On 11/03/2015 15:44, James Hogan wrote: > Now that the code is in place for KVM to support MIPS SIMD Architecutre > (MSA) in MIPS guests, wire up the new KVM_CAP_MIPS_MSA capability. > > For backwards compatibility, the capability must be explicitly enabled > in order to detect or make use of MSA from the guest. > > The capability is not supported if the hardware supports MSA vector > partitioning, since the extra support cannot be tested yet and it > extends the state that the userland program would have to save. > > Signed-off-by: James Hogan <[email protected]> > Cc: Paolo Bonzini <[email protected]> > Cc: Ralf Baechle <[email protected]> > Cc: Gleb Natapov <[email protected]> > Cc: Jonathan Corbet <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Signed-off-by: James Hogan <[email protected]> > --- > Documentation/virtual/kvm/api.txt | 12 ++++++++++++ > arch/mips/kvm/mips.c | 24 ++++++++++++++++++++++++ > include/uapi/linux/kvm.h | 1 + > 3 files changed, 37 insertions(+) > > diff --git a/Documentation/virtual/kvm/api.txt > b/Documentation/virtual/kvm/api.txt > index 47ddf0475211..97dd9ee69ca8 100644 > --- a/Documentation/virtual/kvm/api.txt > +++ b/Documentation/virtual/kvm/api.txt > @@ -3224,6 +3224,18 @@ done the KVM_REG_MIPS_FPR_* and KVM_REG_MIPS_FCR_* > registers can be accessed > Config5.FRE bits are accessible via the KVM API and also from the guest, > depending on them being supported by the FPU. > > +6.10 KVM_CAP_MIPS_MSA > + > +Architectures: mips > +Target: vcpu > +Parameters: args[0] is reserved for future use (should be 0). > + > +This capability allows the use of the MIPS SIMD Architecture (MSA) by the > guest. > +It allows the Config3.MSAP bit to be set to enable the use of MSA by the > guest. > +Once this is done the KVM_REG_MIPS_VEC_* and KVM_REG_MIPS_MSA_* registers > can be > +accessed, and the Config5.MSAEn bit is accessible via the KVM API and also > from > +the guest. > + > 7. Capabilities that can be enabled on VMs > ------------------------------------------ > > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c > index 9319c4360285..3b3530f493eb 100644 > --- a/arch/mips/kvm/mips.c > +++ b/arch/mips/kvm/mips.c > @@ -880,6 +880,15 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu > *vcpu, > return -EINVAL; > vcpu->arch.fpu_enabled = true; > break; > + case KVM_CAP_MIPS_MSA: > + /* > + * MSA vector partitioning not supported, > + * see kvm_vm_ioctl_check_extension(). > + */ > + if (!cpu_has_msa || boot_cpu_data.msa_id & MSA_IR_WRPF) > + return -EINVAL;
Perhaps you can call kvm_vm_ioctl_check_extension directly, outside the switch (it's okay if it's called for a capability other than FPU and MSA)? Apart from this nit, Acked-by: Paolo Bonzini <[email protected]> Paolo > + vcpu->arch.msa_enabled = true; > + break; > default: > r = -EINVAL; > break; > @@ -1071,6 +1080,21 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long > ext) > case KVM_CAP_MIPS_FPU: > r = !!cpu_has_fpu; > break; > + case KVM_CAP_MIPS_MSA: > + /* > + * We don't support MSA vector partitioning yet: > + * 1) It would require explicit support which can't be tested > + * yet due to lack of support in current hardware. > + * 2) It extends the state that would need to be saved/restored > + * by e.g. QEMU for migration. > + * > + * When vector partitioning hardware becomes available, support > + * could be added by requiring a flag when enabling > + * KVM_CAP_MIPS_MSA capability to indicate that userland knows > + * to save/restore the appropriate extra state. > + */ > + r = cpu_has_msa && !(boot_cpu_data.msa_id & MSA_IR_WRPF); > + break; > default: > r = 0; > break; > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index 98f6e5c653ff..5f859888e3ad 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -761,6 +761,7 @@ struct kvm_ppc_smmu_info { > #define KVM_CAP_CHECK_EXTENSION_VM 105 > #define KVM_CAP_S390_USER_SIGP 106 > #define KVM_CAP_MIPS_FPU 107 > +#define KVM_CAP_MIPS_MSA 108 > > #ifdef KVM_CAP_IRQ_ROUTING > > -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
