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-rw-r--r--arch/x86/kernel/amd_iommu_init.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c90a15eba5c..c6cc22815d3 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;