Re: [PATCH v11 07/10] iommu/vt-d: Add svm/sva invalidate function

[Jacob Pan]

On Thu, 9 Apr 2020 10:50:34 +0200
Auger Eric <eric.auger@xxxxxxxxxx> wrote:

> Hi Jacob,
> 
> On 4/3/20 8:42 PM, Jacob Pan wrote:
> > When Shared Virtual Address (SVA) is enabled for a guest OS via
> > vIOMMU, we need to provide invalidation support at IOMMU API and
> > driver level. This patch adds Intel VT-d specific function to
> > implement iommu passdown invalidate API for shared virtual address.
> > 
> > The use case is for supporting caching structure invalidation
> > of assigned SVM capable devices. Emulated IOMMU exposes queue
> > invalidation capability and passes down all descriptors from the
> > guest to the physical IOMMU.
> > 
> > The assumption is that guest to host device ID mapping should be
> > resolved prior to calling IOMMU driver. Based on the device handle,
> > host IOMMU driver can replace certain fields before submit to the
> > invalidation queue.
> > 
> > ---
> > v11 - Removed 2D map array, use -EINVAL in granularity lookup array.
> >       Fixed devTLB invalidation granularity mapping. Disregard G=1
> > case and use address selective invalidation only.
> > 
> > v7 review fixed in v10
> > ---
> > 
> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
> > Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > ---
> >  drivers/iommu/intel-iommu.c | 158
> > ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 158
> > insertions(+)
> > 
> > diff --git a/drivers/iommu/intel-iommu.c
> > b/drivers/iommu/intel-iommu.c index 94c7993dac6a..045c5c08d71d
> > 100644 --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -5594,6 +5594,163 @@ static void
> > intel_iommu_aux_detach_device(struct iommu_domain *domain,
> > aux_domain_remove_dev(to_dmar_domain(domain), dev); }
> >  
> > +/*
> > + * 2D array for converting and sanitizing IOMMU generic TLB
> > granularity to
> > + * VT-d granularity. Invalidation is typically included in the
> > unmap operation
> > + * as a result of DMA or VFIO unmap. However, for assigned devices
> > guest
> > + * owns the first level page tables. Invalidations of translation
> > caches in the
> > + * guest are trapped and passed down to the host.
> > + *
> > + * vIOMMU in the guest will only expose first level page tables,
> > therefore
> > + * we do not support IOTLB granularity for request without PASID
> > (second level).
> > + *
> > + * For example, to find the VT-d granularity encoding for IOTLB
> > + * type and page selective granularity within PASID:
> > + * X: indexed by iommu cache type
> > + * Y: indexed by enum iommu_inv_granularity
> > + * [IOMMU_CACHE_INV_TYPE_IOTLB][IOMMU_INV_GRANU_ADDR]
> > + */
> > +
> > +const static int
> > inv_type_granu_table[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU_NR] =
> > {
> > +	/*
> > +	 * PASID based IOTLB invalidation: PASID selective (per
> > PASID),
> > +	 * page selective (address granularity)
> > +	 */
> > +	{-EINVAL, QI_GRAN_NONG_PASID, QI_GRAN_PSI_PASID},
> > +	/* PASID based dev TLBs */
> > +	{-EINVAL, -EINVAL, QI_DEV_IOTLB_GRAN_PASID_SEL},
> > +	/* PASID cache */
> > +	{-EINVAL, -EINVAL, -EINVAL}
> > +};
> > +
> > +static inline int to_vtd_granularity(int type, int granu)
> > +{
> > +	return inv_type_granu_table[type][granu];
> > +}
> > +
> > +static inline u64 to_vtd_size(u64 granu_size, u64 nr_granules)
> > +{
> > +	u64 nr_pages = (granu_size * nr_granules) >>
> > VTD_PAGE_SHIFT; +
> > +	/* VT-d size is encoded as 2^size of 4K pages, 0 for 4k, 9
> > for 2MB, etc.
> > +	 * IOMMU cache invalidate API passes granu_size in bytes,
> > and number of
> > +	 * granu size in contiguous memory.
> > +	 */
> > +	return order_base_2(nr_pages);
> > +}
> > +
> > +#ifdef CONFIG_INTEL_IOMMU_SVM
> > +static int intel_iommu_sva_invalidate(struct iommu_domain *domain,
> > +		struct device *dev, struct
> > iommu_cache_invalidate_info *inv_info) +{
> > +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +	struct device_domain_info *info;
> > +	struct intel_iommu *iommu;
> > +	unsigned long flags;
> > +	int cache_type;
> > +	u8 bus, devfn;
> > +	u16 did, sid;
> > +	int ret = 0;
> > +	u64 size = 0;
> > +
> > +	if (!inv_info || !dmar_domain ||
> > +		inv_info->version !=
> > IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
> > +		return -EINVAL;
> > +
> > +	if (!dev || !dev_is_pci(dev))
> > +		return -ENODEV;  
> 
> Check (domain->flags & DOMAIN_FLAG_NESTING_MODE)?
Good point

> > +
> > +	iommu = device_to_iommu(dev, &bus, &devfn);
> > +	if (!iommu)
> > +		return -ENODEV;
> > +
> > +	spin_lock_irqsave(&device_domain_lock, flags);
> > +	spin_lock(&iommu->lock);
> > +	info = iommu_support_dev_iotlb(dmar_domain, iommu, bus,
> > devfn);
> > +	if (!info) {
> > +		ret = -EINVAL;
> > +		goto out_unlock;
> > +	}
> > +	did = dmar_domain->iommu_did[iommu->seq_id];
> > +	sid = PCI_DEVID(bus, devfn);
> > +
> > +	/* Size is only valid in non-PASID selective invalidation
> > */
> > +	if (inv_info->granularity != IOMMU_INV_GRANU_PASID)
> > +		size =
> > to_vtd_size(inv_info->addr_info.granule_size,
> > +
> > inv_info->addr_info.nb_granules); +
> > +	for_each_set_bit(cache_type, (unsigned long
> > *)&inv_info->cache, IOMMU_CACHE_INV_TYPE_NR) {
> > +		int granu = 0;
> > +		u64 pasid = 0;
> > +
> > +		granu = to_vtd_granularity(cache_type,
> > inv_info->granularity);
> > +		if (granu == -EINVAL) {
> > +			pr_err("Invalid cache type and granu
> > combination %d/%d\n", cache_type,
> > +				inv_info->granularity);  
> rate unlimited traces here and after.
> ret = -EINVAL?
> also related to the discussion we had on the VFIO series. What is the
> error policy?
Invalidation should not fail, there is no way to tell the guest. this
can be a void function or VFIO can ignore it similar to what is done to
iommu_unmap.


> > +			break;
> > +		}
> > +
> > +		/* PASID is stored in different locations based on
> > granularity */  
> not sure the above comment really is requested
Just to explain the situation where PASID can be in pasid_info or
addr_info.

> > +		if (inv_info->granularity == IOMMU_INV_GRANU_PASID
> > &&
> > +			inv_info->pasid_info.flags &
> > IOMMU_INV_PASID_FLAGS_PASID)
> > +			pasid = inv_info->pasid_info.pasid;
> > +		else if (inv_info->granularity ==
> > IOMMU_INV_GRANU_ADDR &&
> > +			inv_info->addr_info.flags &
> > IOMMU_INV_ADDR_FLAGS_PASID)
> > +			pasid = inv_info->addr_info.pasid;
> > +
> > +		switch (BIT(cache_type)) {
> > +		case IOMMU_CACHE_INV_TYPE_IOTLB:
> > +			if ((inv_info->granularity ==
> > IOMMU_INV_GRANU_ADDR) &&
> > +				size && (inv_info->addr_info.addr
> > & ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
> > +				pr_err("Address out of range,
> > 0x%llx, size order %llu\n",
> > +					inv_info->addr_info.addr,
> > size);
> > +				ret = -ERANGE;
> > +				goto out_unlock;
> > +			}
> > +
> > +			qi_flush_piotlb(iommu, did,
> > +					pasid,
> > +
> > mm_to_dma_pfn(inv_info->addr_info.addr),  
> This does not sound correct to me:
> inv_info->addr_info.addr and inv_info->addr_info.flags are not valid
> in case of PASID-selective invalidation
If granu is PASID-selective, this address is ignored. Since npages = -1.

> > +					(granu ==
> > QI_GRAN_NONG_PASID) ? -1 : 1 << size,
> > +					inv_info->addr_info.flags
> > & IOMMU_INV_ADDR_FLAGS_LEAF); +
> > +			/*
> > +			 * Always flush device IOTLB if ATS is
> > enabled. vIOMMU
> > +			 * in the guest may assume IOTLB flush is
> > inclusive,
> > +			 * which is more efficient.
> > +			 */
> > +			if (info->ats_enabled)
> > +				qi_flush_dev_iotlb_pasid(iommu,
> > sid, info->pfsid,
> > +						pasid,
> > info->ats_qdep,
> > +
> > inv_info->addr_info.addr, size,  
> same
> > +						granu);
> > +			break;
> > +		case IOMMU_CACHE_INV_TYPE_DEV_IOTLB:
> > +			if (info->ats_enabled)
> > +				qi_flush_dev_iotlb_pasid(iommu,
> > sid, info->pfsid,
> > +
> > inv_info->addr_info.pasid, info->ats_qdep,  
> nit: use pasid directly
will do.

> > +
> > inv_info->addr_info.addr, size,
> > +						granu);
> > +			else
> > +				pr_warn("Passdown device IOTLB
> > flush w/o ATS!\n");
> > +			break;
> > +		case IOMMU_CACHE_INV_TYPE_PASID:
> > +			qi_flush_pasid_cache(iommu, did, granu,
> > inv_info->pasid_info.pasid);
> > +			break;
> > +		default:
> > +			dev_err(dev, "Unsupported IOMMU
> > invalidation type %d\n",
> > +				cache_type);
> > +			ret = -EINVAL;
> > +		}
> > +	}
> > +out_unlock:
> > +	spin_unlock(&iommu->lock);
> > +	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +
> > +	return ret;
> > +}
> > +#endif
> > +
> >  static int intel_iommu_map(struct iommu_domain *domain,
> >  			   unsigned long iova, phys_addr_t hpa,
> >  			   size_t size, int iommu_prot, gfp_t gfp)
> > @@ -6179,6 +6336,7 @@ const struct iommu_ops intel_iommu_ops = {
> >  	.is_attach_deferred	=
> > intel_iommu_is_attach_deferred, .pgsize_bitmap		=
> > INTEL_IOMMU_PGSIZES, #ifdef CONFIG_INTEL_IOMMU_SVM
> > +	.cache_invalidate	= intel_iommu_sva_invalidate,
> >  	.sva_bind_gpasid	= intel_svm_bind_gpasid,
> >  	.sva_unbind_gpasid	= intel_svm_unbind_gpasid,
> >  #endif
> >   
> Thanks
> 
> Eric
> 

[Jacob Pan]