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

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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 8dc6cca556 ("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: 8dc6cca556 ("KVM: PPC: Book3S HV: Don't rely on host's page size information")
Fixes: 7a84084c60 ("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>
This commit is contained in:
Paul Mackerras 2017-11-22 14:38:53 +11:00
parent cf9b0772f2
commit ded13fc11b
3 changed files with 25 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/powerpc/include/asm/kvm_ppc.h
View File

@ -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);

37
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -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;

3
arch/powerpc/kvm/book3s_hv.c
View File

@ -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;