Re: [PATCH for-9.1 0/7] target/i386/kvm: Cleanup the kvmclock feature name

[Zhao Liu]

Hi maintainers,

Ping. Do you like this diea?

Thanks,
Zhao

On Fri, Mar 29, 2024 at 06:19:47PM +0800, Zhao Liu wrote:
> Date: Fri, 29 Mar 2024 18:19:47 +0800
> From: Zhao Liu <zhao1.liu@linux.intel.com>
> Subject: [PATCH for-9.1 0/7] target/i386/kvm: Cleanup the kvmclock feature
>  name
> X-Mailer: git-send-email 2.34.1
> 
> From: Zhao Liu <zhao1.liu@intel.com>
> 
> Hi list,
> 
> This series is based on Paolo's guest_phys_bits patchset [1].
> 
> Currently, the old and new kvmclocks have the same feature name
> "kvmclock" in FeatureWordInfo[FEAT_KVM].
> 
> When I tried to dig into the history of this unusual naming and fix it,
> I realized that Tim was already trying to rename it, so I picked up his
> renaming patch [2] (with a new commit message and other minor changes).
> 
> 13 years age, the same name was introduced in [3], and its main purpose
> is to make it easy for users to enable/disable 2 kvmclocks. Then, in
> 2012, Don tried to rename the new kvmclock, but the follow-up did not
> address Igor and Eduardo's comments about compatibility.
> 
> Tim [2], not long ago, and I just now, were both puzzled by the naming
> one after the other.
> 
> So, this series is to push for renaming the new kvmclock feature to
> "kvmclock2" and adding compatibility support for older machines (PC 9.0
> and older).
> 
> Finally, let's put an end to decades of doubt about this name.
> 
> 
> Next Step
> =========
> 
> This series just separates the two kvmclocks from the naming, and in
> subsequent patches I plan to stop setting kvmclock(old kcmclock) by
> default as long as KVM supports kvmclock2 (new kvmclock).
> 
> Also, try to deprecate the old kvmclock in KVM side.
> 
> [1]: 
> https://lore.kernel.org/qemu-devel/20240325141422.1380087-1-pbonzini@redhat.com/
> [2]: 
> https://lore.kernel.org/qemu-devel/20230908124534.25027-4-twiederh@redhat.com/
> [3]: 
> https://lore.kernel.org/qemu-devel/1300401727-5235-3-git-send-email-glommer@redhat.com/
> [4]: 
> https://lore.kernel.org/qemu-devel/1348171412-23669-3-git-send-email-Don@CloudSwitch.com/
> 
> Thanks and Best Regards,
> Zhao
> 
> ---
> Tim Wiederhake (1):
>   target/i386: Fix duplicated kvmclock name in FEAT_KVM
> 
> Zhao Liu (6):
>   target/i386/kvm: Add feature bit definitions for KVM CPUID
>   target/i386/kvm: Remove local MSR_KVM_WALL_CLOCK and
>     MSR_KVM_SYSTEM_TIME definitions
>   target/i386/kvm: Only Save/load kvmclock MSRs when kvmclock enabled
>   target/i386/kvm: Save/load MSRs of new kvmclock
>     (KVM_FEATURE_CLOCKSOURCE2)
>   target/i386/kvm: Add legacy_kvmclock cpu property
>   target/i386/kvm: Update comment in kvm_cpu_realizefn()
> 
>  hw/i386/kvm/clock.c       |  5 ++--
>  hw/i386/pc.c              |  1 +
>  target/i386/cpu.c         |  3 +-
>  target/i386/cpu.h         | 32 +++++++++++++++++++++
>  target/i386/kvm/kvm-cpu.c | 25 ++++++++++++++++-
>  target/i386/kvm/kvm.c     | 59 +++++++++++++++++++++++++--------------
>  6 files changed, 99 insertions(+), 26 deletions(-)
> 
> -- 
> 2.34.1
>