Re: [PATCH v3 10/27] KVM: arm64: Correctly handle ACCDATA_EL1 traps

From: Jing Zhang <jingzhangos@google.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org,
	 Catalin Marinas <catalin.marinas@arm.com>,
	Eric Auger <eric.auger@redhat.com>,
	 Mark Brown <broonie@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Will Deacon <will@kernel.org>,
	 Alexandru Elisei <alexandru.elisei@arm.com>,
	Andre Przywara <andre.przywara@arm.com>,
	 Chase Conklin <chase.conklin@arm.com>,
	 Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	 Darren Hart <darren@os.amperecomputing.com>,
	Miguel Luis <miguel.luis@oracle.com>,
	 James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	 Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH v3 10/27] KVM: arm64: Correctly handle ACCDATA_EL1 traps
Date: Fri, 11 Aug 2023 08:31:13 -0700	[thread overview]
Message-ID: <CAAdAUtjOo_Bhpy2hvmVTEeG4vTmdHF9uoqnphdKBBW8jKRAndA@mail.gmail.com> (raw)
In-Reply-To: <20230808114711.2013842-11-maz@kernel.org>

Hi Marc,

On Tue, Aug 8, 2023 at 4:48 AM Marc Zyngier <maz@kernel.org> wrote:
>
> As we blindly reset some HFGxTR_EL2 bits to 0, we also randomly trap
> unsuspecting sysregs that have their trap bits with a negative
> polarity.
>
> ACCDATA_EL1 is one such register that can be accessed by the guest,
> causing a splat on the host as we don't have a proper handler for
> it.
>
> Adding such handler addresses the issue, though there are a number
> of other registers missing as the current architecture documentation
> doesn't describe them yet.
>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
> ---
>  arch/arm64/include/asm/sysreg.h | 2 ++
>  arch/arm64/kvm/sys_regs.c       | 2 ++
>  2 files changed, 4 insertions(+)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 043c677e9f04..818c111009ca 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -387,6 +387,8 @@
>  #define SYS_ICC_IGRPEN0_EL1            sys_reg(3, 0, 12, 12, 6)
>  #define SYS_ICC_IGRPEN1_EL1            sys_reg(3, 0, 12, 12, 7)
>
> +#define SYS_ACCDATA_EL1                        sys_reg(3, 0, 13, 0, 5)
> +
>  #define SYS_CNTKCTL_EL1                        sys_reg(3, 0, 14, 1, 0)
>
>  #define SYS_AIDR_EL1                   sys_reg(3, 1, 0, 0, 7)
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 2ca2973abe66..38f221f9fc98 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -2151,6 +2151,8 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>         { SYS_DESC(SYS_CONTEXTIDR_EL1), access_vm_reg, reset_val, CONTEXTIDR_EL1, 0 },
>         { SYS_DESC(SYS_TPIDR_EL1), NULL, reset_unknown, TPIDR_EL1 },
>
> +       { SYS_DESC(SYS_ACCDATA_EL1), undef_access },
> +
>         { SYS_DESC(SYS_SCXTNUM_EL1), undef_access },
>
>         { SYS_DESC(SYS_CNTKCTL_EL1), NULL, reset_val, CNTKCTL_EL1, 0},
> --
> 2.34.1
>
>

Reviewed-by: Jing Zhang <jingzhangos@google.com>

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