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| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-09-24 15:45:27 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-09-28 14:59:52 +0300 |
| commit | 0c899c25d754ae386940f0e1b86b31d3921480b6 (patch) | |
| tree | f88648c3c9ef85bbc14a3da9bb9688ebb386ccef /tools/testing/selftests/kvm/Makefile | |
| parent | a7d5c7ce41ac1e2537d78ddb57ef0ac4f737aa19 (diff) | |
| download | linux-0c899c25d754ae386940f0e1b86b31d3921480b6.tar.xz | |
KVM: x86: do not attempt TSC synchronization on guest writes
KVM special-cases writes to MSR_IA32_TSC so that all CPUs have
the same base for the TSC. This logic is complicated, and we
do not want it to have any effect once the VM is started.
In particular, if any guest started to synchronize its TSCs
with writes to MSR_IA32_TSC rather than MSR_IA32_TSC_ADJUST,
the additional effect of kvm_write_tsc code would be uncharted
territory.
Therefore, this patch makes writes to MSR_IA32_TSC behave
essentially the same as writes to MSR_IA32_TSC_ADJUST when
they come from the guest. A new selftest (which passes
both before and after the patch) checks the current semantics
of writes to MSR_IA32_TSC and MSR_IA32_TSC_ADJUST originating
from both the host and the guest.
Upcoming work to remove the special side effects
of host-initiated writes to MSR_IA32_TSC and MSR_IA32_TSC_ADJUST
will be able to build onto this test, adjusting the host side
to use the new APIs and achieve the same effect.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'tools/testing/selftests/kvm/Makefile')
| -rw-r--r-- | tools/testing/selftests/kvm/Makefile | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 80d5c348354c..7ebe71fbca53 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -55,6 +55,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test TEST_GEN_PROGS_x86_64 += x86_64/debug_regs +TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test TEST_GEN_PROGS_x86_64 += x86_64/user_msr_test TEST_GEN_PROGS_x86_64 += clear_dirty_log_test TEST_GEN_PROGS_x86_64 += demand_paging_test |