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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Tue, 8 Jun 2021 09:26:29 -0700
Message-ID: <CAPcyv4hC=OCpgM5gWNHV3Z77zKH7Bh_vqvPAvD6246+J4c2ORA@mail.gmail.com>
Subject: Re: [RFC v2-fix-v2 3/3] x86/tdx: Handle port I/O
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kirill Shutemov <kirill.shutemov@linux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        Raj Ashok <ashok.raj@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tue, Jun 8, 2021 at 8:40 AM Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
>
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> TDX hypervisors cannot emulate instructions directly. This
> includes port IO which is normally emulated in the hypervisor.
> All port IO instructions inside TDX trigger the #VE exception
> in the guest and would be normally emulated there.
>
> Also string I/O is not supported in TDX guest. So, unroll the
> string I/O operation into a loop operating on one element at
> a time. This method is similar to AMD SEV, so just extend the
> support for TDX guest platform.
>
> Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> ---
> Changes since RFC v2-fix-v1:
>  * Fixed commit log to adapt to decompression support code split.

Looks good to me:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>