Re: [PATCH v4 0/9] Linear Address Masking (LAM) KVM Enabling

Robert Hoo
2023-02-13T13:16:55Z

On Mon, 2023-02-13 at 17:02 +0800, Binbin Wu wrote:
> > 3. For user mode address, it is possible that 5-level paging and
> > LAM_U48 are both
> > set, in this case, the effective usable linear address width is
> > 48, i.e. bit
> > 56:47 is reserved by LAM. [2]
>
> How to understand "reserved by LAM"?
>
> According to the spec, bits 56:48 of the pointer contained metadata.
>
Emm, looks it's superfluous words, I'll remove it in next version.
I meant the same as your understanding: bit 56:48 could be used by
metadata, and cleared before translation, therefore not usable by 5-
level paging, "reserved by LAM".