linux-kernel - Re: [PATCH v2 06/25] x86/virt/tdx: Add SEAMCALL wrappers for TDX TD creation

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Message-ID: <4df744b9-041a-4ed7-aa34-a78923f79cf9@intel.com>
Date: Tue, 12 Nov 2024 12:17:28 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>, pbonzini@...hat.com,
 seanjc@...gle.com
Cc: yan.y.zhao@...el.com, isaku.yamahata@...il.com, kai.huang@...el.com,
 kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 tony.lindgren@...ux.intel.com, xiaoyao.li@...el.com,
 reinette.chatre@...el.com, Isaku Yamahata <isaku.yamahata@...el.com>,
 Sean Christopherson <sean.j.christopherson@...el.com>,
 Binbin Wu <binbin.wu@...ux.intel.com>, Yuan Yao <yuan.yao@...el.com>
Subject: Re: [PATCH v2 06/25] x86/virt/tdx: Add SEAMCALL wrappers for TDX TD
 creation

On 10/30/24 12:00, Rick Edgecombe wrote:
> +u64 tdh_mng_create(u64 tdr, u64 hkid)
> +{
> +	struct tdx_module_args args = {
> +		.rcx = tdr,
> +		.rdx = hkid,
> +	};
> +	clflush_cache_range(__va(tdr), PAGE_SIZE);
> +	return seamcall(TDH_MNG_CREATE, &args);
> +}
> +EXPORT_SYMBOL_GPL(tdh_mng_create);

I'd _prefer_ that this explain why the clflush is there.

The other goofy thing here is why it's getting a physical address passed
in.  It's my old 32-bit paranoia kicking in, but everything that has a
valid virtual address _also_ has a valid physical address.  The inverse
is not true, though.  So I like to keep things as pointers as long as
possible.