KVM: PPC: Book3S HV: Fix migration and HPT resizing of HPT guests on radix hosts

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@gmail.com>
Tested-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 96753f3..941c2a3 100644 (file)
--- 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 (file)
--- 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_VRMASD);
+                               } 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 (file)
--- 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;