[PATCH v6 4/5] VT-d: Reduce spin timeout to 1ms, which can be boot-time changed

[Quan Xu <quan.xu@intel.com>]

Signed-off-by: Quan Xu <quan.xu@intel.com>
---
 docs/misc/xen-command-line.markdown  |  7 +++++++
 xen/drivers/passthrough/vtd/qinval.c | 15 +++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index a565c1b..1f5a111 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1466,6 +1466,13 @@ Note that if **watchdog** option is also specified vpmu will be turned off.
 As the BTS virtualisation is not 100% safe and because of the nehalem quirk
 don't use the vpmu flag on production systems with Intel cpus!
 
+### vtd\_qi\_timeout (VT-d)
+> `= <integer>`
+
+> Default: `1`
+
+Specify the timeout of the VT-d Queued Invalidation in milliseconds.
+
 ### watchdog
 > `= force | <boolean>`
 
diff --git a/xen/drivers/passthrough/vtd/qinval.c b/xen/drivers/passthrough/vtd/qinval.c
index b81b0bd..882b9f4 100644
--- a/xen/drivers/passthrough/vtd/qinval.c
+++ b/xen/drivers/passthrough/vtd/qinval.c
@@ -28,6 +28,11 @@
 #include "vtd.h"
 #include "extern.h"
 
+static unsigned int __read_mostly vtd_qi_timeout = 1;
+integer_param("vtd_qi_timeout", vtd_qi_timeout);
+
+#define IOMMU_QI_TIMEOUT (vtd_qi_timeout * MILLISECS(1))
+
 static void print_qi_regs(struct iommu *iommu)
 {
     u64 val;
@@ -130,6 +135,10 @@ static void queue_invalidate_iotlb(struct iommu *iommu,
     spin_unlock_irqrestore(&iommu->register_lock, flags);
 }
 
+/*
+ * NB. We must check all kinds of error and all the way up the
+ * call trees.
+ */
 static int queue_invalidate_wait(struct iommu *iommu,
     u8 iflag, u8 sw, u8 fn)
 {
@@ -167,10 +176,12 @@ static int queue_invalidate_wait(struct iommu *iommu,
         start_time = NOW();
         while ( poll_slot != QINVAL_STAT_DONE )
         {
-            if ( NOW() > (start_time + DMAR_OPERATION_TIMEOUT) )
+            if ( NOW() > (start_time + IOMMU_QI_TIMEOUT) )
             {
                 print_qi_regs(iommu);
-                panic("queue invalidate wait descriptor was not executed");
+                printk(XENLOG_WARNING VTDPREFIX
+                       "Queue invalidate wait descriptor was timeout.\n");
+                return -ETIMEDOUT;
             }
             cpu_relax();
         }
-- 
1.9.1


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