On Sat, Feb 18, 2017 at 08:41:40AM +1100, Paul Mackerras wrote:
> The new HPT resizing code added in commit b5baa6877315 ("KVM: PPC:
> Book3S HV: KVM-HV HPT resizing implementation", 2016-12-20) doesn't
> have code to handle the new HPTE format which POWER9 uses. Thus it
> would be best not to advertise it to userspace on POWER9 systems
> until it works properly.
>
> Also, since resize_hpt_rehash_hpte() contains BUG_ON() calls that
> could be hit on POWER9, let's prevent it from being called on POWER9
> for now.
>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Acked-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
I probably would have put the check on entry to the prepare path,
rather than deep in the rehashing, but we need the fix one way or
another.
> ---
> arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++++++
> arch/powerpc/kvm/powerpc.c | 3 ++-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index b68b342..f3158fb 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -1370,6 +1370,12 @@ static int resize_hpt_rehash(struct kvm_resize_hpt *resize)
> unsigned long i;
> int rc;
>
> + /*
> + * resize_hpt_rehash_hpte() doesn't handle the new-format HPTEs
> + * that POWER9 uses, and could well hit a BUG_ON on POWER9.
> + */
> + if (cpu_has_feature(CPU_FTR_ARCH_300))
> + return -EIO;
> for (i = 0; i < kvmppc_hpt_npte(&kvm->arch.hpt); i++) {
> rc = resize_hpt_rehash_hpte(resize, i);
> if (rc != 0)
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 2b3e4e6..fcb253b 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -613,7 +613,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> r = 1;
> break;
> case KVM_CAP_SPAPR_RESIZE_HPT:
> - r = !!hv_enabled;
> + /* Disable this on POWER9 until code handles new HPTE format */
> + r = !!hv_enabled && !cpu_has_feature(CPU_FTR_ARCH_300);
> break;
> #endif
> case KVM_CAP_PPC_HTM:
--
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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