linux-kernel - Re: [PATCH 3/4] x86,module: Detect VMX vs SLD conflicts

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Message-ID: <67d4f6d6-0ada-f899-f736-7a13434b60b9@citrix.com>
Date:   Wed, 8 Apr 2020 11:15:11 +0100
From:   Andrew Cooper <andrew.cooper3@...rix.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
CC:     <tglx@...utronix.de>, <linux-kernel@...r.kernel.org>,
        <hch@...radead.org>, <sean.j.christopherson@...el.com>,
        <mingo@...hat.com>, <bp@...en8.de>, <hpa@...or.com>,
        <x86@...nel.org>, <kenny@...ix.com>, <jeyu@...nel.org>,
        <rasmus.villemoes@...vas.dk>, <pbonzini@...hat.com>,
        <fenghua.yu@...el.com>, <xiaoyao.li@...el.com>,
        <nadav.amit@...il.com>, <thellstrom@...are.com>,
        <tony.luck@...el.com>, <rostedt@...dmis.org>,
        <gregkh@...uxfoundation.org>, <jannh@...gle.com>,
        <keescook@...omium.org>, <David.Laight@...lab.com>,
        <dcovelli@...are.com>
Subject: Re: [PATCH 3/4] x86,module: Detect VMX vs SLD conflicts

On 08/04/2020 10:56, Peter Zijlstra wrote:
>>> +		case 0xc1: /* VMCALL */
>>> +		case 0xc2: /* VMLAUNCH */
>>> +		case 0xc3: /* VMRESUME */
>>> +		case 0xc4: /* VMXOFF */
>> 		case 0xd4:	/* VMFUNC */
> As per Andrew, VMCALL and VMFUNC are SMV, and I really only need VMX in
> this case. Including SMV is probably harmless, but I'm thinking a
> smaller function is better.

VMCALL and VMFUNC are both VMX instructions.  VMMCALL (count the M's -
yes it is a different instruction) is SVM, and I forgot VMGEXIT from the
list yesterday which is also SVM.

However, searching for them is probably not helpful.  They are all
guest-only instructions and you wouldn't expect to see them in
hypervisor code.

~Andrew