Re: [RFC PATCH 09/15] x86/virt/tdx: Add interface to generate a Quote

[Peter Fang]

On Wed, Jul 01, 2026 at 02:46:16PM +0300, Nikolay Borisov wrote:
> 
> 
> > @@ -1228,6 +1230,86 @@ bool tdx_quote_enabled(void)
> >   }
> >   EXPORT_SYMBOL_FOR_KVM(tdx_quote_enabled);
> > +#define QUOTE_ID_MASK		GENMASK_U64(47, 32)
> > +
> > +static u64 tdx_quote_get(struct tdx_td *td, u64 in_data_pa, u64 in_data_len,
> > +			 u64 hpa_list_pa, u64 total_len, u64 *quote_len)
> > +{
> > +	struct tdx_module_args args = {
> > +		.rcx = tdx_tdr_pa(td),
> > +		/* Don't bother specifying the quote id */
> > +		.rdx = QUOTE_ID_MASK & (u64)-1,
> 
> This is simply equal to QUOTE_ID_MASK, so why not create a special value
> meaning "ANY QUOTE" i.e
> 
> #define QUOTE_ID_MASK ....
> #define ANY_QUOTE QUOTE_ID_MASK
> 
> or some such .

I replaced it with just GENMASK_U64(47, 32) in the v2 series and added a
comment explaining it. QUOTE_ID_MASK isn't really needed since we don't
use any other Quote ID for this SEAMCALL. Hope this is clearer:

        struct tdx_module_args args = {
                .rcx = tdx_tdr_pa(td),
                /* [47:32] QUOTE_ID: All-1s selects the default quote format */
                .rdx = GENMASK_U64(47, 32),
                .r8 = in_data_pa,
                .r9 = in_data_len,
                .r10 = hpa_entries_pa,
                .r11 = total_len,
        };


> 
> > +		.r8 = in_data_pa,
> > +		.r9 = in_data_len,
> > +		.r10 = hpa_list_pa,
> > +		.r11 = total_len,
> > +	};
> > +	u64 r;
> > +
> > +	do {
> > +		r = seamcall_ret(TDH_QUOTE_GET, &args);
> > +	} while (r == TDX_INTERRUPTED_RESUMABLE);
> 
> 
> nit: This pattern seems to repeat a lot, might be worth it to consider
> introducing a wrapper similar to existing sc_retry?

I think Yilun gave some reasoning behind this in a separate reply:

https://lore.kernel.org/linux-coco/akaKmEZnTY4FO2gY@yilunxu-OptiPlex-7050/


> > +void *tdx_quote_generate(struct tdx_td *td, void *in_data, u32 in_data_len,
> > +			 u32 *quote_len)
> > +{
> > +	void *quote_dup = NULL;
> > +	u64 r, out_len;
> > +
> > +	if (!tdx_quote_enabled())
> > +		return NULL;
> > +
> > +	/* TDH.QUOTE.GET expects the input data to fit in a page */
> > +	if (in_data_len > PAGE_SIZE)
> > +		return NULL;
> > +
> > +	mutex_lock(&tdx_quote_lock);
> > +
> > +	/*
> > +	 * Use the first page of the quote buffer for input data. The buffer
> > +	 * must be at least one page in size. @in_data may not be page-aligned,
> > +	 * but TDH.QUOTE.GET expects page-aligned addresses.
> > +	 */
> > +	memcpy(quote_data.buf, in_data, (size_t)in_data_len);
> 
> Perhaps you can use min(PAGE_SIZE, in_data_len) and that way you can
> eliminate the in_data_len check above and copy up-to PAGE_SIZE data, if the
> data is longer - you will copy PAGE_SIZE which will likely result in error
> on generating the quote?

Oh that's an interesting idea. I'm going to change the implementation in
the upcoming v3 series and I'll see if using min() works. Thanks for the
suggestion.

>