linux-kernel - Re: [PATCH v11 06/20] x86/virt/tdx: Handle SEAMCALL running out of entropy error

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Date:   Fri, 9 Jun 2023 17:42:55 +0300
From:   Nikolay Borisov <n.borisov.lkml@...il.com>
To:     Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     linux-mm@...ck.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, tony.luck@...el.com,
        peterz@...radead.org, tglx@...utronix.de, seanjc@...gle.com,
        pbonzini@...hat.com, david@...hat.com, dan.j.williams@...el.com,
        rafael.j.wysocki@...el.com, ying.huang@...el.com,
        reinette.chatre@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, bagasdotme@...il.com,
        sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v11 06/20] x86/virt/tdx: Handle SEAMCALL running out of
 entropy error



On 4.06.23 г. 17:27 ч., Kai Huang wrote:
> Certain SEAMCALL leaf functions may return error due to running out of
> entropy, in which case the SEAMCALL should be retried as suggested by
> the TDX spec.
> 
> Handle this case in SEAMCALL common function.  Mimic the existing
> rdrand_long() to retry RDRAND_RETRY_LOOPS times.
> 
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> ---
> 
> v10 -> v11:
>   - New patch
> 
> ---
>   arch/x86/virt/vmx/tdx/tdx.c | 15 ++++++++++++++-
>   arch/x86/virt/vmx/tdx/tdx.h | 17 +++++++++++++++++
>   2 files changed, 31 insertions(+), 1 deletion(-)
> 

<snip>

> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index 48ad1a1ba737..55dbb1b8c971 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -4,6 +4,23 @@
>   
>   #include <linux/types.h>
>   
> +/*
> + * This file contains both macros and data structures defined by the TDX
> + * architecture and Linux defined software data structures and functions.
> + * The two should not be mixed together for better readability.  The
> + * architectural definitions come first.
> + */
> +
> +/*
> + * TDX SEAMCALL error codes
> + */
> +#define TDX_RND_NO_ENTROPY	0x8000020300000000ULL

Where is this return value documented, in TDX module 1.0 spec there are 
only: 8000020[123]00000000 specified and there's 80000800 
(TDX_KEY_GENERATION_FAILED) and its description mentions the possible 
failure due to lack of entropy?

<snip>