mb/emulation/qemu: Copy page tables to DRAM in assembly
To work around various bugs running KVM enabled, copy page tables to
DRAM in assembly before jumping to x86_64 mode.
Tested on QEMU using KVM, no more stange bugs happen:
Tested on host
- CPU Intel(R) Core(TM) i7-7700HQ
- Linux 5.9
- qemu 4.2.1
Used to crash on emulating MMX instructions and failed to translate
some addresses using the virtual MMU when running in long mode.
Tested on host
- CPU AMD EPYC 7401P 24-Core Processor
- Linux 5.4
- qemu 4.2.1
Used to crash on jumping to long mode.
Change-Id: Ic0bdd2bef7197edd2e7488a8efdeba7eb4ab0dd4
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49228
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/mainboard/emulation/qemu-i440fx/Kconfig b/src/mainboard/emulation/qemu-i440fx/Kconfig
index 62c23ca..1b61871 100644
--- a/src/mainboard/emulation/qemu-i440fx/Kconfig
+++ b/src/mainboard/emulation/qemu-i440fx/Kconfig
@@ -27,6 +27,15 @@
select GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC
select GBB_FLAG_DISABLE_FWMP
+if ARCH_BOOTBLOCK_X86_64
+# Need to install page tables in DRAM as the virtual MMU has problems translating paging
+# request when the page table resides in emulated ROM. This causes undefined behaviour
+# when handling data requests, as well as fetching and decoding instructions
+# Real hardware didn't show any problems until now.
+config ARCH_X86_64_PGTBL_LOC
+ default 0x8000
+endif
+
if VBOOT
config VBOOT_SLOTS_RW_A