linux-kernel - Re: [PATCH 2/4] x86/vmware: Add a header file for hypercall definitions

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Date:   Tue, 20 Aug 2019 13:32:03 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>
Cc:     linux-kernel@...r.kernel.org, pv-drivers@...are.com,
        Thomas Hellstrom <thellstrom@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Doug Covelli <dcovelli@...are.com>
Subject: Re: [PATCH 2/4] x86/vmware: Add a header file for hypercall
 definitions

On Sun, Aug 18, 2019 at 04:33:14PM +0200, Thomas Hellström (VMware) wrote:

> +#define VMWARE_HYPERCALL \
> +	ALTERNATIVE_2(".byte 0xed", \
> +		      ".byte 0x0f, 0x01, 0xc1", X86_FEATURE_VMW_VMCALL,	\
> +		      ".byte 0x0f, 0x01, 0xd9", X86_FEATURE_VMW_VMMCALL)

For sanity, could we either add comments, or macros for those
instrucions?

Something like:

#define INSN_INL	0xed
#define INSN_VMCALL	0x0f,0x01,0xc1
#define INSN_VMMCALL	0x0f,0x01,0xd9

#define VMWARE_HYPERCALL \
	ALTERNATIVE_2(_ASM_MK_NOP(INSN_INL),
		      _ASM_MK_NOP(INSN_VMCALL), X86_FEATURE_VMCALL,
		      _ASM_MK_NOP(INSN_VMMCALL), X86_FEATURE_VMMCALL)

With possibly a patch that does 's/_ASM_MK_NOP/_ASM_MK_INSN/' on
arch/x86/ for further sanity :-)