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From: Brian Woods <brian.woods@amd.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Brian Woods <brian.woods@amd.com>,
	xen-devel@lists.xen.org
Subject: Re: [PATCH 1/3] x86/spec-ctrl: add AMD SSBD LS_CFG in init print
Date: Wed, 1 Aug 2018 16:38:53 -0500	[thread overview]
Message-ID: <20180801213852.GB3914@amd.com> (raw)
In-Reply-To: <5B603E5402000078001D9634@prv1-mh.provo.novell.com>

On Tue, Jul 31, 2018 at 04:47:48AM -0600, Jan Beulich wrote:
> Pointless initializer.

Noted

> Why log the same string twice? Simply OR together both conditions.
> Also please don't omit the blank before the ? operator. Both remarks
> apply as well further down.

Because they're completely different implementation at this point.  I
thought about naming it something else but couldn't think of something.
It also reads easier with having them split up where there isn't a ton
of logic in a single ternary operator.  There can be easily changed.

> I've peeked ahead into the following patches, and I can't see
> why this needs to be a synthetic feature flag. We use such flags
> for the purpose of alternative instruction patching, but you don't
> do anything like that.
> 
> Jan

I was talking Andy earily about a SSBD (via VIRT_SPEC_CTRL)
implementation and he mentioned something about ALTERNATIVE C funcs
which would allow to allow HVM guests to be able control SSBD.  In that
case having a synthetic feature flag is useful for helping to
differiate between SSBD via the LS_CFG MSR vs SPEC_CTRL in the future.


-- 
Brian Woods

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  reply	other threads:[~2018-08-01 21:38 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-20 14:57 [PATCH 0/3] SSBD AMD via LS CFG Enablement Brian Woods
2018-07-20 14:57 ` [PATCH 1/3] x86/spec-ctrl: add AMD SSBD LS_CFG in init print Brian Woods
2018-07-31 10:47   ` Jan Beulich
2018-08-01 21:38     ` Brian Woods [this message]
2018-08-02  6:55       ` Jan Beulich
2018-07-20 14:57 ` [PATCH 2/3] x86/spec-ctrl: Add defines and variables for AMD SSBD support Brian Woods
2018-07-31 10:44   ` Jan Beulich
2018-08-01 21:25     ` Brian Woods
2018-07-20 14:57 ` [PATCH 3/3] x86/spec-ctrl: Add support for modifying SSBD AMD VIA LS_CFG MSR Brian Woods
2018-07-31 11:25   ` Jan Beulich
2018-08-01 22:20     ` Brian Woods
2018-08-02  7:09       ` Jan Beulich
2018-08-06 19:07         ` Brian Woods
2018-08-07  7:51           ` Jan Beulich
2018-08-08 16:43             ` Brian Woods
2018-08-09  6:53               ` Jan Beulich

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