linux-kernel - Re: [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page

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Message-ID: <5111ce8e57dd1e26538fcd191148d624c2707773.camel@intel.com>
Date: Fri, 16 May 2025 17:10:19 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Zhao, Yan Y" <yan.y.zhao@...el.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "Li, Xiaoyao"
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Subject: Re: [RFC PATCH 02/21] x86/virt/tdx: Enhance tdh_mem_page_aug() to
 support huge pages

On Fri, 2025-05-16 at 17:05 +0800, Yan Zhao wrote:
> > So we have loops within loops...  Better to add an arg to tdx_clflush_page()
> > or
> > add a variant that takes one.
> Ok.
> 
> One thing to note is that even with an extra arg, tdx_clflush_page() has to
> call
> clflush_cache_range() page by page because with
> "#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)",
> page virtual addresses are not necessarily contiguous.
> 
> What about Binbin's proposal [1]? i.e.,
> 
> while (nr_pages)
>      tdx_clflush_page(nth_page(page, --nr_pages));
> 
> [1]
> https://lore.kernel.org/all/a7d0988d-037c-454f-bc6b-57e71b357488@linux.intel.com/

These SEAMCALLs are handling physically contiguous pages so I don't think we
need to worry about that. But Binbin's suggestion seems fine too.