From d5321bf2fb6ddbceea21e8b8e38ae89288fcfb1a Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Tue, 30 Jun 2020 20:24:11 +0200 Subject: Documentation: Add TODOs for secure SMM when using x86_64 Change-Id: I157238f18bc1c2eba0adc0b87caa9adaf3fc5d38 Signed-off-by: Patrick Rudolph Reviewed-on: https://review.coreboot.org/c/coreboot/+/42982 Tested-by: build bot (Jenkins) Reviewed-by: Arthur Heymans Reviewed-by: Raul Rangel --- Documentation/arch/x86/index.md | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/arch/x86/index.md b/Documentation/arch/x86/index.md index 536dea3951..30dcc10e91 100644 --- a/Documentation/arch/x86/index.md +++ b/Documentation/arch/x86/index.md @@ -49,6 +49,15 @@ At the moment *$n* is 4, which results in identity mapping the lower 4 GiB. * Add assembly code to return to protected mode - *TODO* * Implement reference code for mainboard `emulation/qemu-q35` - *TODO* +## Future work + +1. Fine grained page tables for SMM: + * Must not have execute and write permissions for the same page. + * Must allow only that TSEG pages can be marked executable + * Must reside in SMRAM +2. Support 64bit PCI BARs above 4GiB +3. Place and run code above 4GiB + ## Porting other boards * Fix compilation errors * Test how well CAR works with x86_64 and paging -- cgit v1.2.3