[34-longterm 010/209] ioat2: catch and recover from broken vtd configurations v6

[Paul Gortmaker]

From: Dan Williams <dan.j.williams@xxxxxxxxx>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 556ab45f9a775bfa4762bacc0a4afb5b44b067bc upstream.

On some platforms (MacPro3,1) the BIOS assigns the ioatdma device to the
incorrect iommu causing faults when the driver initializes.  Add a quirk
to catch this misconfiguration and try falling back to untranslated
operation (which works in the MacPro3,1 case).

Assuming there are other platforms with misconfigured iommus teach the
ioatdma driver to treat initialization failures as non-fatal (just fail
the driver load and emit a warning instead of triggering a BUG_ON).

This can be classified as a boot regression since 2.6.32 on affected
platforms since the ioatdma module did not autoload prior to that
kernel.

[PG: 34 has no WARN_TAINT_ONCE, use WARN_ONCE instead]

Acked-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Reported-by: Chris Li <lkml@xxxxxxxxxxx>
Tested-by: Chris Li <lkml@xxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/dma/ioat/dma.h    |    1 +
 drivers/dma/ioat/dma_v2.c |   24 ++++++++++++++++++++++--
 drivers/dma/ioat/dma_v3.c |    5 ++++-
 drivers/pci/intel-iommu.c |   27 +++++++++++++++++++++++++++
 4 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index 86b97ac..4eda2e5 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -96,6 +96,7 @@ struct ioat_chan_common {
 	#define IOAT_COMPLETION_ACK 1
 	#define IOAT_RESET_PENDING 2
 	#define IOAT_KOBJ_INIT_FAIL 3
+	#define IOAT_RUN 5
 	struct timer_list timer;
 	#define COMPLETION_TIMEOUT msecs_to_jiffies(100)
 	#define IDLE_TIMEOUT msecs_to_jiffies(2000)
diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index b5ae56c..63e6929 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -304,7 +304,10 @@ void ioat2_timer_event(unsigned long data)
 			chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET);
 			dev_err(to_dev(chan), "%s: Channel halted (%x)\n",
 				__func__, chanerr);
-			BUG_ON(is_ioat_bug(chanerr));
+			if (test_bit(IOAT_RUN, &chan->state))
+				BUG_ON(is_ioat_bug(chanerr));
+			else /* we never got off the ground */
+				return;
 		}
 
 		/* if we haven't made progress and we have already
@@ -496,6 +499,8 @@ static struct ioat_ring_ent **ioat2_alloc_ring(struct dma_chan *c, int order, gf
 	return ring;
 }
 
+void ioat2_free_chan_resources(struct dma_chan *c);
+
 /* ioat2_alloc_chan_resources - allocate/initialize ioat2 descriptor ring
  * @chan: channel to be initialized
  */
@@ -504,6 +509,7 @@ int ioat2_alloc_chan_resources(struct dma_chan *c)
 	struct ioat2_dma_chan *ioat = to_ioat2_chan(c);
 	struct ioat_chan_common *chan = &ioat->base;
 	struct ioat_ring_ent **ring;
+	u64 status;
 	int order;
 
 	/* have we already been set up? */
@@ -542,7 +548,20 @@ int ioat2_alloc_chan_resources(struct dma_chan *c)
 	tasklet_enable(&chan->cleanup_task);
 	ioat2_start_null_desc(ioat);
 
-	return 1 << ioat->alloc_order;
+	/* check that we got off the ground */
+	udelay(5);
+	status = ioat_chansts(chan);
+	if (is_ioat_active(status) || is_ioat_idle(status)) {
+		set_bit(IOAT_RUN, &chan->state);
+		return 1 << ioat->alloc_order;
+	} else {
+		u32 chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET);
+
+		dev_WARN(to_dev(chan),
+			"failed to start channel chanerr: %#x\n", chanerr);
+		ioat2_free_chan_resources(c);
+		return -EFAULT;
+	}
 }
 
 bool reshape_ring(struct ioat2_dma_chan *ioat, int order)
@@ -776,6 +795,7 @@ void ioat2_free_chan_resources(struct dma_chan *c)
 	del_timer_sync(&chan->timer);
 	device->cleanup_fn((unsigned long) c);
 	device->reset_hw(chan);
+	clear_bit(IOAT_RUN, &chan->state);
 
 	spin_lock_bh(&ioat->ring_lock);
 	descs = ioat2_ring_space(ioat);
diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c
index 6740e31..52b1e3d 100644
--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -401,7 +401,10 @@ static void ioat3_timer_event(unsigned long data)
 			chanerr = readl(chan->reg_base + IOAT_CHANERR_OFFSET);
 			dev_err(to_dev(chan), "%s: Channel halted (%x)\n",
 				__func__, chanerr);
-			BUG_ON(is_ioat_bug(chanerr));
+			if (test_bit(IOAT_RUN, &chan->state))
+				BUG_ON(is_ioat_bug(chanerr));
+			else /* we never got off the ground */
+				return;
 		}
 
 		/* if we haven't made progress and we have already
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index fff8832..3507692 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -3028,6 +3028,33 @@ static void __init iommu_exit_mempool(void)
 
 }
 
+static void quirk_ioat_snb_local_iommu(struct pci_dev *pdev)
+{
+	struct dmar_drhd_unit *drhd;
+	u32 vtbar;
+	int rc;
+
+	/* We know that this device on this chipset has its own IOMMU.
+	 * If we find it under a different IOMMU, then the BIOS is lying
+	 * to us. Hope that the IOMMU for this device is actually
+	 * disabled, and it needs no translation...
+	 */
+	rc = pci_bus_read_config_dword(pdev->bus, PCI_DEVFN(0, 0), 0xb0, &vtbar);
+	if (rc) {
+		/* "can't" happen */
+		dev_info(&pdev->dev, "failed to run vt-d quirk\n");
+		return;
+	}
+	vtbar &= 0xffff0000;
+
+	/* we know that the this iommu should be at offset 0xa000 from vtbar */
+	drhd = dmar_find_matched_drhd_unit(pdev);
+	if (WARN_ONCE(!drhd || drhd->reg_base_addr - vtbar != 0xa000,
+			    "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"))
+		pdev->dev.archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
+}
+DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IOAT_SNB, quirk_ioat_snb_local_iommu);
+
 static void __init init_no_remapping_devices(void)
 {
 	struct dmar_drhd_unit *drhd;
-- 
1.7.4.4

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