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OvmfPkg/Csm/LegacyBiosDxe: Fix Legacy16GetTableAddress call for E820 data 

The DX register is supposed to contain the required alignment for the
allocation. It was zero, and SeaBIOS doesn't (well, didn't) cope well
with that. Set it appropriately.

Also set BX to indicate the regions it's OK to allocate in too. That
wasn't being initialised and was just using whatever the previous user
of the structure had left there.

Finally, actually return an error if the allocation fails. Instead of
going all the way through into the CSM and just letting it have a bogus
pointer to the E820 data.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
David Woodhouse 2019-06-13 16:40:05 +08:00 committed by Hao A Wu
parent 3207a872a4
commit b0663641c9
1 changed files with 3 additions and 0 deletions
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3
OvmfPkg/Csm/LegacyBiosDxe/LegacyBootSupport.c
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@ -928,7 +928,9 @@ GenericLegacyBoot (
if (CopySize > Private->Legacy16Table->E820Length) {
ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));
Regs.X.AX = Legacy16GetTableAddress;
Regs.X.BX = (UINT16) 0x0; // Any region
Regs.X.CX = (UINT16) CopySize;
Regs.X.DX = (UINT16) 0x4; // Alignment
Private->LegacyBios.FarCall86 (
&Private->LegacyBios,
Private->Legacy16Table->Compatibility16CallSegment,
@ -942,6 +944,7 @@ GenericLegacyBoot (
Private->Legacy16Table->E820Length = (UINT32) CopySize;
if (Regs.X.AX != 0) {
DEBUG ((EFI_D_ERROR, "Legacy16 E820 length insufficient\n"));
return EFI_OUT_OF_RESOURCES;
} else {
CopyMem (
(VOID *)(UINTN) Private->Legacy16Table->E820Pointer,