Re: [PATCH] x86/shim: Simplify compat handling in write_start_info()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.04.2021 16:45, Andrew Cooper wrote:
> Factor out a compat boolean to remove the lfence overhead from multiple
> is_pv_32bit_domain() calls.
> 
> For a compat guest, the upper 32 bits of rdx are zero, so there is no need to
> have any conditional logic at all when mapping the start info page.

Iirc the contents of the upper halves hold unspecified contents after
a switch from compat to 64-bit mode. Therefore only with this part of
the change dropped ...

> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan