Date: Thu, 17 Dec 2015 11:09:23 -0500
From: "Gabriel L. Somlo" <somlo@cmu.edu>
To: gregkh@linuxfoundation.org, robh+dt@kernel.org, pawel.moll@arm.com,
        mark.rutland@arm.com, ijc+devicetree@hellion.org.uk,
        galak@codeaurora.org, arnd@arndb.de, lersek@redhat.com,
        ralf@linux-mips.org, rmk+kernel@arm.linux.org.uk, eric@anholt.net,
        hanjun.guo@linaro.org, zajec5@gmail.com, sudeep.holla@arm.com,
        agross@codeaurora.org, linux-api@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Cc: qemu-devel@nongnu.org, jordan.l.justen@intel.com, mst@redhat.com,
        peter.maydell@linaro.org, leif.lindholm@linaro.org,
        ard.biesheuvel@linaro.org, pbonzini@redhat.com, kraxel@redhat.com,
        luto@amacapital.net, stefanha@gmail.com, revol@free.fr,
        matt@codeblueprint.co.uk
Subject: Re: [PATCH v6 0/4] SysFS driver for QEMU fw_cfg device
Message-ID: <20151217160923.GI19448@HEDWIG.INI.CMU.EDU>
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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 <lersek@redhat.com> 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@amacapital.net>),
> >>		   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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