admin-guide/hw-vuln: Rephrase a section of core-scheduling.rst

Rephrase the "For MDS" section in core-scheduling.rst for the purpose of
making it clearer what is meant by "kernel memory is still considered
untrusted".

Suggested-by: Vineeth Pillai <Vineeth.Pillai@microsoft.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joelaf@google.com>
Link: https://lore.kernel.org/r/20210721190250.26095-1-fmdefrancesco@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/hw-vuln/core-scheduling.rst

@@ -181,10 +181,12 @@ Open cross-HT issues that core scheduling does not solve
 --------------------------------------------------------
 1. For MDS
 ~~~~~~~~~~
-Core scheduling cannot protect against MDS attacks between an HT running in
-user mode and another running in kernel mode. Even though both HTs run tasks
-which trust each other, kernel memory is still considered untrusted. Such
-attacks are possible for any combination of sibling CPU modes (host or guest mode).
+Core scheduling cannot protect against MDS attacks between the siblings
+running in user mode and the others running in kernel mode. Even though all
+siblings run tasks which trust each other, when the kernel is executing
+code on behalf of a task, it cannot trust the code running in the
+sibling. Such attacks are possible for any combination of sibling CPU modes
+(host or guest mode).
 
 2. For L1TF
 ~~~~~~~~~~~