x86/amd-iommu: Panic if IOMMU command buffer reset fails

To prevent the driver from doing recursive command buffer
resets, just panic when that recursion happens.

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 c54bc97..e676746 100644 (file)
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/arch/x86/include/asm/amd_iommu_types.h
@@ -337,6 +337,9 @@ struct amd_iommu {
        /* if one, we need to send a completion wait command */
        bool need_sync;
 
+       /* becomes true if a command buffer reset is running */
+       bool reset_in_progress;
+
        /* default dma_ops domain for that IOMMU */
        struct dma_ops_domain *default_dom;
 };

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 2333d61..b62a2f6 100644 (file)
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -553,9 +553,16 @@ static void reset_iommu_command_buffer(struct amd_iommu *iommu)
 {
        pr_err("AMD-Vi: Resetting IOMMU command buffer\n");
 
+       if (iommu->reset_in_progress)
+               panic("AMD-Vi: ILLEGAL_COMMAND_ERROR while resetting command buffer\n");
+
+       iommu->reset_in_progress = true;
+
        amd_iommu_reset_cmd_buffer(iommu);
        flush_all_devices_for_iommu(iommu);
        flush_all_domains_on_iommu(iommu);
+
+       iommu->reset_in_progress = false;
 }
 
 /****************************************************************************