On 30/11/20 15:11, Maxim Levitsky wrote:
On Mon, 2020-11-30 at 14:54 +0100, Paolo Bonzini wrote:
On 30/11/20 14:35, Maxim Levitsky wrote:
This quirk reflects the fact that we currently treat MSR_IA32_TSC
and MSR_TSC_ADJUST access by the host (e.g qemu) in a way that is different
compared to an access from the guest.
For host's MSR_IA32_TSC read we currently always return L1 TSC value, and for
host's write we do the tsc synchronization.
For host's MSR_TSC_ADJUST write, we don't make the tsc 'jump' as we should
for this msr.
When the hypervisor uses the new TSC GET/SET state ioctls, all of this is no
longer needed, thus leave this enabled only with a quirk
which the hypervisor can disable.
Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
This needs to be covered by a variant of the existing selftests testcase
(running the same guest code, but different host code of course).
Do you think that the test should go to the kernel's kvm unit tests,
or to kvm-unit-tests project?
The latter already has x86_64/tsc_msrs_test.c (which I created in
preparation for this exact change :)).
Paolo
