From: Ian Jackson <iwj@xenproject.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>,
"George Dunlap" <george.dunlap@citrix.com>
Subject: Re: [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors
Date: Fri, 19 Feb 2021 16:30:51 +0000 [thread overview]
Message-ID: <24623.59323.764544.88044@mariner.uk.xensource.com> (raw)
In-Reply-To: <fbac488e-383c-c5a9-585a-6609b81e7acc@suse.com>
Jan Beulich writes ("Re: [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors"):
> On 19.02.2021 17:13, Ian Jackson wrote:
> > Jan Beulich writes ("Re: [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors"):
> > I think 4-6 and 8 are good candidates for the reasons you give, and
> > because they seem low risk to me. Have you used any automatic
> > techniques to check that there is no unintentional codegen change ?
> > (Eg, binary diffs, diffing sedderied versions, or something.)
>
> I did some manual inspection at the time of putting together that
> work, but nothing further to be honest.
I think that something automatic might be worthwhile, but I would like
an opinion from another hypervisor maintainer about the level of risk
posed by the possibility of manual slips. Eg, how likely it would be
for the compiler to catch them.
> > To my naive eye patch 7 looks scary because it might be moving the
> > scope of a critical section. Am I wrong about that ?
>
> At the source level it moves things, yes. Generated code, again as
> per manual inspection, doesn't change, due to the pieces that the
> compiler is able to eliminate. So I guess it's not as scary as it
> may look.
Oh, you eyeballed the generated code ? Cool.
Ian.
next prev parent reply other threads:[~2021-02-19 16:31 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 8:16 [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors Jan Beulich
2021-02-17 8:19 ` [PATCH v2 1/8] x86: split __{get,put}_user() into "guest" and "unsafe" variants Jan Beulich
2021-02-17 8:20 ` [PATCH v2 2/8] x86: split __copy_{from,to}_user() " Jan Beulich
2021-02-17 8:20 ` [PATCH v2 3/8] x86/PV: harden guest memory accesses against speculative abuse Jan Beulich
2021-02-17 8:21 ` [PATCH v2 4/8] x86: rename {get,put}_user() to {get,put}_guest() Jan Beulich
2021-02-22 15:22 ` Roger Pau Monné
2021-02-17 8:21 ` [PATCH v2 5/8] x86/gdbsx: convert "user" to "guest" accesses Jan Beulich
2021-02-22 15:31 ` Roger Pau Monné
2021-02-22 15:55 ` Jan Beulich
2021-02-22 16:08 ` Roger Pau Monné
2021-02-17 8:22 ` [PATCH v2 6/8] x86: rename copy_{from,to}_user() to copy_{from,to}_guest_pv() Jan Beulich
2021-02-23 11:04 ` Roger Pau Monné
2021-02-23 15:15 ` Jan Beulich
2021-02-17 8:22 ` [PATCH v2 7/8] x86: move stac()/clac() from {get,put}_unsafe_asm() Jan Beulich
2021-02-23 11:40 ` Roger Pau Monné
2021-02-17 8:23 ` [PATCH v2 8/8] x86/PV: use get_unsafe() instead of copy_from_unsafe() Jan Beulich
2021-02-23 11:59 ` Roger Pau Monné
2021-02-23 15:25 ` Jan Beulich
2021-02-23 15:37 ` Roger Pau Monné
2021-02-23 16:13 ` Jan Beulich
2021-02-23 18:03 ` Roger Pau Monné
2021-02-19 15:50 ` [PATCH v2 0/8] x86/PV: avoid speculation abuse through guest accessors Ian Jackson
2021-02-19 15:56 ` Jan Beulich
2021-02-19 16:13 ` Ian Jackson
2021-02-19 16:16 ` Jan Beulich
2021-02-19 16:30 ` Ian Jackson [this message]
2021-02-24 11:13 ` Jan Beulich
2021-02-24 13:08 ` Ian Jackson
2021-02-24 13:18 ` Jan Beulich
2021-02-24 13:26 ` Ian Jackson
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