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SubjectRe: [PATCH v2 02/16] iommu/vt-d: add bind_pasid_table function
On Thu, 12 Oct 2017 11:12:46 +0000
"Liu, Yi L" <yi.l.liu@intel.com> wrote:

> > From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> > Sent: Friday, October 6, 2017 7:04 AM
> > To: iommu@lists.linux-foundation.org; LKML
> > <linux-kernel@vger.kernel.org>; Joerg Roedel <joro@8bytes.org>;
> > David Woodhouse <dwmw2@infradead.org>; Greg Kroah-Hartman
> > <gregkh@linuxfoundation.org>; Wysocki, Rafael J
> > <rafael.j.wysocki@intel.com>; Jean-Philippe Brucker <jean-
> > philippe.brucker@arm.com> Cc: Liu, Yi L <yi.l.liu@intel.com>; Lan,
> > Tianyu <tianyu.lan@intel.com>; Tian, Kevin <kevin.tian@intel.com>;
> > Raj, Ashok <ashok.raj@intel.com>; Alex Williamson
> > <alex.williamson@redhat.com>; Jacob Pan
> > <jacob.jun.pan@linux.intel.com>; Liu; Yi L
> > <yi.l.liu@linux.intel.com> Subject: [PATCH v2 02/16] iommu/vt-d:
> > add bind_pasid_table function
> >
> > Add Intel VT-d ops to the generic iommu_bind_pasid_table API
> > functions.
> >
> > The primary use case is for direct assignment of SVM capable
> > device. Originated from emulated IOMMU in the guest, the request
> > goes through many layers (e.g. VFIO). Upon calling host IOMMU
> > driver, caller passes guest PASID table pointer (GPA) and size.
> >
> > Device context table entry is modified by Intel IOMMU specific
> > bind_pasid_table function. This will turn on nesting mode and
> > matching translation type.
> >
> > The unbind operation restores default context mapping.
> >
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > ---
> > drivers/iommu/intel-iommu.c | 117
> > ++++++++++++++++++++++++++++++++++++++++++
> > include/linux/dma_remapping.h | 1 +
> > 2 files changed, 118 insertions(+)
> >
> > diff --git a/drivers/iommu/intel-iommu.c
> > b/drivers/iommu/intel-iommu.c index 209d99a..7ae569c 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -5200,6 +5200,7 @@ static void
> > intel_iommu_put_resv_regions(struct device *dev,
> >
> > #ifdef CONFIG_INTEL_IOMMU_SVM
> > #define MAX_NR_PASID_BITS (20)
> > +#define MIN_NR_PASID_BITS (5)
> > static inline unsigned long intel_iommu_get_pts(struct intel_iommu
> > *iommu) { /*
> > @@ -5326,6 +5327,118 @@ struct intel_iommu
> > *intel_svm_device_to_iommu(struct device *dev)
> >
> > return iommu;
> > }
> > +
> > +static int intel_iommu_bind_pasid_table(struct iommu_domain
> > *domain,
> > + struct device *dev, struct pasid_table_config
> > *pasidt_binfo) {
> > + struct intel_iommu *iommu;
> > + struct context_entry *context;
> > + struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > + struct device_domain_info *info;
> > + struct pci_dev *pdev;
> > + u8 bus, devfn, host_table_pasid_bits;
> > + u16 did, sid;
> > + int ret = 0;
> > + unsigned long flags;
> > + u64 ctx_lo;
> > +
> > + iommu = device_to_iommu(dev, &bus, &devfn);
> > + if (!iommu)
> > + return -ENODEV;
> > + /* VT-d spec 9.4 says pasid table size is encoded as
> > 2^(x+5) */
> > + host_table_pasid_bits = intel_iommu_get_pts(iommu) +
> > MIN_NR_PASID_BITS;
> > + if (!pasidt_binfo || pasidt_binfo->pasid_bits >
> > host_table_pasid_bits ||
> > + pasidt_binfo->pasid_bits < MIN_NR_PASID_BITS) {
> > + pr_err("Invalid gPASID bits %d, host range %d -
> > %d\n",
> > + pasidt_binfo->pasid_bits,
> > + MIN_NR_PASID_BITS, host_table_pasid_bits);
> > + return -ERANGE;
> > + }
> > +
> > + pdev = to_pci_dev(dev);
> > + if (!pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI))
> > + return -EINVAL;
> > + sid = PCI_DEVID(bus, devfn);
> > +
> > + info = dev->archdata.iommu;
> > + if (!info || !info->pasid_supported) {
> > + dev_err(dev, "No PASID support\n");
> > + ret = -EINVAL;
> > + goto out;
> > + }
> > + if (!info->pasid_enabled) {
> > + ret = pci_enable_pasid(pdev, info->pasid_supported
> > & ~1);
> > + if (ret)
> > + goto out;
> > + }
> > + if (!device_context_mapped(iommu, bus, devfn)) {
> > + pr_warn("ctx not mapped for bus devfn %x:%x\n",
> > bus, devfn);
> > + ret = -EINVAL;
> > + goto out;
> > + }
>
> [Liu, Yi L] This is checking whether ctx is present. So if it is
> true, then the following 6 line should be always true. Perhaps, a
> merge could be done here with the following 6 lines.
>
good point, I can do the present check below. no need to hold the lock
twice.
> > + spin_lock_irqsave(&iommu->lock, flags);
> > + context = iommu_context_addr(iommu, bus, devfn, 0);
> > + if (!context) {
> > + ret = -EINVAL;
> > + goto out_unlock;
> > + }
> > +
>
> Regards,
> Yi L

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