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Wed, 09 Apr 2025 07:13:53 -0700 (PDT) Date: Wed, 9 Apr 2025 09:13:51 -0500 From: Gregory Price To: "Zhijian Li (Fujitsu)" Cc: Huaisheng Ye , "Jonathan.Cameron@huawei.com" , "dan.j.williams@intel.com" , "dave.jiang@intel.com" , "pei.p.jia@intel.com" , "linux-cxl@vger.kernel.org" Subject: Re: [RFC PATCH] cxl/core: reenable Mem_Enable bit of DVSEC control when RR decodes outside platform ranges Message-ID: References: <20250406112752.1261855-1-huaisheng.ye@intel.com> <02fbb2a7-3973-4c7f-8b7d-cfabbb379467@fujitsu.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <02fbb2a7-3973-4c7f-8b7d-cfabbb379467@fujitsu.com> On Mon, Apr 07, 2025 at 08:31:13AM +0000, Zhijian Li (Fujitsu) wrote: > [1] https://lore.kernel.org/linux-cxl/20240409075846.85370-1-lizhijian@fujitsu.com/ After looking at this, I see why this hasn't been fixed in QEMU. Basically QEMU doesn't implement the right reset mechanism. ct3_reset calls cxl_component_register_init_common() ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_GLOBAL_CONTROL, HDM_DECODER_ENABLE, 0) But it never resets MEM_ENABLE in the dvsecs. I'm not sure it's sane for Linux to be trying to handle hardware that doesn't itself reset correctly - and doing this fix just for QEMU seems a bit too far. The correct fix here is building an accessor for the existing CXL dvsecs and updating it during ct3_reset. ~Gregory