[PATCH v4 16/17] intel_iommu: Introduce a property to control FS1GP cap bit setting

[Zhenzhong Duan]

This gives user flexibility to turn off FS1GP for debug purpose.

It is also useful for future nesting feature. When host IOMMU doesn't
support FS1GP but vIOMMU does, nested page table on host side works
after turn FS1GP off in vIOMMU.

This property has no effect when vIOMMU isn't in scalable modern
mode.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>
---
 include/hw/i386/intel_iommu.h | 1 +
 hw/i386/intel_iommu.c         | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 48134bda11..4d6acb2314 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -307,6 +307,7 @@ struct IntelIOMMUState {
     bool dma_drain;                 /* Whether DMA r/w draining enabled */
     bool dma_translation;           /* Whether DMA translation supported */
     bool pasid;                     /* Whether to support PASID */
+    bool fs1gp;                     /* First Stage 1-GByte Page Support */
 
     /*
      * Protects IOMMU states in general.  Currently it protects the
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 14578655e1..f8f196aeed 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -3785,6 +3785,7 @@ static Property vtd_properties[] = {
     DEFINE_PROP_BOOL("x-pasid-mode", IntelIOMMUState, pasid, false),
     DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true),
     DEFINE_PROP_BOOL("dma-translation", IntelIOMMUState, dma_translation, 
true),
+    DEFINE_PROP_BOOL("fs1gp", IntelIOMMUState, fs1gp, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -4513,7 +4514,9 @@ static void vtd_cap_init(IntelIOMMUState *s)
     /* TODO: read cap/ecap from host to decide which cap to be exposed. */
     if (s->scalable_modern) {
         s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_FLTS;
-        s->cap |= VTD_CAP_FS1GP;
+        if (s->fs1gp) {
+            s->cap |= VTD_CAP_FS1GP;
+        }
     } else if (s->scalable_mode) {
         s->ecap |= VTD_ECAP_SMTS | VTD_ECAP_SRS | VTD_ECAP_SLTS;
     }
-- 
2.34.1