linux-kernel - Re: [PATCH 30/30] x86, kaiser, xen: Dynamically disable KAISER when running under Xen PV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7e70274c-6ad0-9f9c-0ad3-8d3306d8174a@suse.com>
Date:   Thu, 9 Nov 2017 16:01:42 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, moritz.lipp@...k.tugraz.at,
        daniel.gruss@...k.tugraz.at, michael.schwarz@...k.tugraz.at,
        richard.fellner@...dent.tugraz.at, luto@...nel.org,
        torvalds@...ux-foundation.org, keescook@...gle.com,
        hughd@...gle.com, x86@...nel.org
Subject: Re: [PATCH 30/30] x86, kaiser, xen: Dynamically disable KAISER when
 running under Xen PV

On 08/11/17 20:47, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> If you paravirtualize the MMU, you can not use KAISER.  This boils down
> to the fact that KAISER needs to do CR3 writes in places that it is not
> feasible to do real hypercalls.
> 
> If we detect that Xen PV is in use, do not do the KAISER CR3 switches.
> 
> I don't think this too bug of a deal for Xen.  I was under the
> impression that the Xen guest kernel and Xen guest userspace didn't
> share an address space *anyway* so Xen PV is not normally even exposed
> to the kinds of things that KAISER protects against.
> 
> This allows KAISER=y kernels to deployed in environments that also
> require PARAVIRT=y.
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>

Acked-by: Juergen Gross <jgross@...e.com>


Juergen