linux-kernel - Re: [PATCH RFC v4 5/6] firmware/efi: Process CXL Component Events

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Message-ID: <20231213171351.00004579@Huawei.com>
Date:   Wed, 13 Dec 2023 17:13:51 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ira Weiny <ira.weiny@...el.com>
CC:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        Dan Williams <dan.j.williams@...el.com>,
        Shiju Jose <shiju.jose@...wei.com>,
        "Yazen Ghannam" <yazen.ghannam@....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>,
        "Ard Biesheuvel" <ardb@...nel.org>, <linux-efi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-cxl@...r.kernel.org>
Subject: Re: [PATCH RFC v4 5/6] firmware/efi: Process CXL Component Events

On Wed, 29 Nov 2023 06:28:01 -0800
Ira Weiny <ira.weiny@...el.com> wrote:

> Smita Koralahalli wrote:
> > Hi Ira,
> > 
> > I tested this out. Just one correction below to make it work.
> >   
> 
> [snip]
> 
> > > +
> > > +#define CPER_CXL_DEVICE_ID_VALID		BIT(0)
> > > +#define CPER_CXL_DEVICE_SN_VALID		BIT(1)
> > > +#define CPER_CXL_COMP_EVENT_LOG_VALID		BIT(2)
> > > +struct cper_cxl_event_rec {
> > > +	struct {
> > > +		u32 length;
> > > +		u64 validation_bits;
> > > +		struct cper_cxl_event_devid {
> > > +			u16 vendor_id;
> > > +			u16 device_id;
> > > +			u8 func_num;
> > > +			u8 device_num;
> > > +			u8 bus_num;
> > > +			u16 segment_num;
> > > +			u16 slot_num; /* bits 2:0 reserved */
> > > +			u8 reserved;
> > > +		} device_id;
> > > +		struct cper_cxl_event_sn {
> > > +			u32 lower_dw;
> > > +			u32 upper_dw;
> > > +		} dev_serial_num;
> > > +	} hdr;
> > > +
> > > +	union cxl_event event;
> > > +} __packed;  
> > 
> > __packed attribute just for cper_cxl_event_rec still fails to properly 
> > align structure elements. Looks like, __packed attribute is needed for 
> > all structs (cper_cxl_event_devid and cper_cxl_event_sn) inside 
> > cper_cxl_event_rec.
> > 
> > Seems easier to use global pragma instead.. I could test and obtain the 
> > output as expected using pragma..  
> 
> I did not know that was acceptable in the kernel but I see you used it in
> cper_cxl.h before...
> 
> Ok I'll do that and spin again.
> 
> Thanks so much for testing this!  I was out last week and still don't have
> a test environment.

Easy to hack into QEMU :)  Hmm. I have a CCIX patch set from years ago
somewhere that does similar. Would be easy to repurposed. Looks like
I never published them (just told people to ask if they wanted them :( ).

Anyhow, if useful I can dig them out.

> 
> Ira