[Xen-changelog] [xen stable-4.1] AMD/iommu: SR56x0 Erratum 64 - Reset all head & tail pointers

[patchbot@xxxxxxx]

commit 22de18bb89e776f77256653901a590aad9fc0a52
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu May 23 15:17:04 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu May 23 15:17:04 2013 +0200

    AMD/iommu: SR56x0 Erratum 64 - Reset all head & tail pointers
    
    Reference at time of patch:
    http://support.amd.com/us/ChipsetMotherboard_TechDocs/46303.pdf
    
    Erratum 64 states that the head and tail pointers for the Command buffer and
    Event log are only reset on a cold boot, not a warm boot.
    
    While the erratum is limited to systems using SR56xx chipsets (such as 
Family
    10h CPUs), resetting the pointers is a sensible action in all cases, 
including
    the PPR log for consistency.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
    Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
    master commit: 6d243308e1d75f866679db226159c797d6c83aad
    master date: 2013-05-22 15:26:52 +0200
---
 xen/drivers/passthrough/amd/iommu_init.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index fcb7e87..adf220b 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -119,6 +119,11 @@ static void register_iommu_cmd_buffer_in_mmio_space(struct 
amd_iommu *iommu)
                          IOMMU_CMD_BUFFER_LENGTH_MASK,
                          IOMMU_CMD_BUFFER_LENGTH_SHIFT, &entry);
     writel(entry, iommu->mmio_base+IOMMU_CMD_BUFFER_BASE_HIGH_OFFSET);
+
+    /* Reset head/tail pointer. SR56x0 Erratum 64 means this might not happen
+     * automatically for us. */
+    writel(0, iommu->mmio_base + IOMMU_CMD_BUFFER_HEAD_OFFSET);
+    writel(0, iommu->mmio_base + IOMMU_CMD_BUFFER_TAIL_OFFSET);
 }
 
 static void register_iommu_event_log_in_mmio_space(struct amd_iommu *iommu)
@@ -146,6 +151,11 @@ static void register_iommu_event_log_in_mmio_space(struct 
amd_iommu *iommu)
                         IOMMU_EVENT_LOG_LENGTH_MASK,
                         IOMMU_EVENT_LOG_LENGTH_SHIFT, &entry);
     writel(entry, iommu->mmio_base+IOMMU_EVENT_LOG_BASE_HIGH_OFFSET);
+
+    /* Reset head/tail pointer. SR56x0 Erratum 64 means this might not happen
+     * automatically for us. */
+    writel(0, iommu->mmio_base + IOMMU_EVENT_LOG_HEAD_OFFSET);
+    writel(0, iommu->mmio_base + IOMMU_EVENT_LOG_TAIL_OFFSET);
 }
 
 static void set_iommu_translation_control(struct amd_iommu *iommu,
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.1

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