linux-kernel - RE: [RFC PATCH V3 3/4] x86/Hyper-V: Don't use auto-eoi when Secure AVIC is available

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Message-ID:
 <SN6PR02MB4157FC3B69C9E6FB6884CE99D45EA@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Thu, 24 Jul 2025 23:34:52 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Tianyu Lan <ltykernel@...il.com>, "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>, "arnd@...db.de"
	<arnd@...db.de>, "Neeraj.Upadhyay@....com" <Neeraj.Upadhyay@....com>
CC: Tianyu Lan <tiala@...rosoft.com>, "linux-arch@...r.kernel.org"
	<linux-arch@...r.kernel.org>, "linux-hyperv@...r.kernel.org"
	<linux-hyperv@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [RFC PATCH V3 3/4] x86/Hyper-V: Don't use auto-eoi when Secure
 AVIC is available

From: Tianyu Lan <ltykernel@...il.com> Sent: Wednesday, July 23, 2025 12:03 PM
> 

I'm nit-picking, but the patch Subject: line prefix should be "x86/hyperv:"
for consistency with past patches. Note that there's no capitalization
or dash. I know not everyone is consistent on this if you look at the git log
for mshyperv.c, but I try to flag it and encourage consistency.

> Hyper-V doesn't support auto-eoi with Secure AVIC.
> So set the HV_DEPRECATING_AEOI_RECOMMENDED flag
> to force writing the EIO register after handling an interrupt.
> 
> Signed-off-by: Tianyu Lan <tiala@...rosoft.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index c78f860419d6..8f029650f16c 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -463,6 +463,8 @@ static void __init ms_hyperv_init_platform(void)
>  		 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
> 
>  	hv_identify_partition_type();
> +	if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
> +		ms_hyperv.hints |= HV_DEPRECATING_AEOI_RECOMMENDED;
> 
>  	if (ms_hyperv.hints & HV_X64_HYPERV_NESTED) {
>  		hv_nested = true;
> --
> 2.25.1
>