[edk2-devel] [PATCH v2] OvmfPkg/QemuVideoDxe: Shouldn't assume system in VGA alias mode.
Laszlo Ersek
lersek at redhat.com
Thu Jun 6 07:56:10 UTC 2019
On 06/06/19 09:42, Marc W Chen wrote:
> Query the supported attributes firstly, then bitwise AND (&) both VGA_IO
> and VGA_IO_16. Since the supported attributes should only have one of
> VGA_IO or VGA_IO_16 set, the result of bitwise AND (&) is either VGA_IO
> or IO_16. Then the result can be passed to PciIo->Attributes() to set the
> attributes.
>
> Device driver should consider both since the mReserveVgaAliases in
> PciBusDxe driver is default FALSE(implies that device driver can only set
> VGA_IO_16 to PCI_ROOT_BRIDGE), and Platform code may not return
> EFI_RESERVE_VGA_IO_ALIAS in GetPlatformPolicy of PciPlatformProtocol to
> make mReserveVgaAliases become TRUE(implies that device driver can only
> set VGA_IO to PCI_ROOT_BRIDGE), Currently OvmfPkg doesn't have problem
> due to it has hard code value for PCI_ROOT_BRIDGE's attributes field, so
> an IO access by PciIoProtocol will be successed due to
> RootBridgeIoCheckParameter of PciRootBridgeIo.c will always get pass
> result for legacy IO access.
>
> Usually the attributes field of PCI_ROOT_BRIDGE should be 0, in that case
> it will have issue since the VGA_IO may not be able to be enabled, then
> IO access by PciIoProtocol will be failed, hence the QemuVideoDxe driver
> will not work fine.
>
> Signed-off-by: Marc Chen <marc.w.chen at intel.com>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> Cc: Anthony Perard <anthony.perard at citrix.com>
> Cc: Julien Grall <julien.grall at arm.com>
> Cc: Marc-André Lureau <marcandre.lureau at redhat.com>
> Cc: Stefan Berger <stefanb at linux.ibm.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1880
> ---
> OvmfPkg/QemuVideoDxe/Driver.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/OvmfPkg/QemuVideoDxe/Driver.c b/OvmfPkg/QemuVideoDxe/Driver.c
> index e8a613ef33..522110ef4e 100644
> --- a/OvmfPkg/QemuVideoDxe/Driver.c
> +++ b/OvmfPkg/QemuVideoDxe/Driver.c
> @@ -201,6 +201,7 @@ QemuVideoControllerDriverStart (
> PCI_TYPE00 Pci;
> QEMU_VIDEO_CARD *Card;
> EFI_PCI_IO_PROTOCOL *ChildPciIo;
> + UINT64 SupportedVgaIo;
>
> OldTpl = gBS->RaiseTPL (TPL_CALLBACK);
>
> @@ -277,13 +278,32 @@ QemuVideoControllerDriverStart (
> goto ClosePciIo;
> }
>
> + //
> + // Get supported PCI attributes
> + //
> + Status = Private->PciIo->Attributes (
> + Private->PciIo,
> + EfiPciIoAttributeOperationSupported,
> + 0,
> + &SupportedVgaIo
> + );
> + if (EFI_ERROR (Status)) {
> + goto ClosePciIo;
> + }
> +
> + SupportedVgaIo &= (UINT64)(EFI_PCI_IO_ATTRIBUTE_VGA_IO | EFI_PCI_IO_ATTRIBUTE_VGA_IO_16);
> + if (SupportedVgaIo == 0) {
> + Status = EFI_UNSUPPORTED;
> + goto ClosePciIo;
> + }
> +
> //
> // Set new PCI attributes
> //
> Status = Private->PciIo->Attributes (
> Private->PciIo,
> EfiPciIoAttributeOperationEnable,
> - EFI_PCI_DEVICE_ENABLE | EFI_PCI_IO_ATTRIBUTE_VGA_MEMORY | EFI_PCI_IO_ATTRIBUTE_VGA_IO,
> + EFI_PCI_DEVICE_ENABLE | EFI_PCI_IO_ATTRIBUTE_VGA_MEMORY | SupportedVgaIo,
> NULL
> );
> if (EFI_ERROR (Status)) {
>
Reviewed-by: Laszlo Ersek <lersek at redhat.com>
I will keep this patch tagged on my end, so that I can push it once
edk2-stable201905 has been tagged. Should I forget, please ping me.
Thanks
Laszlo
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