Re: [PATCH v19 033/130] KVM: TDX: Add helper function to read TDX metadata in array

[Binbin Wu]

On 2/26/2024 4:25 PM, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> To read meta data in series, use table.
> Instead of metadata_read(fid0, &data0); metadata_read(...); ...
> table = { {fid0, &data0}, ...}; metadata-read(tables).
> TODO: Once the TDX host code introduces its framework to read TDX metadata,
> drop this patch and convert the code that uses this.

Do you mean the patch 1-5 included in this patch set.
I think the patch 1-5 of this patch set is doing this thing, right?

Since they are already there, I think you can use them directly in this
patch set instead of introducing these temp code?

> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> v18:
> - newly added
> ---
>   arch/x86/kvm/vmx/tdx.c | 45 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 45 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index cde971122c1e..dce21f675155 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -6,6 +6,7 @@
>   #include "capabilities.h"
>   #include "x86_ops.h"
>   #include "x86.h"
> +#include "tdx_arch.h"
>   #include "tdx.h"
>   
>   #undef pr_fmt
> @@ -39,6 +40,50 @@ static void __used tdx_guest_keyid_free(int keyid)
>   	ida_free(&tdx_guest_keyid_pool, keyid);
>   }
>   
> +#define TDX_MD_MAP(_fid, _ptr)			\
> +	{ .fid = MD_FIELD_ID_##_fid,		\
> +	  .ptr = (_ptr), }
> +
> +struct tdx_md_map {
> +	u64 fid;
> +	void *ptr;
> +};
> +
> +static size_t tdx_md_element_size(u64 fid)
> +{
> +	switch (TDX_MD_ELEMENT_SIZE_CODE(fid)) {
> +	case TDX_MD_ELEMENT_SIZE_8BITS:
> +		return 1;
> +	case TDX_MD_ELEMENT_SIZE_16BITS:
> +		return 2;
> +	case TDX_MD_ELEMENT_SIZE_32BITS:
> +		return 4;
> +	case TDX_MD_ELEMENT_SIZE_64BITS:
> +		return 8;
> +	default:
> +		WARN_ON_ONCE(1);
> +		return 0;
> +	}
> +}
> +
> +static int __used tdx_md_read(struct tdx_md_map *maps, int nr_maps)
> +{
> +	struct tdx_md_map *m;
> +	int ret, i;
> +	u64 tmp;
> +
> +	for (i = 0; i < nr_maps; i++) {
> +		m = &maps[i];
> +		ret = tdx_sys_metadata_field_read(m->fid, &tmp);
> +		if (ret)
> +			return ret;
> +
> +		memcpy(m->ptr, &tmp, tdx_md_element_size(m->fid));
> +	}
> +
> +	return 0;
> +}
> +
>   static int __init tdx_module_setup(void)
>   {
>   	int ret;