Date: Sat, 6 Jan 2018 14:02:39 -0800 From: Mark Millard <markmi@dsl-only.net> To: FreeBSD Current <freebsd-current@freebsd.org>, freebsd-amd64@freebsd.org Subject: Re: Intel CPU design flaw - FreeBSD affected? [AMD family Zen/17h status] Message-ID: <B5F69AB5-C027-457B-B780-40459456F61E@dsl-only.net> In-Reply-To: <05382876-0605-424D-9BDD-CE1BF6C744CF@dsl-only.net> References: <05382876-0605-424D-9BDD-CE1BF6C744CF@dsl-only.net>
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On 2018-Jan-4, at 7:32 PM, Mark Millard <markmi at dsl-only.net> wrote: > Darren Reed darrenr at freebsd.org wrote on > Thu Jan 4 11:56:29 UTC 2018 : >=20 >> Most people are only talking about meltdown which doesn't hit AMD. >> spectre impacts *both* Intel and AMD. >>=20 >> SuSE are making available a microcode patch for AMD 17h processors = that >> disables branch prediction: >>=20 >>=20 >> = https://lists.opensuse.org/opensuse-security-announce/2018-01/msg00004.htm= l >=20 > https://www.amd.com/en/corporate/speculative-execution >=20 > reports. . . >=20 > For the Bounds Check Bypass Spectre variant (#1): >=20 > Resolved by software / OS updates to be made available > by system vendors and manufacturers. Negligible performance > impact expected. >=20 > For the Branch Target Injection Spectre variant (#2): >=20 > Differences in AMD architecture mean there is a near zero > risk of exploitation of this variant. Vulnerability to > Variant 2 has not been demonstrated on AMD processors to > date. >=20 > For the Rogue Data Cache Load Meltdown variant (#3): >=20 > Zero AMD vulnerability due to AMD architecture differences. >=20 >=20 >=20 > How long #2 will have a "has not been demonstrated" status > is yet to be seen. = https://www.phoronix.com/scan.php?page=3Dnews_item&px=3DAMD-Branch-Predict= ion-Still reports that SUSE's microcode update for AMD's Zen/17h does not disable branch prediction, despite SUSE's existing description: QUOTE I reached out to AMD and on Friday heard back. They wrote in an email to Phoronix that this Zen/17h microcode update does not disable branch prediction. They'll be working with SUSE to re-clarify this microcode update description... But as far as what this microcode update does in the wake of SPECTRE they have yet to clarify or why this microcode binary has yet to make it to other Linux distributions. If/when I hear anything more, I'll certainly post about it but doesn't appear to be anything as dramatic as disabling branch prediction, which could have slaughtered their CPU performance. END QUOTE =3D=3D=3D Mark Millard markmi at dsl-only.net
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