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Date:   Thu, 20 Oct 2022 17:01:57 -0700
From:   Dan Williams <dan.j.williams@intel.com>
To:     Robert Richter <rrichter@amd.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        "Ira Weiny" <ira.weiny@intel.com>,
        Ben Widawsky <bwidawsk@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>
CC:     <linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        "Davidlohr Bueso" <dave@stgolabs.net>,
        Robert Richter <rrichter@amd.com>
Subject: RE: [PATCH v2 02/12] cxl/core: Check physical address before mapping
 it in devm_cxl_iomap_block()
Message-ID: <6351e175b24e9_4da32946e@dwillia2-xfh.jf.intel.com.notmuch>
References: <20221018132341.76259-1-rrichter@amd.com>
 <20221018132341.76259-3-rrichter@amd.com>
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Robert Richter wrote:
> The physical base address of a CXL range can be invalid and is then
> set to CXL_RESOURCE_NONE. In general software shall prevent such
> situations, but it is hard to proof this may never happen. E.g. in
> add_port_attach_ep() there this the following:
> 
>       component_reg_phys = find_component_registers(uport_dev);
>       port = devm_cxl_add_port(&parent_port->dev, uport_dev,
>               component_reg_phys, parent_dport);
> 
> find_component_registers() and subsequent functions (e.g.
> cxl_regmap_to_base()) may return CXL_RESOURCE_NONE. But it is written
> to port without any further check in cxl_port_alloc():
> 
>       port->component_reg_phys = component_reg_phys;
> 
> It is then later directly used in devm_cxl_setup_hdm() to map io
> ranges with devm_cxl_iomap_block(). Just an example...
> 
> Check this condition. Also do not fail silently like an ioremap()
> failure, use a WARN_ON_ONCE() for it.
> 
> Signed-off-by: Robert Richter <rrichter@amd.com>

Looks good to me, applied for v6.2