linux-kernel - Re: [RFC PATCH 1/6] x86/Hyper-V: Not use hv apic driver when Secure AVIC is available

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Message-ID: <CAMvTesBnO2crBYRbZQS=2RWta-M1azvsv7Q9RR1-he+iR-4jOA@mail.gmail.com>
Date: Thu, 15 May 2025 20:56:58 +0800
From: Tianyu Lan <ltykernel@...il.com>
To: Michael Kelley <mhklinux@...look.com>
Cc: "kys@...rosoft.com" <kys@...rosoft.com>, "haiyangz@...rosoft.com" <haiyangz@...rosoft.com>, 
	"wei.liu@...nel.org" <wei.liu@...nel.org>, "decui@...rosoft.com" <decui@...rosoft.com>, 
	"tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>, 
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, 
	"hpa@...or.com" <hpa@...or.com>, "Neeraj.Upadhyay@....com" <Neeraj.Upadhyay@....com>, 
	"yuehaibing@...wei.com" <yuehaibing@...wei.com>, "kvijayab@....com" <kvijayab@....com>, 
	"jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>, "jpoimboe@...nel.org" <jpoimboe@...nel.org>, 
	"tiala@...rosoft.com" <tiala@...rosoft.com>, 
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/6] x86/Hyper-V: Not use hv apic driver when Secure
 AVIC is available

On Thu, May 15, 2025 at 12:54 AM Michael Kelley <mhklinux@...look.com> wrote:
>
> From: Tianyu Lan <ltykernel@...il.com> Sent: Tuesday, May 6, 2025 6:07 AM
> >
> >  void __init hv_apic_init(void)
> >  {
> > +     if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
> > +             return;
> > +
> >       if (ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) {
> >               pr_info("Hyper-V: Using IPI hypercalls\n");
> >               /*
>
> It seems like this patch will cause a bisect problem if a bisect includes
> this patch but none of the subsequent patches in this series. The
> Hyper-V guest VM could see Secure AVIC is enabled, but the VM
> wouldn't boot because the code to allow Hyper-V to inject an interrupt
> haven't been added yet.
>
> This patch probably should come later in the patch series after Secure
> AVIC can be functional in a Hyper-V guest.
>

Good idea! Will rework patch order.

-- 
Thanks
Tianyu Lan