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Commit ded13fc1 authored by Paul Mackerras's avatar Paul Mackerras
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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 8dc6cca5 ("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: 8dc6cca5 ("KVM: PPC: Book3S HV: Don't rely on host's page size information")
Fixes: 7a84084c ("KVM: PPC: Book3S HV: Set partition table rather than SDR1 on POWER9")
Reported-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Tested-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent cf9b0772

arch/powerpc/include/asm/kvm_ppc.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -180,6 +180,7 @@ extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm, 
		struct iommu_group *grp);

		struct iommu_group *grp);

extern int kvmppc_switch_mmu_to_hpt(struct kvm *kvm);

extern int kvmppc_switch_mmu_to_hpt(struct kvm *kvm);

extern int kvmppc_switch_mmu_to_radix(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,

extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,

				struct kvm_create_spapr_tce_64 *args);

				struct kvm_create_spapr_tce_64 *args);

arch/powerpc/kvm/book3s_64_mmu_hv.c

+23 −14
Original line number Original line Diff line number Diff line
@@ -1238,8 +1238,9 @@ static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize, 
	unsigned long vpte, rpte, guest_rpte;

	unsigned long vpte, rpte, guest_rpte;

	int ret;

	int ret;

	struct revmap_entry *rev;

	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;

	unsigned long new_idx, new_pteg, replace_vpte;

	int pshift;





	hptep = (__be64 *)(old->virt + (idx << 4));

	hptep = (__be64 *)(old->virt + (idx << 4));
@@ -1298,8 +1299,8 @@ static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize, 
		goto out;

		goto out;





	rpte = be64_to_cpu(hptep[1]);

	rpte = be64_to_cpu(hptep[1]);

	psize = hpte_base_page_size(vpte, rpte);

	pshift = kvmppc_hpte_base_page_shift(vpte, rpte);

	avpn = HPTE_V_AVPN_VAL(vpte) & ~((psize - 1) >> 23);

	avpn = HPTE_V_AVPN_VAL(vpte) & ~(((1ul << pshift) - 1) >> 23);

	pteg = idx / HPTES_PER_GROUP;

	pteg = idx / HPTES_PER_GROUP;

	if (vpte & HPTE_V_SECONDARY)

	if (vpte & HPTE_V_SECONDARY)

		pteg = ~pteg;

		pteg = ~pteg;
@@ -1311,20 +1312,20 @@ static unsigned long resize_hpt_rehash_hpte(struct kvm_resize_hpt *resize, 
		offset = (avpn & 0x1f) << 23;

		offset = (avpn & 0x1f) << 23;

		vsid = avpn >> 5;

		vsid = avpn >> 5;

		/* We can find more bits from the pteg value */

		/* We can find more bits from the pteg value */

		if (psize < (1ULL << 23))

		if (pshift < 23)

			offset |= ((vsid ^ pteg) & old_hash_mask) * psize;

			offset |= ((vsid ^ pteg) & old_hash_mask) << pshift;





		hash = vsid ^ (offset / psize);

		hash = vsid ^ (offset >> pshift);

	} else {

	} else {

		unsigned long offset, vsid;

		unsigned long offset, vsid;





		/* We only have 40 - 23 bits of seg_off in avpn */

		/* We only have 40 - 23 bits of seg_off in avpn */

		offset = (avpn & 0x1ffff) << 23;

		offset = (avpn & 0x1ffff) << 23;

		vsid = avpn >> 17;

		vsid = avpn >> 17;

		if (psize < (1ULL << 23))

		if (pshift < 23)

			offset |= ((vsid ^ (vsid << 25) ^ pteg) & old_hash_mask) * psize;

			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;

	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;

	ssize_t nb;

	long int err, ret;

	long int err, ret;

	int mmu_ready;

	int mmu_ready;

	int pshift;





	if (!access_ok(VERIFY_READ, buf, count))

	if (!access_ok(VERIFY_READ, buf, count))

		return -EFAULT;

		return -EFAULT;
@@ -1855,6 +1857,9 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf, 
			err = -EINVAL;

			err = -EINVAL;

			if (!(v & HPTE_V_VALID))

			if (!(v & HPTE_V_VALID))

				goto out;

				goto out;

			pshift = kvmppc_hpte_base_page_shift(v, r);

			if (pshift <= 0)

				goto out;

			lbuf += 2;

			lbuf += 2;

			nb += HPTE_SIZE;

			nb += HPTE_SIZE;
@@ -1869,14 +1874,18 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf, 
				goto out;

				goto out;

			}

			}

			if (!mmu_ready && is_vrma_hpte(v)) {

			if (!mmu_ready && is_vrma_hpte(v)) {

				unsigned long psize = hpte_base_page_size(v, r);

				unsigned long senc, lpcr;

				unsigned long senc = slb_pgsize_encoding(psize);

				unsigned long lpcr;





				senc = slb_pgsize_encoding(1ul << pshift);

				kvm->arch.vrma_slb_v = senc | SLB_VSID_B_1T |

				kvm->arch.vrma_slb_v = senc | SLB_VSID_B_1T |

					(VRMA_VSID << SLB_VSID_SHIFT_1T);

					(VRMA_VSID << SLB_VSID_SHIFT_1T);

				if (!cpu_has_feature(CPU_FTR_ARCH_300)) {

					lpcr = senc << (LPCR_VRMASD_SH - 4);

					lpcr = senc << (LPCR_VRMASD_SH - 4);

				kvmppc_update_lpcr(kvm, lpcr, LPCR_VRMASD);

					kvmppc_update_lpcr(kvm, lpcr,

							   LPCR_VRMASD);

				} else {

					kvmppc_setup_partition_table(kvm);

				}

				mmu_ready = 1;

				mmu_ready = 1;

			}

			}

			++i;

			++i;

arch/powerpc/kvm/book3s_hv.c

+1 −2
Original line number Original line Diff line number Diff line
@@ -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 void kvmppc_end_cede(struct kvm_vcpu *vcpu);

static int kvmppc_hv_setup_htab_rma(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,

static inline struct kvm_vcpu *next_runnable_thread(struct kvmppc_vcore *vc,

		int *ip)

		int *ip)
@@ -3574,7 +3573,7 @@ static void kvmppc_mmu_destroy_hv(struct kvm_vcpu *vcpu) 
	return;

	return;

}

}





static void kvmppc_setup_partition_table(struct kvm *kvm)

void kvmppc_setup_partition_table(struct kvm *kvm)

{

{

	unsigned long dw0, dw1;

	unsigned long dw0, dw1;