path: root/drivers/firmware/efi/Kconfig
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 09:03:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 09:03:40 -0800
commit634cd4b6afe15dca8df02bcba242b9b0c5e9b5a5 (patch)
tree4865e4ec64a0575614a81d88f523269c04e17f09 /drivers/firmware/efi/Kconfig
parentMerge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff)
parentefi/x86: Disable instrumentation in the EFI runtime handling code (diff)
Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull EFI updates from Ingo Molnar: "The main changes in this cycle were: - Cleanup of the GOP [graphics output] handling code in the EFI stub - Complete refactoring of the mixed mode handling in the x86 EFI stub - Overhaul of the x86 EFI boot/runtime code - Increase robustness for mixed mode code - Add the ability to disable DMA at the root port level in the EFI stub - Get rid of RWX mappings in the EFI memory map and page tables, where possible - Move the support code for the old EFI memory mapping style into its only user, the SGI UV1+ support code. - plus misc fixes, updates, smaller cleanups. ... and due to interactions with the RWX changes, another round of PAT cleanups make a guest appearance via the EFI tree - with no side effects intended" * 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) efi/x86: Disable instrumentation in the EFI runtime handling code efi/libstub/x86: Fix EFI server boot failure efi/x86: Disallow efi=old_map in mixed mode x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lld efi/x86: avoid KASAN false positives when accessing the 1: 1 mapping efi: Fix handling of multiple efi_fake_mem= entries efi: Fix efi_memmap_alloc() leaks efi: Add tracking for dynamically allocated memmaps efi: Add a flags parameter to efi_memory_map efi: Fix comment for efi_mem_type() wrt absent physical addresses efi/arm: Defer probe of PCIe backed efifb on DT systems efi/x86: Limit EFI old memory map to SGI UV machines efi/x86: Avoid RWX mappings for all of DRAM efi/x86: Don't map the entire kernel text RW for mixed mode x86/mm: Fix NX bit clearing issue in kernel_map_pages_in_pgd efi/libstub/x86: Fix unused-variable warning efi/libstub/x86: Use mandatory 16-byte stack alignment in mixed mode efi/libstub/x86: Use const attribute for efi_is_64bit() efi: Allow disabling PCI busmastering on bridges during boot efi/x86: Allow translating 64-bit arguments for mixed mode calls ...
Diffstat (limited to 'drivers/firmware/efi/Kconfig')
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index bcc378c19ebe..ecc83e2f032c 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -215,6 +215,28 @@ config EFI_RCI2_TABLE
Say Y here for Dell EMC PowerEdge systems.
+ bool "Clear Busmaster bit on PCI bridges during ExitBootServices()"
+ help
+ Disable the busmaster bit in the control register on all PCI bridges
+ while calling ExitBootServices() and passing control to the runtime
+ kernel. System firmware may configure the IOMMU to prevent malicious
+ PCI devices from being able to attack the OS via DMA. However, since
+ firmware can't guarantee that the OS is IOMMU-aware, it will tear
+ down IOMMU configuration when ExitBootServices() is called. This
+ leaves a window between where a hostile device could still cause
+ damage before Linux configures the IOMMU again.
+ If you say Y here, the EFI stub will clear the busmaster bit on all
+ PCI bridges before ExitBootServices() is called. This will prevent
+ any malicious PCI devices from being able to perform DMA until the
+ kernel reenables busmastering after configuring the IOMMU.
+ This option will cause failures with some poorly behaved hardware
+ and should not be enabled without testing. The kernel commandline
+ options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma"
+ may be used to override this option.
config UEFI_CPER