KVM: selftests: Restore assert for non-nested VMs in access tracking test

Restore the assert (on x86-64) that <10% of pages are still idle when NOT
running as a nested VM in the access tracking test. The original assert
was converted to a "warning" to avoid false failures when running the
test in a VM, but the non-nested case does not suffer from the same
"infinite TLB size" issue.

Using the HYPERVISOR flag isn't infallible as VMMs aren't strictly
required to enumerate the "feature" in CPUID, but practically speaking
anyone that is running KVM selftests in VMs is going to be using a VMM
and hypervisor that sets the HYPERVISOR flag.

Cc: David Matlack <dmatlack@google.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221129175300.4052283-3-seanjc@google.com

KVM: selftests: Fix inverted "warning" in access tracking perf test

Warn if the number of idle pages is greater than or equal to 10% of the
total number of pages, not if the percentage of idle pages is less than
10%. The original code asserted that less than 10% of pages were still
idle, but the check got inverted when the assert was converted to a
warning.

Opportunistically clean up the warning; selftests are 64-bit only, there
is no need to use "%PRIu64" instead of "%lu".

Fixes: 6336a810db5c ("KVM: selftests: replace assertion with warning in access_tracking_perf_test")
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221129175300.4052283-2-seanjc@google.com

KVM: selftests: Have perf_test_util signal when to stop vCPUs

Signal that a test run is complete through perf_test_args instead of
having tests open code a similar solution. Ensure that the field resets
to false at the beginning of a test run as the structure is reused
between test runs, eliminating a couple of bugs:

access_tracking_perf_test hangs indefinitely on a subsequent test run,
as 'done' remains true. The bug doesn't amount to much right now, as x86
supports a single guest mode. However, this is a precondition of
enabling the test for other architectures with >1 guest mode, like
arm64.

memslot_modification_stress_test has the exact opposite problem, where
subsequent test runs complete immediately as 'run_vcpus' remains false.

Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
[oliver: added commit message, preserve spin_wait_for_next_iteration()]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221118211503.4049023-2-oliver.upton@linux.dev

KVM: selftests: Rename perf_test_util symbols to memstress

Replace the perf_test_ prefix on symbol names with memstress_ to match
the new file name.

"memstress" better describes the functionality proveded by this library,
which is to provide functionality for creating and running a VM that
stresses VM memory by reading and writing to guest memory on all vCPUs
in parallel.

"memstress" also contains the same number of chracters as "perf_test",
making it a drop-in replacement in symbols, e.g. function names, without
impacting line lengths. Also the lack of underscore between "mem" and
"stress" makes it clear "memstress" is a noun.

Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221012165729.3505266-4-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Rename perf_test_util.[ch] to memstress.[ch]

Rename the perf_test_util.[ch] files to memstress.[ch]. Symbols are
renamed in the following commit to reduce the amount of churn here in
hopes of playiing nice with git's file rename detection.

The name "memstress" was chosen to better describe the functionality
proveded by this library, which is to create and run a VM that
reads/writes to guest memory on all vCPUs in parallel.

"memstress" also contains the same number of chracters as "perf_test",
making it a drop-in replacement in symbols, e.g. function names, without
impacting line lengths. Also the lack of underscore between "mem" and
"stress" makes it clear "memstress" is a noun.

Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221012165729.3505266-2-dmatlack@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: randomize which pages are written vs read

Randomize which pages are written vs read using the random number
generator.

Change the variable wr_fract and associated function calls to
write_percent that now operates as a percentage from 0 to 100 where X
means each page has an X% chance of being written. Change the -f
argument to -w to reflect the new variable semantics. Keep the same
default of 100% writes.

Population always uses 100% writes to ensure all memory is actually
populated and not just mapped to the zero page. The prevents expensive
copy-on-write faults from occurring during the dirty memory iterations
below, which would pollute the performance results.

Each vCPU calculates its own random seed by adding its index to the
seed provided.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20221107182208.479157-4-coltonlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add atoi_positive() and atoi_non_negative() for input validation

Many KVM selftests take command line arguments which are supposed to be
positive (>0) or non-negative (>=0). Some tests do these validation and
some missed adding the check.

Add atoi_positive() and atoi_non_negative() to validate inputs in
selftests before proceeding to use those values.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221103191719.1559407-7-vipinsh@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: Add atoi_paranoid() to catch errors missed by atoi()

atoi() doesn't detect errors. There is no way to know that a 0 return
is correct conversion or due to an error.

Introduce atoi_paranoid() to detect errors and provide correct
conversion. Replace all atoi() calls with atoi_paranoid().

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Suggested-by: David Matlack <dmatlack@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221103191719.1559407-4-vipinsh@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

KVM: selftests: replace assertion with warning in access_tracking_perf_test

Page_idle uses {ptep/pmdp}_clear_young_notify which in turn calls
the mmu notifier callback ->clear_young(), which purposefully
does not flush the TLB.

When running the test in a nested guest, point 1. of the test
doc header is violated, because KVM TLB is unbounded by size
and since no flush is forced, KVM does not update the sptes
accessed/idle bits resulting in guest assertion failure.

More precisely, only the first ACCESS_WRITE in run_test() actually
makes visible changes, because sptes are created and the accessed
bit is set to 1 (or idle bit is 0). Then the first mark_memory_idle()
passes since access bit is still one, and sets all pages as idle
(or not accessed). When the next write is performed, the update
is not flushed therefore idle is still 1 and next mark_memory_idle()
fails.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220926082923.299554-1-eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Add TEST_REQUIRE macros to reduce skipping copy+paste

Add TEST_REQUIRE() and __TEST_REQUIRE() to replace the myriad open coded
instances of selftests exiting with KSFT_SKIP after printing an
informational message. In addition to reducing the amount of boilerplate
code in selftests, the UPPERCASE macro names make it easier to visually
identify a test's requirements.

Convert usage that erroneously uses something other than print_skip()
and/or "exits" with '0' or some other non-KSFT_SKIP value.

Intentionally drop a kvm_vm_free() in aarch64/debug-exceptions.c as part
of the conversion. All memory and file descriptors are freed on process
exit, so the explicit free is superfluous.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Purge vm+vcpu_id == vcpu silliness

Take a vCPU directly instead of a VM+vcpu pair in all vCPU-scoped helpers
and ioctls.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Stop conflating vCPU index and ID in perf tests

Track vCPUs by their 'struct kvm_vcpu' object, and stop assuming that a
vCPU's ID is the same as its index when referencing a vCPU's metadata.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Move vCPU thread creation and joining to common helpers

Move vCPU thread creation and joining to common helper functions. This
is in preparation for the next commit which ensures that all vCPU
threads are fully created before entering guest mode on any one
vCPU.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211111001257.1446428-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Start at iteration 0 instead of -1

Start at iteration 0 instead of -1 to avoid having to initialize
vcpu_last_completed_iteration when setting up vCPU threads. This
simplifies the next commit where we move vCPU thread initialization
out to a common helper.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20211111001257.1446428-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Sync perf_test_args to guest during VM creation

Copy perf_test_args to the guest during VM creation instead of relying on
the caller to do so at their leisure. Ideally, tests wouldn't even be
able to modify perf_test_args, i.e. they would have no motivation to do
the sync, but enforcing that is arguably a net negative for readability.

No functional change intended.

[Set wr_fract=1 by default and add helper to override it since the new
access_tracking_perf_test needs to set it dynamically.]

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211111000310.1435032-13-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Fill per-vCPU struct during "perf_test" VM creation

Fill the per-vCPU args when creating the perf_test VM instead of having
the caller do so. This helps ensure that any adjustments to the number
of pages (and thus vcpu_memory_bytes) are reflected in the per-VM args.
Automatically filling the per-vCPU args will also allow a future patch
to do the sync to the guest during creation.

Signed-off-by: Sean Christopherson <seanjc@google.com>
[Updated access_tracking_perf_test as well.]
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211111000310.1435032-12-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Refactor help message for -s backing_src

All selftests that support the backing_src option were printing their
own description of the flag and then calling backing_src_help() to dump
the list of available backing sources. Consolidate the flag printing in
backing_src_help() to align indentation, reduce duplicated strings, and
improve consistency across tests.

Note: Passing "-s" to backing_src_help is unnecessary since every test
uses the same flag. However I decided to keep it for code readability
at the call sites.

While here this opportunistically fixes the incorrectly interleaved
printing -x help message and list of backing source types in
dirty_log_perf_test.

Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210917173657.44011-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Move vcpu_args_set into perf_test_util

perf_test_util is used to set up KVM selftests where vCPUs touch a
region of memory. The guest code is implemented in perf_test_util.c (not
the calling selftests). The guest code requires a 1 parameter, the
vcpuid, which has to be set by calling vcpu_args_set(vm, vcpu_id, 1,
vcpu_id).

Today all of the selftests that use perf_test_util are making this call.
Instead, perf_test_util should just do it. This will save some code but
more importantly prevents mistakes since totally non-obvious that this
needs to be called and failing to do so results in vCPUs not accessing
the right regions of memory.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210805172821.2622793-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Support multiple slots in dirty_log_perf_test

Introduce a new option to dirty_log_perf_test: -x number_of_slots. This
causes the test to attempt to split the region of memory into the given
number of slots. If the region cannot be evenly divided, the test will
fail.

This allows testing with more than one slot and therefore measure how
performance scales with the number of memslots.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210804222844.1419481-8-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM: selftests: Introduce access_tracking_perf_test

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 <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210713220957.3493520-7-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>