On Wed, 17 May 2023 19:38:14 +0100, Oliver Upton <oliver.upton@xxxxxxxxx> wrote: > > Hi Salil, > > On Wed, May 17, 2023 at 06:00:18PM +0000, Salil Mehta wrote: > > [...] > > > > > Should we expose the ESR, or at least ESR_EL2.IL as an additional > > > > flag? > > > > > > I think we would need "Immediate value" of the ESR_EL2 register in the > > user-space/VMM to be able to construct the syndrome value. I cannot see > > where it is being sent? > > The immediate value is not exposed to userspace, although by definition > the immediate value must be zero. The SMCCC spec requires all compliant > calls to use an immediate of zero (DEN0028E 2.9). > > Is there a legitimate use case for hypercalls with a nonzero immediate? > They would no longer be considered SMCCC calls at that point, so they > wouldn't work with the new UAPI. I agree. The use of non-zero immediate has long been deprecated. I guess we should actually reject non-zero immediate for HVC just like we do for SMC. If there is an actual need for a non-zero immediate to be propagated to userspace (want to emulate Xen's infamous 'HVC #0xEA1'?), then this should be an extension to the current API. Thanks, M. -- Without deviation from the norm, progress is not possible.
