On Mon, Oct 08, 2018 at 04:31:19PM +1100, Paul Mackerras wrote:
> This adds a KVM_PPC_NO_HASH flag to the flags field of the
> kvm_ppc_smmu_info struct, and arranges for it to be set when
> running as a nested hypervisor, as an unambiguous indication
> to userspace that HPT guests are not supported. Reporting the
> KVM_CAP_PPC_MMU_HASH_V3 capability as false could be taken as
> indicating only that the new HPT features in ISA V3.0 are not
> supported, leaving it ambiguous whether pre-V3.0 HPT features
> are supported.
>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> Documentation/virtual/kvm/api.txt | 4 ++++
> arch/powerpc/kvm/book3s_hv.c | 4 ++++
> include/uapi/linux/kvm.h | 1 +
> 3 files changed, 9 insertions(+)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index fde48b6..df98b63 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2270,6 +2270,10 @@ The supported flags are:
> The emulated MMU supports 1T segments in addition to the
> standard 256M ones.
>
> + - KVM_PPC_NO_HASH
> + This flag indicates that HPT guests are not supported by KVM,
> + thus all guests must use radix MMU mode.
> +
> The "slb_size" field indicates how many SLB entries are supported
>
> The "sps" array contains 8 entries indicating the supported base
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index fa61647..f565403 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -4245,6 +4245,10 @@ static int kvm_vm_ioctl_get_smmu_info_hv(struct kvm *kvm,
> kvmppc_add_seg_page_size(&sps, 16, SLB_VSID_L | SLB_VSID_LP_01);
> kvmppc_add_seg_page_size(&sps, 24, SLB_VSID_L);
>
> + /* If running as a nested hypervisor, we don't support HPT guests */
> + if (kvmhv_on_pseries())
> + info->flags |= KVM_PPC_NO_HASH;
> +
> return 0;
> }
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index d9cec6b..7f2ff3a 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -719,6 +719,7 @@ struct kvm_ppc_one_seg_page_size {
>
> #define KVM_PPC_PAGE_SIZES_REAL 0x00000001
> #define KVM_PPC_1T_SEGMENTS 0x00000002
> +#define KVM_PPC_NO_HASH 0x00000004
>
> struct kvm_ppc_smmu_info {
> __u64 flags;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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