linux-kernel - RE: [PATCH v2 4/6] x86/tdx: Expand __tdx_hypercall() to handle more arguments

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Date:   Thu, 8 Dec 2022 15:54:32 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "arnd@...db.de" <arnd@...db.de>, "bp@...en8.de" <bp@...en8.de>,
        "brijesh.singh@....com" <brijesh.singh@....com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "jane.chu@...cle.com" <jane.chu@...cle.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        KY Srinivasan <kys@...rosoft.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "luto@...nel.org" <luto@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 4/6] x86/tdx: Expand __tdx_hypercall() to handle more
 arguments

> From: Sathyanarayanan Kuppuswamy
> Sent: Wednesday, December 7, 2022 2:14 PM
>  [...]
> > --- a/arch/x86/coco/tdx/tdcall.S
> > +++ b/arch/x86/coco/tdx/tdcall.S
> > @@ -13,6 +13,12 @@
> >  /*
> >   * Bitmasks of exposed registers (with VMM).
> >   */
> > +#define TDX_RDX		BIT(2)
> > +#define TDX_RBX		BIT(3)
> > +#define TDX_RSI		BIT(6)
> > +#define TDX_RDI		BIT(7)
> > +#define TDX_R8		BIT(8)
> > +#define TDX_R9		BIT(9)
> >  #define TDX_R10		BIT(10)
> >  #define TDX_R11		BIT(11)
> >  #define TDX_R12		BIT(12)
> > @@ -27,9 +33,9 @@
> >   * details can be found in TDX GHCI specification, section
> >   * titled "TDCALL [TDG.VP.VMCALL] leaf".
> >   */
> > -#define TDVMCALL_EXPOSE_REGS_MASK	( TDX_R10 | TDX_R11 | \
> > -					  TDX_R12 | TDX_R13 | \
> > -					  TDX_R14 | TDX_R15 )
> > +#define TDVMCALL_EXPOSE_REGS_MASK	\
> > +	( TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8  | TDX_R9  | \
> > +	  TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15 )
> >
> 
> You seem to have expanded the list to include all VMCALL supported
> registers except RBP. Why not include it as well? That way, it will be
> a complete support.

Hi Kirill, can you please share your thoughts?