The bochs-display mmio bar has some sub-regions with the actual hardware
registers. What happens when the guest access something outside those
regions depends on the archirecture. On x86 those reads succeed (and
return 0xff I think). On risc-v qemu aborts.
This patch adds handlers for the parent region, to make the wanted
behavior explicit and to make things consistent across architectures.
v2:
- use existing unassigned_io_ops.
- also cover stdvga.
Cc: Alistair Francis <alistair23@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20200309100009.17624-1-kraxel@redhat.com
In my "build everything" tree, changing hw/qdev-properties.h triggers
a recompile of some 2700 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h).
Many places including hw/qdev-properties.h (directly or via hw/qdev.h)
actually need only hw/qdev-core.h. Include hw/qdev-core.h there
instead.
hw/qdev.h is actually pointless: all it does is include hw/qdev-core.h
and hw/qdev-properties.h, which in turn includes hw/qdev-core.h.
Replace the remaining uses of hw/qdev.h by hw/qdev-properties.h.
While there, delete a few superfluous inclusions of hw/qdev-core.h.
Touching hw/qdev-properties.h now recompiles some 1200 objects.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190812052359.30071-22-armbru@redhat.com>
In my "build everything" tree, changing hw/hw.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 previous commits have left only the declaration of hw_error() in
hw/hw.h. This permits dropping most of its inclusions. Touching it
now recompiles less than 200 objects.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-19-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
In my "build everything" tree, changing migration/vmstate.h triggers a
recompile of some 2700 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h).
hw/hw.h supposedly includes it for convenience. Several other headers
include it just to get VMStateDescription. The previous commit made
that unnecessary.
Include migration/vmstate.h only where it's still needed. Touching it
now recompiles only some 1600 objects.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-16-armbru@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Set QEMU_PCI_CAP_EXPRESS unconditionally in init(), then clear it in
realize() in case the device is not connected to a PCIe bus.
This makes sure the pci config space allocation is big enough, so
accessing the PCIe extended config space doesn't overflow the pci
config space buffer.
PCI(e) config space is guest writable. Writes are limited by
write mask (which probably is also filled with random stuff),
so the guest can only flip enabled bits. But I suspect it
still might be exploitable, so rather serious because it might
be a host escape for the guest. On the other hand the device
is probably not yet in widespread use.
(For a QEMU version without this commit, a mitigation for the
bug is available: use "-device bochs-display" as a conventional pci
device only.)
Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20190812065221.20907-2-kraxel@redhat.com
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
After writing up the virtual mdev device emulating a display supporting
the bochs vbe dispi interface (mbochs.ko) and seeing how simple it
actually is I've figured that would be useful for qemu too.
So, here it is, -device bochs-display. It is basically -device VGA
without legacy vga emulation. PCI bar 0 is the framebuffer, PCI bar 2
is mmio with the registers. The vga registers are simply not there
though, neither in the legacy ioport location nor in the mmio bar.
Consequently it is PCI class DISPLAY_OTHER not DISPLAY_VGA.
So there is no text mode emulation, no weird video modes (planar,
256color palette), no memory window at 0xa0000. Just a linear
framebuffer in the pci memory bar. And the amount of code to emulate
this (and therefore the attack surface) is an order of magnitude smaller
when compared to vga emulation.
Compatibility wise it works with OVMF (latest git master).
The bochs-drm.ko linux kernel module can handle it just fine too.
So UEFI guests should not see any functional difference to VGA.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20180522165058.15404-4-kraxel@redhat.com
