From: Sai Praneeth <sai.praneeth.prak...@intel.com> Presently, in x86, to invoke any efi function like efi_set_virtual_address_map() or any efi_runtime_service() the code path typically involves read_cr3() (save previous pgd), write_cr3() (write efi_pgd) and calling efi function. Likewise after returning from efi function the code path typically involves read_cr3() (save efi_pgd), write_cr3() (write previous pgd). We do this couple of times in efi subsystem of Linux kernel, instead we can use helper function efi_switch_mm() to do this. This improves readability and maintainability. Also, instead of maintaining a separate struct "efi_scratch" to store/restore efi_pgd, we can use mm_struct to do this.
I have tested this patch set against LUV (Linux UEFI Validation), so I think I didn't break any existing configurations. I have tested this patch set for 1. x86_64, 2. x86_32, 3. Mixed mode with efi=old_map and for kexec kernel. Please let me know if I have missed any other configurations. Changes in V2: 1. Resolve mm_dropping() issue by not mm_dropping()/mm_grabbing() any mm, as we are not losing/creating any references. Changes in V3: 1. When CPUMASK_OFFSTACK is enabled, switch_mm_irqs_off() sets cpumask by calling cpumask_set_cpu(). This panics kernel as efi_mm is not initialized, therefore initialize efi_mm in efi_alloc_page_tables(). Changes in V4: 1. Remove the unintended removal of local_irq_restore(flags) (in 3rd patch). IRQ flags should be restored after switching to orginal mm. Note: This patch set is based on Linus's tree v4.15-rc8 Sai Praneeth (3): efi: Use efi_mm in x86 as well as ARM x86/efi: Replace efi_pgd with efi_mm.pgd x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 arch/x86/include/asm/efi.h | 29 +++++++++--------- arch/x86/platform/efi/efi_64.c | 58 +++++++++++++++++++----------------- arch/x86/platform/efi/efi_thunk_64.S | 2 +- drivers/firmware/efi/arm-runtime.c | 9 ------ drivers/firmware/efi/efi.c | 9 ++++++ include/linux/efi.h | 2 ++ 6 files changed, 57 insertions(+), 52 deletions(-) Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prak...@intel.com> Cc: Lee, Chun-Yi <j...@suse.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Tony Luck <tony.l...@intel.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: Michael S. Tsirkin <m...@redhat.com> Cc: Ricardo Neri <ricardo.n...@intel.com> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Ravi Shankar <ravi.v.shan...@intel.com> Tested-by: Bhupesh Sharma <bhsha...@redhat.com> -- 2.1.4
