linux-kernel - Re: [RFC 00/14] AMD: Add Secure AVIC Guest Support

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Message-ID: <submtt3ajyq54jyyywf3pb36nto27ojtuchjvhzycrplvfzrke@sieiu6mqa6xi>
Date: Tue, 29 Oct 2024 13:51:55 +0200
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
Cc: Borislav Petkov <bp@...en8.de>, 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
Subject: Re: [RFC 00/14] AMD: Add Secure AVIC Guest Support

On Tue, Oct 29, 2024 at 03:54:24PM +0530, Neeraj Upadhyay wrote:
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index aeda74bf15e6..08156ac4ec6c 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -1163,6 +1163,9 @@ void disable_local_APIC(void)
>         if (!apic_accessible())
>                 return;
> 
> +       if (apic->teardown)
> +               apic->teardown();
> +
>         apic_soft_disable();
> 
>  #ifdef CONFIG_X86_32

Hm. I think it will call apic->teardown() for all but the one CPU that
does kexec. I believe we need to disable SAVIC for all CPUs.

Have you tested the case when the target kernel doesn't support SAVIC and
tries to use a new interrupt vector on the boot CPU? I think it will
break.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov