On Wed, 2017-11-22 at 14:41 +1100, Paul Mackerras wrote:
> From a038eb6fa13cc49cc91e6e81409c230ef8086038 Mon Sep 17 00:00:00
> 2001
> From: Paul Mackerras <paulus@xxxxxxxxxx>
> Date: Wed, 22 Nov 2017 14:38:53 +1100
> Subject:
>
> This fixes two errors that prevent a guest using the HPT MMU from
> successfully migrating to a POWER9 host in radix MMU mode, or
> resizing
> its HPT when running on a radix host.
>
> The first bug was that commit 8dc6cca556e4 ("KVM: PPC: Book3S HV:
> Don't rely on host's page size information", 2017-09-11) missed two
> uses of hpte_base_page_size(), one in the HPT rehashing code and
> one in kvm_htab_write() (which is used on the destination side in
> migrating a HPT guest). Instead we use
> kvmppc_hpte_base_page_shift().
> Having the shift count means that we can use left and right shifts
> instead of multiplication and division in a few places.
>
> Along the way, this adds a check in kvm_htab_write() to ensure that
> the
> page size encoding in the incoming HPTEs is recognized, and if not
> return an EINVAL error to userspace.
>
> The second bug was that kvm_htab_write was performing some but not
> all
> of the functions of kvmhv_setup_mmu(), resulting in the destination
> VM
> being left in radix mode as far as the hardware is concerned. The
> simplest fix for now is make kvm_htab_write() call
> kvmppc_setup_partition_table() like kvmppc_hv_setup_htab_rma() does.
> In future it would be better to refactor the code more extensively
> to remove the duplication.
>
> Fixes: 8dc6cca556e4 ("KVM: PPC: Book3S HV: Don't rely on host's page
> size information")
> Fixes: 7a84084c6054 ("KVM: PPC: Book3S HV: Set partition table rather
> than SDR1 on POWER9")
> Reported-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Tested-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> ---
> arch/powerpc/include/asm/kvm_ppc.h | 1 +
> arch/powerpc/kvm/book3s_64_mmu_hv.c | 37 +++++++++++++++++++++++--
> ------------
> arch/powerpc/kvm/book3s_hv.c | 3 +--
> 3 files changed, 25 insertions(+), 16 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h
> b/arch/powerpc/include/asm/kvm_ppc.h
> index 96753f3..941c2a3 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -180,6 +180,7 @@ extern void
> kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
> struct iommu_group *grp);
> extern int kvmppc_switch_mmu_to_hpt(struct kvm *kvm);
> extern int kvmppc_switch_mmu_to_radix(struct kvm *kvm);
> +extern void kvmppc_setup_partition_table(struct kvm *kvm);
>
> extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
> struct kvm_create_spapr_tce_64
> *args);
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index 235319c..9660972 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -1238,8 +1238,9 @@ static unsigned long
> resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize,
> unsigned long vpte, rpte, guest_rpte;
> int ret;
> struct revmap_entry *rev;
> - unsigned long apsize, psize, avpn, pteg, hash;
> + unsigned long apsize, avpn, pteg, hash;
> unsigned long new_idx, new_pteg, replace_vpte;
> + int pshift;
>
> hptep = (__be64 *)(old->virt + (idx << 4));
>
> @@ -1298,8 +1299,8 @@ static unsigned long
> resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize,
> goto out;
>
> rpte = be64_to_cpu(hptep[1]);
> - psize = hpte_base_page_size(vpte, rpte);
> - avpn = HPTE_V_AVPN_VAL(vpte) & ~((psize - 1) >> 23);
> + pshift = kvmppc_hpte_base_page_shift(vpte, rpte);
> + avpn = HPTE_V_AVPN_VAL(vpte) & ~(((1ul << pshift) - 1) >>
> 23);
> pteg = idx / HPTES_PER_GROUP;
> if (vpte & HPTE_V_SECONDARY)
> pteg = ~pteg;
> @@ -1311,20 +1312,20 @@ static unsigned long
> resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize,
> offset = (avpn & 0x1f) << 23;
> vsid = avpn >> 5;
> /* We can find more bits from the pteg value */
> - if (psize < (1ULL << 23))
> - offset |= ((vsid ^ pteg) & old_hash_mask) *
> psize;
> + if (pshift < 23)
> + offset |= ((vsid ^ pteg) & old_hash_mask) <<
> pshift;
>
> - hash = vsid ^ (offset / psize);
> + hash = vsid ^ (offset >> pshift);
> } else {
> unsigned long offset, vsid;
>
> /* We only have 40 - 23 bits of seg_off in avpn */
> offset = (avpn & 0x1ffff) << 23;
> vsid = avpn >> 17;
> - if (psize < (1ULL << 23))
> - offset |= ((vsid ^ (vsid << 25) ^ pteg) &
> old_hash_mask) * psize;
> + if (pshift < 23)
> + offset |= ((vsid ^ (vsid << 25) ^ pteg) &
> old_hash_mask) << pshift;
>
> - hash = vsid ^ (vsid << 25) ^ (offset / psize);
> + hash = vsid ^ (vsid << 25) ^ (offset >> pshift);
> }
>
> new_pteg = hash & new_hash_mask;
> @@ -1801,6 +1802,7 @@ static ssize_t kvm_htab_write(struct file
> *file, const char __user *buf,
> ssize_t nb;
> long int err, ret;
> int mmu_ready;
> + int pshift;
>
> if (!access_ok(VERIFY_READ, buf, count))
> return -EFAULT;
> @@ -1855,6 +1857,9 @@ static ssize_t kvm_htab_write(struct file
> *file, const char __user *buf,
> err = -EINVAL;
> if (!(v & HPTE_V_VALID))
> goto out;
> + pshift = kvmppc_hpte_base_page_shift(v, r);
> + if (pshift <= 0)
> + goto out;
> lbuf += 2;
> nb += HPTE_SIZE;
>
> @@ -1869,14 +1874,18 @@ static ssize_t kvm_htab_write(struct file
> *file, const char __user *buf,
> goto out;
> }
> if (!mmu_ready && is_vrma_hpte(v)) {
> - unsigned long psize =
> hpte_base_page_size(v, r);
> - unsigned long senc =
> slb_pgsize_encoding(psize);
> - unsigned long lpcr;
> + unsigned long senc, lpcr;
>
> + senc = slb_pgsize_encoding(1ul <<
> pshift);
> kvm->arch.vrma_slb_v = senc |
> SLB_VSID_B_1T |
> (VRMA_VSID <<
> SLB_VSID_SHIFT_1T);
> - lpcr = senc << (LPCR_VRMASD_SH - 4);
> - kvmppc_update_lpcr(kvm, lpcr,
> LPCR_VRMASD);
> + if
> (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> + lpcr = senc <<
> (LPCR_VRMASD_SH - 4);
> + kvmppc_update_lpcr(kvm,
> lpcr,
> + LPCR_VRMA
> SD);
> + } else {
> + kvmppc_setup_partition_table
> (kvm);
> + }
> mmu_ready = 1;
> }
> ++i;
> diff --git a/arch/powerpc/kvm/book3s_hv.c
> b/arch/powerpc/kvm/book3s_hv.c
> index 79ea3d9..2d46037 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -120,7 +120,6 @@ MODULE_PARM_DESC(h_ipi_redirect, "Redirect H_IPI
> wakeup to a free host core");
>
> static void kvmppc_end_cede(struct kvm_vcpu *vcpu);
> static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu);
> -static void kvmppc_setup_partition_table(struct kvm *kvm);
>
> static inline struct kvm_vcpu *next_runnable_thread(struct
> kvmppc_vcore *vc,
> int *ip)
> @@ -3574,7 +3573,7 @@ static void kvmppc_mmu_destroy_hv(struct
> kvm_vcpu *vcpu)
> return;
> }
>
> -static void kvmppc_setup_partition_table(struct kvm *kvm)
> +void kvmppc_setup_partition_table(struct kvm *kvm)
> {
> unsigned long dw0, dw1;
>
--
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