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| author | Laszlo Ersek <lersek@redhat.com> | 2017-01-12 19:24:15 +0100 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2017-01-18 22:59:53 +0200 |
| commit | e12f3a13e2e134fe9b8d3d1a160a8e54de1e8fa7 (patch) | |
| tree | b4caa2a8ecd7ed28ee9302a934db45935701de24 /docs | |
| parent | baf2d5bfbac015b27f4db74feab235e167df0c84 (diff) | |
| download | qemu-e12f3a13e2e134fe9b8d3d1a160a8e54de1e8fa7.zip qemu-e12f3a13e2e134fe9b8d3d1a160a8e54de1e8fa7.tar.gz qemu-e12f3a13e2e134fe9b8d3d1a160a8e54de1e8fa7.tar.bz2 | |
fw-cfg: turn FW_CFG_FILE_SLOTS into a device property
We'd like to raise the value of FW_CFG_FILE_SLOTS. Doing it naively could
lead to problems with backward migration: a more recent QEMU (running an
older machine type) would allow the guest, in fw_cfg_select(), to select a
high key value that is unavailable in the same machine type implemented by
the older (target) QEMU. On the target host, fw_cfg_data_read() for
example could dereference nonexistent entries.
As first step, size the FWCfgState.entries[*] and FWCfgState.entry_order
arrays dynamically. All three array sizes will be influenced by the new
field FWCfgState.file_slots (and matching device property).
Make the following changes:
- Replace the FW_CFG_FILE_SLOTS macro with FW_CFG_FILE_SLOTS_MIN (minimum
count of fw_cfg file slots) in the header file. The value remains 0x10.
- Replace all uses of FW_CFG_FILE_SLOTS with a helper function called
fw_cfg_file_slots(), returning the new property.
- Eliminate the macro FW_CFG_MAX_ENTRY, and replace all its uses with a
helper function called fw_cfg_max_entry().
- In the MMIO- and IO-mapped realize functions both, allocate all three
arrays dynamically, based on the new property.
- The new property defaults to FW_CFG_FILE_SLOTS_MIN. This is going to be
customized in the following patches.
Cc: "Gabriel L. Somlo" <somlo@cmu.edu>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Gabriel Somlo <somlo@cmu.edu>
Tested-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/specs/fw_cfg.txt | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt index a19e2ad..9373bbc 100644 --- a/docs/specs/fw_cfg.txt +++ b/docs/specs/fw_cfg.txt @@ -156,7 +156,7 @@ Selector Reg. Range Usage 0xc000 - 0xffff Arch. Specific (0x0000 - 0x3fff, RW, ignored in v2.4+) In practice, the number of allowed firmware configuration items is given -by the value of FW_CFG_MAX_ENTRY (see fw_cfg.h). +by the value (FW_CFG_FILE_FIRST + FW_CFG_FILE_SLOTS_MIN) (see fw_cfg.h). = Guest-side DMA Interface = |