> From: Marc Zyngier <marc.zyng...@arm.com>
> Date: Thu, 14 Jun 2018 12:54:53 +0100
>
> On 13/06/18 23:41, Mark Kettenis wrote:
> > If desired (and possible) switch into HYP mode or non-secure SVC mode
> > before calling the entry point of an EFI application. This allows
> > U-Boot to provide a usable PSCI implementation and makes it possible
> > to boot kernels into hypervisor mode using an EFI bootloader.
> >
> > Based on diffs from Heinrich Schuchardt and Alexander Graf.
> >
> > Signed-off-by: Mark Kettenis <kette...@openbsd.org>
> > ---
> > cmd/bootefi.c | 32 ++++++++++++++++++++++++++++++++
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> > index 707d159bac..12a6b84ce6 100644
> > --- a/cmd/bootefi.c
> > +++ b/cmd/bootefi.c
> > @@ -20,6 +20,11 @@
> > #include <asm-generic/unaligned.h>
> > #include <linux/linkage.h>
> >
> > +#ifdef CONFIG_ARMV7_NONSEC
> > +#include <asm/armv7.h>
> > +#include <asm/secure.h>
> > +#endif
> > +
> > DECLARE_GLOBAL_DATA_PTR;
> >
> > #define OBJ_LIST_NOT_INITIALIZED 1
> > @@ -189,6 +194,18 @@ static efi_status_t efi_run_in_el2(EFIAPI efi_status_t
> > (*entry)(
> > }
> > #endif
> >
> > +#ifdef CONFIG_ARMV7_NONSEC
> > +static efi_status_t efi_run_in_hyp(EFIAPI efi_status_t (*entry)(
> > + efi_handle_t image_handle, struct efi_system_table *st),
> > + efi_handle_t image_handle, struct efi_system_table *st)
> > +{
> > + /* Enable caches again */
> > + dcache_enable();
> > +
> > + return efi_do_enter(image_handle, st, entry);
> > +}
> > +#endif
> > +
> > /* Carve out DT reserved memory ranges */
> > static efi_status_t efi_carve_out_dt_rsv(void *fdt)
> > {
> > @@ -338,6 +355,21 @@ static efi_status_t do_bootefi_exec(void *efi,
> > }
> > #endif
> >
> > +#ifdef CONFIG_ARMV7_NONSEC
> > + if (armv7_boot_nonsec()) {
> > + dcache_disable(); /* flush cache before switch to HYP */
> > +
>
> What is the rational for disabling/enabling caches across the transition
> to HYP? I'm sure there is a good reason, but I'd rather see it explained
> here.
Can't say I fully understan why. But the AArch64 code does this as
well and if I don't flush the cache here the contents of efi_gd (which
gets initialized before the switch) sometimes gets lost.
> > + armv7_init_nonsec();
> > + secure_ram_addr(_do_nonsec_entry)(efi_run_in_hyp,
> > + (uintptr_t)entry,
> > + (uintptr_t)loaded_image_info_obj.handle,
> > + (uintptr_t)&systab);
> > +
> > + /* Should never reach here, efi exits with longjmp */
> > + while (1) { }
> > + }
> > +#endif
> > +
> > ret = efi_do_enter(loaded_image_info_obj.handle, &systab, entry);
> >
> > exit:
> >
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