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SubjectRE: [PATCH v2 02/16] iommu/vt-d: add bind_pasid_table function
Date
> 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.

> + 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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