linux-kernel - Re: [PATCH v3 08/10] x86/hyperv: Use TDX GHCI to access some MSRs in a TDX VM with the paravisor

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Message-ID: <Zac58P0MgEQ_ITOf@liuwe-devbox-debian-v2>
Date: Wed, 17 Jan 2024 02:22:40 +0000
From: Wei Liu <wei.liu@...nel.org>
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-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,
	Jason@...c4.com, nik.borisov@...e.com, mikelley@...rosoft.com,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, Tianyu.Lan@...rosoft.com,
	rick.p.edgecombe@...el.com, andavis@...hat.com, mheslin@...hat.com,
	vkuznets@...hat.com, xiaoyao.li@...el.com
Subject: Re: [PATCH v3 08/10] x86/hyperv: Use TDX GHCI to access some MSRs in
 a TDX VM with the paravisor

Hi Dave

I was away and only saw your email now. Sorry for the late reply.

On Mon, Dec 04, 2023 at 07:10:29AM -0800, Dave Hansen wrote:
> On 8/24/23 01:07, Dexuan Cui wrote:
> > +#ifdef CONFIG_INTEL_TDX_GUEST
> > +static void hv_tdx_msr_write(u64 msr, u64 val)
> > +{
> > +	struct tdx_hypercall_args args = {
> > +		.r10 = TDX_HYPERCALL_STANDARD,
> > +		.r11 = EXIT_REASON_MSR_WRITE,
> > +		.r12 = msr,
> > +		.r13 = val,
> > +	};
> > +
> > +	u64 ret = __tdx_hypercall(&args);
> > +
> > +	WARN_ONCE(ret, "Failed to emulate MSR write: %lld\n", ret);
> > +}
> 
> First of all, I'd really appreciate if you could seek out explicit acks
> for this kind of stuff before merging it.  This surprised me.
> 

I eyeballed the code and thought it only touched only the Hyper-V files,
so I merged this series without waiting.

> Can you please merge these generic things back into the main TDX code?
> There's nothing Hyper-V specific about any of this code.  Basically, you
> can make a hv_tdx_whatever() variant, but make _that_ in the generic TDX
> code and then export only _that_.

The code is still there. Dexuan, can you send a patch to do the
refactoring?

Wei.