[Xen-devel] [PATCH v5 10/15] mm / iommu: include need_iommu() test in iommu_use_hap_pt()

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

The name 'iommu_use_hap_pt' suggests that that P2M table is in use as the
domain's IOMMU pagetable which, prior to this patch, is not strictly true
since the macro did not test whether the domain actually has IOMMU
mappings.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>

v4:
 - New in v4.
---
 xen/arch/x86/mm/p2m-ept.c       | 6 +++---
 xen/arch/x86/mm/p2m-pt.c        | 6 +++---
 xen/arch/x86/mm/p2m.c           | 2 +-
 xen/drivers/passthrough/iommu.c | 2 +-
 xen/include/asm-arm/iommu.h     | 2 +-
 xen/include/asm-x86/iommu.h     | 5 +++--
 6 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 33e77903d6..e52dbb6203 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -863,12 +863,12 @@ out:
         ept_sync_domain(p2m);
 
     /* For host p2m, may need to change VT-d page table.*/
-    if ( rc == 0 && p2m_is_hostp2m(p2m) && need_iommu(d) &&
+    if ( rc == 0 && p2m_is_hostp2m(p2m) &&
          need_modify_vtd_table )
     {
-        if ( iommu_hap_pt_share )
+        if ( iommu_use_hap_pt(d) )
             rc = iommu_pte_flush(d, gfn, &ept_entry->epte, order, 
vtd_pte_present);
-        else
+        else if ( need_iommu(d) )
         {
             bfn_t bfn = _bfn(gfn);
 
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 9ff0b3fe7a..9255194070 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -677,8 +677,8 @@ p2m_pt_set_entry(struct p2m_domain *p2m, gfn_t gfn_, mfn_t 
mfn,
          && (gfn + (1UL << page_order) - 1 > p2m->max_mapped_pfn) )
         p2m->max_mapped_pfn = gfn + (1UL << page_order) - 1;
 
-    if ( iommu_enabled && need_iommu(p2m->domain) &&
-         (iommu_old_flags != iommu_pte_flags || old_mfn != mfn_x(mfn)) )
+    if ( iommu_enabled && (iommu_old_flags != iommu_pte_flags ||
+                           old_mfn != mfn_x(mfn)) )
     {
         ASSERT(rc == 0);
 
@@ -687,7 +687,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, gfn_t gfn_, mfn_t 
mfn,
             if ( iommu_old_flags )
                 amd_iommu_flush_pages(p2m->domain, gfn, page_order);
         }
-        else
+        else if ( need_iommu(p2m->domain) )
         {
             bfn_t bfn = _bfn(gfn);
 
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 036f52f4f1..7465489074 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -2092,7 +2092,7 @@ static unsigned int mmio_order(const struct domain *d,
      * - exclude PV guests, should execution reach this code for such.
      * So be careful when altering this.
      */
-    if ( !need_iommu(d) || !iommu_use_hap_pt(d) ||
+    if ( !iommu_use_hap_pt(d) ||
          (start_fn & ((1UL << PAGE_ORDER_2M) - 1)) || !(nr >> PAGE_ORDER_2M) )
         return PAGE_ORDER_4K;
 
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 9b7baca93f..ad8ffcfcb2 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -453,7 +453,7 @@ int iommu_do_domctl(
 
 void iommu_share_p2m_table(struct domain* d)
 {
-    if ( iommu_enabled && iommu_use_hap_pt(d) )
+    if ( iommu_use_hap_pt(d) )
         iommu_get_ops()->share_p2m(d);
 }
 
diff --git a/xen/include/asm-arm/iommu.h b/xen/include/asm-arm/iommu.h
index 57d9b1e14a..8d1506c6f7 100644
--- a/xen/include/asm-arm/iommu.h
+++ b/xen/include/asm-arm/iommu.h
@@ -21,7 +21,7 @@ struct arch_iommu
 };
 
 /* Always share P2M Table between the CPU and the IOMMU */
-#define iommu_use_hap_pt(d) (1)
+#define iommu_use_hap_pt(d) (need_iommu(d))
 
 const struct iommu_ops *iommu_get_ops(void);
 void __init iommu_set_ops(const struct iommu_ops *ops);
diff --git a/xen/include/asm-x86/iommu.h b/xen/include/asm-x86/iommu.h
index 14ad0489a6..0e7d66be54 100644
--- a/xen/include/asm-x86/iommu.h
+++ b/xen/include/asm-x86/iommu.h
@@ -77,8 +77,9 @@ static inline int iommu_hardware_setup(void)
     return -ENODEV;
 }
 
-/* Does this domain have a P2M table we can use as its IOMMU pagetable? */
-#define iommu_use_hap_pt(d) (hap_enabled(d) && iommu_hap_pt_share)
+/* Are we using the domain P2M table as its IOMMU pagetable? */
+#define iommu_use_hap_pt(d) \
+    (hap_enabled(d) && need_iommu(d) && iommu_hap_pt_share)
 
 void iommu_update_ire_from_apic(unsigned int apic, unsigned int reg, unsigned 
int value);
 unsigned int iommu_read_apic_from_ire(unsigned int apic, unsigned int reg);
-- 
2.11.0


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