1 files changed, 6 insertions, 1 deletions

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 1188b98e27e..c625800c55c 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -428,6 +428,10 @@ 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;
@@ -1075,7 +1079,8 @@ int __init amd_iommu_init(void)
                 goto free;
 
         /* IOMMU rlookup table - find the IOMMU for a specific device */
-        amd_iommu_rlookup_table = (void *)__get_free_pages(GFP_KERNEL,
+        amd_iommu_rlookup_table = (void *)__get_free_pages(
+                        GFP_KERNEL | __GFP_ZERO,
                         get_order(rlookup_table_size));
         if (amd_iommu_rlookup_table == NULL)
                 goto free;