Re: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain

[Yi Liu <yi.l.liu@xxxxxxxxx>]

On 2023/12/27 17:27, Duan, Zhenzhong wrote:
> > -----Original Message-----
> > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > Subject: [PATCH v7 9/9] iommu/vt-d: Add iotlb flush for nested domain
> >
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> >
> > This implements the .cache_invalidate_user() callback to support iotlb
> > flush for nested domain.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Co-developed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > ---
> > drivers/iommu/intel/nested.c | 116
> > +++++++++++++++++++++++++++++++++++
> > 1 file changed, 116 insertions(+)
> >
> > diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
> > index b5a5563ab32c..c665e2647045 100644
> > --- a/drivers/iommu/intel/nested.c
> > +++ b/drivers/iommu/intel/nested.c
> > @@ -73,9 +73,125 @@ static void intel_nested_domain_free(struct
> > iommu_domain *domain)
> > 	kfree(to_dmar_domain(domain));
> > }
> >
> > +static void nested_flush_pasid_iotlb(struct intel_iommu *iommu,
> > +				     struct dmar_domain *domain, u64 addr,
> > +				     unsigned long npages, bool ih)
> > +{
> > +	u16 did = domain_id_iommu(domain, iommu);
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&domain->lock, flags);
> > +	if (!list_empty(&domain->devices))
> > +		qi_flush_piotlb(iommu, did, IOMMU_NO_PASID, addr,
> > +				npages, ih, NULL);
>
> Is it optimal to check if domain attached to iommu before trigger flush?
> Or the check is redundant if intel_nested_flush_cache() is the only call site.

I think it is possible that userspace issue an invalidation on a hwpt which
does not have any device attached.. Though this is something stupid. So
checking if any device attached before flushing still makes sense.

> Thanks
> Zhenzhong
>
> > +	spin_unlock_irqrestore(&domain->lock, flags);
> > +}
> > +
> > +static void nested_flush_dev_iotlb(struct dmar_domain *domain, u64 addr,
> > +				   unsigned mask, u32 *fault)
> > +{
> > +	struct device_domain_info *info;
> > +	unsigned long flags;
> > +	u16 sid, qdep;
> > +
> > +	spin_lock_irqsave(&domain->lock, flags);
> > +	list_for_each_entry(info, &domain->devices, link) {
> > +		if (!info->ats_enabled)
> > +			continue;
> > +		sid = info->bus << 8 | info->devfn;
> > +		qdep = info->ats_qdep;
> > +		qi_flush_dev_iotlb(info->iommu, sid, info->pfsid,
> > +				   qdep, addr, mask, fault);
> > +		quirk_extra_dev_tlb_flush(info, addr, mask,
> > +					  IOMMU_NO_PASID, qdep);
> > +	}
> > +	spin_unlock_irqrestore(&domain->lock, flags);
> > +}
> > +
> > +static void intel_nested_flush_cache(struct dmar_domain *domain, u64
> > addr,
> > +				     unsigned long npages, u32 *error)
> > +{
> > +	struct iommu_domain_info *info;
> > +	unsigned long i;
> > +	unsigned mask;
> > +	u32 fault = 0;
> > +
> > +	if (npages == U64_MAX)
> > +		mask = 64 - VTD_PAGE_SHIFT;
> > +	else
> > +		mask = ilog2(__roundup_pow_of_two(npages));
> > +
> > +	xa_for_each(&domain->iommu_array, i, info) {
> > +		nested_flush_pasid_iotlb(info->iommu, domain, addr,
> > npages, 0);
> > +
> > +		if (domain->has_iotlb_device)
> > +			continue;
> > +
> > +		nested_flush_dev_iotlb(domain, addr, mask, &fault);
> > +		if (fault & (DMA_FSTS_ITE | DMA_FSTS_ICE))
> > +			break;
> > +	}
> > +
> > +	if (fault & DMA_FSTS_ICE)
> > +		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ICE;
> > +	if (fault & DMA_FSTS_ITE)
> > +		*error |= IOMMU_HWPT_INVALIDATE_VTD_S1_ITE;
> > +}
> > +
> > +static int intel_nested_cache_invalidate_user(struct iommu_domain
> > *domain,
> > +					      struct iommu_user_data_array
> > *array)
> > +{
> > +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +	struct iommu_hwpt_vtd_s1_invalidate inv_entry;
> > +	u32 processed = 0;
> > +	int ret = 0;
> > +	u32 index;
> > +
> > +	if (array->type != IOMMU_HWPT_INVALIDATE_DATA_VTD_S1) {
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +
> > +	for (index = 0; index < array->entry_num; index++) {
> > +		ret = iommu_copy_struct_from_user_array(&inv_entry,
> > array,
> > +
> > 	IOMMU_HWPT_INVALIDATE_DATA_VTD_S1,
> > +							index, inv_error);
> > +		if (ret)
> > +			break;
> > +
> > +		if (inv_entry.flags & ~IOMMU_VTD_INV_FLAGS_LEAF) {
> > +			ret = -EOPNOTSUPP;
> > +			break;
> > +		}
> > +
> > +		if (!IS_ALIGNED(inv_entry.addr, VTD_PAGE_SIZE) ||
> > +		    ((inv_entry.npages == U64_MAX) && inv_entry.addr)) {
> > +			ret = -EINVAL;
> > +			break;
> > +		}
> > +
> > +		inv_entry.inv_error = 0;
> > +		intel_nested_flush_cache(dmar_domain, inv_entry.addr,
> > +					 inv_entry.npages,
> > &inv_entry.inv_error);
> > +
> > +		ret = iommu_respond_struct_to_user_array(array, index,
> > +							 (void *)&inv_entry,
> > +							 sizeof(inv_entry));
> > +		if (ret)
> > +			break;
> > +
> > +		processed++;
> > +	}
> > +
> > +out:
> > +	array->entry_num = processed;
> > +	return ret;
> > +}
> > +
> > static const struct iommu_domain_ops intel_nested_domain_ops = {
> > 	.attach_dev		= intel_nested_attach_dev,
> > 	.free			= intel_nested_domain_free,
> > +	.cache_invalidate_user	= intel_nested_cache_invalidate_user,
> > };
> >
> > struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain
> > *parent,
> > --
> > 2.34.1

--
Regards,
Yi Liu