[Xen-devel] [PATCH v2] x86/vtd: fix iommu_share_p2m_table

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Commit 2916951c1 "mm / iommu: include need_iommu() test in
iommu_use_hap_pt()" changed the check in iommu_share_p2m_table to use
need_iommu(d) (as part of iommu_use_hap_pt) instead of iommu_enabled,
which broke the check because at the point in domain construction
where iommu_share_p2m_table is called need_iommu(d) will always return
false.

Fix this by reverting to the previous logic.

While there turn the hap_enabled check into an ASSERT, since the only
caller of iommu_share_p2m_table already performs the hap_enabled check
before calling the function.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Changes since v1:
 - Add a comment about why iommu_use_hap_pt cannot be used in
   iommu_share_p2m_table.
 - Expand commit message.
 - Convert the hap_enabled check into an ASSERT.
---
 xen/drivers/passthrough/iommu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index debb5e6fe1..75bc410c2c 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -505,7 +505,13 @@ int iommu_do_domctl(
 
 void iommu_share_p2m_table(struct domain* d)
 {
-    if ( iommu_use_hap_pt(d) )
+    ASSERT(hap_enabled(d));
+    /*
+     * iommu_use_hap_pt cannot be used here because at the point in the domain
+     * construction where iommu_share_p2m_table get called need_iommu(d) will
+     * always return false.
+     */
+    if ( iommu_enabled && iommu_hap_pt_share )
         iommu_get_ops()->share_p2m(d);
 }
 
-- 
2.19.0


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