linux-kernel - Re: [PATCH 1/6] x86/tdx: Support hypercalls for TDX guests on Hyper-V

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Date:   Tue, 22 Nov 2022 02:52:37 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Dexuan Cui <decui@...rosoft.com>, ak@...ux.intel.com,
        arnd@...db.de, bp@...en8.de, brijesh.singh@....com,
        dan.j.williams@...el.com, dave.hansen@...ux.intel.com,
        haiyangz@...rosoft.com, hpa@...or.com, jane.chu@...cle.com,
        kirill.shutemov@...ux.intel.com, kys@...rosoft.com,
        linux-arch@...r.kernel.org, linux-hyperv@...r.kernel.org,
        luto@...nel.org, mingo@...hat.com, peterz@...radead.org,
        rostedt@...dmis.org, sathyanarayanan.kuppuswamy@...ux.intel.com,
        seanjc@...gle.com, tglx@...utronix.de, tony.luck@...el.com,
        wei.liu@...nel.org, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] x86/tdx: Support hypercalls for TDX guests on Hyper-V

On Mon, Nov 21, 2022 at 12:38:36PM -0800, Dave Hansen wrote:
> On 11/21/22 11:51, Dexuan Cui wrote:
> > __tdx_hypercall() doesn't work for a TDX guest running on Hyper-V,
> > because Hyper-V uses a different calling convention, so add the
> > new function __tdx_ms_hv_hypercall().
> 
> Other than R10 being variable here and fixed for __tdx_hypercall(), this
> looks *EXACTLY* the same as __tdx_hypercall(), or at least a strict
> subset of what __tdx_hypercall() can do.
> 
> Did I miss something?
> 
> Another way of saying this:  It seems like you could do this with a new
> version of _tdx_hypercall() (and all in C) instead of a new
> __tdx_hypercall().

+1. There should be a strong reason to add another asm helper.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov