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iommu/amd: Workaround for ERBT1312 

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>
Cc: stable@vger.kernel.org
Signed-off-by: Joerg Roedel <joro@8bytes.org>
This commit is contained in:
Joerg Roedel 2013-04-18 17:55:04 +02:00
parent 7d8bfa26f2
commit d3263bc297
1 changed files with 26 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
drivers/iommu/amd_iommu.c
View File

@ -700,14 +700,23 @@ 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);
@ -744,16 +753,25 @@ 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);