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From: mark gross <mgross@linux.intel.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH 3/4] V7 more sampling fun 3
Date: Tue, 14 Apr 2020 14:53:21 -0700	[thread overview]
Message-ID: <20200414215321.GD29751@mtg-dev.jf.intel.com> (raw)
In-Reply-To: <20200414212327.eyo4xdldwuhnqzzz@treble>

On Tue, Apr 14, 2020 at 04:23:27PM -0500, speck for Josh Poimboeuf wrote:
> On Tue, Apr 14, 2020 at 02:03:02PM -0700, speck for mark gross wrote:
> > > > +	[SRBDS_MITIGATION_NOT_AFFECTED_TSX_OFF]	= "Not affected (TSX disabled)",
> > > 
> > > The CPU *is* affected, it just happens to be mitigated, right?
> > This depends on perspective.
> > The only mitigation to SRBS is for the uCode to serialize access to the off
> > core hwRNG and to do a ghost transfer of a through away random number such that
> > if it leaks you don't get the right random number.  I think there may be some
> > buffer clearing in there too.
> > 
> > Disabling TSX from that point of view is not mitigating the issue so much as
> > hiding exposure to it.
> > 
> > I can see it either way.  Not sure which is better.  After reading my logic do
> > you still think it would make more sence to change "Not affected (TSX
> > disabled)" to "Mitigated: TSX disabled"?
> 
> From a user's perspective, "hiding exposure" is the same as a
> mitigation.  So I think it makes sense to call it a mitigation.
done

> > > > +		 */
> > > > +		if ((ia32_cap & ARCH_CAP_MDS_NO) &&
> > > > +		    !((ia32_cap & ARCH_CAP_TSX_CTRL_MSR) ||
> > > > +		      cpu_has(c, X86_FEATURE_RTM)))
> > > > +			goto srbds_not_affected;
> > > > +
> > > > +		setup_force_cpu_bug(X86_BUG_SRBDS);
> > > > +	}
> > > > +srbds_not_affected:
> > > > +
> > > >  	if (cpu_matches(NO_MELTDOWN, cpu_vuln_whitelist))
> > > >  		return;
> > > 
> > > I'm thinking it would be more readable to have the newline between the
> > > bracket and the 'if', instead of between the label and the 'if'.
> > so, lose the newline between the label and the if?
> 
> Yes, and add one between the '}' and the label.
done
--mark

> -- 
> Josh

  reply	other threads:[~2020-04-14 21:53 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-13 18:10 [MODERATED] [PATCH 0/4] V7 more sampling fun 0 mark gross
2020-01-16 22:16 ` [MODERATED] [PATCH 3/4] V7 more sampling fun 3 mark gross
2020-01-30 19:12 ` [MODERATED] [PATCH 4/4] V7 more sampling fun 4 mark gross
2020-03-17  0:56 ` [MODERATED] [PATCH 2/4] V7 more sampling fun 2 mark gross
2020-03-17  0:56 ` [MODERATED] [PATCH 1/4] V7 more sampling fun 1 mark gross
2020-04-14  3:48 ` [MODERATED] Re: [PATCH 3/4] V7 more sampling fun 3 mark gross
2020-04-14 16:23   ` Thomas Gleixner
2020-04-14 20:03     ` [MODERATED] " mark gross
2020-04-14 10:58 ` Thomas Gleixner
2020-04-14 16:43   ` [MODERATED] " mark gross
2020-04-14 20:02 ` Josh Poimboeuf
2020-04-14 21:03   ` mark gross
2020-04-14 21:23     ` Josh Poimboeuf
2020-04-14 21:53       ` mark gross [this message]
2020-04-14 20:05 ` Josh Poimboeuf
2020-04-14 21:59   ` mark gross
2020-04-14 22:46     ` Josh Poimboeuf
2020-04-15 20:59       ` mark gross
2020-04-15 12:58     ` Thomas Gleixner
2020-04-15 22:21       ` [MODERATED] " mark gross
2020-04-15 17:51 ` [MODERATED] Re: [PATCH 1/4] V7 more sampling fun 1 Borislav Petkov
2020-04-15 23:58   ` mark gross

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