[PATCH 26/93] iommu/amd: Re-enable IOMMU event log interrupt after handling.

[Luis Henriques]

3.5.7.15 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Suravee Suthikulpanit <suravee.suthikulpanit at amd.com>

commit 925fe08bce38d1ff052fe2209b9e2b8d5fbb7f98 upstream.

Current driver does not clear the IOMMU event log interrupt bit
in the IOMMU status register after processing an interrupt.
This causes the IOMMU hardware to generate event log interrupt only once.
This has been observed in both IOMMU v1 and V2 hardware.
This patch clears the bit by writing 1 to bit 1 of the IOMMU
status register (MMIO Offset 2020h)

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit at amd.com>
Signed-off-by: Joerg Roedel <joro at 8bytes.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/iommu/amd_iommu.c       | 3 +++
 drivers/iommu/amd_iommu_types.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 33fee0a..257ab08 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -534,6 +534,9 @@ static void iommu_poll_events(struct amd_iommu *iommu)
 	u32 head, tail;
 	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);
 
 	head = readl(iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index c1b1d48..f9addfd 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -99,6 +99,7 @@
 #define PASID_MASK		0x000fffff
 
 /* MMIO status bits */
+#define MMIO_STATUS_EVT_INT_MASK	(1 << 1)
 #define MMIO_STATUS_COM_WAIT_INT_MASK	(1 << 2)
 #define MMIO_STATUS_PPR_INT_MASK	(1 << 6)
 
-- 
1.8.1.2