[Xen-devel] [PATCH v5 3/7] VT-d: Reduce spin timeout to 1ms, which can be boot-time changed.

[Quan Xu <quan.xu@xxxxxxxxx>]

Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
---
 docs/misc/xen-command-line.markdown  |  7 +++++++
 xen/drivers/passthrough/vtd/qinval.c | 11 +++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/docs/misc/xen-command-line.markdown 
b/docs/misc/xen-command-line.markdown
index a565c1b..6ed5cd8 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -968,6 +968,13 @@ Use this to work around firmware issues providing correct 
RMRR entries. Rather
 than only mapping RAM pages for IOMMU accesses for Dom0, with this option all
 pages not marked as unusable in the E820 table will get a mapping established.
 
+### vtd\_qi\_timeout (VT-d)
+> `= <integer>`
+
+> Default: `1`
+
+>> Specify the timeout of the VT-d Queued Invalidation in ms.
+
 ### irq\_ratelimit
 > `= <integer>`
 
diff --git a/xen/drivers/passthrough/vtd/qinval.c 
b/xen/drivers/passthrough/vtd/qinval.c
index 946e812..f9e752b 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;
@@ -167,10 +172,12 @@ 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");
+                dprintk(XENLOG_WARNING VTDPREFIX,
+                        "Queue invalidate wait descriptor was timeout.\n");
+                return -ETIMEDOUT;
             }
             cpu_relax();
         }
-- 
1.9.1


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