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From:   Oliver Upton <oliver.upton@linux.dev>
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>,
        Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH v2 19/26] KVM: arm64: nv: Add trap forwarding for
 HFGxTR_EL2
Message-ID: <ZMQNTKAlxQe61JUe@linux.dev>
References: <20230728082952.959212-1-maz@kernel.org>
 <20230728082952.959212-20-maz@kernel.org>
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Hey Marc,

On Fri, Jul 28, 2023 at 09:29:45AM +0100, Marc Zyngier wrote:

[...]

> @@ -943,6 +1025,27 @@ void __init populate_nv_trap_config(void)
>  	kvm_info("nv: %ld coarse grained trap handlers\n",
>  		 ARRAY_SIZE(encoding_to_cgt));

It might make sense to skip insertion of the FGT trap controls if the
system doesn't have FGT in the first place.

> +	for (int i = 0; i < ARRAY_SIZE(encoding_to_fgt); i++) {
> +		const struct encoding_to_trap_config *fgt = &encoding_to_fgt[i];
> +		union trap_config tc;
> +
> +		tc = get_trap_config(fgt->encoding);
> +
> +		WARN(tc.fgt,
> +		     "Duplicate FGT for sys_reg(%d, %d, %d, %d, %d)\n",
> +		     sys_reg_Op0(fgt->encoding),
> +		     sys_reg_Op1(fgt->encoding),
> +		     sys_reg_CRn(fgt->encoding),
> +		     sys_reg_CRm(fgt->encoding),
> +		     sys_reg_Op2(fgt->encoding));

Same comment here, we should just bail.

> +		tc.val |= fgt->tc.val;
> +		xa_store(&sr_forward_xa, fgt->encoding,
> +			 xa_mk_value(tc.val), GFP_KERNEL);
> +	}
> +
> +	kvm_info("nv: %ld fine grained trap handlers\n",
> +		 ARRAY_SIZE(encoding_to_fgt));
>  }

-- 
Thanks,
Oliver