This is a note to let you know that I've just added the patch titled
iommu/amd: Fix deadlock in ppr-handling error path
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommu-amd-fix-deadlock-in-ppr-handling-error-path.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From eee53537c476c947bf7faa1c916d2f5a0ae8ec93 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <[email protected]>
Date: Fri, 1 Jun 2012 15:20:23 +0200
Subject: iommu/amd: Fix deadlock in ppr-handling error path
From: Joerg Roedel <[email protected]>
commit eee53537c476c947bf7faa1c916d2f5a0ae8ec93 upstream.
In the error path of the ppr_notifer it can happen that the
iommu->lock is taken recursivly. This patch fixes the
problem by releasing the iommu->lock before any notifier is
invoked. This also requires to move the erratum workaround
for the ppr-log (interrupt may be faster than data in the log)
one function up.
Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/iommu/amd_iommu.c | 73 ++++++++++++++++++++++++++++------------------
1 file changed, 45 insertions(+), 28 deletions(-)
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -547,26 +547,12 @@ static void iommu_poll_events(struct amd
spin_unlock_irqrestore(&iommu->lock, flags);
}
-static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u32 head)
+static void iommu_handle_ppr_entry(struct amd_iommu *iommu, u64 *raw)
{
struct amd_iommu_fault fault;
- volatile u64 *raw;
- int i;
INC_STATS_COUNTER(pri_requests);
- raw = (u64 *)(iommu->ppr_log + head);
-
- /*
- * Hardware bug: Interrupt may arrive before the entry is written to
- * memory. If this happens we need to wait for the entry to arrive.
- */
- for (i = 0; i < LOOP_TIMEOUT; ++i) {
- if (PPR_REQ_TYPE(raw[0]) != 0)
- break;
- udelay(1);
- }
-
if (PPR_REQ_TYPE(raw[0]) != PPR_REQ_FAULT) {
pr_err_ratelimited("AMD-Vi: Unknown PPR request received\n");
return;
@@ -578,12 +564,6 @@ static void iommu_handle_ppr_entry(struc
fault.tag = PPR_TAG(raw[0]);
fault.flags = PPR_FLAGS(raw[0]);
- /*
- * To detect the hardware bug we need to clear the entry
- * to back to zero.
- */
- raw[0] = raw[1] = 0;
-
atomic_notifier_call_chain(&ppr_notifier, 0, &fault);
}
@@ -595,25 +575,62 @@ static void iommu_poll_ppr_log(struct am
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);
head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
while (head != tail) {
+ volatile u64 *raw;
+ u64 entry[2];
+ int i;
+
+ raw = (u64 *)(iommu->ppr_log + head);
+
+ /*
+ * Hardware bug: Interrupt may arrive before the entry is
+ * written to memory. If this happens we need to wait for the
+ * entry to arrive.
+ */
+ for (i = 0; i < LOOP_TIMEOUT; ++i) {
+ if (PPR_REQ_TYPE(raw[0]) != 0)
+ break;
+ udelay(1);
+ }
+
+ /* Avoid memcpy function-call overhead */
+ entry[0] = raw[0];
+ entry[1] = raw[1];
+
+ /*
+ * To detect the hardware bug we need to clear the entry
+ * back to zero.
+ */
+ raw[0] = raw[1] = 0UL;
- /* Handle PPR entry */
- iommu_handle_ppr_entry(iommu, head);
-
- /* Update and refresh ring-buffer state*/
+ /* Update head pointer of hardware ring-buffer */
head = (head + PPR_ENTRY_SIZE) % PPR_LOG_SIZE;
writel(head, iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
+
+ /*
+ * Release iommu->lock because ppr-handling might need to
+ * re-aquire it
+ */
+ spin_unlock_irqrestore(&iommu->lock, flags);
+
+ /* Handle PPR entry */
+ iommu_handle_ppr_entry(iommu, entry);
+
+ spin_lock_irqsave(&iommu->lock, flags);
+
+ /* Refresh ring-buffer information */
+ head = readl(iommu->mmio_base + MMIO_PPR_HEAD_OFFSET);
tail = readl(iommu->mmio_base + MMIO_PPR_TAIL_OFFSET);
}
- /* enable ppr interrupts again */
- writel(MMIO_STATUS_PPR_INT_MASK, iommu->mmio_base + MMIO_STATUS_OFFSET);
-
spin_unlock_irqrestore(&iommu->lock, flags);
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/iommu-amd-fix-deadlock-in-ppr-handling-error-path.patch
queue-3.4/iommu-amd-check-for-the-right-tlp-prefix-bit.patch
queue-3.4/iommu-amd-add-workaround-for-event-log-erratum.patch
queue-3.4/iommu-amd-cache-pdev-pointer-to-root-bridge.patch
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