[PATCH 1/2] iommu/amd: Cache pdev pointer to root-bridge

[PATCH 1/2] iommu/amd: Cache pdev pointer to root-bridge

[Joerg Roedel]

At some point pci_get_bus_and_slot started to enable
interrupts. Since this function is used in the
amd_iommu_resume path it will enable interrupts on resume
which causes a warning. The fix will use a cached pointer
to the root-bridge to re-enable the IOMMU in case the BIOS
is broken.

Cc: stable@vger.kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 drivers/iommu/amd_iommu_init.c  |   13 +++++--------
 drivers/iommu/amd_iommu_types.h |    3 +++
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index c567903..542024b 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1029,6 +1029,9 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 	if (!iommu->dev)
 		return 1;
 
+	iommu->root_pdev = pci_get_bus_and_slot(iommu->dev->bus->number,
+						PCI_DEVFN(0, 0));
+
 	iommu->cap_ptr = h->cap_ptr;
 	iommu->pci_seg = h->pci_seg;
 	iommu->mmio_phys = h->mmio_phys;
@@ -1323,20 +1326,16 @@ static void iommu_apply_resume_quirks(struct amd_iommu *iommu)
 {
 	int i, j;
 	u32 ioc_feature_control;
-	struct pci_dev *pdev = NULL;
+	struct pci_dev *pdev = iommu->root_pdev;
 
 	/* RD890 BIOSes may not have completely reconfigured the iommu */
-	if (!is_rd890_iommu(iommu->dev))
+	if (!is_rd890_iommu(iommu->dev) || !pdev)
 		return;
 
 	/*
 	 * First, we need to ensure that the iommu is enabled. This is
 	 * controlled by a register in the northbridge
 	 */
-	pdev = pci_get_bus_and_slot(iommu->dev->bus->number, PCI_DEVFN(0, 0));
-
-	if (!pdev)
-		return;
 
 	/* Select Northbridge indirect register 0x75 and enable writing */
 	pci_write_config_dword(pdev, 0x60, 0x75 | (1 << 7));
@@ -1346,8 +1345,6 @@ static void iommu_apply_resume_quirks(struct amd_iommu *iommu)
 	if (!(ioc_feature_control & 0x1))
 		pci_write_config_dword(pdev, 0x64, ioc_feature_control | 1);
 
-	pci_dev_put(pdev);
-
 	/* Restore the iommu BAR */
 	pci_write_config_dword(iommu->dev, iommu->cap_ptr + 4,
 			       iommu->stored_addr_lo);
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 2452f3b..2435555 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -481,6 +481,9 @@ struct amd_iommu {
 	/* Pointer to PCI device of this IOMMU */
 	struct pci_dev *dev;
 
+	/* Cache pdev to root device for resume quirks */
+	struct pci_dev *root_pdev;
+
 	/* physical address of MMIO space */
 	u64 mmio_phys;
 	/* virtual address of MMIO space */
-- 
1.7.9.5

[PATCH 2/2] iommu/amd: Fix deadlock in ppr-handling error path

[Joerg Roedel]

In the error path of the ppr_notifer it can happen that the
iommu->lock is taken recursivly. This patch fixes the
problem by releasing the iommu->lock before any notifier is
invoked. This also requires to move the erratum workaround
for the ppr-log (interrupt may be faster than data in the log)
one function up.

Cc: stable@vger.kernel.org # v3.3, v3.4
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 drivers/iommu/amd_iommu.c |   71 ++++++++++++++++++++++++++++-----------------
 1 file changed, 44 insertions(+), 27 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index d90a421..a2e418c 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -547,26 +547,12 @@ static void iommu_poll_events(struct amd_iommu *iommu)
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
-static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head)
+static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u64 *raw)
 {
 	struct amd_iommu_fault fault;
-	volatile u64 *raw;
-	int i;
 
 	INC_STATS_COUNTER(pri_requests);
 
-	raw = (u64 *)(iommu->ppr_log + head);
-
-	/*
-	 * Hardware bug: Interrupt may arrive before the entry is written to
-	 * memory. If this happens we need to wait for the entry to arrive.
-	 */
-	for (i = 0; i < LOOP_TIMEOUT; ++i) {
-		if (PPR_REQ_TYPE(raw[0]) != 0)
-			break;
-		udelay(1);
-	}
-
 	if (PPR_REQ_TYPE(raw[0]) != PPR_REQ_FAULT) {
 		pr_err_ratelimited("AMD-Vi: Unknown PPR request received\n");
 		return;
@@ -578,12 +564,6 @@ static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head)
 	fault.tag       = PPR_TAG(raw[0]);
 	fault.flags     = PPR_FLAGS(raw[0]);
 
-	/*
-	 * To detect the hardware bug we need to clear the entry
-	 * to back to zero.
-	 */
-	raw[0] = raw[1] = 0;
-
 	atomic_notifier_call_chain(&ppr_notifier, 0, &fault);
 }
 
@@ -595,25 +575,62 @@ static void iommu_poll_ppr_log(struct amd_iommu *iommu)
 	if (iommu->ppr_log == NULL)
 		return;
 
+	/* enable ppr interrupts again */
+	writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET);
+
 	spin_lock_irqsave(&iommu->lock, flags);
 
 	head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
 	tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
 
 	while (head != tail) {
+		volatile u64 *raw;
+		u64 entry[2];
+		int i;
 
-		/* Handle PPR entry */
-		iommu_handle_ppr_entry(iommu, head);
+		raw = (u64 *)(iommu->ppr_log + head);
+
+		/*
+		 * Hardware bug: Interrupt may arrive before the entry is
+		 * written to memory. If this happens we need to wait for the
+		 * entry to arrive.
+		 */
+		for (i = 0; i < LOOP_TIMEOUT; ++i) {
+			if (PPR_REQ_TYPE(raw[0]) != 0)
+				break;
+			udelay(1);
+		}
+
+		/* Avoid memcpy function-call overhead */
+		entry[0] = raw[0];
+		entry[1] = raw[1];
 
-		/* Update and refresh ring-buffer state*/
+		/*
+		 * To detect the hardware bug we need to clear the entry
+		 * back to zero.
+		 */
+		raw[0] = raw[1] = 0UL;
+
+		/* Update head pointer of hardware ring-buffer */
 		head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE;
 		writel(head, iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
+
+		/*
+		 * Release iommu->lock because ppr-handling might need to
+		 * re-aquire it
+		 */
+		spin_unlock_irqrestore(&iommu->lock, flags);
+
+		/* Handle PPR entry */
+		iommu_handle_ppr_entry(iommu, entry);
+
+		spin_lock_irqsave(&iommu->lock, flags);
+
+		/* Refresh ring-buffer information */
+		head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
 		tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
 	}
 
-	/* enable ppr interrupts again */
-	writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET);
-
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
-- 
1.7.9.5