Re: [PATCH v14 3/5] KVM: arm64: Manage GCS access and registers for guests

On Sat, Oct 05, 2024 at 12:34:20PM +0100, Marc Zyngier wrote:

Mark Brown broonie@kernel.org wrote:

...

• if (!kvm_has_gcs(kvm)) {

• kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nGCS_EL0 |
  

• 				HFGxTR_EL2_nGCS_EL1);
  

• kvm->arch.fgu[HFGITR_GROUP] |= (HFGITR_EL2_nGCSEPP |
  

• 				HFGITR_EL2_nGCSSTR_EL1 |
  

• 				HFGITR_EL2_nGCSPUSHM_EL1);
  

Where is the handling of traps resulting of HFGITR_EL2.nGCSSTR_EL1?

These will trap with an EC of 0x2d which isn't known so I was expecting this to get handled in the same way as for example a return of false from kvm_hyp_handle_fpsimd() for SVE when unsupported, or for the simiarly unknown SME EC, currently. I gather from your comment that you're instead expecting to see an explicit exit handler for this EC that just injects the UNDEF directly?