The real mode interrupt vector table, which we modify for the sake of
Windows 7, starts at address 0, which happens to be the representation of
null pointers on all edk2 architectures. A null pointer may never undergo
pointer arithmetic, and RH covscan justifiedly reports:
> Error: CPPCHECK_WARNING (CWE-682):
> edk2-89910a39dcfd/OvmfPkg/QemuVideoDxe/VbeShim.c:105:
> error[nullPointerArithmetic]: Pointer addition with NULL pointer.
> # 103| //
> # 104| Segment0Pages = 1;
> # 105|-> Int0x10 = (IVT_ENTRY *)(UINTN)Segment0 + 0x10;
> # 106| Segment0AllocationStatus = gBS->AllocatePages (
> # 107| AllocateAddress,
Fix this by calculating the EFI_PHYSICAL_ADDRESS of IVT entry 0x10 first,
and by casting the address to the right type second.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
Issue: scan-1002.txt
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
QemuVideoDxe driver will link VBE SHIM into page 0. If NULL pointer
detection is enabled, this driver will fail to load. NULL pointer detection
bypassing code is added to prevent such problem during boot.
Please note that Windows 7 will try to access VBE SHIM during boot if it's
installed, and then cause boot failure. This can be fixed by setting BIT7
of PcdNullPointerDetectionPropertyMask to disable NULL pointer detection
after EndOfDxe. As far as we know, there's no other OSs has such issue.
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
In commit db27e9f3d8 ("OvmfPkg/LegacyRegion: Support legacy region
manipulation of Q35", 2016-03-15), Ray extended the
OvmfPkg/Csm/CsmSupportLib PAM register manipulation to Q35. However, we
missed that the same should be done to the QemuVideoDxe VBE Shim as well.
The omission has caused no problems in practice on Q35, because QEMU has
let us write to the ROM area, regardless of the PAM1 setting, all this
time. This has now changed with recent QEMU commit 208fa0e43645 ("pc: make
'pc.rom' readonly when machine has PCI enabled", 2017-07-28). The QEMU
commit exposes the OVMF bug when Windows 7 is started on Q35, using QEMU
2.10 -- the VBE Shim is no longer put in place and Windows 7 cannot find
it.
To remedy this, assign the "Pam1Address" local variable a PciLib address
that matches the board type (i440fx vs. q35).
Regarding the PcdLib dependency: QemuVideoDxe already uses PcdLib, both
directly (see "PcdDriverSupportedEfiVersion") and indirectly (e.g. via the
DxePciLibI440FxQ35 PciLib instance). Add PcdLib to [LibraryClasses] for
completeness.
Cc: Aleksei Kovura <alex3kov@zoho.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Ref: https://bugs.launchpad.net/qemu/+bug/1715700
Reported-by: Aleksei Kovura <alex3kov@zoho.com>
Special-thanks-to: Gerd Hoffmann <kraxel@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Aleksei Kovura <alex3kov@zoho.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
This clarifies the purpose of the local variable in InstallVbeShim().
Cc: Aleksei Kovura <alex3kov@zoho.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Ref: https://bugs.launchpad.net/qemu/+bug/1715700
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Aleksei Kovura <alex3kov@zoho.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
In commit 5b2291f956 ("OvmfPkg: QemuVideoDxe uses
MdeModulePkg/FrameBufferLib"), QemuVideoDxe was rebased to
FrameBufferBltLib.
The FrameBufferBltLib instance added in commit b1ca386074
("MdeModulePkg: Add FrameBufferBltLib library instance") logs many
messages on the VERBOSE level; for example, a normal boot with OVMF can
produce 500+ "VideoFill" messages, dependent on the progress bar, when the
VERBOSE bit is set in PcdDebugPrintErrorLevel. While FrameBufferBltLib is
certainly allowed to log such messages on the VERBOSE level, we should
separate those frequent messages from the (infrequent) ones produced by
QemuVideoDxe itself.
QemuVideoDxe logs VERBOSE messages in three locations (in two functions)
at the moment. All of them are infrequent: both QemuVideoBochsModeSetup()
and InstallVbeShim() are called from QemuVideoControllerDriverStart(),
that is, when a device is bound. Upgrade these messages to INFO level, so
that VERBOSE can be disabled in PcdDebugPrintErrorLevel -- perhaps
selectively for OvmfPkg/QemuVideoDxe -- without hiding these infrequent
messages.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Correct some typos (discovered with the codespell utility)
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Thomas Huth <thuth@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
The SegmentC local variable has type EFI_PHYSICAL_ADDRESS for (justified)
style reasons. However, the 64-bit bit-shifts that it undergoes result in
intrinsic calls when built with VS2010 for Ia32 / NOOPT.
The concrete value of SegmentC, 0xC0000, and the results of the bitops
that are based on it, are statically computeable. Cast SegmentC to UINT32
before subjecting it to bitwise operations; we can see in advance that
this won't lead to range loss.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Scott Duplichan <scott@notabs.org>
[lersek@redhat.com: dropped now superfluous outermost parens; commit msg]
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Build-tested-by: Scott Duplichan <scott@notabs.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16385 6f19259b-4bc3-4df7-8a09-765794883524
The Windows 2008 R2 SP1 (and Windows 7) UEFI guest's default video driver
dereferences the real mode Int10h vector, loads the pointed-to handler
code, and executes what it thinks to be VGA BIOS services in an internal
real-mode emulator. Consequently, video mode switching doesn't work in
Windows 2008 R2 SP1 when it runs on the pure UEFI build of OVMF, making
the guest uninstallable.
This patch adds a VGABIOS "shim" to QemuVideoDxe. For the first stdvga or
QXL card bound, an extremely stripped down VGABIOS imitation is installed
in the C segment. It provides a real implementation for the few services
that are in fact necessary for the win2k8r2sp1 UEFI guest, plus some fakes
that the guest invokes but whose effect is not important.
The C segment is not present in the UEFI memory map prepared by OVMF. We
never add memory space that would cover it (either in PEI, in the form of
memory resource descriptor HOBs, or in DXE, via gDS->AddMemorySpace()).
This way the handler body is invisible to all non-buggy UEFI guests, and
the rest of edk2.
The Int10h real-mode IVT entry is covered with a Boot Services Code page,
making that too unaccessible to the rest of edk2. (Thus UEFI guest OSes
different from the Windows 2008 family can reclaim the page. The Windows
2008 family accesses the page at zero regardless of the allocation type.)
The patch is the result of collaboration:
Initial proof of concept IVT entry installation and handler skeleton (in
NASM) by Jordan Justen.
Service tracing and implementation, data collection/analysis, and C coding
by yours truly.
Last minute changes by Gerd Hoffmann:
- Use OEM mode number (0xf1) instead of standard 800x600 mode (0x143). The
resolution of the OEM mode (0xf1) is not standardized; the guest can't
expect anything from it in advance.
- Use 1024x768 rather than 800x600 for more convenience in the Windows
2008 R2 SP1 guest during OS installation, and after normal boot until
the QXL XDDM guest driver is installed.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15540 6f19259b-4bc3-4df7-8a09-765794883524
Laszlo Ersek
Michael D Kinney
Jian J Wang
Thomas Huth
Scott Duplichan
Ruiyu Ni