Implementing RAMFB migration is quite straightforward. One caveat is to
treat the whole RAMFBCfg as a blob, since that's what is exposed to the
guest directly. This avoid having to fiddle with endianness issues if we
were to migrate fields individually as integers.
The devices using RAMFB will have to include ramfb_vmstate in their
migration description.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
The fw_cfg DMA write callback in ramfb prepares a new display surface in
QEMU; this new surface is put to use ("swapped in") upon the next display
update. At that time, the old surface (if any) is released.
If the guest triggers the fw_cfg DMA write callback at least twice between
two adjacent display updates, then the second callback (and further such
callbacks) will leak the previously prepared (but not yet swapped in)
display surface.
The issue can be shown by:
(1) starting QEMU with "-trace displaysurface_free", and
(2) running the following program in the guest UEFI shell:
> #include <Library/ShellCEntryLib.h> // ShellAppMain()
> #include <Library/UefiBootServicesTableLib.h> // gBS
> #include <Protocol/GraphicsOutput.h> // EFI_GRAPHICS_OUTPUT_PROTOCOL
>
> INTN
> EFIAPI
> ShellAppMain (
> IN UINTN Argc,
> IN CHAR16 **Argv
> )
> {
> EFI_STATUS Status;
> VOID *Interface;
> EFI_GRAPHICS_OUTPUT_PROTOCOL *Gop;
> UINT32 Mode;
>
> Status = gBS->LocateProtocol (
> &gEfiGraphicsOutputProtocolGuid,
> NULL,
> &Interface
> );
> if (EFI_ERROR (Status)) {
> return 1;
> }
>
> Gop = Interface;
>
> Mode = 1;
> for ( ; ;) {
> Status = Gop->SetMode (Gop, Mode);
> if (EFI_ERROR (Status)) {
> break;
> }
>
> Mode = 1 - Mode;
> }
>
> return 1;
> }
The symptom is then that:
- only one trace message appears periodically,
- the time between adjacent messages keeps increasing -- implying that
some list structure (containing the leaked resources) keeps growing,
- the "surface" pointer is ever different.
> 18566@1695127471.449586:displaysurface_free surface=0x7f2fcc09a7c0
> 18566@1695127471.529559:displaysurface_free surface=0x7f2fcc9dac10
> 18566@1695127471.659812:displaysurface_free surface=0x7f2fcc441dd0
> 18566@1695127471.839669:displaysurface_free surface=0x7f2fcc0363d0
> 18566@1695127472.069674:displaysurface_free surface=0x7f2fcc413a80
> 18566@1695127472.349580:displaysurface_free surface=0x7f2fcc09cd00
> 18566@1695127472.679783:displaysurface_free surface=0x7f2fcc1395f0
> 18566@1695127473.059848:displaysurface_free surface=0x7f2fcc1cae50
> 18566@1695127473.489724:displaysurface_free surface=0x7f2fcc42fc50
> 18566@1695127473.969791:displaysurface_free surface=0x7f2fcc45dcc0
> 18566@1695127474.499708:displaysurface_free surface=0x7f2fcc70b9d0
> 18566@1695127475.079769:displaysurface_free surface=0x7f2fcc82acc0
> 18566@1695127475.709941:displaysurface_free surface=0x7f2fcc369c00
> 18566@1695127476.389619:displaysurface_free surface=0x7f2fcc32b910
> 18566@1695127477.119772:displaysurface_free surface=0x7f2fcc0d5a20
> 18566@1695127477.899517:displaysurface_free surface=0x7f2fcc086c40
> 18566@1695127478.729962:displaysurface_free surface=0x7f2fccc72020
> 18566@1695127479.609839:displaysurface_free surface=0x7f2fcc185160
> 18566@1695127480.539688:displaysurface_free surface=0x7f2fcc23a7e0
> 18566@1695127481.519759:displaysurface_free surface=0x7f2fcc3ec870
> 18566@1695127482.549930:displaysurface_free surface=0x7f2fcc634960
> 18566@1695127483.629661:displaysurface_free surface=0x7f2fcc26b140
> 18566@1695127484.759987:displaysurface_free surface=0x7f2fcc321700
> 18566@1695127485.940289:displaysurface_free surface=0x7f2fccaad100
We figured this wasn't a CVE-worthy problem, as only small amounts of
memory were leaked (the framebuffer itself is mapped from guest RAM, QEMU
only allocates administrative structures), plus libvirt restricts QEMU
memory footprint anyway, thus the guest can only DoS itself.
Plug the leak, by releasing the last prepared (not yet swapped in) display
surface, if any, in the fw_cfg DMA write callback.
Regarding the "reproducer", with the fix in place, the log is flooded with
trace messages (one per fw_cfg write), *and* the trace message alternates
between just two "surface" pointer values (i.e., nothing is leaked, the
allocator flip-flops between two objects in effect).
This issue appears to date back to the introducion of ramfb (995b30179b,
"hw/display: add ramfb, a simple boot framebuffer living in guest ram",
2018-06-18).
Cc: Gerd Hoffmann <kraxel@redhat.com> (maintainer:ramfb)
Cc: qemu-stable@nongnu.org
Fixes: 995b30179b
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20230919131955.27223-1-lersek@redhat.com>
size calculation isn't correct with guest-supplied stride, the last
display line isn't accounted for correctly.
For the typical case of stride > linesize (add padding) we error on the
safe side (calculated size is larger than actual size).
With stride < linesize (scanlines overlap) the calculated size is
smaller than the actual size though so our guest memory mapping might
end up being too small.
While being at it also fix ramfb_create_display_surface to use hwaddr
for the parameters. That way all calculation are done with hwaddr type
and we can't get funny effects from type castings.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20200429115236.28709-7-kraxel@redhat.com
Store width & height & surface in local variables. Update RAMFBState
with the new values only in case the ramfb_create_display_surface() call
succeeds.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20200429115236.28709-5-kraxel@redhat.com
This reverts commit a9e0cb67b7.
This breaks OVMF. Reproducer: Just hit 'ESC' at early boot to enter
firmware setup. OVMF wants switch from (default) 800x600 to 640x480 for
that, and this patch blocks it.
Cc: Hou Qiming <hqm03ster@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20200429115236.28709-3-kraxel@redhat.com
This reverts commit f79081b4b7.
Patch has broken byteorder handling: RAMFBCfg fields are in bigendian
byteorder, the reset function doesn't care so native byteorder is used
instead. Given this went unnoticed so far the feature is obviously
unused, so just revert the patch.
Cc: Hou Qiming <hqm03ster@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20200429115236.28709-2-kraxel@redhat.com
Use an explicit boolean type.
This commit was produced with the included Coccinelle script
scripts/coccinelle/exec_rw_const.
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
In my "build everything" tree, changing sysemu/sysemu.h triggers a
recompile of some 5400 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h).
Almost a third of its inclusions are actually superfluous. Delete
them. Downgrade two more to qapi/qapi-types-run-state.h, and move one
from char/serial.h to char/serial.c.
hw/semihosting/config.c, monitor/monitor.c, qdev-monitor.c, and
stubs/semihost.c define variables declared in sysemu/sysemu.h without
including it. The compiler is cool with that, but include it anyway.
This doesn't reduce actual use much, as it's still included into
widely included headers. The next commit will tackle that.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-27-armbru@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
In my "build everything" tree, changing sysemu/reset.h triggers a
recompile of some 2600 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h).
The main culprit is hw/hw.h, which supposedly includes it for
convenience.
Include sysemu/reset.h only where it's needed. Touching it now
recompiles less than 200 objects.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190812052359.30071-9-armbru@redhat.com>
If xres / yres were specified in QEMU command line, write them as an initial
resolution to the fw-config space on guest reset, which a later BIOS / OVMF
patch can take advantage of.
Signed-off-by: HOU Qiming <hqm03ster@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Message-id: 20190513115731.17588-4-marcel.apfelbaum@gmail.com
[fixed malformed patch]
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Only allow one resolution change per guest boot, which prevents a
crash when the guest writes garbage to the configuration space (e.g.
when rebooting).
Signed-off-by: HOU Qiming <hqm03ster@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Message-id: 20190513115731.17588-3-marcel.apfelbaum@gmail.com
[fixed malformed patch]
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Pulled back the `qemu_create_displaysurface_guestmem` function to create
the display surface so that the guest memory gets properly unmapped.
Signed-off-by: HOU Qiming <hqm03ster@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Message-id: 20190513115731.17588-2-marcel.apfelbaum@gmail.com
[rename the new functions and use QEMU coding style]
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> CID 1393621: (OVERFLOW_BEFORE_WIDEN)
> Potentially overflowing expression "stride * s->height" with type "unsigned
> int" (32 bits, unsigned) is evaluated using +32-bit arithmetic, and then used
> in a context that expects an expression of type "hwaddr" (64 bits, unsigned).
Fix by changing stride from uint32_t to hwaddr.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20180626083120.19515-1-kraxel@redhat.com
The boot framebuffer is expected to be configured by the firmware, so it
uses fw_cfg as interface. Initialization goes as follows:
(1) Check whenever etc/ramfb is present.
(2) Allocate framebuffer from RAM.
(3) Fill struct RAMFBCfg, write it to etc/ramfb.
Done. You can write stuff to the framebuffer now, and it should appear
automagically on the screen.
Note that this isn't very efficient because it does a full display
update on each refresh. No dirty tracking. Dirty tracking would have
to be active for the whole ram slot, so that wouldn't be very efficient
either. For a boot display which is active for a short time only this
isn't a big deal. As permanent guest display something better should be
used (if possible).
This is the ramfb core code. Some windup is needed for display devices
which want have a ramfb boot display.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 20180613122948.18149-2-kraxel@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
