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Date:   Thu, 9 Aug 2018 16:48:30 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Martin Mares <mj@ucw.cz>, Logan Gunthorpe <logang@deltatee.com>
Cc:     linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-doc@vger.kernel.org, Stephen Bates <sbates@raithlin.com>,
        Christoph Hellwig <hch@lst.de>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Alex Williamson <alex.williamson@redhat.com>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>
Subject: Re: lspci: Display path to device
Message-ID: <20180809234830.GA30835@bombadil.infradead.org>
References: <20180717170204.30470-1-logang@deltatee.com>
 <20180717203900.GA1771@bombadil.infradead.org>
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Martin?  Bjorn's looking to merge this soon and it'd be nice to have
the support in lspci too.

On Tue, Jul 17, 2018 at 01:39:00PM -0700, Matthew Wilcox wrote:
> On Tue, Jul 17, 2018 at 11:02:00AM -0600, Logan Gunthorpe wrote:
> > The second patch expands the new helper to optionally take a path of
> > PCI devfns. This is to address Alex's renumbering concern when using
> > simple bus-devfns. The implementation is essentially how he described it and
> > similar to the Intel VT-d spec (Section 8.3.1).
> 
> I don't like telling the user to grovel around lspci -t by hand.  It's
> not many lines of code to add a new -P option to lspci to show the path
> to each device instead of bus:dev.fn
> 
> Here's three examples, first without, then with -P.
> 
> (my laptop):
> 6d:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM961/PM961
> 00:1d.0/00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM961/PM961
> 
> (tests/PCI-X-bridges-and-domains):
> 0002:42:00.0 Ethernet controller: Trident Microsystems 4DWave DX (rev 26)
> 0002:00:02.4/01.0/00.0 Ethernet controller: Trident Microsystems 4DWave DX (rev 26)
> 
> (my Nehalem system):
> 04:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 02)
> 00:03.0/00.0/00.0/00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 02)
> 
> The Nehalem system makes an interesting testcase because it exposes some
> registers in fake PCIe devices that aren't behind the root ports.  eg:
> 
> ff:06.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Thermal Control Registers (rev 04)
> 
> Martin, what do you think to this patch?  Also, I'm happy to send you
> the lspci -xxxx from the Nehalem system to add to tests/
> 
> diff --git a/lspci.c b/lspci.c
> index 3bf1925..ae0fdd2 100644
> --- a/lspci.c
> +++ b/lspci.c
> @@ -19,6 +19,7 @@ int verbose;				/* Show detailed information */
>  static int opt_hex;			/* Show contents of config space as hexadecimal numbers */
>  struct pci_filter filter;		/* Device filter */
>  static int opt_tree;			/* Show bus tree */
> +static int opt_path;			/* Show bridge path */
>  static int opt_machine;			/* Generate machine-readable output */
>  static int opt_map_mode;		/* Bus mapping mode enabled */
>  static int opt_domains;			/* Show domain numbers (0=disabled, 1=auto-detected, 2=requested) */
> @@ -29,7 +30,7 @@ char *opt_pcimap;			/* Override path to Linux modules.pcimap */
>  
>  const char program_name[] = "lspci";
>  
> -static char options[] = "nvbxs:d:ti:mgp:qkMDQ" GENERIC_OPTIONS ;
> +static char options[] = "nvbxs:d:tPi:mgp:qkMDQ" GENERIC_OPTIONS ;
>  
>  static char help_msg[] =
>  "Usage: lspci [<switches>]\n"
> @@ -247,6 +248,34 @@ sort_them(void)
>  
>  /*** Normal output ***/
>  
> +static void
> +show_slot_path(struct pci_dev *p)
> +{
> +  struct pci_dev *d = NULL;
> +
> +  if (opt_path && p->bus)
> +    {
> +      for (d = p->access->devices; d; d = d->next) {
> +	if (d->hdrtype == -1)
> +	  d->hdrtype = pci_read_byte(d, PCI_HEADER_TYPE) & 0x7f;
> +	if (d->hdrtype != PCI_HEADER_TYPE_BRIDGE &&
> +	    d->hdrtype != PCI_HEADER_TYPE_CARDBUS)
> +	  continue;
> +	if (pci_read_byte(d, PCI_SECONDARY_BUS) > p->bus)
> +	  continue;
> +	if (pci_read_byte(d, PCI_SUBORDINATE_BUS) < p->bus)
> +	  continue;
> +	show_slot_path(d);
> +	break;
> +      }
> +    }
> +
> +  if (d)
> +    printf("/%02x.%d", p->dev, p->func);
> +  else
> +    printf("%02x:%02x.%d", p->bus, p->dev, p->func);
> +}
> +
>  static void
>  show_slot_name(struct device *d)
>  {
> @@ -254,7 +283,7 @@ show_slot_name(struct device *d)
>  
>    if (!opt_machine ? opt_domains : (p->domain || opt_domains >= 2))
>      printf("%04x:", p->domain);
> -  printf("%02x:%02x.%d", p->bus, p->dev, p->func);
> +  show_slot_path(p);
>  }
>  
>  void
> @@ -989,6 +1018,9 @@ main(int argc, char **argv)
>        case 'x':
>  	opt_hex++;
>  	break;
> +      case 'P':
> +	opt_path++;
> +	break;
>        case 't':
>  	opt_tree++;
>  	break;
> diff --git a/lspci.man b/lspci.man
> index 35b3620..565dd5b 100644
> --- a/lspci.man
> +++ b/lspci.man
> @@ -95,6 +95,9 @@ PCI bus instead of as seen by the kernel.
>  .B -D
>  Always show PCI domain numbers. By default, lspci suppresses them on machines which
>  have only domain 0.
> +.TP
> +.B -P
> +Name PCI devices by path through each bridge, instead of by bus number.
>  
>  .SS Options to control resolving ID's to names
>  .TP
> --
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