From 82e111cc2a8795cefca36e57031d3d2da0f919aa Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Thu, 7 Jan 2021 14:12:38 +0100 Subject: 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 Reviewed-on: https://review.coreboot.org/c/coreboot/+/49228 Tested-by: build bot (Jenkins) Reviewed-by: Angel Pons Reviewed-by: Arthur Heymans --- src/mainboard/emulation/qemu-i440fx/Kconfig | 9 +++++++++ src/mainboard/emulation/qemu-i440fx/mainboard.c | 13 ++++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-) (limited to 'src/mainboard/emulation/qemu-i440fx') diff --git a/src/mainboard/emulation/qemu-i440fx/Kconfig b/src/mainboard/emulation/qemu-i440fx/Kconfig index 62c23ca5af..1b618718b3 100644 --- a/src/mainboard/emulation/qemu-i440fx/Kconfig +++ b/src/mainboard/emulation/qemu-i440fx/Kconfig @@ -27,6 +27,15 @@ config VBOOT 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 diff --git a/src/mainboard/emulation/qemu-i440fx/mainboard.c b/src/mainboard/emulation/qemu-i440fx/mainboard.c index 929743ac46..bc97554442 100644 --- a/src/mainboard/emulation/qemu-i440fx/mainboard.c +++ b/src/mainboard/emulation/qemu-i440fx/mainboard.c @@ -28,8 +28,19 @@ static void qemu_nb_init(struct device *dev) pci_assign_irqs(pcidev_on_root(i, 0), qemu_i440fx_irqs + (i % 4)); } +static void qemu_nb_read_resources(struct device *dev) +{ + pci_dev_read_resources(dev); + + if (CONFIG(ARCH_RAMSTAGE_X86_64)) { + /* Reserve page tables in DRAM. FIXME: Remove once x86_64 page tables reside in CBMEM */ + reserved_ram_resource(dev, 0, CONFIG_ARCH_X86_64_PGTBL_LOC / KiB, + (6 * 0x1000) / KiB); + } +} + static struct device_operations nb_operations = { - .read_resources = pci_dev_read_resources, + .read_resources = qemu_nb_read_resources, .set_resources = pci_dev_set_resources, .enable_resources = pci_dev_enable_resources, .init = qemu_nb_init, -- cgit v1.2.3