Re: [PATCH] VT-x: extend LBR Broadwell errata coverage

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 20/05/2020 16:56, Jan Beulich wrote:
> On 20.05.2020 16:07, Andrew Cooper wrote:
>> On 20/05/2020 13:52, Jan Beulich wrote:
>>> @@ -2895,15 +2897,26 @@ static void __init lbr_tsx_fixup_check(v
>>>  static void __init bdf93_fixup_check(void)
>> Seeing as this is no longer just BDF93, how about ler_tsx_fixup_check() ?
> I did consider renaming, and didn't do so just because this would
> grow the patch size quite a bit.

I don't see that as a problem.

> I'm fine doing so, but with the
> name you suggest, is this one really as directly TSX related as the
> other one? I had thought of something like lbr_bdw_fixup_check().

The errata wording doesn't mention TSX, but the breakage manifests in
the same way, with bits 61 and 62 clear but hardware expecting to see a
canonicalised value on restore.

Also, it is very specifically LER-from which gets clobbered, rather than
any of the regular LBR registers.

I'm not overly fussed what the naming is, but it oughtn't to include
bdf93 any more, now the scope of the workaround has been extended.

~Andrew