[Xen-devel] [PATCH 2/3] xen/vt-d: mask interrupt message generation

[Tiejun Chen <tiejun.chen@xxxxxxxxx>]

While initializing VT-D we should mask interrupt message generation
to avoid receiving any interrupt as pending before enable DMA
translation, and also mask that before disable DMA engine.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index c7bda73..72cd854 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1000,15 +1000,21 @@ static void dma_msi_unmask(struct irq_desc *desc)
     iommu->msi.msi_attrib.masked = 0;
 }
 
-static void dma_msi_mask(struct irq_desc *desc)
+static void mask_dma_interrupt(struct iommu *iommu)
 {
     unsigned long flags;
-    struct iommu *iommu = desc->action->dev_id;
 
-    /* mask it */
     spin_lock_irqsave(&iommu->register_lock, flags);
     dmar_writel(iommu->reg, DMAR_FECTL_REG, DMA_FECTL_IM);
     spin_unlock_irqrestore(&iommu->register_lock, flags);
+}
+
+static void dma_msi_mask(struct irq_desc *desc)
+{
+    struct iommu *iommu = desc->action->dev_id;
+
+    /* mask it */
+    mask_dma_interrupt(iommu);
     iommu->msi.msi_attrib.masked = 1;
 }
 
@@ -1997,7 +2003,6 @@ static int init_vtd_hw(void)
     struct iommu *iommu;
     struct iommu_flush *flush = NULL;
     int ret;
-    unsigned long flags;
 
     /*
      * Basic VT-d HW init: set VT-d interrupt, clear VT-d faults.  
@@ -2008,11 +2013,16 @@ static int init_vtd_hw(void)
 
         iommu = drhd->iommu;
 
-        clear_fault_bits(iommu);
+        /*
+         * We shouldn't receive any VT-d interrupt while initializing
+         * VT-d so just mask interrupt message generation.
+         */
+        mask_dma_interrupt(iommu);
 
-        spin_lock_irqsave(&iommu->register_lock, flags);
-        dmar_writel(iommu->reg, DMAR_FECTL_REG, 0);
-        spin_unlock_irqrestore(&iommu->register_lock, flags);
+        /*
+         * And then clear all previous faults.
+         */
+        clear_fault_bits(iommu);
     }
 
     /*
@@ -2350,6 +2360,11 @@ static void vtd_suspend(void)
         if ( force_iommu )
             continue;
 
+        /*
+         * Mask interrupt message generation.
+         */
+        mask_dma_interrupt(iommu);
+
         iommu_disable_translation(iommu);
 
         /* If interrupt remapping is enabled, queued invalidation
-- 
1.9.1


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