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

[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 <address@hidden> 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 <address@hidden>),
> >>               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
> >>>  |       |-- key
> >>>  |       |-- name                        ("bootorder")
> >>>  |       |-- raw
> >>>  |       `-- size
> >>>  |
> >>>  ...
> >>>  
> >>>  Patch 3/4 also gets us a "human readable" "by_name" listing, like so:
> >>>  
> >>>  ...
> >>>  |-- by_name
> >>>  |   |-- bootorder -> ../by_key/42
> >>>  |   |-- etc
> >>>  |   |   |-- acpi
> >>>  |   |   |   |-- rsdp -> ../../../by_key/41
> >>>  |   |   |   `-- tables -> ../../../by_key/38
> >>>  |   |   |-- boot-fail-wait -> ../../by_key/32
> >>>  |   |   |-- e820 -> ../../by_key/35
> >>>  |   |   |-- smbios
> >>>  |   |   |   |-- smbios-anchor -> ../../../by_key/34
> >>>  |   |   |   `-- smbios-tables -> ../../../by_key/33
> >>>  |   |   |-- system-states -> ../../by_key/37
> >>>  |   |   |-- table-loader -> ../../by_key/39
> >>>  |   |   `-- tpm
> >>>  |   |       `-- log -> ../../../by_key/40
> >>>  |   `-- genroms
> >>>  |       `-- kvmvapic.bin -> ../../by_key/36
> >>>  `-- rev
> 
> Gabriel Somlo (4):
>   firmware: introduce sysfs driver for QEMU's fw_cfg device
>   kobject: export kset_find_obj() for module use
>   firmware: create directory hierarchy for sysfs fw_cfg entries
>   devicetree: update documentation for fw_cfg ARM bindings
> 
>  .../ABI/testing/sysfs-firmware-qemu_fw_cfg         | 100 +++
>  Documentation/devicetree/bindings/arm/fw-cfg.txt   |  38 +-
>  drivers/firmware/Kconfig                           |  19 +
>  drivers/firmware/Makefile                          |   1 +
>  drivers/firmware/qemu_fw_cfg.c                     | 735 
> +++++++++++++++++++++
>  lib/kobject.c                                      |   1 +
>  6 files changed, 858 insertions(+), 36 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-firmware-qemu_fw_cfg
>  create mode 100644 drivers/firmware/qemu_fw_cfg.c
> 
> -- 
> 2.4.3
>