[Xen-devel] [PATCH v5 02/10] IOMMU: handle IOMMU mapping and unmapping failures

[Quan Xu <quan.xu@xxxxxxxxx>]

Treat IOMMU mapping and unmapping failures as a fatal to the DomU
If IOMMU mapping and unmapping failed, crash the DomU and propagate
the error up to the call trees.

No spamming can occur. For DomU, we avoid logging any message
for already dying domains. For Dom0, that'll still be more verbose
than we'd really like, but it at least wouldn't outright flood the
console.

Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/drivers/passthrough/iommu.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 9d104d2..7c70306 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -240,21 +240,49 @@ int iommu_map_page(struct domain *d, unsigned long gfn, 
unsigned long mfn,
                    unsigned int flags)
 {
     const struct domain_iommu *hd = dom_iommu(d);
+    int rc;
 
     if ( !iommu_enabled || !hd->platform_ops )
         return 0;
 
-    return hd->platform_ops->map_page(d, gfn, mfn, flags);
+    rc = hd->platform_ops->map_page(d, gfn, mfn, flags);
+
+    if ( unlikely(rc) )
+    {
+        if ( !d->is_shutting_down && printk_ratelimit() )
+            printk(XENLOG_ERR
+                   "d%d: IOMMU mapping gfn %#lx mfn %#lx failed %d.",
+                   d->domain_id, gfn, mfn, rc);
+
+        if ( !is_hardware_domain(d) )
+            domain_crash(d);
+    }
+
+    return rc;
 }
 
 int iommu_unmap_page(struct domain *d, unsigned long gfn)
 {
     const struct domain_iommu *hd = dom_iommu(d);
+    int rc;
 
     if ( !iommu_enabled || !hd->platform_ops )
         return 0;
 
-    return hd->platform_ops->unmap_page(d, gfn);
+    rc = hd->platform_ops->unmap_page(d, gfn);
+
+    if ( unlikely(rc) )
+    {
+        if ( !d->is_shutting_down && printk_ratelimit() )
+            printk(XENLOG_ERR
+                   "d%d: IOMMU unmapping gfn %#lx failed %d.",
+                   d->domain_id, gfn, rc);
+
+        if ( !is_hardware_domain(d) )
+            domain_crash(d);
+    }
+
+    return rc;
 }
 
 static void iommu_free_pagetables(unsigned long unused)
-- 
1.9.1


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