From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 20 Aug 2021 10:30:35 +0000 (+0200)
Subject: AMD/IOMMU: don't leave page table mapped when unmapping ...
X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~42^2~270
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=3cfec6a6aa7a7bf68f8e19e21f450c2febe9acb4;p=xen.git

AMD/IOMMU: don't leave page table mapped when unmapping ...

... an already not mapped page. With all other exit paths doing the
unmap, I have no idea how I managed to miss that aspect at the time.

Fixes: ad591454f069 ("AMD/IOMMU: don't needlessly trigger errors/crashes when unmapping a page")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
---

diff --git a/xen/drivers/passthrough/amd/iommu_map.c b/xen/drivers/passthrough/amd/iommu_map.c
index 560af54b76..1ed39bbee5 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -243,7 +243,10 @@ static int iommu_pde_from_dfn(struct domain *d, unsigned long dfn,
         else if ( !pde->pr )
         {
             if ( !map )
+            {
+                unmap_domain_page(next_table_vaddr);
                 return 0;
+            }
 
             if ( next_table_mfn == 0 )
             {