[PATCH 0/2] pci id documentation updates

[PATCH 0/2] pci id documentation updates

[Gerd Hoffmann]

Gerd Hoffmann (2):
  pci id: clarify pci subsystem id usage
  pci id: assign pci subsystem id for osmates

 docs/specs/pci-ids.rst | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

-- 
2.56.0

[PATCH 1/2] pci id: clarify pci subsystem id usage

[Gerd Hoffmann]

Qemu uses the pci subsystem id not only for emulated devices, but also
for virtio devices and generic pci class devices such as pci bridges,
xhci + nvme controllers etc.  Update the documentation accordingly.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 docs/specs/pci-ids.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/docs/specs/pci-ids.rst b/docs/specs/pci-ids.rst
index 261b0f359fe5..832f8bd1b802 100644
--- a/docs/specs/pci-ids.rst
+++ b/docs/specs/pci-ids.rst
@@ -46,8 +46,9 @@ maintained as part of the virtio specification.
   upstream merge or shipping a distro/product) to avoid conflicts.
 
 1af4:1100
-  Used as PCI Subsystem ID for existing hardware devices emulated
-  by QEMU.
+  Used as PCI Subsystem ID for existing hardware devices emulated by
+  QEMU, such as the intel chipset devices.  Also used for virtio
+  devices and generic pci class devices (1b36:00xx, see below).
 
 1af4:1110
   ivshmem device (:doc:`ivshmem-spec`)
-- 
2.56.0

Re: [PATCH 1/2] pci id: clarify pci subsystem id usage

[Daniel P. Berrangé]

On Thu, Oct 15, 2026 at 10:15:43AM +0200, Gerd Hoffmann wrote:
> Qemu uses the pci subsystem id not only for emulated devices, but also
> for virtio devices and generic pci class devices such as pci bridges,
> xhci + nvme controllers etc.  Update the documentation accordingly.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  docs/specs/pci-ids.rst | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/docs/specs/pci-ids.rst b/docs/specs/pci-ids.rst
> index 261b0f359fe5..832f8bd1b802 100644
> --- a/docs/specs/pci-ids.rst
> +++ b/docs/specs/pci-ids.rst
> @@ -46,8 +46,9 @@ maintained as part of the virtio specification.
>    upstream merge or shipping a distro/product) to avoid conflicts.
>  
>  1af4:1100
> -  Used as PCI Subsystem ID for existing hardware devices emulated
> -  by QEMU.
> +  Used as PCI Subsystem ID for existing hardware devices emulated by
> +  QEMU, such as the intel chipset devices.  Also used for virtio
> +  devices and generic pci class devices (1b36:00xx, see below).

When talking virtio devices, does that include virtio devices
implemented outside QEMU via vhostuser, or only in-QEMU virtio
devices ?

With regards,
Daniel
-- 
|: https://berrange.com       ~~        https://hachyderm.io/@berrange :|
|: https://libvirt.org          ~~          https://entangle-photo.org :|
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Re: [PATCH 1/2] pci id: clarify pci subsystem id usage

[Gerd Hoffmann]

On Thu, Oct 15, 2026 at 09:45:45AM +0100, Daniel P. Berrangé wrote:
> >  1af4:1100
> > -  Used as PCI Subsystem ID for existing hardware devices emulated
> > -  by QEMU.
> > +  Used as PCI Subsystem ID for existing hardware devices emulated by
> > +  QEMU, such as the intel chipset devices.  Also used for virtio
> > +  devices and generic pci class devices (1b36:00xx, see below).
> 
> When talking virtio devices, does that include virtio devices
> implemented outside QEMU via vhostuser, or only in-QEMU virtio
> devices ?

For vhost devices the pci config space emulation is still handled by
qemu.  On a quick check I don't see anything special done for vhost,
so I expect the same subsystem ID being used.

Maybe we should extend the vhost protocol to allow overriding the
subsystem id, so linux kernel / rust-vmm  / ... can have their own
subsystem ids?

take care,
  Gerd

Re: [PATCH 1/2] pci id: clarify pci subsystem id usage

[Daniel P. Berrangé]

On Thu, Oct 15, 2026 at 12:20:59PM +0200, Gerd Hoffmann wrote:
> On Thu, Oct 15, 2026 at 09:45:45AM +0100, Daniel P. Berrangé wrote:
> > >  1af4:1100
> > > -  Used as PCI Subsystem ID for existing hardware devices emulated
> > > -  by QEMU.
> > > +  Used as PCI Subsystem ID for existing hardware devices emulated by
> > > +  QEMU, such as the intel chipset devices.  Also used for virtio
> > > +  devices and generic pci class devices (1b36:00xx, see below).
> > 
> > When talking virtio devices, does that include virtio devices
> > implemented outside QEMU via vhostuser, or only in-QEMU virtio
> > devices ?
> 
> For vhost devices the pci config space emulation is still handled by
> qemu.  On a quick check I don't see anything special done for vhost,
> so I expect the same subsystem ID being used.

So IIUC, the QEMU subsystem ID applies to every PCI device exposed
from QEMU, except for VFIO passthrough of host devices.

> 
> Maybe we should extend the vhost protocol to allow overriding the
> subsystem id, so linux kernel / rust-vmm  / ... can have their own
> subsystem ids?

Would be a good idea as a way to distinguish the QEMU impls for
virtio devices, from 3rd party ones accessed via vhostuser.

With regards,
Daniel
-- 
|: https://berrange.com       ~~        https://hachyderm.io/@berrange :|
|: https://libvirt.org          ~~          https://entangle-photo.org :|
|: https://pixelfed.art/berrange   ~~    https://fstop138.berrange.com :|

[PATCH 2/2] pci id: assign pci subsystem id for osmates

[Gerd Hoffmann]

Allows the guest driver to identify the host implementation,
useful to be more specific when applying quirks etc.

Cc: Đạt Ngô Quốc <datlechin@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 docs/specs/pci-ids.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/specs/pci-ids.rst b/docs/specs/pci-ids.rst
index 832f8bd1b802..45e0d22e71bd 100644
--- a/docs/specs/pci-ids.rst
+++ b/docs/specs/pci-ids.rst
@@ -50,6 +50,10 @@ maintained as part of the virtio specification.
   QEMU, such as the intel chipset devices.  Also used for virtio
   devices and generic pci class devices (1b36:00xx, see below).
 
+1af4:1101
+  PCI Subsystem ID for OSMates (github.com/osmates), will be used
+  for virtio devices and pci class devices (xhci, nvme).
+
 1af4:1110
   ivshmem device (:doc:`ivshmem-spec`)
 
-- 
2.56.0

Re: [PATCH 2/2] pci id: assign pci subsystem id for osmates

[Daniel P. Berrangé]

On Thu, Oct 15, 2026 at 10:15:44AM +0200, Gerd Hoffmann wrote:
> Allows the guest driver to identify the host implementation,
> useful to be more specific when applying quirks etc.
> 
> Cc: Đạt Ngô Quốc <datlechin@gmail.com>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  docs/specs/pci-ids.rst | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/docs/specs/pci-ids.rst b/docs/specs/pci-ids.rst
> index 832f8bd1b802..45e0d22e71bd 100644
> --- a/docs/specs/pci-ids.rst
> +++ b/docs/specs/pci-ids.rst
> @@ -50,6 +50,10 @@ maintained as part of the virtio specification.
>    QEMU, such as the intel chipset devices.  Also used for virtio
>    devices and generic pci class devices (1b36:00xx, see below).
>  
> +1af4:1101
> +  PCI Subsystem ID for OSMates (github.com/osmates), will be used
> +  for virtio devices and pci class devices (xhci, nvme).

github.com/osmates appears to have no repositories, and the
website linked from that profile has no A records. Does this
even exist ? 

With regards,
Daniel
-- 
|: https://berrange.com       ~~        https://hachyderm.io/@berrange :|
|: https://libvirt.org          ~~          https://entangle-photo.org :|
|: https://pixelfed.art/berrange   ~~    https://fstop138.berrange.com :|