RE: [RFC PATCH 2/6] firmware: smccc: Detect hypervisor via RSI host call in CCA Realms

["Kameron Carr" <kameroncarr@linux.microsoft.com>]

On Thursday, June 18, 2026 10:46 AM, Michael Kelley wrote:
> From: Kameron Carr <kameroncarr@linux.microsoft.com> Sent: Tuesday, June
> 9, 2026 11:10 AM
> > diff --git a/drivers/firmware/smccc/smccc.c
> b/drivers/firmware/smccc/smccc.c
> > index bdee057db2fd3..6b465e65472b0 100644
> > --- a/drivers/firmware/smccc/smccc.c
> > +++ b/drivers/firmware/smccc/smccc.c
> > @@ -12,6 +12,12 @@
> >  #include <linux/platform_device.h>
> >  #include <asm/archrandom.h>
> >
> > +#ifdef CONFIG_ARM64
> > +#include <linux/cleanup.h>
> > +#include <linux/spinlock.h>
> > +#include <asm/rsi.h>
> > +#endif
> > +
> >  static u32 smccc_version = ARM_SMCCC_VERSION_1_0;
> >  static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE;
> >
> > @@ -67,12 +73,45 @@ s32 arm_smccc_get_soc_id_revision(void)
> >  }
> >  EXPORT_SYMBOL_GPL(arm_smccc_get_soc_id_revision);
> >
> > +#ifdef CONFIG_ARM64
> > +static struct rsi_host_call uuid_hc;
> > +static DEFINE_SPINLOCK(uuid_hc_lock);
> 
> So evidently Sashiko is wrong in saying that struct rsi_host_call must be
> in decrypted memory?

Yes, Sashiko is wrong. The RMM spec clearly states that the rsi_host_call
struct must be encrypted / "protected". The other two requirements are
256 aligned and not RIPAS_EMPTY.