KVM: PPC: Book3S HV: Make the guest hash table size configurable

This adds a new ioctl to enable userspace to control the size of the guest
hashed page table (HPT) and to clear it out when resetting the guest.
The KVM_PPC_ALLOCATE_HTAB ioctl is a VM ioctl and takes as its parameter
a pointer to a u32 containing the desired order of the HPT (log base 2
of the size in bytes), which is updated on successful return to the
actual order of the HPT which was allocated.

There must be no vcpus running at the time of this ioctl.  To enforce
this, we now keep a count of the number of vcpus running in
kvm->arch.vcpus_running.

If the ioctl is called when a HPT has already been allocated, we don't
reallocate the HPT but just clear it out.  We first clear the
kvm->arch.rma_setup_done flag, which has two effects: (a) since we hold
the kvm->lock mutex, it will prevent any vcpus from starting to run until
we're done, and (b) it means that the first vcpu to run after we're done
will re-establish the VRMA if necessary.

If userspace doesn't call this ioctl before running the first vcpu, the
kernel will allocate a default-sized HPT at that point.  We do it then
rather than when creating the VM, as the code did previously, so that
userspace has a chance to do the ioctl if it wants.

When allocating the HPT, we can allocate either from the kernel page
allocator, or from the preallocated pool.  If userspace is asking for
a different size from the preallocated HPTs, we first try to allocate
using the kernel page allocator.  Then we try to allocate from the
preallocated pool, and then if that fails, we try allocating decreasing
sizes from the kernel page allocator, down to the minimum size allowed
(256kB).  Note that the kernel page allocator limits allocations to
1 << CONFIG_FORCE_MAX_ZONEORDER pages, which by default corresponds to
16MB (on 64-bit powerpc, at least).

Signed-off-by: Paul Mackerras <paulus@samba.org>
[agraf: fix module compilation]
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 8 insertions, 7 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index cec4daddbf31..5c70d19494f9 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -237,7 +237,7 @@ long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 
 	/* Find and lock the HPTEG slot to use */
  do_insert:
-	if (pte_index >= HPT_NPTE)
+	if (pte_index >= kvm->arch.hpt_npte)
 		return H_PARAMETER;
 	if (likely((flags & H_EXACT) == 0)) {
 		pte_index &= ~7UL;
@@ -352,7 +352,7 @@ long kvmppc_h_remove(struct kvm_vcpu *vcpu, unsigned long flags,
 	unsigned long v, r, rb;
 	struct revmap_entry *rev;
 
-	if (pte_index >= HPT_NPTE)
+	if (pte_index >= kvm->arch.hpt_npte)
 		return H_PARAMETER;
 	hpte = (unsigned long *)(kvm->arch.hpt_virt + (pte_index << 4));
 	while (!try_lock_hpte(hpte, HPTE_V_HVLOCK))
@@ -419,7 +419,8 @@ long kvmppc_h_bulk_remove(struct kvm_vcpu *vcpu)
 				i = 4;
 				break;
 			}
-			if (req != 1 || flags == 3 || pte_index >= HPT_NPTE) {
+			if (req != 1 || flags == 3 ||
+			    pte_index >= kvm->arch.hpt_npte) {
 				/* parameter error */
 				args[j] = ((0xa0 | flags) << 56) + pte_index;
 				ret = H_PARAMETER;
@@ -521,7 +522,7 @@ long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsigned long flags,
 	struct revmap_entry *rev;
 	unsigned long v, r, rb, mask, bits;
 
-	if (pte_index >= HPT_NPTE)
+	if (pte_index >= kvm->arch.hpt_npte)
 		return H_PARAMETER;
 
 	hpte = (unsigned long *)(kvm->arch.hpt_virt + (pte_index << 4));
@@ -583,7 +584,7 @@ long kvmppc_h_read(struct kvm_vcpu *vcpu, unsigned long flags,
 	int i, n = 1;
 	struct revmap_entry *rev = NULL;
 
-	if (pte_index >= HPT_NPTE)
+	if (pte_index >= kvm->arch.hpt_npte)
 		return H_PARAMETER;
 	if (flags & H_READ_4) {
 		pte_index &= ~3;
@@ -678,7 +679,7 @@ long kvmppc_hv_find_lock_hpte(struct kvm *kvm, gva_t eaddr, unsigned long slb_v,
 		somask = (1UL << 28) - 1;
 		vsid = (slb_v & ~SLB_VSID_B) >> SLB_VSID_SHIFT;
 	}
-	hash = (vsid ^ ((eaddr & somask) >> pshift)) & HPT_HASH_MASK;
+	hash = (vsid ^ ((eaddr & somask) >> pshift)) & kvm->arch.hpt_mask;
 	avpn = slb_v & ~(somask >> 16);	/* also includes B */
 	avpn |= (eaddr & somask) >> 16;
 
@@ -723,7 +724,7 @@ long kvmppc_hv_find_lock_hpte(struct kvm *kvm, gva_t eaddr, unsigned long slb_v,
 		if (val & HPTE_V_SECONDARY)
 			break;
 		val |= HPTE_V_SECONDARY;
-		hash = hash ^ HPT_HASH_MASK;
+		hash = hash ^ kvm->arch.hpt_mask;
 	}
 	return -1;
 }