[PATCH v3 0/2] Add page alignment check in Intel IOMMU.

[PATCH v3 0/2] Add page alignment check in Intel IOMMU.

[sathyanarayanan.kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

As per Intel vt-d specification, Rev 3.0 (section 7.5.1.1, title
"Page Request Descriptor"), Intel IOMMU page request descriptor
only uses bits[63:12] of the Page Address. Hence its required to
enforce that the device will only send page request with
page-aligned address. So, this patch set adds support to verify
whether the device uses page aligned address before enabling the
ATS service in Intel IOMMU driver.

Changes since v1:
 * Fixed issue with PCI_ATS_CAP_PAGE_ALIGNED macro.
 * Fixed comments.

Changes since v2:
 * Fixed Bjorn Helgaas comments.

Kuppuswamy Sathyanarayanan (2):
  PCI/ATS: Add pci_ats_page_aligned() interface
  iommu/vt-d: Enable ATS only if the device uses page aligned address.

 drivers/iommu/intel-iommu.c   |  1 +
 drivers/pci/ats.c             | 27 +++++++++++++++++++++++++++
 include/linux/pci.h           |  2 ++
 include/uapi/linux/pci_regs.h |  1 +
 4 files changed, 31 insertions(+)

-- 
2.20.1

[PATCH v3 1/2] PCI/ATS: Add pci_ats_page_aligned() interface

[sathyanarayanan.kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Return the Page Aligned Request bit in the ATS Capability Register.

As per PCIe spec r4.0, sec 10.5.1.2, if the Page Aligned Request bit is
set, it indicates the Untranslated Addresses generated by the device are
always aligned to a 4096 byte boundary.

An IOMMU that can only translate page-aligned addresses can only be used
with devices that always produce aligned Untranslated Addresses. This
interface will be used by drivers for such IOMMUs to determine whether
devices can use the ATS service.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/ats.c             | 27 +++++++++++++++++++++++++++
 include/linux/pci.h           |  2 ++
 include/uapi/linux/pci_regs.h |  1 +
 3 files changed, 30 insertions(+)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 5b78f3b1b918..bae74eb90f42 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -142,6 +142,33 @@ int pci_ats_queue_depth(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_ats_queue_depth);
 
+/**
+ * pci_ats_page_aligned - Return Page Aligned Request bit status.
+ * @pdev: the PCI device
+ *
+ * Returns 1, if the Untranslated Addresses generated by the device
+ * are always aligned or 0 otherwise.
+ *
+ * Per PCIe spec r4.0, sec 10.5.1.2, if the Page Aligned Request bit
+ * is set, it indicates the Untranslated Addresses generated by the
+ * device are always aligned to a 4096 byte boundary.
+ */
+int pci_ats_page_aligned(struct pci_dev *pdev)
+{
+	u16 cap;
+
+	if (!pdev->ats_cap)
+		return 0;
+
+	pci_read_config_word(pdev, pdev->ats_cap + PCI_ATS_CAP, &cap);
+
+	if (cap & PCI_ATS_CAP_PAGE_ALIGNED)
+		return 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_ats_page_aligned);
+
 #ifdef CONFIG_PCI_PRI
 /**
  * pci_enable_pri - Enable PRI capability
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 65f1d8c2f082..9724a8c0496b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1524,11 +1524,13 @@ void pci_ats_init(struct pci_dev *dev);
 int pci_enable_ats(struct pci_dev *dev, int ps);
 void pci_disable_ats(struct pci_dev *dev);
 int pci_ats_queue_depth(struct pci_dev *dev);
+int pci_ats_page_aligned(struct pci_dev *dev);
 #else
 static inline void pci_ats_init(struct pci_dev *d) { }
 static inline int pci_enable_ats(struct pci_dev *d, int ps) { return -ENODEV; }
 static inline void pci_disable_ats(struct pci_dev *d) { }
 static inline int pci_ats_queue_depth(struct pci_dev *d) { return -ENODEV; }
+static inline int pci_ats_page_aligned(struct pci_dev *dev) { return 0; }
 #endif
 
 #ifdef CONFIG_PCIE_PTM
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index e1e9888c85e6..7973bb02ed4b 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -866,6 +866,7 @@
 #define PCI_ATS_CAP		0x04	/* ATS Capability Register */
 #define  PCI_ATS_CAP_QDEP(x)	((x) & 0x1f)	/* Invalidate Queue Depth */
 #define  PCI_ATS_MAX_QDEP	32	/* Max Invalidate Queue Depth */
+#define  PCI_ATS_CAP_PAGE_ALIGNED	0x0020 /* Page Aligned Request */
 #define PCI_ATS_CTRL		0x06	/* ATS Control Register */
 #define  PCI_ATS_CTRL_ENABLE	0x8000	/* ATS Enable */
 #define  PCI_ATS_CTRL_STU(x)	((x) & 0x1f)	/* Smallest Translation Unit */
-- 
2.20.1

[PATCH v3 2/2] iommu/vt-d: Enable ATS only if the device uses page aligned address.

[sathyanarayanan.kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

As per Intel vt-d specification, Rev 3.0 (section 7.5.1.1, title "Page
Request Descriptor"), Intel IOMMU page request descriptor only uses
bits[63:12] of the page address. Hence Intel IOMMU driver would only
permit devices that advertise they would only send Page Aligned Requests
to participate in ATS service.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 drivers/iommu/intel-iommu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 78188bf7e90d..bb0e244a0117 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1406,6 +1406,7 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info)
 		info->pri_enabled = 1;
 #endif
 	if (!pdev->untrusted && info->ats_supported &&
+	    pci_ats_page_aligned(pdev) &&
 	    !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
 		info->ats_enabled = 1;
 		domain_update_iotlb(info->domain);
-- 
2.20.1

Re: [PATCH v3 0/2] Add page alignment check in Intel IOMMU.

[Joerg Roedel]

On Tue, Feb 19, 2019 at 11:06:08AM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> Kuppuswamy Sathyanarayanan (2):
>   PCI/ATS: Add pci_ats_page_aligned() interface
>   iommu/vt-d: Enable ATS only if the device uses page aligned address.
> 
>  drivers/iommu/intel-iommu.c   |  1 +
>  drivers/pci/ats.c             | 27 +++++++++++++++++++++++++++
>  include/linux/pci.h           |  2 ++
>  include/uapi/linux/pci_regs.h |  1 +
>  4 files changed, 31 insertions(+)

Applied, thanks.