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From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Oliver Upton <oliver.upton@linux.dev>,
	Joey Gouly <joey.gouly@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Shuah Khan <shuah@kernel.org>,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v15 1/6] arm64/gcs: Ensure FGTs for EL1 GCS instructions are disabled
Date: Wed, 20 Aug 2025 23:24:24 +0100	[thread overview]
Message-ID: <87ikihk4x3.wl-maz@kernel.org> (raw)
In-Reply-To: <20250820-arm64-gcs-v15-1-5e334da18b84@kernel.org>

On Wed, 20 Aug 2025 15:14:41 +0100,
Mark Brown <broonie@kernel.org> wrote:
> 
> The initial EL2 setup for GCS did not include disabling of EL1 usage of
> GCS instructions, also disable these traps.  This is the first disabling
> of instruction traps, use x2 to store the value to be written.

Written where?

> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  arch/arm64/include/asm/el2_setup.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
> index 46033027510c..0ac14ea4dbc8 100644
> --- a/arch/arm64/include/asm/el2_setup.h
> +++ b/arch/arm64/include/asm/el2_setup.h
> @@ -355,6 +355,10 @@
>  
>  .Lskip_gce_fgt_\@:
>  
> +	orr	x2, x2, #HFGITR_EL2_nGCSEPP_MASK

What is x2 set to before this?

> +	orr	x2, x2, #HFGITR_EL2_nGCSSTR_EL1_MASK
> +	orr	x2, x2, #HFGITR_EL2_nGCSPUSHM_EL1_MASK
> +
>  .Lset_fgt_\@:
>  	msr_s	SYS_HFGRTR_EL2, x0
>  	msr_s	SYS_HFGWTR_EL2, x0

Followed by:

	msr_s	SYS_HFGITR_EL2, xzr

Puzzled.

	M.

-- 
Jazz isn't dead. It just smells funny.

  reply	other threads:[~2025-08-20 22:24 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-20 14:14 [PATCH v15 0/6] KVM: arm64: Provide guest support for GCS Mark Brown
2025-08-20 14:14 ` [PATCH v15 1/6] arm64/gcs: Ensure FGTs for EL1 GCS instructions are disabled Mark Brown
2025-08-20 22:24   ` Marc Zyngier [this message]
2025-08-20 22:28     ` Marc Zyngier
2025-08-20 14:14 ` [PATCH v15 2/6] KVM: arm64: Manage GCS access and registers for guests Mark Brown
2025-08-20 21:06   ` Marc Zyngier
2025-08-20 22:13     ` Mark Brown
2025-08-20 14:14 ` [PATCH v15 3/6] KVM: arm64: Forward GCS exceptions to nested guests Mark Brown
2025-08-20 22:15   ` Marc Zyngier
2025-08-21 21:25     ` Mark Brown
2025-08-20 14:14 ` [PATCH v15 4/6] KVM: arm64: Set PSTATE.EXLOCK when entering an exception Mark Brown
2025-08-20 22:02   ` Marc Zyngier
2025-08-21 20:44     ` Mark Brown
2025-08-20 14:14 ` [PATCH v15 5/6] KVM: arm64: Allow GCS to be enabled for guests Mark Brown
2025-08-20 22:18   ` Marc Zyngier
2025-08-20 14:14 ` [PATCH v15 6/6] KVM: selftests: arm64: Add GCS registers to get-reg-list Mark Brown
2025-08-20 22:30 ` [PATCH v15 0/6] KVM: arm64: Provide guest support for GCS Marc Zyngier

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