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authorJoerg Roedel <joro@8bytes.org>2013-04-18 17:55:04 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-07 12:49:48 -0700
commit52462d2f5a520ce96c3ea028d80594375adca04b (patch)
tree721e31a4275ab027dd8e821527f995a4e6a9005d
parenta5d3e60fa23aa401a2f14ed58af32405c9915351 (diff)
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iommu/amd: Workaround for ERBT1312
commit d3263bc29706e42f74d8800807c2dedf320d77f1 upstream. Work around an IOMMU hardware bug where clearing the EVT_INT or PPR_INT bit in the status register may race with the hardware trying to set it again. When not handled the bit might not be cleared and we lose all future event or ppr interrupts. Reported-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Signed-off-by: Joerg Roedel <joro@8bytes.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/iommu/amd_iommu.c34
1 files changed, 26 insertions, 8 deletions
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 48f416aca05..99a8444fc68 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -531,14 +531,23 @@ retry:
static void iommu_poll_events(struct amd_iommu *iommu)
{
- u32 head, tail;
+ u32 head, tail, status;
unsigned long flags;
- /* enable event interrupts again */
- writel(MMIO_STATUS_EVT_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET);
-
spin_lock_irqsave(&iommu->lock, flags);
+ /* enable event interrupts again */
+ do {
+ /*
+ * Workaround for Erratum ERBT1312
+ * Clearing the EVT_INT bit may race in the hardware, so read
+ * it again and make sure it was really cleared
+ */
+ status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
+ writel(MMIO_STATUS_EVT_INT_MASK,
+ iommu->mmio_base + MMIO_STATUS_OFFSET);
+ } while (status & MMIO_STATUS_EVT_INT_MASK);
+
head = readl(iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_EVT_TAIL_OFFSET);
@@ -575,16 +584,25 @@ static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u64 *raw)
static void iommu_poll_ppr_log(struct amd_iommu *iommu)
{
unsigned long flags;
- u32 head, tail;
+ u32 head, tail, status;
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);
+ /* enable ppr interrupts again */
+ do {
+ /*
+ * Workaround for Erratum ERBT1312
+ * Clearing the PPR_INT bit may race in the hardware, so read
+ * it again and make sure it was really cleared
+ */
+ status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
+ writel(MMIO_STATUS_PPR_INT_MASK,
+ iommu->mmio_base + MMIO_STATUS_OFFSET);
+ } while (status & MMIO_STATUS_PPR_INT_MASK);
+
head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);