[Xen-devel] [RFC v1 01/15] iommu: Add iommu_intpost to control VT-d Posted-Interrupts feature

[Feng Wu <feng.wu@xxxxxxxxx>]

VT-d Posted-Interrupts is an enhancement to CPU side Posted-Interrupt.
With VT-d Posted-Interrupts enabled, external interrupts from
direct-assigned devices can be delivered to guests without VMM
intervention when guest is running in non-root mode.

This patch adds variable 'iommu_intpost' to control whether enable VT-d
posted-interrupt or not in the generic IOMMU code.

Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
---
 xen/drivers/passthrough/iommu.c | 11 ++++++++++-
 xen/include/xen/iommu.h         |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 92ea26f..302e3e4 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -39,6 +39,7 @@ static void iommu_dump_p2m_table(unsigned char key);
  *   no-snoop                   Disable VT-d Snoop Control
  *   no-qinval                  Disable VT-d Queued Invalidation
  *   no-intremap                Disable VT-d Interrupt Remapping
+ *   no-intpost                 Disable VT-d Interrupt posting
  */
 custom_param("iommu", parse_iommu_param);
 bool_t __initdata iommu_enable = 1;
@@ -51,6 +52,7 @@ bool_t __read_mostly iommu_passthrough;
 bool_t __read_mostly iommu_snoop = 1;
 bool_t __read_mostly iommu_qinval = 1;
 bool_t __read_mostly iommu_intremap = 1;
+bool_t __read_mostly iommu_intpost = 0;
 bool_t __read_mostly iommu_hap_pt_share = 1;
 bool_t __read_mostly iommu_debug;
 bool_t __read_mostly amd_iommu_perdev_intremap = 1;
@@ -94,7 +96,11 @@ static void __init parse_iommu_param(char *s)
         else if ( !strcmp(s, "qinval") )
             iommu_qinval = val;
         else if ( !strcmp(s, "intremap") )
+        {
             iommu_intremap = val;
+            if ( iommu_intremap == 0 )
+                iommu_intpost = 0;
+        }
         else if ( !strcmp(s, "debug") )
         {
             iommu_debug = val;
@@ -272,7 +278,10 @@ int __init iommu_setup(void)
         iommu_enabled = (rc == 0);
     }
     if ( !iommu_enabled )
+    {
         iommu_intremap = 0;
+        iommu_intpost = 0;
+    }
 
     if ( (force_iommu && !iommu_enabled) ||
          (force_intremap && !iommu_intremap) )
@@ -341,7 +350,7 @@ void iommu_crash_shutdown(void)
     const struct iommu_ops *ops = iommu_get_ops();
     if ( iommu_enabled )
         ops->crash_shutdown();
-    iommu_enabled = iommu_intremap = 0;
+    iommu_enabled = iommu_intremap = iommu_intpost = 0;
 }
 
 bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index bf4aff0..91063bb 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -31,7 +31,7 @@
 extern bool_t iommu_enable, iommu_enabled;
 extern bool_t force_iommu, iommu_verbose;
 extern bool_t iommu_workaround_bios_bug, iommu_passthrough;
-extern bool_t iommu_snoop, iommu_qinval, iommu_intremap;
+extern bool_t iommu_snoop, iommu_qinval, iommu_intremap, iommu_intpost;
 extern bool_t iommu_hap_pt_share;
 extern bool_t iommu_debug;
 extern bool_t amd_iommu_perdev_intremap;
-- 
2.1.0


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