Re: [PATCH 10/18] KVM: PPC: Book3S HV: Set process table for HPT guests on POWER9

[Paul Mackerras <paulus@ozlabs.org>]

On Mon, Jan 23, 2017 at 01:39:27PM +1100, Suraj Jitindar Singh wrote:
> On Thu, 2017-01-12 at 20:07 +1100, Paul Mackerras wrote:
> > This adds the implementation of the KVM_PPC_CONFIGURE_V3_MMU ioctl
> > for HPT guests on POWER9.  With this, we can return 1 for the
> > KVM_CAP_PPC_MMU_HASH_V3 capability.
> > 
> > Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
> > ---
> >  arch/powerpc/include/asm/kvm_host.h |  1 +
> >  arch/powerpc/kvm/book3s_hv.c        | 35
> > +++++++++++++++++++++++++++++++----
> >  arch/powerpc/kvm/powerpc.c          |  2 +-
> >  3 files changed, 33 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/powerpc/include/asm/kvm_host.h
> > b/arch/powerpc/include/asm/kvm_host.h
> > index e59b172..944532d 100644
> > --- a/arch/powerpc/include/asm/kvm_host.h
> > +++ b/arch/powerpc/include/asm/kvm_host.h
> > @@ -264,6 +264,7 @@ struct kvm_arch {
> >  	atomic_t hpte_mod_interest;
> >  	cpumask_t need_tlb_flush;
> >  	int hpt_cma_alloc;
> > +	u64 process_table;
> >  	struct dentry *debugfs_dir;
> >  	struct dentry *htab_dentry;
> >  #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
> > diff --git a/arch/powerpc/kvm/book3s_hv.c
> > b/arch/powerpc/kvm/book3s_hv.c
> > index 1736f87..6bd0f4a 100644
> > --- a/arch/powerpc/kvm/book3s_hv.c
> > +++ b/arch/powerpc/kvm/book3s_hv.c
> > @@ -3092,8 +3092,8 @@ static void kvmppc_setup_partition_table(struct
> > kvm *kvm)
> >  	/* HTABSIZE and HTABORG fields */
> >  	dw0 |= kvm->arch.sdr1;
> >  
> > -	/* Second dword has GR=0; other fields are unused since
> > UPRT=0 */
> > -	dw1 = 0;
> > +	/* Second dword as set by userspace */
> > +	dw1 = kvm->arch.process_table;
> >  
> >  	mmu_partition_table_set_entry(kvm->arch.lpid, dw0, dw1);
> >  }
> > @@ -3658,10 +3658,37 @@ static void init_default_hcalls(void)
> >  	}
> >  }
> >  
> > -/* dummy implementations for now */
> >  static int kvmhv_configure_mmu(struct kvm *kvm, struct
> > kvm_ppc_mmuv3_cfg *cfg)
> >  {
> > -	return -EINVAL;
> > +	unsigned long lpcr;
> > +
> > +	/* If not on a POWER9, reject it */
> > +	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> > +		return -ENODEV;
> > +
> > +	/* If any unknown flags set, reject it */
> > +	if (cfg->flags & ~(KVM_PPC_MMUV3_RADIX |
> > KVM_PPC_MMUV3_GTSE))
> > +		return -EINVAL;
> > +
> > +	/* We can't do radix yet */
> > +	if (cfg->flags & KVM_PPC_MMUV3_RADIX)
> > +		return -EINVAL;
> > +
> > +	/* GR (guest radix) bit in process_table field must match */
> > +	if (cfg->process_table & PATB_GR)
> > +		return -EINVAL;
> > +
> > +	/* Process table size field must be reasonable, i.e. <= 24
> > */
> > +	if ((cfg->process_table & PRTS_MASK) > 24)
> > +		return -EINVAL;
> > +
> > +	kvm->arch.process_table = cfg->process_table;
> > +	kvmppc_setup_partition_table(kvm);
> > +
> > +	lpcr = (cfg->flags & KVM_PPC_MMUV3_GTSE) ? LPCR_GTSE : 0;
> > +	kvmppc_update_lpcr(kvm, lpcr, LPCR_GTSE);
> > +
> > +	return 0;
> >  }
> >  
> >  static int kvmhv_get_rmmu_info(struct kvm *kvm, struct
> > kvm_ppc_rmmu_info *info)
> > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> > index 38c0d15..1476a48 100644
> > --- a/arch/powerpc/kvm/powerpc.c
> > +++ b/arch/powerpc/kvm/powerpc.c
> > @@ -569,7 +569,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm,
> > long ext)
> >  		r = !!(0 && hv_enabled && radix_enabled());
> >  		break;
> >  	case KVM_CAP_PPC_MMU_HASH_V3:
> > -		r = !!(0 && hv_enabled && !radix_enabled() &&
> > +		r = !!(hv_enabled && !radix_enabled() &&
> Just because we have radix enabled, is it correct to preclude a hash
> guest from running? Isn't it the case that we may have support for
> radix but a guest choose to run in hash mode (for what ever reason)?

At the moment it is correct, because we don't (yet) have the code to
switch to hash mode when entering a guest and switch back to radix
mode on exit.

Paul.