linux-kernel - Re: [PATCH RFC RFT v2 15/15] drm/msm/a6xx: Warn if the highest_bank

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <wb46vfuegw2d4mj6pqx6o5my7ii4fhkrzrgte4hvey5ywiszpt@oe3qsptmanuu>
Date: Wed, 14 May 2025 22:25:18 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Konrad Dybcio <konradybcio@...nel.org>
Cc: Bjorn Andersson <andersson@...nel.org>, Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH RFC RFT v2 15/15] drm/msm/a6xx: Warn if the
 highest_bank_bit value is overwritten

On Wed, May 14, 2025 at 05:10:35PM +0200, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> 
> In preparation to resolve the issue of hardcoding HBB, throw a warning
> if the value is being overwritten in the GPU driver.
> 
> The HBB value is directly correlated with the memory configuration.
> On platforms where more than one is supported, the value must differ
> for proper functioning of the hardware, but it also must be consistent
> across all UBWC producers/consumers.
> 
> On platforms supporting only a single DRAM setup, the value may still
> be wrong, or at least inconsistent.
> 
> Print a warning to help catch such cases, until we declare full trust
> to the central database.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index eaf468b67f97ff153e92a73a45581228fcf75e46..ab812338739568d5908ca439e5c53e230a02de5d 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -637,6 +637,10 @@ static int a6xx_calc_ubwc_config(struct adreno_gpu *gpu)
>  	if (adreno_is_a702(gpu))
>  		cfg->highest_bank_bit = 14;
>  
> +	if (cfg->highest_bank_bit != common_cfg->highest_bank_bit)
> +		DRM_WARN_ONCE("Inconclusive highest_bank_bit value: %u (GPU) vs %u (UBWC_CFG)\n",
> +			      cfg->highest_bank_bit, common_cfg->highest_bank_bit);
> +

This really should come in an earlier patch...

>  	gpu->ubwc_config = &gpu->_ubwc_config;
>  
>  	return 0;
> 
> -- 
> 2.49.0
> 

-- 
With best wishes
Dmitry