linux-kernel - Re: [PATCH v9 09/18] x86/sev: Initialize VGIF for secondary VCPUs for Secure AVIC

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Message-ID: <20250825145351.GWaKx4_48rQOqUYvZr@fat_crate.local>
Date: Mon, 25 Aug 2025 16:53:51 +0200
From: Borislav Petkov <bp@...en8.de>
To: "Upadhyay, Neeraj" <neeraj.upadhyay@....com>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	dave.hansen@...ux.intel.com, Thomas.Lendacky@....com,
	nikunj@....com, Santosh.Shukla@....com, Vasant.Hegde@....com,
	Suravee.Suthikulpanit@....com, David.Kaplan@....com, x86@...nel.org,
	hpa@...or.com, peterz@...radead.org, seanjc@...gle.com,
	pbonzini@...hat.com, kvm@...r.kernel.org,
	kirill.shutemov@...ux.intel.com, huibo.wang@....com,
	naveen.rao@....com, francescolavra.fl@...il.com,
	tiala@...rosoft.com
Subject: Re: [PATCH v9 09/18] x86/sev: Initialize VGIF for secondary VCPUs
 for Secure AVIC

On Mon, Aug 25, 2025 at 11:55:44AM +0530, Upadhyay, Neeraj wrote:
> Ok. Below is the updated description:
> 
> Virtual GIF (VGIF) providing masking capability for when virtual interrupts
> (virtual maskable interrupts, virtual NMIs) can be taken by the guest vCPU.
> Secure AVIC hardware reads VGIF state from the vCPU's VMSA. So, set VGIF for
> secondary CPUs (the configuration for boot CPU is done by the hypervisor),
> to unmask delivery of virtual interrupts  to the vCPU.

Yap.

> I also don't see an explicit mention. I will check on documenting it in the
> APM. However, there are references to virtual interrupts (V_NMI, V_INTR)
> (which requires VGIF support)

Oh, I don't doubt that SAVIC requires VGIF - I just spotted a documentation
hole here so let's start the process of documenting this internally.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette