On 05.01.2012, at 10:07, Liu Yu wrote:
> And add a new flag definition in kvm_ppc_pvinfo to indicate
> whether host support EV_IDLE hcall.
>
> Signed-off-by: Liu Yu <yu.liu@xxxxxxxxxxxxx>
> ---
> v2:
> 1. instead of adding new field in kvm_ppc_pvinfo, use flags.
> 2. expose hcall definitions to userspace
>
> arch/powerpc/include/asm/kvm_para.h | 14 ++++++++++++--
> arch/powerpc/kvm/powerpc.c | 8 ++++++++
> include/linux/kvm.h | 2 ++
> 3 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
> index 50533f9..e8632b6 100644
> --- a/arch/powerpc/include/asm/kvm_para.h
> +++ b/arch/powerpc/include/asm/kvm_para.h
> @@ -41,9 +41,19 @@ struct kvm_vcpu_arch_shared {
> };
>
> #define KVM_SC_MAGIC_R0 0x4b564d21 /* "KVM!" */
> -#define HC_VENDOR_KVM (42 << 16)
> +
> +#include <asm/epapr_hcalls.h>
> +
> +/* ePAPR Hypercall Vendor ID */
> +#define HC_VENDOR_EPAPR (EV_EPAPR_VENDOR_ID << 16)
> +#define HC_VENDOR_KVM (EV_KVM_VENDOR_ID << 16)
> +
> +/* ePAPR Hypercall Token */
> +#define HC_EV_IDLE EV_IDLE
> +
> +/* ePAPR Hypercall Return Codes */
> #define HC_EV_SUCCESS 0
> -#define HC_EV_UNIMPLEMENTED 12
> +#define HC_EV_UNIMPLEMENTED EV_UNIMPLEMENTED
>
> #define KVM_FEATURE_MAGIC_PAGE 1
>
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index c33f6a7..1242ee1 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -81,6 +81,10 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
>
> /* Second return value is in r4 */
> break;
> + case HC_VENDOR_EPAPR | HC_EV_IDLE:
> + r = HC_EV_SUCCESS;
> + kvm_vcpu_block(vcpu);
Hrm. This will return on signal. So if the guest sends an idle hcall, then user space gets a random signal, we'll continue executing the guest CPU, getting us out of idle even though the guest didn't expect it, since the guest really wants to get an interrupt after the idle hcall.
Maybe we should just set the MSR_WE bit, so we'll get back into wait state on next vcpu_run? But then again that's guest visible, so I suppose a separate flag would be better.
Alex
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