[PATCH for-4.18] iommu: fix quarantine mode command line documentation

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

With the addition of per-device quarantine page tables the sink page is now
exclusive for each device, and thus writable.  Update the documentation to
reflect the current implementation.

Fixes: 14dd241aad8a ('IOMMU/x86: use per-device page tables for quarantining')
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 docs/misc/xen-command-line.pandoc | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/docs/misc/xen-command-line.pandoc 
b/docs/misc/xen-command-line.pandoc
index 604650aaeeef..9121d8a29404 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1520,15 +1520,14 @@ boolean (e.g. `iommu=no`) can override this and leave 
the IOMMUs disabled.
     should be enabled.  Quarantining can be done in two ways: In its basic
     form, all in-flight DMA will simply be forced to encounter IOMMU
     faults.  Since there are systems where doing so can cause host lockup,
-    an alternative form is available where writes to memory will be made
-    fault, but reads will be directed to a scratch page.  The implication
-    here is that such reads will go unnoticed, i.e. an admin may not
-    become aware of the underlying problem.
+    an alternative form is available where accesses to memory will be directed
+    to a scratch page. The implication here is that such accesses will go
+    unnoticed, i.e. an admin may not become aware of the underlying problem.
 
     Therefore, if this option is set to true (the default), Xen always
     quarantines such devices; they must be explicitly assigned back to Dom0
     before they can be used there again.  If set to "scratch-page", still
-    active DMA reads will additionally be directed to a "scratch" page.  If
+    active DMA operations will additionally be directed to a "scratch" page.  
If
     set to false, Xen will only quarantine devices the toolstack has arranged
     for getting quarantined, and only in the "basic" form.
 
-- 
2.42.0