On 15.07.2013, at 13:11, Bharat Bhushan wrote:

> Exit to guest user space if kvm does not implement the hcall.
> 
> Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
> ---
> arch/powerpc/kvm/booke.c   |   47 +++++++++++++++++++++++++++++++++++++------
> arch/powerpc/kvm/powerpc.c |    1 +
> include/uapi/linux/kvm.h   |    1 +
> 3 files changed, 42 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 17722d8..c8b41b4 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -1005,9 +1005,25 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
> kvm_vcpu *vcpu,
>               break;
> 
> #ifdef CONFIG_KVM_BOOKE_HV
> -     case BOOKE_INTERRUPT_HV_SYSCALL:
> +     case BOOKE_INTERRUPT_HV_SYSCALL: {

This is getting large. Please extract hcall handling into its own function. 
Maybe you can merge the HV and non-HV case then too.

> +             int i;
>               if (!(vcpu->arch.shared->msr & MSR_PR)) {
> -                     kvmppc_set_gpr(vcpu, 3, kvmppc_kvm_pv(vcpu));
> +                     r = kvmppc_kvm_pv(vcpu);
> +                     if (r != EV_UNIMPLEMENTED) {
> +                             /* except unimplemented return to guest */
> +                             kvmppc_set_gpr(vcpu, 3, r);
> +                             kvmppc_account_exit(vcpu, SYSCALL_EXITS);
> +                             r = RESUME_GUEST;
> +                             break;
> +                     }
> +                     /* Exit to userspace for unimplemented hcalls in kvm */
> +                     run->epapr_hcall.nr = kvmppc_get_gpr(vcpu, 11);
> +                     run->epapr_hcall.ret = 0;
> +                     for (i = 0; i < 8; i++)
> +                             run->epapr_hcall.args[i] = kvmppc_get_gpr(vcpu, 
> 3 + i);
> +                     vcpu->arch.hcall_needed = 1;
> +                     kvmppc_account_exit(vcpu, SYSCALL_EXITS);
> +                     r = RESUME_HOST;
>               } else {
>                       /*
>                        * hcall from guest userspace -- send privileged
> @@ -1016,22 +1032,39 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
> kvm_vcpu *vcpu,
>                       kvmppc_core_queue_program(vcpu, ESR_PPR);
>               }
> 
> -             r = RESUME_GUEST;
> +             run->exit_reason = KVM_EXIT_EPAPR_HCALL;

This looks odd. Your exit reason only changes when you do the hcall exiting, 
right?

You also need to guard user space hcall exits with an ENABLE_CAP. Otherwise 
older user space will break, as it doesn't know about the exit type yet.


Alex

>               break;
> +     }
> #else
> -     case BOOKE_INTERRUPT_SYSCALL:
> +     case BOOKE_INTERRUPT_SYSCALL: {
> +             int i;
> +             r = RESUME_GUEST;
>               if (!(vcpu->arch.shared->msr & MSR_PR) &&
>                   (((u32)kvmppc_get_gpr(vcpu, 0)) == KVM_SC_MAGIC_R0)) {
>                       /* KVM PV hypercalls */
> -                     kvmppc_set_gpr(vcpu, 3, kvmppc_kvm_pv(vcpu));
> -                     r = RESUME_GUEST;
> +                     r = kvmppc_kvm_pv(vcpu);
> +                     if (r != EV_UNIMPLEMENTED) {
> +                             /* except unimplemented return to guest */
> +                             kvmppc_set_gpr(vcpu, 3, r);
> +                             kvmppc_account_exit(vcpu, SYSCALL_EXITS);
> +                             r = RESUME_GUEST;
> +                             break;
> +                     }
> +                     /* Exit to userspace for unimplemented hcalls in kvm */
> +                     run->epapr_hcall.nr = kvmppc_get_gpr(vcpu, 11);
> +                     run->epapr_hcall.ret = 0;
> +                     for (i = 0; i < 8; i++)
> +                             run->epapr_hcall.args[i] = kvmppc_get_gpr(vcpu, 
> 3 + i);
> +                     vcpu->arch.hcall_needed = 1;
> +                     run->exit_reason = KVM_EXIT_EPAPR_HCALL;
> +                     r = RESUME_HOST;
>               } else {
>                       /* Guest syscalls */
>                       kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_SYSCALL);
>               }
>               kvmppc_account_exit(vcpu, SYSCALL_EXITS);
> -             r = RESUME_GUEST;
>               break;
> +     }
> #endif
> 
>       case BOOKE_INTERRUPT_DTLB_MISS: {
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 4e05f8c..6c6199d 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -307,6 +307,7 @@ int kvm_dev_ioctl_check_extension(long ext)
>       case KVM_CAP_PPC_BOOKE_SREGS:
>       case KVM_CAP_PPC_BOOKE_WATCHDOG:
>       case KVM_CAP_PPC_EPR:
> +     case KVM_CAP_EXIT_EPAPR_HCALL:
> #else
>       case KVM_CAP_PPC_SEGSTATE:
>       case KVM_CAP_PPC_HIOR:
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 01ee50e..b5266e5 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -674,6 +674,7 @@ struct kvm_ppc_smmu_info {
> #define KVM_CAP_PPC_RTAS 91
> #define KVM_CAP_IRQ_XICS 92
> #define KVM_CAP_ARM_EL1_32BIT 93
> +#define KVM_CAP_EXIT_EPAPR_HCALL 94
> 
> #ifdef KVM_CAP_IRQ_ROUTING
> 
> -- 
> 1.7.0.4
> 
> 
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