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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>,
	"Ian Jackson" <Ian.Jackson@citrix.com>,
	"Paul Durrant" <paul@xen.org>, "Wei Liu" <wl@xen.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH 7/9] x86/hvm: Disable MPX by default
Date: Wed, 17 Jun 2020 13:41:42 +0200	[thread overview]
Message-ID: <7d0b514c-7af6-e1b2-4b95-1ab62fe02e1c@suse.com> (raw)
In-Reply-To: <be0e11e0-8d94-b3e2-da81-94a281eb371a@citrix.com>

On 17.06.2020 13:28, Andrew Cooper wrote:
> We actually have AVX512 disabled by default in XenServer.  The perf
> implications of letting 1 guest play with it is very severe.
> 
> Now I think about it, I'm tempted to recommend it moves out of default
> generally.

Hmm, I'm tempted to ask whether you're kidding. This is the kind of
feature that I see no reason at all to move out of default. Imo we
shouldn't put in place policy like this - if anything shouldn't be
on by default, it should imo be because of limitations in our
handling (I've recently revived my UMIP emulation patch, which
comes to mind here) or because of uncertainty on some aspects (like
is the case for MOVDIR / ENQCMD for example). Anything else should
be left to the admins to decide.

Jan


  reply	other threads:[~2020-06-17 11:42 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15 14:15 [PATCH for-4.14 0/9] XSA-320 follow for IvyBridge Andrew Cooper
2020-06-15 14:15 ` [PATCH 1/9] tools/libx[cl]: Introduce struct xc_xend_cpuid for xc_cpuid_set() Andrew Cooper
2020-06-15 14:51   ` Ian Jackson
2020-06-15 14:15 ` [PATCH 2/9] tests/cpu-policy: Confirm that CPUID serialisation is sorted Andrew Cooper
2020-06-15 14:52   ` Ian Jackson
2020-06-15 15:00     ` Andrew Cooper
2020-06-15 15:34       ` Ian Jackson
2020-06-15 16:12         ` Andrew Cooper
2020-06-16  6:51           ` Jan Beulich
2020-06-16  9:01   ` Jan Beulich
2020-06-15 14:15 ` [PATCH 3/9] tools/libx[cl]: Move processing loop down into xc_cpuid_set() Andrew Cooper
2020-06-15 14:54   ` Ian Jackson
2020-06-16  9:16   ` Jan Beulich
2020-06-16 15:58     ` Andrew Cooper
2020-06-15 14:15 ` [PATCH 4/9] tools/libx[cl]: Merge xc_cpuid_set() into xc_cpuid_apply_policy() Andrew Cooper
2020-06-15 14:55   ` Ian Jackson
2020-06-15 14:15 ` [PATCH 5/9] tools/libx[cl]: Plumb bool restore down " Andrew Cooper
2020-06-15 14:55   ` Ian Jackson
2020-06-15 14:15 ` [PATCH 6/9] x86/gen-cpuid: Distinguish default vs max in feature annotations Andrew Cooper
2020-06-15 14:15 ` [PATCH 7/9] x86/hvm: Disable MPX by default Andrew Cooper
2020-06-16  9:33   ` Jan Beulich
2020-06-16 16:15     ` Andrew Cooper
2020-06-17 10:32       ` Jan Beulich
2020-06-17 11:16         ` Andrew Cooper
2020-06-17 11:24           ` Jan Beulich
2020-06-17 11:28             ` Andrew Cooper
2020-06-17 11:41               ` Jan Beulich [this message]
2020-06-17 11:47                 ` Andrew Cooper
2020-06-15 14:15 ` [PATCH 8/9] x86/cpuid: Introduce missing feature adjustment in calculate_pv_def_policy() Andrew Cooper
2020-06-16  9:40   ` Jan Beulich
2020-06-16 16:17     ` Andrew Cooper
2020-06-15 14:15 ` [PATCH 9/9] x86/spec-ctrl: Hide RDRAND by default on IvyBridge Andrew Cooper
2020-06-16 10:00   ` Jan Beulich
2020-06-16 16:26     ` Andrew Cooper
2020-06-17 10:39       ` Jan Beulich
2020-06-17 11:21         ` Andrew Cooper
2020-06-15 17:04 ` [PATCH for-4.14 0/9] XSA-320 follow for IvyBridge Paul Durrant
2020-06-17 12:46   ` Paul Durrant
2020-06-18  7:18 ` Jan Beulich
2020-06-18  9:37   ` Andrew Cooper

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