linux-kernel - Re: [PATCH 1/3] KVM: arm64: vgic: Add Apple M2 cpus to the list of broken SEIS implementations

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Date:   Tue, 3 Jan 2023 10:59:12 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     kvmarm@...ts.cs.columbia.edu, kvmarm@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        Sven Peter <sven@...npeter.dev>,
        Catalin Marinas <catalin.marinas@....com>,
        Hector Martin <marcan@...can.st>, linux-kernel@...r.kernel.org,
        asahi@...ts.linux.dev, Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: Re: [PATCH 1/3] KVM: arm64: vgic: Add Apple M2 cpus to the list of
 broken SEIS implementations

Hi Marc,

I have only been lurking on the kvmarm mailing list for a little bit and
it has mainly just been reading patches/review to get more familiar with
various virtualization concepts so I apologize if the following review
is rather shallow but...

On Tue, Jan 03, 2023 at 09:50:20AM +0000, Marc Zyngier wrote:
> I really hoped that Apple had fixed their not-quite-a-vgic implementation
> when moving from M1 to M2. Alas, it seems they didn't, and running
> a buggy EFI version results in the vgic generating SErrors outside
> of the guest and taking the host down.
> 
> Apply the same workaround as for M1. Yes, this is all a bit crap.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---
>  arch/arm64/include/asm/cputype.h | 4 ++++
>  arch/arm64/kvm/vgic/vgic-v3.c    | 3 ++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> index 4e8b66c74ea2..683ca3af4084 100644
> --- a/arch/arm64/include/asm/cputype.h
> +++ b/arch/arm64/include/asm/cputype.h
> @@ -124,6 +124,8 @@
>  #define APPLE_CPU_PART_M1_FIRESTORM_PRO	0x025
>  #define APPLE_CPU_PART_M1_ICESTORM_MAX	0x028
>  #define APPLE_CPU_PART_M1_FIRESTORM_MAX	0x029
> +#define APPLE_CPU_PART_M2_BLIZZARD	0x032
> +#define APPLE_CPU_PART_M2_AVALANCHE	0x033
>  
>  #define AMPERE_CPU_PART_AMPERE1		0xAC3
>  
> @@ -177,6 +179,8 @@
>  #define MIDR_APPLE_M1_FIRESTORM_PRO MIDR_CPU_MODEL(ARM_CPU_IMP_APPLE, APPLE_CPU_PART_M1_FIRESTORM_PRO)
>  #define MIDR_APPLE_M1_ICESTORM_MAX MIDR_CPU_MODEL(ARM_CPU_IMP_APPLE, APPLE_CPU_PART_M1_ICESTORM_MAX)
>  #define MIDR_APPLE_M1_FIRESTORM_MAX MIDR_CPU_MODEL(ARM_CPU_IMP_APPLE, APPLE_CPU_PART_M1_FIRESTORM_MAX)
> +#define MIDR_APPLE_M2_BLIZZARD MIDR_CPU_MODEL(ARM_CPU_IMP_APPLE, APPLE_CPU_PART_M2_BLIZZARD)
> +#define MIDR_APPLE_M2_AVALANCHE MIDR_CPU_MODEL(ARM_CPU_IMP_APPLE, APPLE_CPU_PART_M2_AVALANCHE)
>  #define MIDR_AMPERE1 MIDR_CPU_MODEL(ARM_CPU_IMP_AMPERE, AMPERE_CPU_PART_AMPERE1)
>  
>  /* Fujitsu Erratum 010001 affects A64FX 1.0 and 1.1, (v0r0 and v1r0) */
> diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
> index 826ff6f2a4e7..c6442b08fe80 100644
> --- a/arch/arm64/kvm/vgic/vgic-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-v3.c
> @@ -615,7 +615,8 @@ static const struct midr_range broken_seis[] = {
>  	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM_PRO),
>  	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM_PRO),
>  	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM_MAX),
> -	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM_MAX),

The commit message makes no note of this removal, was it intentional?
MIDR_APPLE_M1_FIRESTORM_MAX is only used here so I assume it is not.

> +	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD),
> +	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE),
>  	{},
>  };
>  
> -- 
> 2.34.1
> 

Cheers,
Nathan