linux-kernel - Re: [PATCH v3 06/26] x86/virt/tdx: Prepare to support P-SEAMLDR SEAMCALLs

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Message-ID: <ec744e5a-3bf6-4ed0-9309-0d1d1b834c68@intel.com>
Date: Thu, 29 Jan 2026 08:08:50 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Xu Yilun <yilun.xu@...ux.intel.com>
Cc: Chao Gao <chao.gao@...el.com>, linux-coco@...ts.linux.dev,
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org, x86@...nel.org,
 reinette.chatre@...el.com, ira.weiny@...el.com, kai.huang@...el.com,
 dan.j.williams@...el.com, sagis@...gle.com, vannapurve@...gle.com,
 paulmck@...nel.org, nik.borisov@...e.com, zhenzhong.duan@...el.com,
 seanjc@...gle.com, rick.p.edgecombe@...el.com, kas@...nel.org,
 dave.hansen@...ux.intel.com, vishal.l.verma@...el.com,
 Farrah Chen <farrah.chen@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v3 06/26] x86/virt/tdx: Prepare to support P-SEAMLDR
 SEAMCALLs

On 1/29/26 01:46, Xu Yilun wrote:
...
> Then with all the doc fixes, we only need minor code change:
> 
> @@ -127,7 +127,8 @@ static __always_inline u64 sc_retry(sc_func_t func, u64 fn,
>                 preempt_disable();
>                 ret = __seamcall_dirty_cache(func, fn, args);
>                 preempt_enable();
> -       } while (ret == TDX_RND_NO_ENTROPY && --retry);
> +       } while ((ret == TDX_RND_NO_ENTROPY ||
> +                 ret == SEAMLDR_RND_NO_ENTROPY) && --retry);

That's better than what was there in the past, but I do think even this
is pretty silly.

I mean, we (Intel) control all the components. These errors are for the
same dang thing. The people who wrote both components probably sit next
to each other. :)

I think I'd be a bit less grumpy if there was _anything_ else that
demanded a retry. So, let's try to extract the guarantee that the error
spaces are at least unified, in that a TDX module will never return
SEAMLDR_RND_NO_ENTROPY to mean something else and a SEAMLDR will never
return TDX_RND_NO_ENTROPY. Then, maybe talk them into doing a unified
thing from here on out.

But, for now, drop this patch. We'll just assume the P-SEAMLDR doesn't
have "no entropy" errors until this is sorted.