Re: [PATCH 2/2] xen/arm: Mitigate straight-line speculation for SMC call

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/06/2020 22:57, Julien Grall wrote:
> On Tue, 16 Jun 2020 at 22:34, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> wrote:
>> On Tue, 16 Jun 2020, Julien Grall wrote:
>>> From: Julien Grall <jgrall@xxxxxxxxxx>
>>>
>>> SMC call will update some of registers (typically only x0) depending on
>>   ^a SMC call

An SMC call.

>>
>>> the arguments provided.
>>>
>>> Some CPUs can speculate past a SMC instruction and potentially perform
>>> speculative access to emrmoy using the pre-call values before executing
>>                         ^ memory
>>
>>> the SMC.
>>>
>>> There is no known gadget available after the SMC call today. However
>>> some of the registers may contain values from the guest and are expected
>>> to be updated by the SMC call.
>>>
>>> In order to harden the code, it would be better to prevent straight-line
>>> speculation from an SMC. Architecturally executing the speculation
>>                    ^ a? any?
> "any" might be better.

"an SMC" is correct, but "any" is also fine.

'a' vs 'an' is based on the sound of the following.  S in "S-M-C" as an
abbreviation starts with an 'e' vowel sound, unlike 's' in secure, so
the correct grammar is "an SMC" and "a secure monitor call".

~Andrew