Hi Sai, On Sun, Dec 17, 2017 at 5:35 AM, Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx> wrote: > From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx> > > 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(). Thanks for the v3. I confirmed that the issue I saw with the v2 when I enabled 'efi=debug' on the sgi-uv 300 machine (i.e the NULL pointer access while accessing mm_cpumask(next), in the function call 'switch_mm_irqs_off') is fixed in the v3. Also as I noted during the v2 review, introducing the 'efi_switch_mm() ' helper instead of manually twiddling with %cr3 seems more cleaner (having personally debugged this leg several times on the underlying x86 EFI machines). So in addition to me testing this on the sgi-uv300 and Dell Optiplex EFI enabled machine, please feel free to add: Reviewed-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx> Thanks, Bhupesh > Note: > This patch set is based on Linus's tree v4.15-rc3 > > 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 | 59 +++++++++++++++++++----------------- > 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(+), 53 deletions(-) > > Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx> > Cc: Lee, Chun-Yi <jlee@xxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Cc: Tony Luck <tony.luck@xxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> > Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx> > Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx> > Tested-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx> > > -- > 2.1.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-efi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
