to mark every
   page in their region as idle through page_idle.

 * "Writing to idle memory" / "Reading from idle memory": The time it
   takes for all vCPUs to write and read to every page in their region
   after it has been marked idle.

This test should be portable across architectures but it is only enabled
for x86_64 since that's all I have tested.

Reviewed-by: Ben Gardon &lt;bgardon@google.com&gt;
Signed-off-by: David Matlack &lt;dmatlack@google.com&gt;
Message-Id: &lt;20210713220957.3493520-7-dmatlack@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
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<pre>
This test measures the performance effects of KVM's access tracking.
Access tracking is driven by the MMU notifiers test_young, clear_young,
and clear_flush_young. These notifiers do not have a direct userspace
API, however the clear_young notifier can be triggered by marking a
pages as idle in /sys/kernel/mm/page_idle/bitmap. This test leverages
that mechanism to enable access tracking on guest memory.

To measure performance this test runs a VM with a configurable number of
vCPUs that each touch every page in disjoint regions of memory.
Performance is measured in the time it takes all vCPUs to finish
touching their predefined region.

Example invocation:

  $ ./access_tracking_perf_test -v 8
  Testing guest mode: PA-bits:ANY, VA-bits:48,  4K pages
  guest physical test memory offset: 0xffdfffff000

  Populating memory             : 1.337752570s
  Writing to populated memory   : 0.010177640s
  Reading from populated memory : 0.009548239s
  Mark memory idle              : 23.973131748s
  Writing to idle memory        : 0.063584496s
  Mark memory idle              : 24.924652964s
  Reading from idle memory      : 0.062042814s

Breaking down the results:

 * "Populating memory": The time it takes for all vCPUs to perform the
   first write to every page in their region.

 * "Writing to populated memory" / "Reading from populated memory": The
   time it takes for all vCPUs to write and read to every page in their
   region after it has been populated. This serves as a control for the
   later results.

 * "Mark memory idle": The time it takes for every vCPU to mark every
   page in their region as idle through page_idle.

 * "Writing to idle memory" / "Reading from idle memory": The time it
   takes for all vCPUs to write and read to every page in their region
   after it has been marked idle.

This test should be portable across architectures but it is only enabled
for x86_64 since that's all I have tested.

Reviewed-by: Ben Gardon &lt;bgardon@google.com&gt;
Signed-off-by: David Matlack &lt;dmatlack@google.com&gt;
Message-Id: &lt;20210713220957.3493520-7-dmatlack@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
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