linux-kernel - Re: [PATCH 2/6] arm64: errata: Add QCOM_KRYO_2XX_GOLD to the spectre_bhb_firmware_mitigated

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Message-ID: <wx6qbdbcrvbq34snzkxawlbpxm6vogt5ccjmdqqyazukfbjy7t@qkvax7tr27bs>
Date: Tue, 10 Dec 2024 01:13:19 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Douglas Anderson <dianders@...omium.org>
Cc: Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Julius Werner <jwerner@...omium.org>, Jeffrey Hugo <quic_jhugo@...cinc.com>, 
	Roxana Bradescu <roxabee@...gle.com>, bjorn.andersson@....qualcomm.com, 
	linux-arm-kernel@...ts.infradead.org, Trilok Soni <quic_tsoni@...cinc.com>, 
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] arm64: errata: Add QCOM_KRYO_2XX_GOLD to the
 spectre_bhb_firmware_mitigated_list

On Mon, Dec 09, 2024 at 09:43:12AM -0800, Douglas Anderson wrote:
> Qualcomm Kryo 200-series Gold cores appear to have a derivative of an
> ARM Cortex A73 in them. Since A73 needs Spectre mitigation then the
> Kyro 200-series Gold cores also should need Spectre mitigation.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> I don't really have any good way to test this patch but it seems
> likely it's needed. If nothing else the claim is that that Qualcomm
> Kyro 280 CPU is vulnerable [1] but I don't see any mitigations in the
> kernel for it.
> 
> NOTE: presumably this patch won't actually do much on its own because
> (I believe) it requires a firmware update to go with it.

Why? is_spectre_bhb_fw_affected() returns true if (cpu in list OR fw
mitigated)

> 
> [1] https://spectreattack.com/spectre.pdf
> 
>  arch/arm64/kernel/proton-pack.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c
> index e149efadff20..0437be7c83bc 100644
> --- a/arch/arm64/kernel/proton-pack.c
> +++ b/arch/arm64/kernel/proton-pack.c
> @@ -925,6 +925,7 @@ static bool is_spectre_bhb_fw_affected(int scope)
>  	static const struct midr_range spectre_bhb_firmware_mitigated_list[] = {
>  		MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
>  		MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
> +		MIDR_ALL_VERSIONS(MIDR_QCOM_KRYO_2XX_GOLD),
>  		{},
>  	};
>  	bool cpu_in_list = is_midr_in_range_list(read_cpuid_id(),
> -- 
> 2.47.0.338.g60cca15819-goog
> 

-- 
With best wishes
Dmitry