Re: [PATCH v8 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster

Zhangfei Gao
2025-04-08T11:44:48Z

On Tue, 8 Apr 2025 at 02:00, Nicolin Chen <nicolinc@nvidia.com> wrote:
>
> On Mon, Apr 07, 2025 at 08:08:57PM +0800, Zhangfei Gao wrote:
> > Hi, Nico
> >
> > On Wed, 26 Feb 2025 at 01:35, Nicolin Chen <nicolinc@nvidia.com> wrote:
> > >
> > > Use it to store all vSMMU-related data. The vsid (Virtual Stream ID) will
> > > be the first use case. Since the vsid reader will be the eventq handler
> > > that already holds a streams_mutex, reuse that to fenche the vmaster too.
> > >
> > > Also add a pair of arm_smmu_attach_prepare/commit_vmaster helpers to set
> > > or unset the master->vmaster point. Put these helpers inside the existing
> > > arm_smmu_attach_prepare/commit().
> > >
> > > For identity/blocked ops that don't call arm_smmu_attach_prepare/commit(),
> > > add a simpler arm_smmu_master_clear_vmaster helper to unset the vmaster.
> > >
> > > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> > > Reviewed-by: Pranjal Shrivastavat <praan@google.com>
> > > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > > ---
> >
> > >
> > > +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
> > > + struct arm_smmu_nested_domain *nested_domain)
> > > +{
> > > + struct arm_smmu_vmaster *vmaster;
> > > + unsigned long vsid;
> > > + int ret;
> > > +
> > > + iommu_group_mutex_assert(state->master->dev);
> > > +
> > > + /* Skip invalid vSTE */
> > > + if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V)))
> > > + return 0;
> >
> > Why this is removed in v9 and 6.15-rc1?
> >
> > I tested 6.15-rc1 the qemu failed to boot with qemu branch:
> > for_iommufd_veventq-v8
> > "failed to attach the bypass pagetable"
>
> Here is the problem: v9 isn't compatible with v8 :)
>
> Would you please try for-v9 version?
> https://github.com/nicolinc/qemu/commits/wip/for_iommufd_veventq-v9

Thanks Nico

I tried this branch, it works with 6.15-rc1

Thanks