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>

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index 5e46e78..86a0ff0 100644 (file)
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/arch/x86/include/asm/amd_iommu_types.h
@@ -141,6 +141,7 @@
 
 /* constants to configure the command buffer */
 #define CMD_BUFFER_SIZE    8192
+#define CMD_BUFFER_UNINITIALIZED 1
 #define CMD_BUFFER_ENTRIES 512
 #define MMIO_CMD_SIZE_SHIFT 56
 #define MMIO_CMD_SIZE_512 (0x9ULL << MMIO_CMD_SIZE_SHIFT)

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index b06f29e..71dfc0a 100644 (file)
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -392,6 +392,7 @@ static int __iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
        u32 tail, head;
        u8 *target;
 
+       WARN_ON(iommu->cmd_buf_size & CMD_BUFFER_UNINITIALIZED);
        tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
        target = iommu->cmd_buf + tail;
        memcpy_toio(target, cmd, sizeof(*cmd));

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 8975965..5edf41c 100644 (file)
--- 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 */