[RFC PATCH 6/9] iommu: Pass additional use_iommu argument to iommu_domain_init()

[Oleksandr Tyshchenko <olekstysh@gmail.com>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

The presence of this flag lets us know that the guest
has devices which will most likely be used for passthrough.
In that case we have to call iommu_construct(), actually
what the real assign_device call usually does.

As iommu_domain_init() is called with forced to false use_iommu flag
for now, no functional change is intended.

Basically, this patch is needed for unshared IOMMUs on ARM only
since the unshared IOMMUs on x86 are ok if iommu_construct() is called
later. But, in order to be more generic and for possible future optimization
make this change applicable for both platforms.
So, the patch target is to make ARM happy and not to brake x86.
Confirmation from x86 guys is needed.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
---
 xen/arch/arm/domain.c           |  2 +-
 xen/arch/x86/domain.c           |  2 +-
 xen/drivers/passthrough/iommu.c | 11 +++++++++--
 xen/include/xen/iommu.h         |  2 +-
 4 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index bb327da..bab62ee 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -550,7 +550,7 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags,
     ASSERT(config != NULL);
 
     /* p2m_init relies on some value initialized by the IOMMU subsystem */
-    if ( (rc = iommu_domain_init(d)) != 0 )
+    if ( (rc = iommu_domain_init(d, false)) != 0 )
         goto fail;
 
     if ( (rc = p2m_init(d)) != 0 )
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 479aee6..8ef4160 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -646,7 +646,7 @@ int arch_domain_create(struct domain *d, unsigned int domcr_flags,
         if ( (rc = init_domain_irq_mapping(d)) != 0 )
             goto fail;
 
-        if ( (rc = iommu_domain_init(d)) != 0 )
+        if ( (rc = iommu_domain_init(d, false)) != 0 )
             goto fail;
     }
     spin_lock_init(&d->arch.e820_lock);
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 115698f..6c17c59 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -129,7 +129,7 @@ static void __init parse_iommu_param(char *s)
     } while ( ss );
 }
 
-int iommu_domain_init(struct domain *d)
+int iommu_domain_init(struct domain *d, bool_t use_iommu)
 {
     struct domain_iommu *hd = dom_iommu(d);
     int ret = 0;
@@ -142,7 +142,14 @@ int iommu_domain_init(struct domain *d)
         return 0;
 
     hd->platform_ops = iommu_get_ops();
-    return hd->platform_ops->init(d);
+    ret = hd->platform_ops->init(d);
+    if ( ret )
+        return ret;
+
+    if ( use_iommu && !is_hardware_domain(d) )
+        ret = iommu_construct(d);
+
+    return ret;
 }
 
 static void __hwdom_init check_hwdom_reqs(struct domain *d)
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 0446ed3..ab68ae2 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -56,7 +56,7 @@ int iommu_setup(void);
 int iommu_add_device(struct pci_dev *pdev);
 int iommu_enable_device(struct pci_dev *pdev);
 int iommu_remove_device(struct pci_dev *pdev);
-int iommu_domain_init(struct domain *d);
+int iommu_domain_init(struct domain *d, bool_t use_iommu);
 void iommu_hwdom_init(struct domain *d);
 void iommu_domain_destroy(struct domain *d);
 int deassign_device(struct domain *d, u16 seg, u8 bus, u8 devfn);
-- 
2.7.4


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