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 <lersek@xxxxxxxxxx> 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 <luto@xxxxxxxxxxxxxx>),
>> 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
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