Re: [PATCH v7 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster

[Nicolin Chen <nicolinc@nvidia.com>]

On Tue, Feb 25, 2025 at 12:02:25PM -0400, Jason Gunthorpe wrote:
> On Mon, Feb 24, 2025 at 03:45:33PM -0800, Nicolin Chen wrote:
> 
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
> > @@ -95,8 +95,6 @@ int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state,
> >  
> >  	iommu_group_mutex_assert(state->master->dev);
> >  
> > -	if (domain->type != IOMMU_DOMAIN_NESTED)
> > -		return 0;
> >  	nested_domain = to_smmu_nested_domain(domain);
> >  
> >  	/* Skip invalid vSTE */
> > @@ -122,19 +120,9 @@ void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state)
> >  {
> >  	struct arm_smmu_master *master = state->master;
> >  
> > -	mutex_lock(&master->smmu->streams_mutex);
> > -	if (state->vmaster != master->vmaster) {
> > -		kfree(master->vmaster);
> > -		master->vmaster = state->vmaster;
> > -	}
> > -	mutex_unlock(&master->smmu->streams_mutex);
> > -}
> > -
> > -void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master)
> > -{
> >  	mutex_lock(&master->smmu->streams_mutex);
> >  	kfree(master->vmaster);
> > -	master->vmaster = NULL;
> > +	master->vmaster = state->vmaster;
> >  	mutex_unlock(&master->smmu->streams_mutex);
> >  }
> 
> I'd leave the clear_vmaster just for clarity. Commit should not be
> unpaired with prepare in the other functions.
> 
> It looks fine with this on top too
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Ack. I added it back and a #ifdef to the vmaster: 

+void arm_smmu_master_clear_vmaster(struct arm_smmu_master *master)
+{
+       struct arm_smmu_attach_state state = { .master = master };
+
+       arm_smmu_attach_commit_vmaster(&state);
+}
[...]
@@ -824,6 +829,9 @@ struct arm_smmu_master {
        struct arm_smmu_device          *smmu;
        struct device                   *dev;
        struct arm_smmu_stream          *streams;
+#ifdef CONFIG_ARM_SMMU_V3_IOMMUFD
+       struct arm_smmu_vmaster         *vmaster; /* use smmu->streams_mutex */
+#endif
        /* Locked by the iommu core using the group mutex */
        struct arm_smmu_ctx_desc_cfg    cd_table;
        unsigned int                    num_streams;
@@ -972,6 +980,9 @@ struct arm_smmu_attach_state {
        bool disable_ats;
        ioasid_t ssid;
        /* Resulting state */
+#ifdef CONFIG_ARM_SMMU_V3_IOMMUFD
+       struct arm_smmu_vmaster *vmaster;
+#endif
        bool ats_enabled;
 };

Thanks
Nicolin