linux-kernel - Re: [PATCH 4/6 v6] acpi/ghes: Add helper for CXL protocol errors checks

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Message-ID: <2925654.DJkKcVGEfx@fdefranc-mobl3>
Date: Tue, 04 Nov 2025 18:41:04 +0100
From: "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: linux-cxl@...r.kernel.org, "Rafael J . Wysocki" <rafael@...nel.org>,
 Len Brown <lenb@...nel.org>, Tony Luck <tony.luck@...el.com>,
 Borislav Petkov <bp@...en8.de>, Hanjun Guo <guohanjun@...wei.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Shuai Xue <xueshuai@...ux.alibaba.com>, Davidlohr Bueso <dave@...olabs.net>,
 Dave Jiang <dave.jiang@...el.com>,
 Alison Schofield <alison.schofield@...el.com>,
 Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>,
 Dan Williams <dan.j.williams@...el.com>,
 Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
 Oliver O'Halloran <oohall@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Sunil V L <sunilvl@...tanamicro.com>, Xiaofei Tan <tanxiaofei@...wei.com>,
 Mario Limonciello <mario.limonciello@....com>,
 Huacai Chen <chenhuacai@...nel.org>,
 Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
 Arnd Bergmann <arnd@...db.de>, Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>, Guo Weikang <guoweikang.kernel@...il.com>,
 Xin Li <xin@...or.com>, Will Deacon <will@...nel.org>,
 Huang Yiwei <quic_hyiwei@...cinc.com>, Gavin Shan <gshan@...hat.com>,
 Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
 Uwe Kleine-König <u.kleine-koenig@...libre.com>,
 Li Ming <ming.li@...omail.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
 Karolina Stolarek <karolina.stolarek@...cle.com>,
 Jon Pan-Doh <pandoh@...gle.com>, Lukas Wunner <lukas@...ner.de>,
 Shiju Jose <shiju.jose@...wei.com>, linux-kernel@...r.kernel.org,
 linux-acpi@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-pci@...r.kernel.org
Subject:
 Re: [PATCH 4/6 v6] acpi/ghes: Add helper for CXL protocol errors checks

On Tuesday, October 28, 2025 3:54:15 PM Central European Standard Time Jonathan Cameron wrote:
> On Thu, 23 Oct 2025 14:25:39 +0200
> "Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com> wrote:
> 
> > Move the CPER CXL protocol errors validity out of
> 
> validity check
> 
> > cxl_cper_post_prot_err() to cxl_cper_sec_prot_err_valid() and limit the
> 
> to new cxl_cper_sec_prot_err_valid() 
> 
> as otherwise it sounds like it already exists.
> 
> > serial number check only to CXL agents that are CXL devices (UEFI v2.10,
> > Appendix N.2.13).
> 
> Perhaps a little more here on why.  I assume because you are going to have
> a second user for it, but good to say that. Also serves to justify the
> export.
> 
Hi Jonathan,

All the corrections you made will be applied to the next version.
> > 
> > Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@...ux.intel.com>
> > ---
> >  drivers/acpi/apei/ghes.c | 32 ++++++++++++++++++++++----------
> >  include/cxl/event.h      | 10 ++++++++++
> >  2 files changed, 32 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index d6fe5f020e96..e69ae864f43d 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -706,30 +706,42 @@ static DEFINE_KFIFO(cxl_cper_prot_err_fifo, struct cxl_cper_prot_err_work_data,
> >  static DEFINE_SPINLOCK(cxl_cper_prot_err_work_lock);
> >  struct work_struct *cxl_cper_prot_err_work;
> >  
> > -static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
> > -				   int severity)
> > +int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
> 
> Useful to return an error number?  Or would a bool be better given it is either
> valid or not?
> 
I prefer to return more information when reasonable and leave the callers free
to use or ignore the specific error number.

Fabio
>
> Otherwise looks good to me,
> 
> Jonathan
> 
> >  {
> > -	struct cxl_cper_prot_err_work_data wd;
> > -	u8 *dvsec_start, *cap_start;
> > -
> >  	if (!(prot_err->valid_bits & PROT_ERR_VALID_AGENT_ADDRESS)) {
> >  		pr_err_ratelimited("CXL CPER invalid agent type\n");
> > -		return;
> > +		return -EINVAL;
> >  	}
> >  
> >  	if (!(prot_err->valid_bits & PROT_ERR_VALID_ERROR_LOG)) {
> >  		pr_err_ratelimited("CXL CPER invalid protocol error log\n");
> > -		return;
> > +		return -EINVAL;
> >  	}
> >  
> >  	if (prot_err->err_len != sizeof(struct cxl_ras_capability_regs)) {
> >  		pr_err_ratelimited("CXL CPER invalid RAS Cap size (%u)\n",
> >  				   prot_err->err_len);
> > -		return;
> > +		return -EINVAL;
> >  	}
> >  
> > -	if (!(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
> > -		pr_warn(FW_WARN "CXL CPER no device serial number\n");
> > +	if ((prot_err->agent_type == RCD || prot_err->agent_type == DEVICE ||
> > +	     prot_err->agent_type == LD || prot_err->agent_type == FMLD) &&
> > +	    !(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
> > +		pr_warn_ratelimited(FW_WARN
> > +				    "CXL CPER no device serial number\n");
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(cxl_cper_sec_prot_err_valid);
> > +
> > +static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
> > +				   int severity)
> > +{
> > +	struct cxl_cper_prot_err_work_data wd;
> > +	u8 *dvsec_start, *cap_start;
> > +
> > +	if (cxl_cper_sec_prot_err_valid(prot_err))
> > +		return;
> >  
> >  	guard(spinlock_irqsave)(&cxl_cper_prot_err_work_lock);
> >  
> 
> 
>