x86/amd-iommu: warn when issuing command to uninitialized cmd buffer

To catch future potential issues we can add a warning whenever we issue
a command before the command buffer is fully initialized.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 8975965f3e6..5edf41c7127 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -438,7 +438,7 @@ static u8 * __init alloc_command_buffer(struct amd_iommu *iommu)
         if (cmd_buf == NULL)
                 return NULL;
 
-        iommu->cmd_buf_size = CMD_BUFFER_SIZE;
+        iommu->cmd_buf_size = CMD_BUFFER_SIZE | CMD_BUFFER_UNINITIALIZED;
 
         return cmd_buf;
 }
@@ -474,12 +474,13 @@ static void iommu_enable_command_buffer(struct amd_iommu *iommu)
                     &entry, sizeof(entry));
 
         amd_iommu_reset_cmd_buffer(iommu);
+        iommu->cmd_buf_size &= ~(CMD_BUFFER_UNINITIALIZED);
 }
 
 static void __init free_command_buffer(struct amd_iommu *iommu)
 {
         free_pages((unsigned long)iommu->cmd_buf,
-                   get_order(iommu->cmd_buf_size));
+                   get_order(iommu->cmd_buf_size & ~(CMD_BUFFER_UNINITIALIZED)));
 }
 
 /* allocates the memory where the IOMMU will log its events to */