On Mon, 8 Jun 2020 at 12:46, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > > On 6/8/20 1:08 AM, Ard Biesheuvel wrote: > > On Sun, 7 Jun 2020 at 19:24, Heinrich Schuchardt <xypron.glpk@xxxxxx> wrote: > >> > >> On 6/7/20 3:58 PM, Ard Biesheuvel wrote: > >>> EFI on ARM only supports short descriptors, and given that it mandates > >>> that the MMU and caches are on, it is implied that booting in HYP mode > >>> is not supported. > >>> > >>> However, implementations of EFI exist (i.e., U-Boot) that ignore this > >>> requirement, which is not entirely unreasonable, given that it makes > >>> HYP mode inaccessible to the operating system. > >>> > >>> So let's make sure that we can deal with this condition gracefully. > >>> We already tolerate booting the EFI stub with the caches off (even > >>> though this violates the EFI spec as well), and so we should deal > >>> with HYP mode boot with MMU and caches either on or off. > >>> > >>> - When the MMU and caches are on, we can ignore the HYP stub altogether, > >>> since we can carry on executing at HYP. We do need to ensure that we > >>> disable the MMU at HYP before entering the kernel proper. > >>> > >>> - When the MMU and caches are off, we have to drop to SVC mode so that > >>> we can set up the page tables using short descriptors. In this case, > >>> we need to install the HYP stub as usual, so that we can return to HYP > >>> mode before handing over to the kernel proper. ... > > Hello Ard, > > thanks for supplying a branch for testing: > https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/?h=efi-arm-hyp-mode > > The OrangePi PC boots fine with this branch. PSCI is enabled. Rebooting > the system works fine. See log below. > > With the patch 2/2 you add an output line for the exceptions level and > the MMU status. Above you state "We already tolerate booting the EFI > stub with the caches off." This relates to a workaround in U-Boot > accomodating old GRUB versions (CONFIG_EFI_GRUB_ARM32_WORKAROUND=y). > > Would a further diagnostic line showing if D-cache and I-cache is > enabled make sense? > > Tested-by: Heinrich Schuchardt <xypron.glpk@xxxxxx> > > Loading Linux 5.7.0-armmp-lpae+ ... > Loading initial ramdisk ... > EFI stub: Running in HYP mode with MMU enabled BTW is this with or without the GRUB hack? > EFI stub: Booting Linux Kernel... > EFI stub: ERROR: Could not determine UEFI Secure Boot status. > EFI stub: Using DTB from configuration table > EFI stub: Exiting boot services and installing virtual address map... > EHCI failed to shut down host controller. > [ 0.000000] Booting Linux on physical CPU 0x0 > [ 0.000000] Linux version 5.7.0-armmp-lpae+ (user@node) > (arm-linux-gnueabihf-gcc (Debian 9.3.0-13) 9.3.0, GNU ld (GNU Binutils > for Debian) 2.34) #10 SMP Mon Jun 8 03:44:37 CEST 2020 > [ 0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), > cr=30c5387d > [ 0.000000] CPU: div instructions available: patching division code > [ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing > instruction cache > [ 0.000000] OF: fdt: Machine model: Xunlong Orange Pi PC > [ 0.000000] Memory policy: Data cache writealloc > [ 0.000000] efi: EFI v2.80 by Das U-Boot > [ 0.000000] efi: RTPROP=0x78f30040 SMBIOS=0x78f2a000 > MEMRESERVE=0x6a1fa040 > [ 0.000000] cma: Reserved 16 MiB at 0x000000007f000000 > [ 0.000000] Zone ranges: > [ 0.000000] DMA [mem 0x0000000040000000-0x000000006fffffff] > [ 0.000000] Normal empty > [ 0.000000] HighMem [mem 0x0000000070000000-0x000000007fffffff] > [ 0.000000] Movable zone start for each node > [ 0.000000] Early memory node ranges > [ 0.000000] node 0: [mem 0x0000000040000000-0x0000000078f07fff] > [ 0.000000] node 0: [mem 0x0000000078f08000-0x0000000078f09fff] > [ 0.000000] node 0: [mem 0x0000000078f0a000-0x0000000078f24fff] > [ 0.000000] node 0: [mem 0x0000000078f25000-0x0000000078f28fff] > [ 0.000000] node 0: [mem 0x0000000078f29000-0x0000000078f29fff] > [ 0.000000] node 0: [mem 0x0000000078f2a000-0x0000000078f2afff] > [ 0.000000] node 0: [mem 0x0000000078f2b000-0x0000000078f2cfff] > [ 0.000000] node 0: [mem 0x0000000078f2d000-0x0000000078f2dfff] > [ 0.000000] node 0: [mem 0x0000000078f2e000-0x0000000078f2ffff] > [ 0.000000] node 0: [mem 0x0000000078f30000-0x0000000078f32fff] > [ 0.000000] node 0: [mem 0x0000000078f33000-0x0000000078f33fff] > [ 0.000000] node 0: [mem 0x0000000078f34000-0x0000000078f34fff] > [ 0.000000] node 0: [mem 0x0000000078f35000-0x0000000078f35fff] > [ 0.000000] node 0: [mem 0x0000000078f36000-0x0000000078f36fff] > [ 0.000000] node 0: [mem 0x0000000078f37000-0x0000000078f38fff] > [ 0.000000] node 0: [mem 0x0000000078f39000-0x0000000078f3efff] > [ 0.000000] node 0: [mem 0x0000000078f3f000-0x000000007df65fff] > [ 0.000000] node 0: [mem 0x000000007df66000-0x000000007df66fff] > [ 0.000000] node 0: [mem 0x000000007df67000-0x000000007dfb9fff] > [ 0.000000] node 0: [mem 0x000000007dfba000-0x000000007dfbcfff] > [ 0.000000] node 0: [mem 0x000000007dfbd000-0x000000007fffffff] > [ 0.000000] Initmem setup node 0 [mem > 0x0000000040000000-0x000000007fffffff] > [ 0.000000] psci: probing for conduit method from DT. > [ 0.000000] psci: Using PSCI v0.1 Function IDs from DT
