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KVM: PPC: Book3S HV: KVM-HV HPT resizing implementation

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This adds the "guts" of the implementation for the HPT resizing PAPR
extension.  It has the code to allocate and clear a new HPT, rehash an
existing HPT's entries into it, and accomplish the switchover for a
KVM guest from the old HPT to the new one.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
David Gibson 2016-12-20 16:49:06 +11:00 committed by Paul Mackerras
parent 5e9859699a
commit b5baa68773
1 changed files with 187 additions and 1 deletions
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188
arch/powerpc/kvm/book3s_64_mmu_hv.c
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@ -66,6 +66,10 @@ struct kvm_resize_hpt {
/* These fields protected by kvm->lock */
int error;
bool prepare_done;
/* Private to the work thread, until prepare_done is true,
* then protected by kvm->resize_hpt_sem */
struct kvm_hpt_info hpt;
};
static void kvmppc_rmap_reset(struct kvm *kvm);
@ -1209,21 +1213,203 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa,
*/
static int resize_hpt_allocate(struct kvm_resize_hpt *resize)
{
int rc;
rc = kvmppc_allocate_hpt(&resize->hpt, resize->order);
if (rc < 0)
return rc;
resize_hpt_debug(resize, "resize_hpt_allocate(): HPT @ 0x%lx\n",
resize->hpt.virt);
return 0;
}
static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize,
unsigned long idx)
{
struct kvm *kvm = resize->kvm;
struct kvm_hpt_info *old = &kvm->arch.hpt;
struct kvm_hpt_info *new = &resize->hpt;
unsigned long old_hash_mask = (1ULL << (old->order - 7)) - 1;
unsigned long new_hash_mask = (1ULL << (new->order - 7)) - 1;
__be64 *hptep, *new_hptep;
unsigned long vpte, rpte, guest_rpte;
int ret;
struct revmap_entry *rev;
unsigned long apsize, psize, avpn, pteg, hash;
unsigned long new_idx, new_pteg, replace_vpte;
hptep = (__be64 *)(old->virt + (idx << 4));
/* Guest is stopped, so new HPTEs can't be added or faulted
* in, only unmapped or altered by host actions. So, it's
* safe to check this before we take the HPTE lock */
vpte = be64_to_cpu(hptep[0]);
if (!(vpte & HPTE_V_VALID) && !(vpte & HPTE_V_ABSENT))
return 0; /* nothing to do */
while (!try_lock_hpte(hptep, HPTE_V_HVLOCK))
cpu_relax();
vpte = be64_to_cpu(hptep[0]);
ret = 0;
if (!(vpte & HPTE_V_VALID) && !(vpte & HPTE_V_ABSENT))
/* Nothing to do */
goto out;
/* Unmap */
rev = &old->rev[idx];
guest_rpte = rev->guest_rpte;
ret = -EIO;
apsize = hpte_page_size(vpte, guest_rpte);
if (!apsize)
goto out;
if (vpte & HPTE_V_VALID) {
unsigned long gfn = hpte_rpn(guest_rpte, apsize);
int srcu_idx = srcu_read_lock(&kvm->srcu);
struct kvm_memory_slot *memslot =
__gfn_to_memslot(kvm_memslots(kvm), gfn);
if (memslot) {
unsigned long *rmapp;
rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn];
lock_rmap(rmapp);
kvmppc_unmap_hpte(kvm, idx, rmapp, gfn);
unlock_rmap(rmapp);
}
srcu_read_unlock(&kvm->srcu, srcu_idx);
}
/* Reload PTE after unmap */
vpte = be64_to_cpu(hptep[0]);
BUG_ON(vpte & HPTE_V_VALID);
BUG_ON(!(vpte & HPTE_V_ABSENT));
ret = 0;
if (!(vpte & HPTE_V_BOLTED))
goto out;
rpte = be64_to_cpu(hptep[1]);
psize = hpte_base_page_size(vpte, rpte);
avpn = HPTE_V_AVPN_VAL(vpte) & ~((psize - 1) >> 23);
pteg = idx / HPTES_PER_GROUP;
if (vpte & HPTE_V_SECONDARY)
pteg = ~pteg;
if (!(vpte & HPTE_V_1TB_SEG)) {
unsigned long offset, vsid;
/* We only have 28 - 23 bits of offset in avpn */
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;
hash = vsid ^ (offset / psize);
} 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;
hash = vsid ^ (vsid << 25) ^ (offset / psize);
}
new_pteg = hash & new_hash_mask;
if (vpte & HPTE_V_SECONDARY) {
BUG_ON(~pteg != (hash & old_hash_mask));
new_pteg = ~new_pteg;
} else {
BUG_ON(pteg != (hash & old_hash_mask));
}
new_idx = new_pteg * HPTES_PER_GROUP + (idx % HPTES_PER_GROUP);
new_hptep = (__be64 *)(new->virt + (new_idx << 4));
replace_vpte = be64_to_cpu(new_hptep[0]);
if (replace_vpte & (HPTE_V_VALID | HPTE_V_ABSENT)) {
BUG_ON(new->order >= old->order);
if (replace_vpte & HPTE_V_BOLTED) {
if (vpte & HPTE_V_BOLTED)
/* Bolted collision, nothing we can do */
ret = -ENOSPC;
/* Discard the new HPTE */
goto out;
}
/* Discard the previous HPTE */
}
new_hptep[1] = cpu_to_be64(rpte);
new->rev[new_idx].guest_rpte = guest_rpte;
/* No need for a barrier, since new HPT isn't active */
new_hptep[0] = cpu_to_be64(vpte);
unlock_hpte(new_hptep, vpte);
out:
unlock_hpte(hptep, vpte);
return ret;
}
static int resize_hpt_rehash(struct kvm_resize_hpt *resize)
{
return -EIO;
struct kvm *kvm = resize->kvm;
unsigned long i;
int rc;
for (i = 0; i < kvmppc_hpt_npte(&kvm->arch.hpt); i++) {
rc = resize_hpt_rehash_hpte(resize, i);
if (rc != 0)
return rc;
}
return 0;
}
static void resize_hpt_pivot(struct kvm_resize_hpt *resize)
{
struct kvm *kvm = resize->kvm;
struct kvm_hpt_info hpt_tmp;
/* Exchange the pending tables in the resize structure with
* the active tables */
resize_hpt_debug(resize, "resize_hpt_pivot()\n");
spin_lock(&kvm->mmu_lock);
asm volatile("ptesync" : : : "memory");
hpt_tmp = kvm->arch.hpt;
kvmppc_set_hpt(kvm, &resize->hpt);
resize->hpt = hpt_tmp;
spin_unlock(&kvm->mmu_lock);
synchronize_srcu_expedited(&kvm->srcu);
resize_hpt_debug(resize, "resize_hpt_pivot() done\n");
}
static void resize_hpt_release(struct kvm *kvm, struct kvm_resize_hpt *resize)
{
BUG_ON(kvm->arch.resize_hpt != resize);
if (resize->hpt.virt)
kvmppc_free_hpt(&resize->hpt);
kvm->arch.resize_hpt = NULL;
kfree(resize);
}