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From: Paul Durrant <xadimgnik@gmail.com>
To: "'Jan Beulich'" <jbeulich@suse.com>,
	"'Andrew Cooper'" <andrew.cooper3@citrix.com>
Cc: 'Xen-devel' <xen-devel@lists.xenproject.org>,
	"\'Wei Liu\'" <wl@xen.org>,
	"\'Roger Pau Monné\'" <roger.pau@citrix.com>
Subject: RE: [PATCH for-4.14] x86/spec-ctrl: Protect against CALL/JMP straight-line speculation
Date: Wed, 1 Jul 2020 14:23:18 +0100
Message-ID: <001201d64faa$ca8a6370$5f9f2a50$@xen.org> (raw)
In-Reply-To: <41b49d79-e0fa-161a-bb27-a9a2ccf361f5@suse.com>

> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 01 July 2020 13:27
> To: Andrew Cooper <andrew.cooper3@citrix.com>
> Cc: Xen-devel <xen-devel@lists.xenproject.org>; Wei Liu <wl@xen.org>; Roger Pau Monné
> <roger.pau@citrix.com>; Paul Durrant <paul@xen.org>
> Subject: Re: [PATCH for-4.14] x86/spec-ctrl: Protect against CALL/JMP straight-line speculation
> On 01.07.2020 13:58, Andrew Cooper wrote:
> > Some x86 CPUs speculatively execute beyond indirect CALL/JMP instructions.
> >
> > With CONFIG_INDIRECT_THUNK / Retpolines, indirect CALL/JMP instructions are
> > converted to direct CALL/JMP's to __x86_indirect_thunk_REG(), leaving just a
> > handful of indirect JMPs implementing those stubs.
> >
> > There is no architectrual execution beyond an indirect JMP, so use INT3 as
> > recommended by vendors to halt speculative execution.  This is shorter than
> > LFENCE (which would also work fine), but also shows up in logs if we do
> > unexpected execute them.
> >
> > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

Release-acked-by: Paul Durrant <paul@xen.org>

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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01 11:58 Andrew Cooper
2020-07-01 12:26 ` Jan Beulich
2020-07-01 13:23   ` Paul Durrant [this message]

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