[PATCH] ioat2: catch and recover from broken vtd configurations v6

[Dan Williams]

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.

Cc: <stable@xxxxxxxxxx>
Cc: 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>
---
David, looking for your sign-off to take this final version through my
tree.

Thanks,
Dan

 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 |   28 ++++++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index 6d3a73b..5216c8a 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -97,6 +97,7 @@ struct ioat_chan_common {
 	#define IOAT_RESET_PENDING 2
 	#define IOAT_KOBJ_INIT_FAIL 3
 	#define IOAT_RESHAPE_PENDING 4
+	#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 3c8b32a..216f9d3 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -287,7 +287,10 @@ 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
@@ -492,6 +495,8 @@ 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
  */
@@ -500,6 +505,7 @@ 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? */
@@ -540,7 +546,20 @@ 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)
@@ -778,6 +797,7 @@ 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(&chan->cleanup_lock);
 	spin_lock_bh(&ioat->prep_lock);
diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c
index 1cdd22e..d0f4990 100644
--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -361,7 +361,10 @@ 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 796828f..90938c7 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -3029,6 +3029,34 @@ 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_TAINT_ONCE(!drhd || drhd->reg_base_addr - vtbar != 0xa000,
+			    TAINT_FIRMWARE_WORKAROUND,
+			    "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;

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