HYP Kernel boot requirements

[Dave Martin]

On Tue, Nov 26, 2013 at 09:47:13AM -0500, Santosh Shilimkar wrote:
> On Tuesday 26 November 2013 09:13 AM, Catalin Marinas wrote:
> > On Mon, Nov 25, 2013 at 07:44:08PM +0000, Santosh Shilimkar wrote:
> >> On Monday 25 November 2013 12:28 PM, Catalin Marinas wrote:
> >>> On Mon, Nov 25, 2013 at 04:59:16PM +0000, Santosh Shilimkar wrote:
> >>>> What I am saying is the platforms like OMAP5 already support PM in
> >>>> mainline kernel and we can't break that for KVM. Boot-loaders
> >>>> would be thrashed after boot so you need something which runs
> >>>> in Kernel or along with Kernel to have equivalent of hyp
> >>>> switching.
> >>>>
> >>>> Am not challenging the agreed direction but we need to solve the
> >>>> PM problem as well before making "all CPU runs boot-loader for
> >>>> HYP kernels" as a must have. At least its is a change in boot
> >>>> strategy from existing kernels.
> >>>
> >>> Of course I recommend PSCI which covers both hotplug and suspend ;), but
> >>> I guess it's not the case for OMAP5. Since OMAP has its own secondary
> >>> booting protocol and CPU hotplug re-entry, can you not just use
> >>> different entry point when the primary CPU was initially started in Hyp
> >>> mode (e.g. omap5_hyp_secondary_startup)?
> >>>
> >> How will that solve the guest secondary boot failure case when using
> >> the same kernel binary for guest-boot ? Even for primary CPU which
> >> will be suspended it needs to resume already in HYP mode and its not
> >> going to go through boot-loader. So the low power code needs to have
> >> HYP switch code so that CPU resumes in HYP mode.
> > 
> > Is it late to rewrite the OMAP5 firmware?
> > 
> Well its ROM'ed unfortunately so no choice. OMAP5 ROM did implement
> a secure API which lets you enter into HYP mode and thats the only
> thing can be used.

If the ROM is capable of loading some additional signed Secure World
firmware after the ROM itself has booted, PSCI could be implemented
in the second, resident firmware payload.

Some SoCs ship with boot ROMs that can do that -- is this not the case
for OMAP5?

Cheers
---Dave