linux-stable.git/tools/testing/selftests/kvm, branch v6.8

KVM: selftests: Add a testcase to verify GUEST_MEMFD and READONLY are exclusive

2024-02-23T01:07:06+00:00

Extend set_memory_region_test's invalid flags subtest to verify that
GUEST_MEMFD is incompatible with READONLY.  GUEST_MEMFD doesn't currently
support writes from userspace and KVM doesn't support emulated MMIO on
private accesses, and so KVM is supposed to reject the GUEST_MEMFD+READONLY
in order to avoid configuration that KVM can't support.

Link: https://lore.kernel.org/r/20240222190612.2942589-6-seanjc@google.com
Signed-off-by: Sean Christopherson

KVM: selftests: Create GUEST_MEMFD for relevant invalid flags testcases

2024-02-23T01:07:06+00:00

Actually create a GUEST_MEMFD instance and pass it to KVM when doing
negative tests for KVM_SET_USER_MEMORY_REGION2 + KVM_MEM_GUEST_MEMFD.
Without a valid GUEST_MEMFD file descriptor, KVM_SET_USER_MEMORY_REGION2
will always fail with -EINVAL, resulting in false passes for any and all
tests of illegal combinations of KVM_MEM_GUEST_MEMFD and other flags.

Fixes: 5d74316466f4 ("KVM: selftests: Add a memory region subtest to validate invalid flags")
Link: https://lore.kernel.org/r/20240222190612.2942589-5-seanjc@google.com
Signed-off-by: Sean Christopherson

Merge tag 'kvm-x86-selftests-6.8-rcN' of https://github.com/kvm-x86/linux into HEAD

2024-02-14T17:34:58+00:00

KVM selftests fixes/cleanups (and one KVM x86 cleanup) for 6.8:

 - Remove redundant newlines from error messages.

 - Delete an unused variable in the AMX test (which causes build failures when
   compiling with -Werror).

 - Fail instead of skipping tests if open(), e.g. of /dev/kvm, fails with an
   error code other than ENOENT (a Hyper-V selftest bug resulted in an EMFILE,
   and the test eventually got skipped).

 - Fix TSC related bugs in several Hyper-V selftests.

 - Fix a bug in the dirty ring logging test where a sem_post() could be left
   pending across multiple runs, resulting in incorrect synchronization between
   the main thread and the vCPU worker thread.

 - Relax the dirty log split test's assertions on 4KiB mappings to fix false
   positives due to the number of mappings for memslot 0 (used for code and
   data that is NOT being dirty logged) changing, e.g. due to NUMA balancing.

 - Have KVM's gtod_is_based_on_tsc() return "bool" instead of an "int" (the
   function generates boolean values, and all callers treat the return value as
   a bool).

KVM: selftests: Don't assert on exact number of 4KiB in dirty log split test

2024-02-06T18:55:13+00:00

Drop dirty_log_page_splitting_test's assertion that the number of 4KiB
pages remains the same across dirty logging being enabled and disabled, as
the test doesn't guarantee that mappings outside of the memslots being
dirty logged are stable, e.g. KVM's mappings for code and pages in
memslot0 can be zapped by things like NUMA balancing.

To preserve the spirit of the check, assert that (a) the number of 4KiB
pages after splitting is _at least_ the number of 4KiB pages across all
memslots under test, and (b) the number of hugepages before splitting adds
up to the number of pages across all memslots under test.  (b) is a little
tenuous as it relies on memslot0 being incompatible with transparent
hugepages, but that holds true for now as selftests explicitly madvise()
MADV_NOHUGEPAGE for memslot0 (__vm_create() unconditionally specifies the
backing type as VM_MEM_SRC_ANONYMOUS).

Reported-by: Yi Lai 
Reported-by: Tao Su 
Reviewed-by: Tao Su 
Link: https://lore.kernel.org/r/20240131222728.4100079-1-seanjc@google.com
Signed-off-by: Sean Christopherson

KVM: selftests: Fix a semaphore imbalance in the dirty ring logging test

2024-02-06T18:53:30+00:00

When finishing the final iteration of dirty_log_test testcase, set
host_quit _before_ the final "continue" so that the vCPU worker doesn't
run an extra iteration, and delete the hack-a-fix of an extra "continue"
from the dirty ring testcase.  This fixes a bug where the extra post to
sem_vcpu_cont may not be consumed, which results in failures in subsequent
runs of the testcases.  The bug likely was missed during development as
x86 supports only a single "guest mode", i.e. there aren't any subsequent
testcases after the dirty ring test, because for_each_guest_mode() only
runs a single iteration.

For the regular dirty log testcases, letting the vCPU run one extra
iteration is a non-issue as the vCPU worker waits on sem_vcpu_cont if and
only if the worker is explicitly told to stop (vcpu_sync_stop_requested).
But for the dirty ring test, which needs to periodically stop the vCPU to
reap the dirty ring, letting the vCPU resume the guest _after_ the last
iteration means the vCPU will get stuck without an extra "continue".

However, blindly firing off an post to sem_vcpu_cont isn't guaranteed to
be consumed, e.g. if the vCPU worker sees host_quit==true before resuming
the guest.  This results in a dangling sem_vcpu_cont, which leads to
subsequent iterations getting out of sync, as the vCPU worker will
continue on before the main task is ready for it to resume the guest,
leading to a variety of asserts, e.g.

  ==== Test Assertion Failure ====
  dirty_log_test.c:384: dirty_ring_vcpu_ring_full
  pid=14854 tid=14854 errno=22 - Invalid argument
     1  0x00000000004033eb: dirty_ring_collect_dirty_pages at dirty_log_test.c:384
     2  0x0000000000402d27: log_mode_collect_dirty_pages at dirty_log_test.c:505
     3   (inlined by) run_test at dirty_log_test.c:802
     4  0x0000000000403dc7: for_each_guest_mode at guest_modes.c:100
     5  0x0000000000401dff: main at dirty_log_test.c:941 (discriminator 3)
     6  0x0000ffff9be173c7: ?? ??:0
     7  0x0000ffff9be1749f: ?? ??:0
     8  0x000000000040206f: _start at ??:?
  Didn't continue vcpu even without ring full

Alternatively, the test could simply reset the semaphores before each
testcase, but papering over hacks with more hacks usually ends in tears.

Reported-by: Shaoqin Huang 
Fixes: 84292e565951 ("KVM: selftests: Add dirty ring buffer test")
Reviewed-by: Peter Xu 
Reviewed-by: Shaoqin Huang 
Link: https://lore.kernel.org/r/20240202231831.354848-1-seanjc@google.com
Signed-off-by: Sean Christopherson

KVM: selftests: Make hyperv_clock require TSC based system clocksource

2024-02-01T16:58:15+00:00

KVM sets up Hyper-V TSC page clocksource for its guests when system
clocksource is 'based on TSC' (see gtod_is_based_on_tsc()), running
hyperv_clock with any other clocksource leads to imminent failure.

Add the missing requirement to make the test skip gracefully.

Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20240109141121.1619463-5-vkuznets@redhat.com
Signed-off-by: Sean Christopherson

KVM: selftests: Run clocksource dependent tests with hyperv_clocksource_tsc_page too

2024-02-01T16:58:14+00:00

KVM's 'gtod_is_based_on_tsc()' recognizes two clocksources: 'tsc' and
'hyperv_clocksource_tsc_page' and enables kvmclock in 'masterclock'
mode when either is in use. Transform 'sys_clocksource_is_tsc()' into
'sys_clocksource_is_based_on_tsc()' to support the later. This affects
two tests: kvm_clock_test and vmx_nested_tsc_scaling_test, both seem
to work well when system clocksource is 'hyperv_clocksource_tsc_page'.

Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20240109141121.1619463-4-vkuznets@redhat.com
Signed-off-by: Sean Christopherson

KVM: selftests: Use generic sys_clocksource_is_tsc() in vmx_nested_tsc_scaling_test

2024-02-01T16:58:13+00:00

Despite its name, system_has_stable_tsc() just checks that system
clocksource is 'tsc'; this can now be done with generic
sys_clocksource_is_tsc().

No functional change intended.

Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20240109141121.1619463-3-vkuznets@redhat.com
Signed-off-by: Sean Christopherson

KVM: selftests: Generalize check_clocksource() from kvm_clock_test

2024-02-01T16:58:13+00:00

Several existing x86 selftests need to check that the underlying system
clocksource is TSC or based on TSC but every test implements its own
check. As a first step towards unification, extract check_clocksource()
from kvm_clock_test and split it into two functions: arch-neutral
'sys_get_cur_clocksource()' and x86-specific 'sys_clocksource_is_tsc()'.
Fix a couple of pre-existing issues in kvm_clock_test: memory leakage in
check_clocksource() and using TEST_ASSERT() instead of TEST_REQUIRE().
The change also makes the test fail when system clocksource can't be read
from sysfs.

Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20240109141121.1619463-2-vkuznets@redhat.com
[sean: eliminate if-elif pattern just to set a bool true]
Signed-off-by: Sean Christopherson

KVM: selftests: Fail tests when open() fails with !ENOENT

2024-01-30T20:32:03+00:00

open_path_or_exit() is used for '/dev/kvm', '/dev/sev', and
'/sys/module/%s/parameters/%s' and skipping test when the entry is missing
is completely reasonable. Other errors, however, may indicate a real issue
which is easy to miss. E.g. when 'hyperv_features' test was entering an
infinite loop the output was:

./hyperv_features
Testing access to Hyper-V specific MSRs
1..0 # SKIP - /dev/kvm not available (errno: 24)

and this can easily get overlooked.

Keep ENOENT case 'special' for skipping tests and fail when open() results
in any other errno.

Signed-off-by: Vitaly Kuznetsov 
Link: https://lore.kernel.org/r/20240129085847.2674082-2-vkuznets@redhat.com
Signed-off-by: Sean Christopherson