From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad@darnok.org>
Subject: Re: [RFC 09/10] x86/enter: Create macros to restrict/unrestrict
 Indirect Branch Speculation
Date: Sat, 27 Jan 2018 08:42:43 -0500
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Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
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To: "Hansen, Dave" <dave.hansen@intel.com>
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On Fri, Jan 26, 2018 at 07:11:47PM +0000, Hansen, Dave wrote:
> The need for RSB stuffing in all the various scenarios and what the heck it actually mitigates is freakishly complicated.  I've tried to write it all down in one place: https://goo.gl/pXbvBE

Thank you for sharing that.

One question on the third from the top (' RSB Stuff (16) After
irq/nmi/#PF/...').

It says that :"Return from interrupt path (more than 16 deep) can empty
RSB".

Just to clarify - you mean all the returns ('ret') that are happening after
we call do_IRQ and the stack unwinds - but before we do an 'iret' correct?

I am 99% sure that is what you mean, but just confirming as one could read
this as: 'Need to do RSB after an iret' (say you are in the kernel
and then get an interrupt and iret back to kernel).