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Message-ID: <c7ce1d6e1f83ddb3c0af5607563bc26056df7fe3.camel@intel.com>
Date: Sat, 26 Aug 2023 00:45:27 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>
CC: "Hansen, Dave" <dave.hansen@...el.com>,
"Christopherson,, Sean" <seanjc@...gle.com>,
"x86@...nel.org" <x86@...nel.org>, "bp@...en8.de" <bp@...en8.de>,
"peterz@...radead.org" <peterz@...radead.org>,
"hpa@...or.com" <hpa@...or.com>,
"mingo@...hat.com" <mingo@...hat.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"pbonzini@...hat.com" <pbonzini@...hat.com>,
"Yamahata, Isaku" <isaku.yamahata@...el.com>,
"sathyanarayanan.kuppuswamy@...ux.intel.com"
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
"n.borisov.lkml@...il.com" <n.borisov.lkml@...il.com>
Subject: Re: [PATCH v4 12/12] x86/virt/tdx: Adjust 'struct tdx_module_args' to
use x86 "register index" layout
On Sat, 2023-08-26 at 02:44 +0300, kirill.shutemov@...ux.intel.com wrote:
> On Tue, Aug 15, 2023 at 11:02:06PM +1200, Kai Huang wrote:
> > diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
> > index 74fc466dfdcd..8d1427562c63 100644
> > --- a/arch/x86/include/asm/shared/tdx.h
> > +++ b/arch/x86/include/asm/shared/tdx.h
> > @@ -58,24 +58,31 @@
> > * Used in __tdcall*() to gather the input/output registers' values of the
> > * TDCALL instruction when requesting services from the TDX module. This is a
> > * software only structure and not part of the TDX module/VMM ABI
> > + *
> > + * Note those *_unused are not used by the TDX_MODULE_CALL assembly.
> > + * The layout of this structure also matches KVM's kvm_vcpu_arch::regs[]
> > + * layout, which follows the "register index" order of x86 GPRs. KVM
> > + * then can simply type cast kvm_vcpu_arch::regs[] to this structure to
> > + * avoid the extra memory copy between two structures when making
> > + * TDH.VP.ENTER SEAMCALL.
>
> I still don't like KVM details leak here. I don't feel strong enough about
> it to NAK the patch, but...
>
I am fine dropping it. It's an optimization anyway.
I'll leave to Peter. :-)
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