[SeaBIOS] [PATCH v7 0/5] QEMU: Add capability to write back fw_cfg address to QEMU

[Igor Mammedov]

On Mon, 20 Feb 2017 19:56:14 -0800
ben at skyportsystems.com wrote:

> From: Ben Warren <ben at skyportsystems.com>
> 
> This patch set adds the capability to write to QEMU across the fw_cfg DMA
> link.   It adds a higher-level command to write the BIOS-allocated address of
> one fw_cfg file into an arbitrary point within another, writeable fw_cfg file
> across the above-mentioned link.
> 
> The initial use case is for Windows VM
> Generation ID, where QEMU needs to change the contents of fw_cfg
> data at runtime, while still having BIOS allocate and manage the memory.
> 
> The final corresponding QEMU patch can be found here:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg430490.html


Tested-by: Igor Mammedov <imammedo at redhat.com>

Tested with WS201R2
 * migrated to file and then restored from file
    - guest gets notification and new GUID
 * make guest go into S3 and resume then migrate to file
    - vmgenid_addr_le value is not 0 in migration stream
      so SeaBIOS replayed fw_cfg write after reset at S3 resume time
     

> v6->v7: - minor refactoring of qemu_cfg_write_file* functions
> 
> v5->v6: - Rebased to top-of-tree
>         - Minor refactoring and conditional execution based on code review
> 
> v4->v5: - Minor changes to range checking and data validation
>         - Added code for replaying COMMAND_WRITE_POINTER commands on S3 resume
> 
> v3->v4: - Added a 'src_offset' field in the message so the pointer need not
>           point to the beginning of the file.
>         - Changed the command struct definitions from anonymous to named.
> 
> v2->v3: - fixed up the qemu_cfg_write* functions to allow writing to an
>           arbitrary offset within the destination file. 
>         - Changed function name to COMMAND_WRITE_POINTER and its functionality
>           to not patch memory at all, but write back to a specified offset.
> v1->v2: - separated patch into two functional units.
>         - changed so writes only occur over the DMA interface.
>         - fixed coding style.
>         - removed change to romfile struct definition
>           (removed new write_back method).
> 
> Ben Warren (5):
>   QEMU DMA: Add DMA write capability
>   romfile-loader: Switch to using named structs
>   QEMU fw_cfg: Add command to write back address of file
>   QEMU fw_cfg: Add functions for accessing files by key
>   QEMU fw_cfg: Write fw_cfg back on S3 resume
> 
>  src/fw/paravirt.c       |  68 +++++++++++++++++++++++++++++
>  src/fw/paravirt.h       |   5 +++
>  src/fw/romfile_loader.c | 112 ++++++++++++++++++++++++++++++++++++++++--------
>  src/fw/romfile_loader.h |  65 ++++++++++++++++++----------
>  src/resume.c            |   4 ++
>  5 files changed, 214 insertions(+), 40 deletions(-)
>