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>

2 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index c54bc979dc17..e676746a4a30 100644
--- 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 2333d615f5ee..b62a2f64dfc5 100644
--- 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;
 }
 
 /****************************************************************************