On Wed, Nov 11, 2020 at 12:10:50PM +0530, Sai Prakash Ranjan wrote:
> On 2020-11-10 17:48, Will Deacon wrote:
> > On Fri, Oct 30, 2020 at 02:53:09PM +0530, Sai Prakash Ranjan wrote:
> > > Add iommu domain attribute for using system cache aka last level
> > > cache by client drivers like GPU to set right attributes for caching
> > > the hardware pagetables into the system cache.
> > >
> > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > > ---
> > > drivers/iommu/arm/arm-smmu/arm-smmu.c | 17 +++++++++++++++++
> > > drivers/iommu/arm/arm-smmu/arm-smmu.h | 1 +
> > > include/linux/iommu.h | 1 +
> > > 3 files changed, 19 insertions(+)
> > >
> > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > index b1cf8f0abc29..070d13f80c7e 100644
> > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > > @@ -789,6 +789,9 @@ static int arm_smmu_init_domain_context(struct
> > > iommu_domain *domain,
> > > if (smmu_domain->non_strict)
> > > pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
> > >
> > > + if (smmu_domain->sys_cache)
> > > + pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_SYS_CACHE;
> > > +
> > > pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
> > > if (!pgtbl_ops) {
> > > ret = -ENOMEM;
> > > @@ -1520,6 +1523,9 @@ static int arm_smmu_domain_get_attr(struct
> > > iommu_domain *domain,
> > > case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
> > > *(int *)data = smmu_domain->non_strict;
> > > return 0;
> > > + case DOMAIN_ATTR_SYS_CACHE:
> > > + *((int *)data) = smmu_domain->sys_cache;
> > > + return 0;
> > > default:
> > > return -ENODEV;
> > > }
> > > @@ -1551,6 +1557,17 @@ static int arm_smmu_domain_set_attr(struct
> > > iommu_domain *domain,
> > > else
> > > smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
> > > break;
> > > + case DOMAIN_ATTR_SYS_CACHE:
> > > + if (smmu_domain->smmu) {
> > > + ret = -EPERM;
> > > + goto out_unlock;
> > > + }
> > > +
> > > + if (*((int *)data))
> > > + smmu_domain->sys_cache = true;
> > > + else
> > > + smmu_domain->sys_cache = false;
> > > + break;
> > > default:
> > > ret = -ENODEV;
> > > }
> > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > > b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > > index 885840f3bec8..dfc44d806671 100644
> > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> > > @@ -373,6 +373,7 @@ struct arm_smmu_domain {
> > > struct mutex init_mutex; /* Protects smmu pointer */
> > > spinlock_t cb_lock; /* Serialises ATS1* ops and TLB syncs */
> > > struct iommu_domain domain;
> > > + bool sys_cache;
> > > };
> > >
> > > struct arm_smmu_master_cfg {
> > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > > index b95a6f8db6ff..4f4bb9c6f8f6 100644
> > > --- a/include/linux/iommu.h
> > > +++ b/include/linux/iommu.h
> > > @@ -118,6 +118,7 @@ enum iommu_attr {
> > > DOMAIN_ATTR_FSL_PAMUV1,
> > > DOMAIN_ATTR_NESTING, /* two stages of translation */
> > > DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> > > + DOMAIN_ATTR_SYS_CACHE,
> >
> > I think you're trying to make this look generic, but it's really not.
> > If we need to funnel io-pgtable quirks through domain attributes, then I
> > think we should be open about that and add something like
> > DOMAIN_ATTR_IO_PGTABLE_CFG which could take a struct of page-table
> > configuration data for the domain (this could just be quirks initially,
> > but maybe it's worth extending to take ias, oas and page size)
> >
>
> Actually the initial versions used DOMAIN_ATTR_QCOM_SYS_CACHE
> to make it QCOM specific and not generic, I don't see anyone else
> using this attribute, would that work?
No -- I'd prefer to have _one_ domain attribute for funneling all the
IP_PGTABLE_CFG data. Otherwise, we'll just end up with things like
DOMAIN_ATTR_QCOM_SYS_CACHE_EXT or DOMAIN_ATTR_QCOM_QUIRKS later on.
Will
