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From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	"Paul Durrant" <paul@xen.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 14:26:49 +0200
Message-ID: <41b49d79-e0fa-161a-bb27-a9a2ccf361f5@suse.com> (raw)
In-Reply-To: <20200701115842.18583-1-andrew.cooper3@citrix.com>

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>


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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 [this message]
2020-07-01 13:23   ` Paul Durrant

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