[Xen-devel] [PATCH MM-PART1 v3 8/8] xen/arm: mm: Flush the TLBs even if a mapping failed in create_xen_entries

[Julien Grall <julien.grall@xxxxxxx>]

At the moment, create_xen_entries will only flush the TLBs if the full
range has successfully been updated. This may lead to leave unwanted
entries in the TLBs if we fail to update some entries.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

---
    Changes in v2:
        - Add Andrii's reviewed-by
        - Add Stefano's reviewed-by
---
 xen/arch/arm/mm.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 8ee828d445..9d584e4cbf 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -984,7 +984,7 @@ static int create_xen_entries(enum xenmap_operation op,
                               unsigned long nr_mfns,
                               unsigned int flags)
 {
-    int rc;
+    int rc = 0;
     unsigned long addr = virt, addr_end = addr + nr_mfns * PAGE_SIZE;
     lpae_t pte, *entry;
     lpae_t *third = NULL;
@@ -1013,7 +1013,8 @@ static int create_xen_entries(enum xenmap_operation op,
                 {
                     printk("%s: trying to replace an existing mapping addr=%lx 
mfn=%"PRI_mfn"\n",
                            __func__, addr, mfn_x(mfn));
-                    return -EINVAL;
+                    rc = -EINVAL;
+                    goto out;
                 }
                 if ( op == RESERVE )
                     break;
@@ -1030,7 +1031,8 @@ static int create_xen_entries(enum xenmap_operation op,
                 {
                     printk("%s: trying to %s a non-existing mapping 
addr=%lx\n",
                            __func__, op == REMOVE ? "remove" : "modify", addr);
-                    return -EINVAL;
+                    rc = -EINVAL;
+                    goto out;
                 }
                 if ( op == REMOVE )
                     pte.bits = 0;
@@ -1043,7 +1045,8 @@ static int create_xen_entries(enum xenmap_operation op,
                     {
                         printk("%s: Incorrect combination for addr=%lx\n",
                                __func__, addr);
-                        return -EINVAL;
+                        rc = -EINVAL;
+                        goto out;
                     }
                 }
                 write_pte(entry, pte);
@@ -1052,11 +1055,14 @@ static int create_xen_entries(enum xenmap_operation op,
                 BUG();
         }
     }
+out:
+    /*
+     * Flush the TLBs even in case of failure because we may have
+     * partially modified the PT. This will prevent any unexpected
+     * behavior afterwards.
+     */
     flush_xen_tlb_range_va(virt, PAGE_SIZE * nr_mfns);
 
-    rc = 0;
-
-out:
     return rc;
 }
 
-- 
2.11.0


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