[Xen-changelog] [xen master] VT-d Posted-Interrupts feature detection

[patchbot@xxxxxxx]

commit 1d028f7f2bce751b457d5551eb5fa17d4ad79600
Author:     Feng Wu <feng.wu@xxxxxxxxx>
AuthorDate: Tue Nov 24 12:10:10 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Nov 24 12:10:10 2015 +0100

    VT-d Posted-Interrupts feature detection
    
    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.
    
    Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
    Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c |   14 ++++++++++++--
 xen/drivers/passthrough/vtd/iommu.h |    1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index d95f4d4..1d17769 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2156,8 +2156,8 @@ int __init intel_vtd_setup(void)
     }
 
     /* We enable the following features only if they are supported by all VT-d
-     * engines: Snoop Control, DMA passthrough, Queued Invalidation and
-     * Interrupt Remapping.
+     * engines: Snoop Control, DMA passthrough, Queued Invalidation, Interrupt
+     * Remapping, and Posted Interrupt
      */
     for_each_drhd_unit ( drhd )
     {
@@ -2185,6 +2185,14 @@ int __init intel_vtd_setup(void)
         if ( iommu_intremap && !ecap_intr_remap(iommu->ecap) )
             iommu_intremap = 0;
 
+        /*
+         * We cannot use posted interrupt if X86_FEATURE_CX16 is
+         * not supported, since we count on this feature to
+         * atomically update 16-byte IRTE in posted format.
+         */
+        if ( !cap_intr_post(iommu->cap) || !cpu_has_cx16 )
+            iommu_intpost = 0;
+
         if ( !vtd_ept_page_compatible(iommu) )
             iommu_hap_pt_share = 0;
 
@@ -2210,6 +2218,7 @@ int __init intel_vtd_setup(void)
     P(iommu_passthrough, "Dom0 DMA Passthrough");
     P(iommu_qinval, "Queued Invalidation");
     P(iommu_intremap, "Interrupt Remapping");
+    P(iommu_intpost, "Posted Interrupt");
     P(iommu_hap_pt_share, "Shared EPT tables");
 #undef P
 
@@ -2229,6 +2238,7 @@ int __init intel_vtd_setup(void)
     iommu_passthrough = 0;
     iommu_qinval = 0;
     iommu_intremap = 0;
+    iommu_intpost = 0;
     return ret;
 }
 
diff --git a/xen/drivers/passthrough/vtd/iommu.h 
b/xen/drivers/passthrough/vtd/iommu.h
index ac71ed1..22abefe 100644
--- a/xen/drivers/passthrough/vtd/iommu.h
+++ b/xen/drivers/passthrough/vtd/iommu.h
@@ -61,6 +61,7 @@
 /*
  * Decoding Capability Register
  */
+#define cap_intr_post(c)       (((c) >> 59) & 1)
 #define cap_read_drain(c)      (((c) >> 55) & 1)
 #define cap_write_drain(c)     (((c) >> 54) & 1)
 #define cap_max_amask_val(c)   (((c) >> 48) & 0x3f)
--
generated by git-patchbot for /home/xen/git/xen.git#master

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