[PATCH 6/6] Introduce domain flag (dont_flush_iotlb) to avoid unnecessary iotlb flush.

[Jean Guyader <jean.guyader@eu.citrix.com>]

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Add a domain level flag that will be check by the iommu low level code
to skip iotlb flush. iommu_iotlb_flush has to be called explicitly.

Signed-off-by: Jean Guyader <jean.guyader@eu.citrix.com>
---
 xen/arch/x86/mm.c                   |   12 +++++++++++-
 xen/drivers/passthrough/iommu.c     |    6 ++++++
 xen/drivers/passthrough/vtd/iommu.c |    6 ++++--
 xen/include/xen/sched.h             |    1 +
 4 files changed, 22 insertions(+), 3 deletions(-)


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diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 77ae77f..4e23875 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4699,7 +4699,7 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
     {
     case XENMEM_add_to_physmap:
     {
-        struct xen_add_to_physmap xatp;
+        struct xen_add_to_physmap xatp, start_xatp;
         struct domain *d;
         unsigned int size, i;
 
@@ -4720,8 +4720,11 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
         if ( xatp.space == XENMAPSPACE_gmfn_range )
         {
             size = xatp.size;
+            if ( need_iommu(d) )
+                d->dont_flush_iotlb = 1;
         }
 
+        start_xatp = xatp;
         for ( i = 0; i < size; i++ )
         {
             xenmem_add_to_physmap(d, xatp);
@@ -4729,6 +4732,13 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg)
             xatp.gpfn++;
         }
 
+        if ( xatp.space == XENMAPSPACE_gmfn_range && need_iommu(d) )
+        {
+            d->dont_flush_iotlb = 0;
+            iommu_iotlb_flush(d, start_xatp.idx, size);
+            iommu_iotlb_flush(d, start_xatp.gpfn, size);
+        }
+
         rcu_unlock_domain(d);
 
         return rc;
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 9c62861..7f87aed 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -113,10 +113,13 @@ void __init iommu_dom0_init(struct domain *d)
         return;
 
     d->need_iommu = !!iommu_dom0_strict;
+    d->dont_flush_iotlb = 0;
     if ( need_iommu(d) )
     {
         struct page_info *page;
         unsigned int i = 0;
+
+        d->dont_flush_iotlb = 1;
         page_list_for_each ( page, &d->page_list )
         {
             unsigned long mfn = page_to_mfn(page);
@@ -129,6 +132,8 @@ void __init iommu_dom0_init(struct domain *d)
             if ( !(i++ & 0xfffff) )
                 process_pending_softirqs();
         }
+        d->dont_flush_iotlb = 0;
+        iommu_iotlb_flush_all(d);
     }
 
     return hd->platform_ops->dom0_init(d);
@@ -210,6 +215,7 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn)
     if ( has_arch_pdevs(d) && !need_iommu(d) )
     {
         d->need_iommu = 1;
+        d->dont_flush_iotlb = 0;
         if ( !iommu_use_hap_pt(d) )
             rc = iommu_populate_page_table(d);
         goto done;
diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index 7ec9541..336232e 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -660,7 +660,8 @@ static void dma_pte_clear_one(struct domain *domain, u64 addr)
     spin_unlock(&hd->mapping_lock);
     iommu_flush_cache_entry(pte, sizeof(struct dma_pte));
 
-    __intel_iommu_iotlb_flush(domain, addr >> PAGE_SHIFT_4K , 0, 1);
+    if ( !domain->dont_flush_iotlb )
+        __intel_iommu_iotlb_flush(domain, addr >> PAGE_SHIFT_4K , 0, 1);
 
     unmap_vtd_domain_page(page);
 
@@ -1753,7 +1754,8 @@ static int intel_iommu_map_page(
     spin_unlock(&hd->mapping_lock);
     unmap_vtd_domain_page(page);
 
-    __intel_iommu_iotlb_flush(d, gfn, dma_pte_present(old), 1);
+    if ( !d->dont_flush_iotlb )
+        __intel_iommu_iotlb_flush(d, gfn, dma_pte_present(old), 1);
 
     return 0;
 }
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 3ba5495..922f068 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -244,6 +244,7 @@ struct domain
     bool_t           is_hvm;
     /* Does this guest need iommu mappings? */
     bool_t           need_iommu;
+    bool_t           dont_flush_iotlb;
     /* Is this guest fully privileged (aka dom0)? */
     bool_t           is_privileged;
     /* Which guest this guest has privileges on */

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