amd-iommu: set event buffer head and tail to 0 manually
These registers may contain values from previous kernels. So reset them
to known values before enable the event buffer again.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 48a79b9..068a356 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -486,6 +486,10 @@
memcpy_toio(iommu->mmio_base + MMIO_EVT_BUF_OFFSET,
&entry, sizeof(entry));
+ /* set head and tail to zero manually */
+ writel(0x00, iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);
+ writel(0x00, iommu->mmio_base + MMIO_EVT_TAIL_OFFSET);
+
iommu_feature_enable(iommu, CONTROL_EVT_LOG_EN);
}