ARM CPUs with the virtualization extension have a new mode called HYP mode, which allows hypervisors to safely control and monitor guests. The current hypervisor (KVM and Xen) implementations require the kernel to be entered in that HYP mode.
This patch series introduces a new U-Boot command called "hypmode" which can be used at any time at the U-Boot command prompt to switch the CPU into HYP mode - ideally this would be done before starting the kernel. Since U-Boot does not use the MMU, it runs fine in HYP mode, so you could as well enter HYP mode earlier.
The process of switching into HYP mode requires the CPU to be in non-secure state, which requires the GIC to be programmed properly first. Explanations about the details are in the commit messages of the respective patches.
The code aims to be as generic as possible, though currently it has only been tested on the Versatile Express TC-2 board. The last patch thus enables the feature for that board and relies on the Versatile Express updates patches sent out lately[1].
I would like to get some feedback on the patches, especially about: 1) Is the code in the right places? I used arch/arm/lib/ and arch/arm/cpu/armv7/ as directories for the ARM code and common/ for the actual command. 2) Is a command to switch to HYP actually the right thing? Should HYP be entered automatically instead? Or provide an option to skip HYP mode if requested by the user? 3) Does it make sense to provide a "nonsec" command also? I cannot name any usecases by now, but the implementation would be rather easy with basically all the functionality already there.
In general I appreciate any comments about coding style, patch layout or the actual implementation.
Thanks for watching!
Andre.
[1] http://lists.denx.de/pipermail/u-boot/2013-April/151366.html
Andre Przywara (6): ARM: add secure monitor handler to switch to non-secure state ARM: add assembly routine to switch to non-secure state ARM: add U-Boot command "hypmode" to switch to non-secure state ARM: add SMP support for non-secure switch ARM: extend non-secure switch to also go into HYP mode ARM: VExpress: enable ARMv7 virt support for VExpress A15
arch/arm/cpu/armv7/start.S | 116 ++++++++++++++++++++++++++++--- arch/arm/include/asm/armv7.h | 2 + arch/arm/lib/Makefile | 2 + arch/arm/lib/virt-v7.c | 132 ++++++++++++++++++++++++++++++++++++ common/Makefile | 1 + common/cmd_virt.c | 65 ++++++++++++++++++ include/configs/vexpress_ca15_tc2.h | 3 + 7 files changed, 311 insertions(+), 10 deletions(-) create mode 100644 arch/arm/lib/virt-v7.c create mode 100644 common/cmd_virt.c