[xen master] CHANGELOG: record changed PCI device quarantining default

[patchbot@xxxxxxx]

commit 1d3250f8c4cb750bb0dcf9fdbe01f8de85780281
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jul 13 10:17:33 2021 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jul 13 10:17:33 2021 +0200

    CHANGELOG: record changed PCI device quarantining default
    
    This amends commit 980d6acf1517 ("IOMMU: make DMA containment of
    quarantined devices optional").
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
---
 CHANGELOG.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6896d70757..22cfdb4298 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,13 @@ The format is based on [Keep a 
Changelog](https://keepachangelog.com/en/1.0.0/)
  - XENSTORED_ROOTDIR environment variable from configuartion files and
    initscripts, due to being unused.
 
+### Changed
+ - Quarantining of passed-through PCI devices no longer defaults to directing 
I/O to a scratch
+   page, matching original post-XSA-302 behavior (albeit the change was also 
backported, first
+   appearing in 4.12.2 and 4.11.4). Prior (4.13...4.15-like) behavior can be 
arranged for
+   either by enabling the IOMMU_QUARANTINE_SCRATCH_PAGE setting at build 
(configuration) time
+   or by passing "iommu=quarantine=scratch-page" on the hypervisor command 
line.
+
 ## [4.15.0 
UNRELEASED](https://xenbits.xen.org/gitweb/?p=xen.git;a=shortlog;h=RELEASE-4.15.0)
 - TBD
 
 ### Added / support upgraded
--
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