diff mbox series

[4/9] x86/virt/tdx: Abstract reading multiple global metadata fields as a helper

Message ID dd4ab4f97fc12780e4052f7ece94ceadffafd24d.1718538552.git.kai.huang@intel.com (mailing list archive)
State New, archived
Headers show
Series TDX host: metadata reading tweaks, bug fix and info dump | expand

Commit Message

Kai Huang June 16, 2024, 12:01 p.m. UTC
For now the kernel only reads "TD Memory Region" (TDMR) related global
metadata fields to a 'struct tdx_tdmr_sysinfo' for initializing the TDX
module.  Future changes will need to read other metadata fields that
don't make sense to populate to the "struct tdx_tdmr_sysinfo".

Now the code in get_tdx_tdmr_sysinfo() to read multiple global metadata
fields is not bound to the 'struct tdx_tdmr_sysinfo', and can support
reading all metadata element sizes.  Abstract this code as a helper for
future use.

Signed-off-by: Kai Huang <kai.huang@intel.com>
---
 arch/x86/virt/vmx/tdx/tdx.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

Comments

Nikolay Borisov June 18, 2024, 11:45 a.m. UTC | #1
On 16.06.24 г. 15:01 ч., Kai Huang wrote:
> For now the kernel only reads "TD Memory Region" (TDMR) related global
> metadata fields to a 'struct tdx_tdmr_sysinfo' for initializing the TDX
> module.  Future changes will need to read other metadata fields that
> don't make sense to populate to the "struct tdx_tdmr_sysinfo".
> 
> Now the code in get_tdx_tdmr_sysinfo() to read multiple global metadata
> fields is not bound to the 'struct tdx_tdmr_sysinfo', and can support
> reading all metadata element sizes.  Abstract this code as a helper for
> future use.
> 
> Signed-off-by: Kai Huang <kai.huang@intel.com>
> ---
>   arch/x86/virt/vmx/tdx/tdx.c | 27 ++++++++++++++++-----------
>   1 file changed, 16 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 4392e82a9bcb..c68fbaf4aa15 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -304,6 +304,21 @@ struct field_mapping {
>   	  .offset   = offsetof(_struct, _member),		\
>   	  .size	    = sizeof(typeof(((_struct *)0)->_member)) }
>   
> +static int stbuf_read_sysmd_multi(const struct field_mapping *fields,

Rename it to read_system_metadata_fields i.e just use the plural form of 
the single field function. Whatever you choose to rename the singular 
form, just make this function be the plural. But as a general remark - I 
don't see what value the "stbuf" prefix brings. 'sysmd' is also somewhat 
unintuitive. Any of 
read_metadata_fields/read_sys_metadata_fields/read_system_metadata_fields 
seem better.

> +				  int nr_fields, void *stbuf)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < nr_fields; i++) {
> +		ret = stbuf_read_sysmd_field(fields[i].field_id, stbuf,
> +				      fields[i].offset, fields[i].size);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>   #define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member)	\
>   	TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
>   

<snip>
Kai Huang June 18, 2024, 11:42 p.m. UTC | #2
On Tue, 2024-06-18 at 14:45 +0300, Nikolay Borisov wrote:
> 
> On 16.06.24 г. 15:01 ч., Kai Huang wrote:
> > For now the kernel only reads "TD Memory Region" (TDMR) related global
> > metadata fields to a 'struct tdx_tdmr_sysinfo' for initializing the TDX
> > module.  Future changes will need to read other metadata fields that
> > don't make sense to populate to the "struct tdx_tdmr_sysinfo".
> > 
> > Now the code in get_tdx_tdmr_sysinfo() to read multiple global metadata
> > fields is not bound to the 'struct tdx_tdmr_sysinfo', and can support
> > reading all metadata element sizes.  Abstract this code as a helper for
> > future use.
> > 
> > Signed-off-by: Kai Huang <kai.huang@intel.com>
> > ---
> >   arch/x86/virt/vmx/tdx/tdx.c | 27 ++++++++++++++++-----------
> >   1 file changed, 16 insertions(+), 11 deletions(-)
> > 
> > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> > index 4392e82a9bcb..c68fbaf4aa15 100644
> > --- a/arch/x86/virt/vmx/tdx/tdx.c
> > +++ b/arch/x86/virt/vmx/tdx/tdx.c
> > @@ -304,6 +304,21 @@ struct field_mapping {
> >   	  .offset   = offsetof(_struct, _member),		\
> >   	  .size	    = sizeof(typeof(((_struct *)0)->_member)) }
> >   
> > +static int stbuf_read_sysmd_multi(const struct field_mapping *fields,
> 
> Rename it to read_system_metadata_fields i.e just use the plural form of 
> the single field function. Whatever you choose to rename the singular 
> form, just make this function be the plural. But as a general remark - I 
> don't see what value the "stbuf" prefix brings. 'sysmd' is also somewhat 
> unintuitive. Any of 
> read_metadata_fields/read_sys_metadata_fields/read_system_metadata_fields 
> seem better.

read_sys_metadata_field() vs read_sys_metadata_fields() is hard to
distinguish due to there's only one character difference.  This is one
reason I added "stbuf" prefix hoping to make it more clear that this
function reads multiple fields to a buffer of a structure.

In terms of "sysmd" I just wanted to make the function name shorter.  This
function is only used by tdx.c internally so I think it's fine.

Anyway I am open on this.  Let's wait for some more time to see whether
other people have comments or not.
diff mbox series

Patch

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 4392e82a9bcb..c68fbaf4aa15 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -304,6 +304,21 @@  struct field_mapping {
 	  .offset   = offsetof(_struct, _member),		\
 	  .size	    = sizeof(typeof(((_struct *)0)->_member)) }
 
+static int stbuf_read_sysmd_multi(const struct field_mapping *fields,
+				  int nr_fields, void *stbuf)
+{
+	int i, ret;
+
+	for (i = 0; i < nr_fields; i++) {
+		ret = stbuf_read_sysmd_field(fields[i].field_id, stbuf,
+				      fields[i].offset, fields[i].size);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 #define TD_SYSINFO_MAP_TDMR_INFO(_field_id, _member)	\
 	TD_SYSINFO_MAP(_field_id, struct tdx_tdmr_sysinfo, _member)
 
@@ -318,18 +333,8 @@  static const struct field_mapping fields[] = {
 
 static int get_tdx_tdmr_sysinfo(struct tdx_tdmr_sysinfo *tdmr_sysinfo)
 {
-	int ret;
-	int i;
-
 	/* Populate 'tdmr_sysinfo' fields using the mapping structure above: */
-	for (i = 0; i < ARRAY_SIZE(fields); i++) {
-		ret = stbuf_read_sysmd_field(fields[i].field_id, tdmr_sysinfo,
-				fields[i].offset, fields[i].size);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return stbuf_read_sysmd_multi(fields, ARRAY_SIZE(fields), tdmr_sysinfo);
 }
 
 /* Calculate the actual TDMR size */