On 24.09.24 г. 14:28 ч., Kai Huang wrote:
The TDX module provides a set of "Global Metadata Fields". They report
things like TDX module version, supported features, and fields related
to create/run TDX guests and so on. TDX supports 8/16/32/64 bits
metadata field element sizes. For a given metadata field, the element
size is encoded in the metadata field ID.
For now the kernel only reads "TD Memory Region" (TDMR) related metadata
fields and they are all 16-bit. Thus the kernel only has one primitive
__read_sys_metadata_field16() to read 16-bit metadata field and the
macro, read_sys_metadata_field16(), which does additional build-time
check of the field ID makes sure the field is indeed 16-bit.
Future changes will need to read more metadata fields with different
element sizes. Choose to provide one primitive for each element size to
support that. Similar to the build_mmio_read() macro, reimplement the
body of __read_sys_metadata_field16() as a macro build_sysmd_read(_size)
in size-agnostic way, so it can be used to generate one primitive for
each element size:
build_sysmd_read(8)
build_sysmd_read(16)
..
Also extend read_sys_metadata_field16() take the '_size' as argument
(and rename it to read_sys_metadata_field() to make it size-agnostic) to
allow the READ_SYS_INFO() macro to choose which primitive to use.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
<snip>
+#define build_sysmd_read(_size) \
+static int __read_sys_metadata_field##_size(u64 field_id, u##_size *val) \
+{ \
+ u64 tmp; \
+ int ret; \
+ \
+ ret = tdh_sys_rd(field_id, &tmp); \
+ if (ret) \
+ return ret; \
+ \
+ *val = tmp; \
+ \
+ return 0; \
}
-#define read_sys_metadata_field16(_field_id, _val) \
+build_sysmd_read(16)
nit: Generally the unwritten convention for this kind of macro
definition is to capitalize them and be of the from:
DEFINE_xxxxx - similar to how event classes are defined.
perhaps naming this macro:
DEFINE_TDX_METADATA_READER() ought to be more descriptive, also the
"md" contraction of metadata also seems a bit quirky (at least to me).
It's not a deal breaker but if there is going to be another posting this
might be something to consider.
<snip>
