Re: [PATCH v3 2/6] arm64: KVM: Move SPE and trace registers to the sysreg array

From: Marc Zyngier <maz@kernel.org>
To: James Clark <james.clark@arm.com>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.linux.dev, suzuki.poulose@arm.com,
	broonie@kernel.org, Oliver Upton <oliver.upton@linux.dev>,
	James Morse <james.morse@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Mike Leach <mike.leach@linaro.org>,
	Leo Yan <leo.yan@linaro.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Rob Herring <robh@kernel.org>,
	Jintack Lim <jintack.lim@linaro.org>,
	Akihiko Odaki <akihiko.odaki@daynix.com>,
	Fuad Tabba <tabba@google.com>, Joey Gouly <joey.gouly@arm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/6] arm64: KVM: Move SPE and trace registers to the sysreg array
Date: Mon, 04 Dec 2023 09:29:20 +0000	[thread overview]
Message-ID: <86plzmb9jj.wl-maz@kernel.org> (raw)
In-Reply-To: <20231019165510.1966367-3-james.clark@arm.com>

On Thu, 19 Oct 2023 17:55:00 +0100,
James Clark <james.clark@arm.com> wrote:
> 
> pmscr_el1 and trfcr_el1 are currently special cased in the
> host_debug_state struct, but they're just registers after all so give
> them entries in the sysreg array and refer to them through the host
> context.
> 
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
>  arch/arm64/include/asm/kvm_host.h  |  6 ++--
>  arch/arm64/include/asm/kvm_hyp.h   |  4 +--
>  arch/arm64/kvm/hyp/nvhe/debug-sr.c | 44 +++++++++++++++---------------
>  arch/arm64/kvm/hyp/nvhe/switch.c   |  4 +--
>  4 files changed, 28 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 4a966c0d7373..7c82927ddaf2 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -437,6 +437,8 @@ enum vcpu_sysreg {
>  	CNTHP_CVAL_EL2,
>  	CNTHV_CTL_EL2,
>  	CNTHV_CVAL_EL2,
> +	PMSCR_EL1,	/* Statistical profiling extension */
> +	TRFCR_EL1,	/* Self-hosted trace filters */

Why this move? Are you also adding guest support for SPE?

Until you do, I don't see the need to pollute the guest's sysreg
namespace.

	M.

-- 
Without deviation from the norm, progress is not possible.