On Sat, Mar 1, 2025 at 9:04 PM Ani Sinha <anisi...@redhat.com> wrote:
>
> On Thu, Feb 20, 2025 at 12:36 PM Zhao Liu <zhao1....@intel.com> wrote:
> >
> > On Thu, Feb 20, 2025 at 12:23:26PM +0530, Ani Sinha wrote:
> > > Date: Thu, 20 Feb 2025 12:23:26 +0530
> > > From: Ani Sinha <anisi...@redhat.com>
> > > Subject: [PATCH v2] microvm: do not use the lastest cpu version
> > > X-Mailer: git-send-email 2.45.2
> > >
> > > commit 0788a56bd1ae3 ("i386: Make unversioned CPU models be aliases")
> > > introduced 'default_cpu_version' for PCMachineClass. This created three
> > > categories of CPU models:
> > > - Most unversioned CPU models would use version 1 by default.
> > > - For machines 4.0.1 and older that do not support cpu model aliases, a
> > > special default_cpu_version value of CPU_VERSION_LEGACY is used.
> > > - It was thought that future machines would use the latest value of cpu
> > > versions corresponding to default_cpu_version value of
> > > CPU_VERSION_LATEST [1].
> > >
> > > All pc machines still use the default cpu version of 1 for
> > > unversioned cpu models. CPU_VERSION_LATEST is a moving target and
> > > changes with time. Therefore, if machines use CPU_VERSION_LATEST, it would
> > > mean that over a period of time, for the same versioned machine type,
> > > the cpu version would be different depending on what the latest was at
> > > that
> > > time. This would break guests even when they use a constant specific
> > > versioned machine type.
> > > Additionally, microvm machines are not versioned anyway and therefore
> > > there is no requirement to use the latest cpu model by default.
> > > Let microvms use the non-versioned cpu model and remove all references
> > > to CPU_VERSION_LATEST as there are no other users (nor we anticipate
> > > future consumers of CPU_VERSION_LATEST).
> > >
> > > Those users who need spefific cpu versions can use explicit version in
> > > the QEMU command line to select the specific cpu version desired.
> > >
> > > CI pipline does not break with this change.
> > >
> > > 1) See commit dcafd1ef0af227 ("i386: Register versioned CPU models")
> > >
> > > CC: imamm...@redhat.com
> > > CC: zhao1....@intel.com
> > > Reviewed-by: Igor Mammedov <imamm...@redhat.com>
> > > Reviewed-by: Sergio Lopez <s...@redhat.com>
> > > Signed-off-by: Ani Sinha <anisi...@redhat.com>
> > > ---
> > > hw/i386/microvm.c | 2 +-
> > > target/i386/cpu.c | 15 ---------------
> > > target/i386/cpu.h | 4 ----
> > > 3 files changed, 1 insertion(+), 20 deletions(-)
> > >
> > > changelog:
> > > v2: tags added, more explanation in the commit log.
> >
> > Reviewed-by: Zhao Liu <zhao1....@intel.com>
> >
>
> Who is picking this up?
I sent a pull request for this and a couple other reviewed patches
myself. Two reasons:
- wanted to see this in the upstream sooner as some other bits of the
work is pending on it.
- I never sent a pull request before and wanted to go through the
process to learn how to do it in case I needed it in the future.
i hope the PR is ok. If not, I can resend after corrections. I used
Peter's script
https://git.linaro.org/people/peter.maydell/misc-scripts.git/plain/make-pullreq
