Re: [Qemu-devel] [PATCH v4 00/17] arm_gic: Add security and grouping support

[Peter Maydell <peter.maydell@linaro.org>]

On 5 May 2015 at 03:08, Edgar E. Iglesias <edgar.iglesias@gmail.com> wrote:
> On Fri, May 01, 2015 at 06:50:26PM +0100, Peter Maydell wrote:
>> This patch series adds support for GICv1 and GICv2 security
>> extensions, as well as support for GIC interrupt grouping on GICv2.
>
> A question. Once we enable the the security extensions on the GICs,
> do you have any suggestions on howto best handle direct boots into
> NS EL2/1 (Linux)?
>
> The GIC resets to all interrupts configured for Group0 and Linux running
> in NS mode cannot change that so we need some kind of boot-loader
> code or magic to do what firmware would have been expected to do
> at boot time (switch some irqs to NS).

This is what I had in mind with the bit about:

>>  * if boot.c is starting the CPUs directly in NonSecure
>>    mode (because we're booting a kernel directly rather than
>>    starting firmware, and arm_boot_info::secure_boot is false)
>>    then it must also manually configure the GIC distributor
>>    to put all interrupts into Group1. This is boot.c having
>>    to do a firmware configuration job since it's effectively
>>    acting as lightweight builtin firmware.

I hadn't made up my mind whether this was easier to do via
boot.c writing a bunch of values to GICD registers or by
having the GIC provide a function/method to call to do the job.

-- PMM