Re: [PATCH v3 6/6] PCI/AER: Unmask RCEC internal errors to enable RCH downstream port error handling

From: Robert Richter <rrichter@amd.com>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Terry Bowman <terry.bowman@amd.com>, <alison.schofield@intel.com>,
	<vishal.l.verma@intel.com>, <ira.weiny@intel.com>,
	<bwidawsk@kernel.org>, <dan.j.williams@intel.com>,
	<dave.jiang@intel.com>, <linux-cxl@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <bhelgaas@google.com>,
	Oliver O'Halloran <oohall@gmail.com>,
	Mahesh J Salgaonkar <mahesh@linux.ibm.com>,
	<linuxppc-dev@lists.ozlabs.org>, <linux-pci@vger.kernel.org>
Subject: Re: [PATCH v3 6/6] PCI/AER: Unmask RCEC internal errors to enable RCH downstream port error handling
Date: Fri, 14 Apr 2023 13:58:03 +0200	[thread overview]
Message-ID: <ZDk/y/w5IjuRkPyu@rric.localdomain> (raw)
In-Reply-To: <20230413180508.00003f13@Huawei.com>

On 13.04.23 18:05:08, Jonathan Cameron wrote:
> On Thu, 13 Apr 2023 15:38:07 +0200
> Robert Richter <rrichter@amd.com> wrote:
> 
> > On 12.04.23 16:29:01, Bjorn Helgaas wrote:
> > > On Tue, Apr 11, 2023 at 01:03:02PM -0500, Terry Bowman wrote:  

> > > With the exception of this function, this patch looks like all CXL
> > > code that maybe could be with other CXL code.  Would require making
> > > pcie_walk_rcec() available outside drivers/pci, I guess.  
> > 
> > Even this is CXL code, it implements AER support and fits better here
> > around AER code. Export of pcie_walk_rcec() (and others?) is not the
> > main issue here. CXL drivers can come as modules and would need to
> > register a hook at the aer handler.  This would add even more
> > complexity here. In contrast, current solution just adds two functions
> > for enablement and handling which are empty stubs if code is disabled.
> > 
> > I could move that code to aer_cxl.c similar to aer_inject.c. Since the
> > CXL part is small compared to the remaining aer code I left it in
> > aer.c. Also, it is guarded by #ifdef which additionally encapsulates
> > it.
> > 
> 
> To throw another option in there (what Bjorn suggested IIRC for the more
> general case..) 
> 
> Just enable internal errors always.  No need to know if they are CXL
> or something else.
> 
> There will/might be fallout and it will be fun.

I left the fun part to others. :-)

If some PCI root port goes crazy it tears down the whole system, would
avoid that.

Since internal error are implementation specific, I would only enable
them once a handler exists. What's why enablement is limited to CXL
RCECs only.

-Robert