Re: [PATCH v4 3/8] x86/virt/tdx: Prepare to support reading other global metadata fields

Huang, Kai
2024-10-01T21:41:03Z

On Tue, 2024-10-01 at 08:19 -0700, Dave Hansen wrote:
> On 10/1/24 03:44, Huang, Kai wrote:
> > Please let me know if you have any concern? Otherwise I will go with
> > this route.
> I still see some long unwieldy #defines in the mail thread. That's my
> biggest worry.

I suppose you mean the read_sys_metadata_field() macro?

We can split that into two smaller macros by moving BUILD_BUG_ON() out:

/* Don't use this directly, use read_sys_metadata_read() instead. */
#define __read_sys_metadata_field(_field_id, _valptr) \
({ \
u64 ___tmp; \
int ___ret; \
\
___ret = tdh_sys_rd(_field_id, &___tmp); \
*_valptr = ___tmp; \
\
___ret; \
})

/* @_valptr must be pointer of u8/u16/u32/u64. */
#define read_sys_metadata_field(_field_id, _valptr) \
({ \
BUILD_BUG_ON(MD_FIELD_ELE_SIZE(_field_id) != \
sizeof(*_valptr)); \
__read_sys_metadata_field(_field_id, _valptr); \
})

Does this look good to you?