linux-stable.git/tools/testing/selftests/kvm, branch linux-5.11.y

KVM: selftests: Always run vCPU thread with blocked SIG_IPI

2021-05-14T08:49:32+00:00

commit bf1e15a82e3b74ee86bb119d6038b41e1ed2b319 upstream.

The main thread could start to send SIG_IPI at any time, even before signal
blocked on vcpu thread.  Therefore, start the vcpu thread with the signal
blocked.

Without this patch, on very busy cores the dirty_log_test could fail directly
on receiving a SIGUSR1 without a handler (when vcpu runs far slower than main).

Reported-by: Peter Xu 
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: selftests: Sync data verify of dirty logging with guest sync

2021-05-14T08:49:32+00:00

commit 016ff1a442d9a8f36dcb3beca0bcdfc35e281e18 upstream.

This fixes a bug that can trigger with e.g. "taskset -c 0 ./dirty_log_test" or
when the testing host is very busy.

A similar previous attempt is done [1] but that is not enough, the reason is
stated in the reply [2].

As a summary (partly quotting from [2]):

The problem is I think one guest memory write operation (of this specific test)
contains a few micro-steps when page is during kvm dirty tracking (here I'm
only considering write-protect rather than pml but pml should be similar at
least when the log buffer is full):

  (1) Guest read 'iteration' number into register, prepare to write, page fault
  (2) Set dirty bit in either dirty bitmap or dirty ring
  (3) Return to guest, data written

When we verify the data, we assumed that all these steps are "atomic", say,
when (1) happened for this page, we assume (2) & (3) must have happened.  We
had some trick to workaround "un-atomicity" of above three steps, as previous
version of this patch wanted to fix atomicity of step (2)+(3) by explicitly
letting the main thread wait for at least one vmenter of vcpu thread, which
should work.  However what I overlooked is probably that we still have race
when (1) and (2) can be interrupted.

One example calltrace when it could happen that we read an old interation, got
interrupted before even setting the dirty bit and flushing data:

    __schedule+1742
    __cond_resched+52
    __get_user_pages+530
    get_user_pages_unlocked+197
    hva_to_pfn+206
    try_async_pf+132
    direct_page_fault+320
    kvm_mmu_page_fault+103
    vmx_handle_exit+288
    vcpu_enter_guest+2460
    kvm_arch_vcpu_ioctl_run+325
    kvm_vcpu_ioctl+526
    __x64_sys_ioctl+131
    do_syscall_64+51
    entry_SYSCALL_64_after_hwframe+68

It means iteration number cached in vcpu register can be very old when dirty
bit set and data flushed.

So far I don't see an easy way to guarantee all steps 1-3 atomicity but to sync
at the GUEST_SYNC() point of guest code when we do verification of the dirty
bits as what this patch does.

[1] https://lore.kernel.org/lkml/20210413213641.23742-1-peterx@redhat.com/
[2] https://lore.kernel.org/lkml/20210417140956.GV4440@xz-x1/

Cc: Paolo Bonzini 
Cc: Sean Christopherson 
Cc: Andrew Jones 
Cc: stable@vger.kernel.org
Signed-off-by: Peter Xu 
Message-Id: <20210417143602.215059-2-peterx@redhat.com>
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: selftests: Implement perf_test_util more conventionally

2021-01-07T23:07:31+00:00

It's not conventional C to put non-inline functions in header
files. Create a source file for the functions instead. Also
reduce the amount of globals and rename the functions to
something less generic.

Reviewed-by: Ben Gardon 
Reviewed-by: Peter Xu 
Signed-off-by: Andrew Jones 
Message-Id: <20201218141734.54359-4-drjones@redhat.com>
Signed-off-by: Paolo Bonzini

KVM: selftests: Use vm_create_with_vcpus in create_vm

2021-01-07T23:07:30+00:00

Reviewed-by: Ben Gardon 
Signed-off-by: Andrew Jones 
Message-Id: <20201218141734.54359-3-drjones@redhat.com>
Signed-off-by: Paolo Bonzini

KVM: selftests: Factor out guest mode code

2021-01-07T23:07:29+00:00

demand_paging_test, dirty_log_test, and dirty_log_perf_test have
redundant guest mode code. Factor it out.

Also, while adding a new include, remove the ones we don't need.

Reviewed-by: Ben Gardon 
Reviewed-by: Peter Xu 
Signed-off-by: Andrew Jones 
Message-Id: <20201218141734.54359-2-drjones@redhat.com>
Signed-off-by: Paolo Bonzini

Merge branch 'kvm-master' into kvm-next

2021-01-07T23:06:52+00:00

Fixes to get_mmio_spte, destined to 5.10 stable branch.

Merge tag 'kvmarm-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

2020-12-15T17:48:24+00:00

KVM/arm64 updates for Linux 5.11

- PSCI relay at EL2 when "protected KVM" is enabled
- New exception injection code
- Simplification of AArch32 system register handling
- Fix PMU accesses when no PMU is enabled
- Expose CSV3 on non-Meltdown hosts
- Cache hierarchy discovery fixes
- PV steal-time cleanups
- Allow function pointers at EL2
- Various host EL2 entry cleanups
- Simplification of the EL2 vector allocation

Merge tag 'kvm-s390-next-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2020-12-12T08:58:31+00:00

KVM: s390: Features and Test for 5.11

- memcg accouting for s390 specific parts of kvm and gmap
- selftest for diag318
- new kvm_stat for when async_pf falls back to sync

The selftest even triggers a non-critical bug that is unrelated
to diag318, fix will follow later.

selftests: kvm: Merge user_msr_test into userspace_msr_exit_test

2020-12-12T00:00:58+00:00

Both user_msr_test and userspace_msr_exit_test tests the functionality
of kvm_msr_filter.  Instead of testing this feature in two tests, merge
them together, so there is only one test for this feature.

Signed-off-by: Aaron Lewis 
Message-Id: <20201204172530.2958493-1-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini

selftests: kvm: Test MSR exiting to userspace

2020-12-12T00:00:57+00:00

Add a selftest to test that when the ioctl KVM_X86_SET_MSR_FILTER is
called with an MSR list, those MSRs exit to userspace.

This test uses 3 MSRs to test this:
  1. MSR_IA32_XSS, an MSR the kernel knows about.
  2. MSR_IA32_FLUSH_CMD, an MSR the kernel does not know about.
  3. MSR_NON_EXISTENT, an MSR invented in this test for the purposes of
     passing a fake MSR from the guest to userspace.  KVM just acts as a
     pass through.

Userspace is also able to inject a #GP.  This is demonstrated when
MSR_IA32_XSS and MSR_IA32_FLUSH_CMD are misused in the test.  When this
happens a #GP is initiated in userspace to be thrown in the guest which is
handled gracefully by the exception handling framework introduced earlier
in this series.

Tests for the generic instruction emulator were also added.  For this to
work the module parameter kvm.force_emulation_prefix=1 has to be enabled.
If it isn't enabled the tests will be skipped.

A test was also added to ensure the MSR permission bitmap is being set
correctly by executing reads and writes of MSR_FS_BASE and MSR_GS_BASE
in the guest while alternating which MSR userspace should intercept.  If
the permission bitmap is being set correctly only one of the MSRs should
be coming through at a time, and the guest should be able to read and
write the other one directly.

Signed-off-by: Aaron Lewis 
Reviewed-by: Alexander Graf 
Message-Id: <20201012194716.3950330-5-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini