Re: [PATCH 3/9] x86/virt/tdx: Support global metadata read for all element sizes

Nikolay Borisov
2024-06-18T11:42:22Z

<snip>

>
> -static int read_sys_metadata_field16(u64 field_id,
> - int offset,
> - void *stbuf)
> +/*
> + * Read one global metadata field and store the data to a location of a
> + * given buffer specified by the offset and size (in bytes).
> + */
> +static int stbuf_read_sysmd_field(u64 field_id, void *stbuf, int offset,

read_system_metadat_field or read_sys_metadata_field or simply
read_metadata_field

> + int bytes)
s/bytes/size
> {
> - u16 *st_member = stbuf + offset;
> + void *st_member = stbuf + offset;

Again, this could be renamed to just 'member', what value does the 'st'
prefix bring?

> u64 tmp;
> int ret;
>
> - if (WARN_ON_ONCE(MD_FIELD_ID_ELE_SIZE_CODE(field_id) !=
> - MD_FIELD_ID_ELE_SIZE_16BIT))
> + if (WARN_ON_ONCE(MD_FIELD_BYTES(field_id) != bytes))
> return -EINVAL;
>
> ret = read_sys_metadata_field(field_id, &tmp);
> if (ret)
> return ret;
>
> - *st_member = tmp;
> + memcpy(st_member, &tmp, bytes);
>
> return 0;
> }
> @@ -294,11 +296,13 @@ static int read_sys_metadata_field16(u64 field_id,
> struct field_mapping {
> u64 field_id;
> int offset;
> + int size;
> };
>
> -#define TD_SYSINFO_MAP(_field_id, _struct, _member) \
> - { .field_id = MD_FIELD_ID_##_field_id, \
> - .offset = offsetof(_struct, _member) }
> +#define TD_SYSINFO_MAP(_field_id, _struct, _member) \
> + { .field_id = MD_FIELD_ID_##_field_id, \
> + .offset = offsetof(_struct, _member), \
> + .size = sizeof(typeof(((_struct *)0)->_member)) }
>
> #define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member) \
> TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
> @@ -319,9 +323,8 @@ static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
>
> /* Populate 'tdmr_sysinfo' fields using the mapping structure above: */
> for (i = 0; i < ARRAY_SIZE(fields); i++) {
> - ret = read_sys_metadata_field16(fields[i].field_id,
> - fields[i].offset,
> - tdmr_sysinfo);
> + ret = stbuf_read_sysmd_field(fields[i].field_id, tdmr_sysinfo,
> + fields[i].offset, fields[i].size);
> if (ret)
> return ret;
> }
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index b701f69485d3..812943516946 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -53,7 +53,8 @@
> #define MD_FIELD_ID_ELE_SIZE_CODE(_field_id) \
> (((_field_id) & GENMASK_ULL(33, 32)) >> 32)
>
> -#define MD_FIELD_ID_ELE_SIZE_16BIT 1
> +#define MD_FIELD_BYTES(_field_id) \

Just name it MD_FIELD_SIZE, even the MD_FIELD_ID member is called
ELEMENT_SIZE_CODE, rather than ELEMENT_BYTES_CODE or some such.

> + (1 << MD_FIELD_ID_ELE_SIZE_CODE(_field_id))
>
> struct tdmr_reserved_area {
> u64 offset;