-----Original Message-----
From: Bhushan Bharat-R65777
Sent: Wednesday, October 16, 2013 10:20 PM
To: Sethi Varun-B16395; joro@8bytes.org; iommu@lists.linux-
foundation.org; linuxppc-dev@lists.ozlabs.org; linux-
kernel@vger.kernel.org; Yoder Stuart-B08248; Wood Scott-B07421;
alex.williamson@redhat.com
Subject: RE: [PATCH 2/3 v2] iommu/fsl: Enable default DMA window for PCIe
devices
=20
=20
=20

quoted

-----Original Message-----
From: Sethi Varun-B16395
Sent: Wednesday, October 16, 2013 4:53 PM
To: joro@8bytes.org; iommu@lists.linux-foundation.org; linuxppc-
dev@lists.ozlabs.org; linux-kernel@vger.kernel.org; Yoder
Stuart-B08248; Wood Scott-B07421; alex.williamson@redhat.com; Bhushan
Bharat-R65777
Cc: Sethi Varun-B16395
Subject: [PATCH 2/3 v2] iommu/fsl: Enable default DMA window for PCIe
devices

Once the PCIe device assigned to a guest VM (via VFIO) gets detached
from the iommu domain (when guest terminates), its PAMU table entry is
disabled. So, this would prevent the device from being used once it's

assigned back to the host.

quoted

This patch allows for creation of a default DMA window corresponding
to the device and subsequently enabling the PAMU table entry. Before
we enable the entry, we ensure that the device's bus master capability
is disabled (device quiesced).

Signed-off-by: Varun Sethi <redacted>
---
 drivers/iommu/fsl_pamu.c        |   43 ++++++++++++++++++++++++++++---

-----

quoted

 drivers/iommu/fsl_pamu.h        |    1 +
 drivers/iommu/fsl_pamu_domain.c |   46

++++++++++++++++++++++++++++++++++++---

quoted

 3 files changed, 78 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c index

cba0498..fb4a031 100644

--- a/drivers/iommu/fsl_pamu.c
+++ b/drivers/iommu/fsl_pamu.c

@@ -225,6 +225,21 @@ static struct paace *pamu_get_spaace(struct paace

*paace,
u32 wnum)
 	return spaace;
 }

+/*
+ * Defaul PPAACE settings for an LIODN.
+ */
+static void setup_default_ppaace(struct paace *ppaace) {
+	pamu_init_ppaace(ppaace);
+	/* window size is 2^(WSE+1) bytes */
+	set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
+	ppaace->wbah =3D 0;
+	set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
+	set_bf(ppaace->impl_attr, PAACE_IA_ATM,
+		PAACE_ATM_NO_XLATE);
+	set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
+		PAACE_AP_PERMS_ALL);
+}
 /**
  * pamu_get_fspi_and_allocate() - Allocates fspi index and reserves

subwindows

quoted

  *                                required for primary PAACE in the

secondary

quoted

@@ -253,6 +268,24 @@ static unsigned long

pamu_get_fspi_and_allocate(u32
subwin_cnt)
 	return (spaace_addr - (unsigned long)spaact) / (sizeof(struct
paace));  }

+/* Reset the PAACE entry to the default state */ void
+enable_default_dma_window(int liodn) {
+	struct paace *ppaace;
+
+	ppaace =3D pamu_get_ppaace(liodn);
+	if (!ppaace) {
+		pr_debug("Invalid liodn entry\n");
+		return;
+	}
+
+	memset(ppaace, 0, sizeof(struct paace));
+
+	setup_default_ppaace(ppaace);
+	mb();
+	pamu_enable_liodn(liodn);
+}
+
 /* Release the subwindows reserved for a particular LIODN */  void
pamu_free_subwins(int liodn)  { @@ -752,15 +785,7 @@ static void
__init
setup_liodns(void)
 				continue;
 			}
 			ppaace =3D pamu_get_ppaace(liodn);
-			pamu_init_ppaace(ppaace);
-			/* window size is 2^(WSE+1) bytes */
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WSE, 35);
-			ppaace->wbah =3D 0;
-			set_bf(ppaace->addr_bitfields, PPAACE_AF_WBAL, 0);
-			set_bf(ppaace->impl_attr, PAACE_IA_ATM,
-				PAACE_ATM_NO_XLATE);
-			set_bf(ppaace->addr_bitfields, PAACE_AF_AP,
-				PAACE_AP_PERMS_ALL);
+			setup_default_ppaace(ppaace);
 			if (of_device_is_compatible(node, "fsl,qman-portal"))
 				setup_qbman_paace(ppaace, QMAN_PORTAL_PAACE);
 			if (of_device_is_compatible(node, "fsl,qman")) diff --

git

quoted

a/drivers/iommu/fsl_pamu.h b/drivers/iommu/fsl_pamu.h index
8fc1a12..0edcbbbb
100644

--- a/drivers/iommu/fsl_pamu.h
+++ b/drivers/iommu/fsl_pamu.h

@@ -406,5 +406,6 @@ void get_ome_index(u32 *omi_index, struct device

*dev);  int pamu_update_paace_stash(int liodn, u32 subwin, u32 value);
int pamu_disable_spaace(int liodn, u32 subwin);
 u32 pamu_get_max_subwin_cnt(void);
+void enable_default_dma_window(int liodn);

 #endif  /* __FSL_PAMU_H */

diff --git a/drivers/iommu/fsl_pamu_domain.c

b/drivers/iommu/fsl_pamu_domain.c index 966ae70..dd6cafc 100644

--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c

@@ -340,17 +340,57 @@ static inline struct device_domain_info

*find_domain(struct device *dev)
 	return dev->archdata.iommu_domain;
 }

+/* Disable device DMA capability and enable default DMA window */
+static void disable_device_dma(struct device_domain_info *info,
+				int enable_dma_window)
+{
+#ifdef CONFIG_PCI
+	if (info->dev->bus =3D=3D &pci_bus_type) {
+		struct pci_dev *pdev =3D NULL;
+		pdev =3D to_pci_dev(info->dev);
+		if (pci_is_enabled(pdev))
+			pci_disable_device(pdev);
+	}
+#endif
+
+	if (enable_dma_window)
+		enable_default_dma_window(info->liodn);
+}
+
+static int check_for_shared_liodn(struct device_domain_info *info) {
+	struct device_domain_info *tmp;
+
+	/*
+	 * Sanity check, to ensure that this is not a
+	 * shared LIODN. In case of a PCIe controller
+	 * it's possible that all PCIe devices share
+	 * the same LIODN.
+	 */
+	list_for_each_entry(tmp, &info->domain->devices, link) {
+		if (info->liodn =3D=3D tmp->liodn)
+			return 1;
+	}
+
+	return 0;
+}
+
 static void remove_device_ref(struct device_domain_info *info, u32

win_cnt)  {

quoted

 	unsigned long flags;
+	int enable_dma_window =3D 0;

 	list_del(&info->link);
 	spin_lock_irqsave(&iommu_lock, flags);
-	if (win_cnt > 1)
-		pamu_free_subwins(info->liodn);
-	pamu_disable_liodn(info->liodn);
+	if (!check_for_shared_liodn(info)) {

=20
One query; Do we really need to check for this?
=20

[Sethi Varun-B16395] Yes, just a sanity check to ensure that there are no m=
ore devices linked to this LIODN and we can disable it.

-Varun

Otherwise this patch series looks good to me.
=20
Thanks
-Bharat
=20

quoted

+		if (win_cnt > 1)
+			pamu_free_subwins(info->liodn);
+		pamu_disable_liodn(info->liodn);
+		enable_dma_window =3D 1;
+	}
 	spin_unlock_irqrestore(&iommu_lock, flags);
 	spin_lock_irqsave(&device_domain_lock, flags);
+	disable_device_dma(info, enable_dma_window);
 	info->dev->archdata.iommu_domain =3D NULL;
 	kmem_cache_free(iommu_devinfo_cache, info);
 	spin_unlock_irqrestore(&device_domain_lock, flags);
--
1.7.9.5