Nicholas Piggin <npig...@gmail.com> writes:
> Rather than tie this to KVMPPC_NR_LPIDS which is becoming more dynamic,
> fix it to 4096 (12-bits) explicitly for now.
>
> kvmhv_get_nested() does not have to check against KVM_MAX_NESTED_GUESTS
> because the L1 partition table registration hcall already did that, and
> it checks against the partition table size.
>
> This patch also puts all the partition table size calculations into the
> same form, using 12 for the architected size field shift and 4 for the
> shift corresponding to the partition table entry size.
>
> Signed-of-by: Nicholas Piggin <npig...@gmail.com>
Reviewed-by: Fabiano Rosas <faro...@linux.ibm.com>
> ---
> arch/powerpc/include/asm/kvm_host.h | 7 ++++++-
> arch/powerpc/kvm/book3s_64_mmu_hv.c | 2 +-
> arch/powerpc/kvm/book3s_hv_nested.c | 24 +++++++++++-------------
> 3 files changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h
> b/arch/powerpc/include/asm/kvm_host.h
> index 5fd0564e5c94..e6fb03884dcc 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -34,7 +34,12 @@
> #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> #include <asm/kvm_book3s_asm.h> /* for MAX_SMT_THREADS */
> #define KVM_MAX_VCPU_IDS (MAX_SMT_THREADS * KVM_MAX_VCORES)
> -#define KVM_MAX_NESTED_GUESTS KVMPPC_NR_LPIDS
> +
> +/*
> + * Limit the nested partition table to 4096 entries (because that's what
> + * hardware supports). Both guest and host use this value.
> + */
> +#define KVM_MAX_NESTED_GUESTS_SHIFT 12
>
> #else
> #define KVM_MAX_VCPU_IDS KVM_MAX_VCPUS
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index 5be92d5bc099..f983fb36cbf2 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -266,7 +266,7 @@ int kvmppc_mmu_hv_init(void)
> return -EINVAL;
> nr_lpids = 1UL << mmu_lpid_bits;
> } else {
> - nr_lpids = KVM_MAX_NESTED_GUESTS;
> + nr_lpids = 1UL << KVM_MAX_NESTED_GUESTS_SHIFT;
> }
>
> if (nr_lpids > KVMPPC_NR_LPIDS)
> diff --git a/arch/powerpc/kvm/book3s_hv_nested.c
> b/arch/powerpc/kvm/book3s_hv_nested.c
> index 1eff969b095c..75169e0753ce 100644
> --- a/arch/powerpc/kvm/book3s_hv_nested.c
> +++ b/arch/powerpc/kvm/book3s_hv_nested.c
> @@ -439,10 +439,11 @@ long kvmhv_nested_init(void)
> if (!radix_enabled())
> return -ENODEV;
>
> - /* find log base 2 of KVMPPC_NR_LPIDS, rounding up */
> - ptb_order = __ilog2(KVMPPC_NR_LPIDS - 1) + 1;
> - if (ptb_order < 8)
> - ptb_order = 8;
> + /* Partition table entry is 1<<4 bytes in size, hence the 4. */
> + ptb_order = KVM_MAX_NESTED_GUESTS_SHIFT + 4;
> + /* Minimum partition table size is 1<<12 bytes */
> + if (ptb_order < 12)
> + ptb_order = 12;
> pseries_partition_tb = kmalloc(sizeof(struct patb_entry) << ptb_order,
> GFP_KERNEL);
> if (!pseries_partition_tb) {
> @@ -450,7 +451,7 @@ long kvmhv_nested_init(void)
> return -ENOMEM;
> }
>
> - ptcr = __pa(pseries_partition_tb) | (ptb_order - 8);
> + ptcr = __pa(pseries_partition_tb) | (ptb_order - 12);
> rc = plpar_hcall_norets(H_SET_PARTITION_TABLE, ptcr);
> if (rc != H_SUCCESS) {
> pr_err("kvm-hv: Parent hypervisor does not support nesting
> (rc=%ld)\n",
> @@ -534,16 +535,14 @@ long kvmhv_set_partition_table(struct kvm_vcpu *vcpu)
> long ret = H_SUCCESS;
>
> srcu_idx = srcu_read_lock(&kvm->srcu);
> - /*
> - * Limit the partition table to 4096 entries (because that's what
> - * hardware supports), and check the base address.
> - */
> - if ((ptcr & PRTS_MASK) > 12 - 8 ||
> + /* Check partition size and base address. */
> + if ((ptcr & PRTS_MASK) + 12 - 4 > KVM_MAX_NESTED_GUESTS_SHIFT ||
> !kvm_is_visible_gfn(vcpu->kvm, (ptcr & PRTB_MASK) >> PAGE_SHIFT))
> ret = H_PARAMETER;
> srcu_read_unlock(&kvm->srcu, srcu_idx);
> if (ret == H_SUCCESS)
> kvm->arch.l1_ptcr = ptcr;
> +
> return ret;
> }
>
> @@ -639,7 +638,7 @@ static void kvmhv_update_ptbl_cache(struct
> kvm_nested_guest *gp)
>
> ret = -EFAULT;
> ptbl_addr = (kvm->arch.l1_ptcr & PRTB_MASK) + (gp->l1_lpid << 4);
> - if (gp->l1_lpid < (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 8))) {
> + if (gp->l1_lpid < (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 12 - 4))) {
> int srcu_idx = srcu_read_lock(&kvm->srcu);
> ret = kvm_read_guest(kvm, ptbl_addr,
> &ptbl_entry, sizeof(ptbl_entry));
> @@ -809,8 +808,7 @@ struct kvm_nested_guest *kvmhv_get_nested(struct kvm
> *kvm, int l1_lpid,
> {
> struct kvm_nested_guest *gp, *newgp;
>
> - if (l1_lpid >= KVM_MAX_NESTED_GUESTS ||
> - l1_lpid >= (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 12 - 4)))
> + if (l1_lpid >= (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 12 - 4)))
> return NULL;
>
> spin_lock(&kvm->mmu_lock);
