Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device

2015-12-19 Thread Pavel Machek 
Hi!

On Thu 2015-12-17 11:09:23, Gabriel L. Somlo wrote:
> ping ?
> 
> Also, for the corresponding patch set on the QEMU end of things,
> ping on http://thread.gmane.org/gmane.comp.emulators.qemu/376321

I guess missing information is why such access is a good
idea. Debugging?

Pavel

> On Fri, Dec 04, 2015 at 10:29:02AM -0500, Gabriel L. Somlo wrote:
> > Allow access to QEMU firmware blobs, passed into the guest VM via
> > the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
> > size, and fw_cfg key), as well as the raw binary blob data may be
> > accessed.
> > 
> > The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
> > selected based on overall similarity to the type of information
> > exposed under /sys/firmware/dmi/entries/...

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device

2015-12-19 Thread Gabriel L. Somlo 
Hi Pavel,

On Sat, Dec 19, 2015 at 10:12:28AM +0100, Pavel Machek wrote:
> On Thu 2015-12-17 11:09:23, Gabriel L. Somlo wrote:
> > ping ?
> > 
> > Also, for the corresponding patch set on the QEMU end of things,
> > ping on http://thread.gmane.org/gmane.comp.emulators.qemu/376321
> 
> I guess missing information is why such access is a good
> idea. Debugging?

Debugging did come up in earlier threads as well. However, personally,
I am interested in a mechanism for the host to pass information to the
guest in a way that's both

- asynchronous: i.e., host doesn't need to wait for guest to
  be ready to accept data (e.g. by first starting an agent)

- out-of-band: don't commandeer guest elements normally visible
  and available to guest *users* (e.g. kernel command line,
  mount a floppy/cdrom image, etc).

QEMU now allows arbitrary fw_cfg blobs to be added via the command
line, so it would be nice to make it easy to access them from the
guest OS -- and what's nicer and easier than:

cat /sys/firmware/qemu-fw-cfg/.../some-blob-name/raw

Thanks,
--Gabriel

> > On Fri, Dec 04, 2015 at 10:29:02AM -0500, Gabriel L. Somlo wrote:
> > > Allow access to QEMU firmware blobs, passed into the guest VM via
> > > the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
> > > size, and fw_cfg key), as well as the raw binary blob data may be
> > > accessed.
> > > 
> > > The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
> > > selected based on overall similarity to the type of information
> > > exposed under /sys/firmware/dmi/entries/...
> 
> -- 
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) 
> http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device

2015-12-17 Thread Gabriel L. Somlo 
ping ?

Also, for the corresponding patch set on the QEMU end of things,
ping on http://thread.gmane.org/gmane.comp.emulators.qemu/376321

Thanks,
--Gabriel

On Fri, Dec 04, 2015 at 10:29:02AM -0500, Gabriel L. Somlo wrote:
> Allow access to QEMU firmware blobs, passed into the guest VM via
> the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
> size, and fw_cfg key), as well as the raw binary blob data may be
> accessed.
> 
> The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
> selected based on overall similarity to the type of information
> exposed under /sys/firmware/dmi/entries/...
> 
> New since v5:
> 
>   - fixed typos in documentation files (Patches 1/4 and 4/4
> 
>   - printf/scanf type modifier for phys_addr_t now matches
> arch-specific width (u32 vs. u64), avoiding compiler warnings.
> (tested on i386 with and without PAE, and on armv7hl with and
>  without lpae -- the latter pair took quite a while on an
>  emulated QEMU guest :) )
> 
> Thanks,
>   --Gabriel
> 
> >New since v4:
> >
> > Documentation (Patches 1/4 and 4/4) now points to the authoritative
> > file in the QEMU source tree for any details related to the "hardware
> > interface" of the fw_cfg device; Only details specific to sysfs (1/4) 
> > and DT (4/4) should stay in the kernel docs.
> >
> >>New (since v3):
> >>
> >>Patch 1/4: Device probing now works with either ACPI, DT, or
> >>   optionally by manually specifying a base, size, and
> >>   register offsets on the command line. This way, all
> >>   architectures offering fw_cfg can be supported, although
> >>   x86 and ARM get *automatic* support via ACPI and/or DT.
> >>
> >>   HUGE thanks to Laszlo Ersek  for
> >>   pointing out drivers/virtio/virtio_mmio.c, as an example
> >>   on how to pull this off !!!
> >>
> >>   Stefan: I saw Marc's DMA patches to fw_cfg. Since only
> >>   x86 and ARM will support it starting with QEMU 2.5, and
> >>   since I expect to get lots of otherwise interesting (but
> >>   otherwise orthogonal) feedback on this series, I'd like
> >>   to stick with ioread8() across the board for now. We can
> >>   always patch in DMA support in a backward compatible way
> >>   later, once this series gets (hopefully) accepted :)
> >>
> >>Patch 2/4: (was 3/4 in v3): unchanged. Exports kset_find_obj() so
> >>   modules can call it.
> >>
> >>Patch 3/4: (was 4/4 in v3): rebased, but otherwise the same.
> >>   Essentially, creates a "human readable" directory
> >>   hierarchy from "path-like" tokens making up fw_cfg
> >>   blob names. I'm not really sure there's a way to make
> >>   this happen via udev rules, but I have at least one
> >>   potential use case for doing it *before* udev becomes
> >>   available (cc: Andy Lutomirski ),
> >>   so I'd be happy to leave this functionality in the
> >>   kernel module. See further below for an illustration
> >>   of this.
> >>
> >>Patch 4/4: Updates the existing ARM DT documentation for fw_cfg,
> >>   mainly by pointing at the more comprehensive document
> >>   introduced with Patch 1/4 for details on the fw_cfg
> >>   device interface, leaving only the specific ARM/DT
> >>   address/size node information in place.
> >>
> >>>  In addition to the "by_key" blob listing, e.g.:
> >>>  
> >>>  $ tree /sys/firmware/qemu_fw_cfg/
> >>>  /sys/firmware/qemu_fw_cfg/
> >>>  |-- by_key
> >>>  |   |-- 32
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/boot-fail-wait")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 33
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/smbios/smbios-tables")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 34
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/smbios/smbios-anchor")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 35
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/e820")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 36
> >>>  |   |   |-- key
> >>>  |   |   |-- name("genroms/kvmvapic.bin")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 37
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/system-states")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 38
> >>>  |   |   |-- key
> >>>  |   |   |-- name("etc/acpi/tables")
> >>>  |   |   |-- raw
> >>>  |   |   `-- size
> >>>  |   |-- 39
> >>>  |   |   |-- key
> >>>  |   |   |-- name

[Qemu-devel] [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device

2015-12-04 Thread Gabriel L. Somlo 
Allow access to QEMU firmware blobs, passed into the guest VM via
the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name,
size, and fw_cfg key), as well as the raw binary blob data may be
accessed.

The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was
selected based on overall similarity to the type of information
exposed under /sys/firmware/dmi/entries/...

New since v5:

- fixed typos in documentation files (Patches 1/4 and 4/4

- printf/scanf type modifier for phys_addr_t now matches
  arch-specific width (u32 vs. u64), avoiding compiler warnings.
  (tested on i386 with and without PAE, and on armv7hl with and
   without lpae -- the latter pair took quite a while on an
   emulated QEMU guest :) )

Thanks,
  --Gabriel

>New since v4:
>
>   Documentation (Patches 1/4 and 4/4) now points to the authoritative
>   file in the QEMU source tree for any details related to the "hardware
>   interface" of the fw_cfg device; Only details specific to sysfs (1/4) 
>   and DT (4/4) should stay in the kernel docs.
>
>>New (since v3):
>>
>>  Patch 1/4: Device probing now works with either ACPI, DT, or
>> optionally by manually specifying a base, size, and
>> register offsets on the command line. This way, all
>> architectures offering fw_cfg can be supported, although
>> x86 and ARM get *automatic* support via ACPI and/or DT.
>>
>> HUGE thanks to Laszlo Ersek  for
>> pointing out drivers/virtio/virtio_mmio.c, as an example
>> on how to pull this off !!!
>>
>> Stefan: I saw Marc's DMA patches to fw_cfg. Since only
>> x86 and ARM will support it starting with QEMU 2.5, and
>> since I expect to get lots of otherwise interesting (but
>> otherwise orthogonal) feedback on this series, I'd like
>> to stick with ioread8() across the board for now. We can
>> always patch in DMA support in a backward compatible way
>> later, once this series gets (hopefully) accepted :)
>>
>>  Patch 2/4: (was 3/4 in v3): unchanged. Exports kset_find_obj() so
>> modules can call it.
>>
>>  Patch 3/4: (was 4/4 in v3): rebased, but otherwise the same.
>> Essentially, creates a "human readable" directory
>> hierarchy from "path-like" tokens making up fw_cfg
>> blob names. I'm not really sure there's a way to make
>> this happen via udev rules, but I have at least one
>> potential use case for doing it *before* udev becomes
>> available (cc: Andy Lutomirski ),
>> so I'd be happy to leave this functionality in the
>> kernel module. See further below for an illustration
>> of this.
>>
>>  Patch 4/4: Updates the existing ARM DT documentation for fw_cfg,
>> mainly by pointing at the more comprehensive document
>> introduced with Patch 1/4 for details on the fw_cfg
>> device interface, leaving only the specific ARM/DT
>> address/size node information in place.
>>
>>>  In addition to the "by_key" blob listing, e.g.:
>>>  
>>>  $ tree /sys/firmware/qemu_fw_cfg/
>>>  /sys/firmware/qemu_fw_cfg/
>>>  |-- by_key
>>>  |   |-- 32
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/boot-fail-wait")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 33
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/smbios/smbios-tables")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 34
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/smbios/smbios-anchor")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 35
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/e820")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 36
>>>  |   |   |-- key
>>>  |   |   |-- name("genroms/kvmvapic.bin")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 37
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/system-states")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 38
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/acpi/tables")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 39
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/table-loader")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 40
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/tpm/log")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   |-- 41
>>>  |   |   |-- key
>>>  |   |   |-- name("etc/acpi/rsdp")
>>>  |   |   |-- raw
>>>  |   |   `-- size
>>>  |   `-- 42
>>>  |