[Xen-devel] [PATCH] amd iommu: Introduce a new lock for event and ppr logging

[Wei Wang <wei.wang2@xxxxxxx>]

# HG changeset patch
# User Wei Wang <wei.wang2@xxxxxxx>
# Date 1330438725 -3600
# Node ID 928b131ba6558387e546725fa955996434171a95
# Parent  a43eeaedf61ccaf269d0823ea80d3dfa8157cc63
amd iommu: Introduce a new lock for event and ppr logging

iommu->lock is used with irq disabled, so it cannot be used to protect ppr log.
Otherwise, after c/s 24770, get_gfn will trigger a BUG() if called by
parse_ppr_log_entry(). This patch adds an additional lock to protect ppr and
event pointers in iommu_read_log().

signed-off-by: Wei Wang <wei.wang2@xxxxxxx>

diff -r a43eeaedf61c -r 928b131ba655 xen/drivers/passthrough/amd/iommu_init.c
--- a/xen/drivers/passthrough/amd/iommu_init.c  Tue Feb 28 10:17:27 2012 +0000
+++ b/xen/drivers/passthrough/amd/iommu_init.c  Tue Feb 28 15:18:45 2012 +0100
@@ -367,6 +367,8 @@ static int iommu_read_log(struct amd_iom
     u32 tail, head, *entry, tail_offest, head_offset;
 
     BUG_ON(!iommu || ((log != &iommu->event_log) && (log != &iommu->ppr_log)));
+    
+    spin_lock(&log->lock);
 
     /* make sure there's an entry in the log */
     tail_offest = ( log == &iommu->event_log ) ?
@@ -396,6 +398,8 @@ static int iommu_read_log(struct amd_iom
         writel(head, iommu->mmio_base + head_offset);
     }
 
+    spin_unlock(&log->lock);
+   
     return 0;
 }
 
@@ -618,11 +622,11 @@ static void iommu_check_event_log(struct
     u32 entry;
     unsigned long flags;
 
-    spin_lock_irqsave(&iommu->lock, flags);
-
     iommu_read_log(iommu, &iommu->event_log,
                    sizeof(event_entry_t), parse_event_log_entry);
 
+    spin_lock_irqsave(&iommu->lock, flags);
+    
     /*check event overflow */
     entry = readl(iommu->mmio_base + IOMMU_STATUS_MMIO_OFFSET);
 
@@ -651,14 +655,10 @@ void parse_ppr_log_entry(struct amd_iomm
     bus = PCI_BUS(device_id);
     devfn = PCI_DEVFN2(device_id);
 
-    local_irq_enable();
-
     spin_lock(&pcidevs_lock);
     pdev = pci_get_pdev(iommu->seg, bus, devfn);
     spin_unlock(&pcidevs_lock);
 
-    local_irq_disable();
-
     if ( pdev == NULL )
         return;
 
@@ -672,10 +672,10 @@ static void iommu_check_ppr_log(struct a
     u32 entry;
     unsigned long flags;
 
-    spin_lock_irqsave(&iommu->lock, flags);
-
     iommu_read_log(iommu, &iommu->ppr_log,
                    sizeof(ppr_entry_t), parse_ppr_log_entry);
+    
+    spin_lock_irqsave(&iommu->lock, flags);
 
     /*check event overflow */
     entry = readl(iommu->mmio_base + IOMMU_STATUS_MMIO_OFFSET);
@@ -852,6 +852,8 @@ static void * __init allocate_ring_buffe
     ring_buf->head = 0;
     ring_buf->tail = 0;
 
+    spin_lock_init(&ring_buf->lock);
+    
     ring_buf->alloc_size = PAGE_SIZE << get_order_from_bytes(entries *
                                                              entry_size);
     ring_buf->entries = ring_buf->alloc_size / entry_size;
diff -r a43eeaedf61c -r 928b131ba655 xen/include/asm-x86/amd-iommu.h
--- a/xen/include/asm-x86/amd-iommu.h   Tue Feb 28 10:17:27 2012 +0000
+++ b/xen/include/asm-x86/amd-iommu.h   Tue Feb 28 15:18:45 2012 +0100
@@ -65,6 +65,7 @@ struct ring_buffer {
     unsigned long alloc_size;
     uint32_t tail;
     uint32_t head;
+    spinlock_t lock;    /* protect buffer pointers */
 };
 
 typedef struct iommu_cap {


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