Date:   Wed, 1 Apr 2020 06:32:36 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
CC:     Auger Eric <eric.auger@...hat.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        "David Woodhouse" <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Jonathan Cameron" <jic23@...nel.org>
Subject: RE: [PATCH V10 08/11] iommu/vt-d: Add svm/sva invalidate function

> From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Sent: Wednesday, April 1, 2020 5:08 AM
> 
> On Tue, 31 Mar 2020 03:34:22 +0000
> "Tian, Kevin" <kevin.tian@...el.com> wrote:
> 
> > > From: Auger Eric <eric.auger@...hat.com>
> > > Sent: Monday, March 30, 2020 12:05 AM
> > >
> > > On 3/28/20 11:01 AM, Tian, Kevin wrote:
> > > >> From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > > >> Sent: Saturday, March 21, 2020 7:28 AM
> > > >>
> > > >> 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
> > > >
> > > > emulated IOMMU -> vIOMMU, since virito-iommu could use the
> > > > interface as well.
> > > >
> > > >> 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.
> > > >>
> > > >> ---
> > > >> v7 review fixed in v10
> > > >> ---
> > > >>
> > > >> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > > >> Signed-off-by: Ashok Raj <ashok.raj@...el.com>
> > > >> Signed-off-by: Liu, Yi L <yi.l.liu@...el.com>
> > > >> ---
> > > >>  drivers/iommu/intel-iommu.c | 182
> > > >> ++++++++++++++++++++++++++++++++++++++++++++
> > > >>  1 file changed, 182 insertions(+)
> > > >>
> > > >> diff --git a/drivers/iommu/intel-iommu.c
> > > >> b/drivers/iommu/intel-iommu.c index b1477cd423dd..a76afb0fd51a
> > > >> 100644 --- a/drivers/iommu/intel-iommu.c
> > > >> +++ b/drivers/iommu/intel-iommu.c
> > > >> @@ -5619,6 +5619,187 @@ 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 include IOTLB granularity for request without
> > > >> PASID (second level).
> > > >
> > > > I would revise above as "We do not support IOTLB granularity for
> > > > request without PASID (second level), therefore any vIOMMU
> > > > implementation that exposes the SVA capability to the guest
> > > > should only expose the first level page tables, implying all
> > > > invalidation requests from the guest will include a valid PASID"
> > > >
> > > >> + *
> > > >> + * 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]
> > > >> + *
> > > >> + * Granu_map array indicates validity of the table. 1: valid,
> > > >> 0: invalid
> > > >> + *
> > > >> + */
> > > >> +const static int
> > > >>
> > >
> inv_type_granu_map[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU_
> > > >> NR] = {
> > > >> +	/*
> > > >> +	 * PASID based IOTLB invalidation: PASID selective (per
> > > >> PASID),
> > > >> +	 * page selective (address granularity)
> > > >> +	 */
> > > >> +	{0, 1, 1},
> > > >> +	/* PASID based dev TLBs, only support all PASIDs or
> > > >> single PASID */
> > > >> +	{1, 1, 0},
> > > >
> > > > Is this combination correct? when single PASID is being
> > > > specified, it is essentially a page-selective invalidation since
> > > > you need provide Address and Size.
> > > >
> > > >> +	/* PASID cache */
> > > >
> > > > PASID cache is fully managed by the host. Guest PASID cache
> > > > invalidation is interpreted by vIOMMU for bind and unbind
> > > > operations. I don't think we should accept any PASID cache
> > > > invalidation from userspace or guest.
> > > I tend to agree here.
> > > >
> > > >> +	{1, 1, 0}
> > > >> +};
> > > >> +
> > > >> +const static int
> > > >>
> > >
> inv_type_granu_table[IOMMU_CACHE_INV_TYPE_NR][IOMMU_INV_GRANU
> > > >> _NR] = {
> > > >> +	/* PASID based IOTLB */
> > > >> +	{0, QI_GRAN_NONG_PASID, QI_GRAN_PSI_PASID},
> > > >> +	/* PASID based dev TLBs */
> > > >> +	{QI_DEV_IOTLB_GRAN_ALL, QI_DEV_IOTLB_GRAN_PASID_SEL, 0},
> > > >> +	/* PASID cache */
> > > >> +	{QI_PC_ALL_PASIDS, QI_PC_PASID_SEL, 0},
> > > >> +};
> > > >> +
> > > >> +static inline int to_vtd_granularity(int type, int granu, int
> > > >> *vtd_granu) +{
> > > >> +	if (type >= IOMMU_CACHE_INV_TYPE_NR || granu >=
> > > >> IOMMU_INV_GRANU_NR ||
> > > >> +		!inv_type_granu_map[type][granu])
> > > >> +		return -EINVAL;
> > > >> +
> > > >> +	*vtd_granu = inv_type_granu_table[type][granu];
> > > >> +
> > > >
> > > > btw do we really need both map and table here? Can't we just
> > > > use one table with unsupported granularity marked as a special
> > > > value?
> > > I asked the same question some time ago. If I remember correctly the
> > > issue is while a granu can be supported in inv_type_granu_map, the
> > > associated value in inv_type_granu_table can be 0. This typically
> > > matches both values of G field (0 or 1) in the invalidation cmd. See
> > > other comment below.
> >
> > I didn't fully understand it. Also what does a value '0' imply? also
> > it's interesting to see below in [PATCH 07/11]:
> >
> 0 in 2D map array means invalid.
> 0 in granu table can be either valid or invalid
> That is why we need the map table to tell the difference.
> I will add following comments since this causes lots of confusion.
> 
>  * Granu_map array indicates validity of the table. 1: valid, 0: invalid
>  * This is useful when the entry in the granu table has a value of 0,
>  * which can be a valid or invalid value.
> 
> 
> > +/* QI Dev-IOTLB inv granu */
> > +#define QI_DEV_IOTLB_GRAN_ALL		1
> > +#define QI_DEV_IOTLB_GRAN_PASID_SEL	0
> > +
> >
> Sorry I didn't get the point? These are the valid vt-d granu values.
> Per Spec CH 6.5.2.6

well, I thought '0' means invalid then why we define a valid granu
as invalid. But with your latest explanation I think I get the
rationale behind now. 

just one more thought, since the element type is int in the
granular table, why not using -1 to represent invalid then you
can still use one table?

> 
> > > >
> > > >> +	return 0;
> > > >> +}
> > > >> +
> > > >> +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;
> > > >> +
> > > >> +	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;
> > > >
> > > > -ENOTSUPP?
> > > >
> > > >> +	}
> > > >> +	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;
> > > >> +
> > > >> +		ret = to_vtd_granularity(cache_type,
> > > >> inv_info->granularity, &granu);
> > > >> +		if (ret) {
> > > >> +			pr_err("Invalid cache type and granu
> > > >> combination %d/%d\n", cache_type,
> > > >> +				inv_info->granularity);
> > > >> +			break;
> > > >> +		}
> > > >> +
> > > >> +		/* PASID is stored in different locations based
> > > >> on granularity */
> > > >> +		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;
> > > >> +		else {
> > > >> +			pr_err("Cannot find PASID for given
> > > >> cache type and granularity\n");
> > > >> +			break;
> > > >> +		}
> > > >> +
> > > >> +		switch (BIT(cache_type)) {
> > > >> +		case IOMMU_CACHE_INV_TYPE_IOTLB:
> > > >> +			if ((inv_info->granularity !=
> > > >> IOMMU_INV_GRANU_PASID) &&
> > > >
> > > > granularity == IOMMU_INV_GRANU_ADDR? otherwise it's unclear
> > > > why IOMMU_INV_GRANU_DOMAIN also needs size check.
> > > >
> > > >> +				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),
> > > >> +					(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 since guest
> > > >> +			 * vIOMMU exposes CM = 1, no device
> > > >> IOTLB flush will be passed
> > > >> +			 * down.
> > > >> +			 */
> > > >
> > > > Does VT-d spec mention that no device IOTLB flush is required
> > > > when CM=1?
> > > >> +			if (info->ats_enabled) {
> > > >> +				qi_flush_dev_iotlb_pasid(iommu,
> > > >> sid, info-
> > > >>> pfsid,
> > > >> +						pasid,
> > > >> info->ats_qdep,
> > > >> +
> > > >> inv_info->addr_info.addr, size,
> > > >> +						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,
> > > >> +
> > > >> inv_info->addr_info.addr, size,
> > > >> +						granu);
> > > >
> > > > I'm confused here. There are two granularities allowed for
> > > > devtlb, but here you only handle one of them?
> > > granu is the result of to_vtd_granularity() so it can take either
> > > of the 2 values.
> >
> > yes, you're right.
> >
> > >
> > > Thanks
> > >
> > > Eric
> > > >
> > > >> +			} 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);
> > > >> +
> > > >
> > > > as earlier comment, we shouldn't allow userspace or guest to
> > > > invalidate PASID cache
> > > >
> > > >> +			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) @@ -6204,6 +6385,7 @@ 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
> > > >> --
> > > >> 2.7.4
> > > >
> >
> 
> [Jacob Pan]

Thanks
Kevin

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