Re: [edk2] Corrupted EFI region

Borislav Petkov
2013-08-05T13:02:59Z

On Mon, Aug 05, 2013 at 01:27:16PM +0200, Laszlo Ersek wrote:
> > --- before 2013-07-31 22:20:52.316039492 +0200
> > +++ after 2013-07-31 22:21:30.960731706 +0200
> > @@ -9,7 +9,7 @@ efi: mem07: type=2, attr=0xf, range=[0x0
> > efi: mem08: type=7, attr=0xf, range=[0x0000000040000000-0x000000007c000000) (960MB)
> > efi: mem09: type=4, attr=0xf, range=[0x000000007c000000-0x000000007c020000) (0MB)
> > efi: mem10: type=7, attr=0xf, range=[0x000000007c020000-0x000000007e0ad000) (32MB)
> > -efi: mem11: type=4, attr=0xf, range=[0x000000007e0ad000-0x000000007e0cc000) (0MB)
> > +efi: mem11: type=4, attr=0xf, range=[0x000000007e0ad000-0x000000007e0ad000) (0MB)
>
> (type 4 is EfiBootServicesData)

Yes.

> > efi: mem12: type=7, attr=0xf, range=[0x000000007e0cc000-0x000000007e0cd000) (0MB)
> > efi: mem13: type=4, attr=0xf, range=[0x000000007e0cd000-0x000000007e55d000) (4MB)
> > efi: mem14: type=3, attr=0xf, range=[0x000000007e55d000-0x000000007e59c000) (0MB)
> >
> > That second boundary of region mem11 suddenly changes *before* we merge
> > the regions. edk2 bug?
>
> I take it you mean this change (ie. appearance of the zero-sized range)
> occurs when you enable KVM acceleration in qemu?

Right. And I'm booting with qemu -enable-kvm so KVM acceleration is
enabled?? Or do you mean something else.

> If so, please locate "gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel"
> in OvmfPkg/OvmfPkgX64.dsc, and set the following bit in its value:
>
> # DEBUG_GCD 0x00100000 Global Coherency Database changes
>
> Then please rebuild OVMF, and capture the debug port output of qemu
> ("-debugcon file:debug.log -global isa-debugcon.iobase=0x402") both with
> and without KVM.
>
> DEBUG_GCD should produce messages related to CoreAllocateSpace(), and
> might help us find the spot the difference is introduced.

Ok, I'll try to get this thing done before my vacation. If not, we'll
deal with it afterwards but I won't forget, I promise! :-)

> BTW does this have anything to do with the NX bit report of yours, or
> have you noticed this independently?

Independently, while testing my runtime services mapping patchset. I was
getting an empty region and was wondering whether to discard it from the
mapping or not and then I looked at why I get it in the first place.

Basically, I get this empty region which appears at some point. It is
there when we enter efi_enter_virtual_mode in the kernel to setup the
runtime mappings:

[ 0.005012] efi: efi_enter_virtual_mode: enter
[ 0.006004] efi: mem00: type=7, attr=0xf, range=[0x0000000000000000-0x000000000009f000) (0MB)
[ 0.007004] efi: mem01: type=2, attr=0xf, range=[0x000000000009f000-0x00000000000a0000) (0MB)
[ 0.008003] efi: mem02: type=7, attr=0xf, range=[0x0000000000100000-0x0000000000800000) (7MB)
[ 0.009004] efi: mem03: type=4, attr=0xf, range=[0x0000000000800000-0x0000000001000000) (8MB)
[ 0.010004] efi: mem04: type=7, attr=0xf, range=[0x0000000001000000-0x0000000002000000) (16MB)
[ 0.011004] efi: mem05: type=2, attr=0xf, range=[0x0000000002000000-0x00000000036e3000) (22MB)
[ 0.012004] efi: mem06: type=7, attr=0xf, range=[0x00000000036e3000-0x000000003fffb000) (969MB)
[ 0.013003] efi: mem07: type=2, attr=0xf, range=[0x000000003fffb000-0x0000000040000000) (0MB)
[ 0.014004] efi: mem08: type=7, attr=0xf, range=[0x0000000040000000-0x000000007c000000) (960MB)
[ 0.015004] efi: mem09: type=4, attr=0xf, range=[0x000000007c000000-0x000000007c020000) (0MB)
[ 0.016004] efi: mem10: type=7, attr=0xf, range=[0x000000007c020000-0x000000007e0ad000) (32MB)
[ 0.017004] efi: mem11: type=4, attr=0xf, range=[0x000000007e0ad000-0x000000007e0ad000) (0MB)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[ 0.018003] efi: mem12: type=7, attr=0xf, range=[0x000000007e0cc000-0x000000007e0cd000) (0MB)

When we dump the EFI regions initially, it is ok.

[ 0.000000] efi: mem10: type=7, attr=0xf, range=[0x000000007c020000-0x000000007e0ad000) (32MB)
[ 0.000000] efi: mem11: type=4, attr=0xf, range=[0x000000007e0ad000-0x000000007e0cc000) (0MB)
[ 0.000000] efi: mem12: type=7, attr=0xf, range=[0x000000007e0cc000-0x000000007e0cd000) (0MB)

So what basically happens is the end boundary of the region becomes the
start, practically turning it into a 0-size one.

Thanks for looking into it.

--
Regards/Gruss,
Boris.

Sent from a fat crate under my desk. Formatting is fine.
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