Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 27 Mar 2023 08:30:24 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        Shuah Khan <shuah@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        "H . Peter Anvin" <hpa@zytor.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Wander Lairson Costa <wander@redhat.com>,
        Erdem Aktas <erdemaktas@google.com>,
        Guorui Yu <GuoRui.Yu@linux.alibaba.com>,
        Du Fan <fan.du@intel.com>, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v1 2/3] virt: tdx-guest: Add Quote generation support
Message-ID: <ZCE4AJBX8zM53XCM@kroah.com>
References: <20230326062039.341479-1-sathyanarayanan.kuppuswamy@linux.intel.com>
 <20230326062039.341479-3-sathyanarayanan.kuppuswamy@linux.intel.com>
 <ZB/njYsTTwgTtAeA@kroah.com>
 <d09f30f5-23da-4fb6-141e-3dd9483217c7@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <d09f30f5-23da-4fb6-141e-3dd9483217c7@linux.intel.com>
Precedence: bulk

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