[PATCH 5/9] VT-d: clear_fault_bits() should clear all fault bits

[Jan Beulich <jbeulich@xxxxxxxx>]

If there is any way for one fault to be left set in the recording
registers, there's no reason there couldn't also be multiple ones. If
PPF set set (being the OR or all F fields), simply loop over the entire
range of fault recording registers, clearing F everywhere.

Since PPF is a r/o bit, also remove it from DMA_FSTS_FAULTS (arguably
the constant's name is ambiguous as well).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2094,13 +2094,23 @@ static int __hwdom_init setup_hwdom_devi
 
 void clear_fault_bits(struct vtd_iommu *iommu)
 {
-    u64 val;
     unsigned long flags;
 
     spin_lock_irqsave(&iommu->register_lock, flags);
-    val = dmar_readq(iommu->reg, cap_fault_reg_offset(iommu->cap) + 8);
-    dmar_writeq(iommu->reg, cap_fault_reg_offset(iommu->cap) + 8, val);
+
+    if ( dmar_readl(iommu->reg, DMAR_FSTS_REG) & DMA_FSTS_PPF )
+    {
+        unsigned int reg = cap_fault_reg_offset(iommu->cap);
+        unsigned int end = reg + cap_num_fault_regs(iommu->cap);
+
+        do {
+           dmar_writel(iommu->reg, reg + 12, DMA_FRCD_F);
+           reg += PRIMARY_FAULT_REG_LEN;
+        } while ( reg < end );
+    }
+
     dmar_writel(iommu->reg, DMAR_FSTS_REG, DMA_FSTS_FAULTS);
+
     spin_unlock_irqrestore(&iommu->register_lock, flags);
 }
 
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -174,9 +174,8 @@
 #define DMA_FSTS_IQE (1u << 4)
 #define DMA_FSTS_ICE (1u << 5)
 #define DMA_FSTS_ITE (1u << 6)
-#define DMA_FSTS_FAULTS (DMA_FSTS_PFO | DMA_FSTS_PPF | DMA_FSTS_AFO | \
-                         DMA_FSTS_APF | DMA_FSTS_IQE | DMA_FSTS_ICE | \
-                         DMA_FSTS_ITE)
+#define DMA_FSTS_FAULTS (DMA_FSTS_PFO | DMA_FSTS_AFO | DMA_FSTS_APF | \
+                         DMA_FSTS_IQE | DMA_FSTS_ICE | DMA_FSTS_ITE)
 #define dma_fsts_fault_record_index(s) (((s) >> 8) & 0xff)
 
 /* FRCD_REG, 32 bits access */