2 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index a7b6dec6fc3f..0a60d60ed036 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -235,8 +235,9 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
         status &= ~MMIO_STATUS_COM_WAIT_INT_MASK;
         writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);
 
-        if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
-                printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");
+        if (unlikely(i == EXIT_LOOP_COUNT))
+                panic("AMD IOMMU: Completion wait loop failed\n");
+
 out:
         spin_unlock_irqrestore(&iommu->lock, flags);
 
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c90a15eba5c5..c6cc22815d35 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -427,6 +427,10 @@ static u8 * __init alloc_command_buffer(struct amd_iommu *iommu)
         memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
                         &entry, sizeof(entry));
 
+        /* set head and tail to zero manually */
+        writel(0x00, iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
+        writel(0x00, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
+
         iommu_feature_enable(iommu, CONTROL_CMDBUF_EN);
 
         return cmd_buf;