linux-kernel - Re: [PATCH v1 2/3] virt: tdx-guest: Add Quote generation support

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Date:   Mon, 27 Mar 2023 08:30:24 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Shuah Khan <shuah@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        "H . Peter Anvin" <hpa@...or.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Wander Lairson Costa <wander@...hat.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Guorui Yu <GuoRui.Yu@...ux.alibaba.com>,
        Du Fan <fan.du@...el.com>, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v1 2/3] virt: tdx-guest: Add Quote generation support

On Sun, Mar 26, 2023 at 12:06:26PM -0700, Sathyanarayanan Kuppuswamy wrote:
> If usage of DMA APIs / platform device is not acceptable for this use case,

It is not ok to use a platform device for this because you just do not
have a platform device for it, don't make one up out of thin air please,
as that really doesn't even have the correct bindings to the DMA memory
that you want here.

> an alternative approach is to allocate a fixed number of shared buffers during
> the TDX guest driver probe and use it for GetQuote requests. Although it would
> limit the amount of memory we can use for GetQuote requests at a time and also
> reserve a chunk of memory during the init() time, I think it is an acceptable
> tradeoff when compared to alternative choices. The AMD SEV guest driver also
> adopts the similar approach. Please let me know if this approach is acceptable.

This sounds like a better approach.

thanks,

greg k-h