Re: [PATCH v2 2/8] ArmPkg: PCD to select conduit for monitor calls

["Leif Lindholm" <leif@nuviainc.com>]

On Wed, Nov 24, 2021 at 14:03:51 +0100, Ard Biesheuvel wrote:
> On Wed, 24 Nov 2021 at 13:07, Leif Lindholm <leif@nuviainc.com> wrote:
> >
> > Ard - how does this interact with e.g. ArmVirtPsciResetSystemLib,
> > which reads its conduit out of the DT passed to it by QEMU?
> >
> 
> As long as ArmCallSmc() and ArmCallHvc() continue to exist and behave
> as before, I don't think those libraries are affected.

Well, I was thinking more that you can now end up with a firmware
build where the conduit is sometimes dynamically determined, and
sometimes compile-time determined.

/
    Leif

> > On Tue, Nov 16, 2021 at 11:32:54 +0000, Sami Mujawar wrote:
> > > Bugzilla: 3668 (https://bugzilla.tianocore.org/show_bug.cgi?id=3668)
> > >
> > > Define a PCD 'PcdMonitorConduitHvc' to select the conduit to use for
> > > monitor calls. PcdMonitorConduitHvc is defined as FALSE by default,
> > > meaning the SMC conduit is enabled as default.
> > >
> > > Adding PcdMonitorConduitHvc allows selection of HVC conduit to be used
> > > by virtual firmware implementations.
> > >
> > > Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> > > ---
> > >
> > > Notes:
> > >     v2:
> > >      - No code change since v1. Re-sending with V2 series.   [SAMI]
> > >
> > >  ArmPkg/ArmPkg.dec | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > >
> > > diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
> > > index 9da1bbc9f2166dc8ae93f96a34d3165fffed34dc..9a53888ae52f00eec50e631cf1bfcacecf8bba87 100644
> > > --- a/ArmPkg/ArmPkg.dec
> > > +++ b/ArmPkg/ArmPkg.dec
> > > @@ -132,6 +132,11 @@ [PcdsFeatureFlag.common]
> > >    # Define if the GICv3 controller should use the GICv2 legacy
> > >    gArmTokenSpaceGuid.PcdArmGicV3WithV2Legacy|FALSE|BOOLEAN|0x00000042
> > >
> > > +  ## Define the conduit to use for monitor calls.
> > > +  # Default PcdMonitorConduitHvc = FALSE, conduit = SMC
> > > +  # If PcdMonitorConduitHvc = TRUE, conduit = HVC
> > > +  gArmTokenSpaceGuid.PcdMonitorConduitHvc|FALSE|BOOLEAN|0x00000047
> > > +
> > >  [PcdsFeatureFlag.ARM]
> > >    # Whether to map normal memory as non-shareable. FALSE is the safe choice, but
> > >    # TRUE may be appropriate to fix performance problems if you don't care about
> > > --
> > > 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
> > >