On Thu, Oct 03, 2013 at 08:24:57AM +0200, Albert ARIBAUD wrote:
Hi Andre,
On Thu, 19 Sep 2013 18:06:45 +0200, Andre Przywara andre.przywara@linaro.org wrote:
For the KVM and XEN hypervisors to be usable, we need to enter the kernel in HYP mode. Now that we already are in non-secure state, HYP mode switching is within short reach.
While doing the non-secure switch, we have to enable the HVC instruction and setup the HYP mode HVBAR (while still secure).
The actual switch is done by dropping back from a HYP mode handler without actually leaving HYP mode, so we introduce a new handler routine in our new secure exception vector table.
In the assembly switching routine we save and restore the banked LR and SP registers around the hypercall to do the actual HYP mode switch.
The C routine first checks whether we are in HYP mode already and also whether the virtualization extensions are available. It also checks whether the HYP mode switch was finally successful. The bootm command part only calls the new function after the non-secure switch.
Signed-off-by: Andre Przywara andre.przywara@linaro.org
arch/arm/cpu/armv7/Makefile | 2 +- arch/arm/cpu/armv7/nonsec_virt.S | 43 +++++++++++++++++++++++++++++++++++----- arch/arm/cpu/armv7/virt-v7.c | 37 ++++++++++++++++++++++++++++++++++ arch/arm/include/asm/armv7.h | 6 ++++-- arch/arm/lib/bootm.c | 7 ++++++- 5 files changed, 86 insertions(+), 9 deletions(-)
Changes: v3..v4: w/s fixes, embed error output v4..v5: none
Seems like Christoffer's comment was not addressed here but IIUC, it was in other files (Christoffer, feel free to comment). Any reason why the "older asm" comments form was not replaced in here?
I think these comments are a bit superflous, but not exactly harmful, so I didn't raise the flag when they were not corrected. My thought was that if you're building for a board that has support for the virtualization extensions you should be using a toolchain that knows about them too, but Andre pointed out that his (I think Debian) still used an old enough cross toolchain not to have this support.
In any case, I don't think this warrants holding back the patches but can be fixed as a follow-up if the community agrees that we need to support older toolchains by some define that encodes the hvc and eret instructions properly.
Thanks, -Christoffer