[PATCH v5 1/7] kvmppc: HMM backend driver to manage pages of secure guest

[Bharata B Rao <bharata@linux.ibm.com>]

HMM driver for KVM PPC to manage page transitions of
secure guest via H_SVM_PAGE_IN and H_SVM_PAGE_OUT hcalls.

H_SVM_PAGE_IN: Move the content of a normal page to secure page
H_SVM_PAGE_OUT: Move the content of a secure page to normal page

Private ZONE_DEVICE memory equal to the amount of secure memory
available in the platform for running secure guests is created
via a HMM device. The movement of pages between normal and secure
memory is done by ->alloc_and_copy() callback routine of migrate_vma().

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h         |   4 +
 arch/powerpc/include/asm/kvm_book3s_hmm.h |  29 ++
 arch/powerpc/include/asm/kvm_host.h       |  12 +
 arch/powerpc/include/asm/ultravisor-api.h |   2 +
 arch/powerpc/include/asm/ultravisor.h     |  17 +
 arch/powerpc/kvm/Makefile                 |   3 +
 arch/powerpc/kvm/book3s_hv.c              |  19 +
 arch/powerpc/kvm/book3s_hv_hmm.c          | 482 ++++++++++++++++++++++
 8 files changed, 568 insertions(+)
 create mode 100644 arch/powerpc/include/asm/kvm_book3s_hmm.h
 create mode 100644 arch/powerpc/kvm/book3s_hv_hmm.c

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 463c63a9fcf1..2f6b952deb0f 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -337,6 +337,10 @@
 #define H_TLB_INVALIDATE	0xF808
 #define H_COPY_TOFROM_GUEST	0xF80C
 
+/* Platform-specific hcalls used by the Ultravisor */
+#define H_SVM_PAGE_IN		0xEF00
+#define H_SVM_PAGE_OUT		0xEF04
+
 /* Values for 2nd argument to H_SET_MODE */
 #define H_SET_MODE_RESOURCE_SET_CIABR		1
 #define H_SET_MODE_RESOURCE_SET_DAWR		2
diff --git a/arch/powerpc/include/asm/kvm_book3s_hmm.h b/arch/powerpc/include/asm/kvm_book3s_hmm.h
new file mode 100644
index 000000000000..21f3de5f2acb
--- /dev/null
+++ b/arch/powerpc/include/asm/kvm_book3s_hmm.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __POWERPC_KVM_PPC_HMM_H__
+#define __POWERPC_KVM_PPC_HMM_H__
+
+#ifdef CONFIG_PPC_UV
+extern unsigned long kvmppc_h_svm_page_in(struct kvm *kvm,
+					  unsigned long gra,
+					  unsigned long flags,
+					  unsigned long page_shift);
+extern unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
+					  unsigned long gra,
+					  unsigned long flags,
+					  unsigned long page_shift);
+#else
+static inline unsigned long
+kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gra,
+		     unsigned long flags, unsigned long page_shift)
+{
+	return H_UNSUPPORTED;
+}
+
+static inline unsigned long
+kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gra,
+		      unsigned long flags, unsigned long page_shift)
+{
+	return H_UNSUPPORTED;
+}
+#endif /* CONFIG_PPC_UV */
+#endif /* __POWERPC_KVM_PPC_HMM_H__ */
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 184becb62ea4..ac1a101beb07 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -858,4 +858,16 @@ static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
+#ifdef CONFIG_PPC_UV
+extern int kvmppc_hmm_init(void);
+extern void kvmppc_hmm_free(void);
+#else
+static inline int kvmppc_hmm_init(void)
+{
+	return 0;
+}
+
+static inline void kvmppc_hmm_free(void) {}
+#endif /* CONFIG_PPC_UV */
+
 #endif /* __POWERPC_KVM_HOST_H__ */
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index 7c4d0b4ced12..f1c5800ac705 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -20,5 +20,7 @@
 /* opcodes */
 #define UV_WRITE_PATE			0xF104
 #define UV_RETURN			0xF11C
+#define UV_PAGE_IN			0xF128
+#define UV_PAGE_OUT			0xF12C
 
 #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index 996c1efd6c6d..16f8e0e8ec3f 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -44,6 +44,23 @@ static inline int uv_register_pate(u64 lpid, u64 dw0, u64 dw1)
 	return ucall(UV_WRITE_PATE, retbuf, lpid, dw0, dw1);
 }
 
+static inline int uv_page_in(u64 lpid, u64 src_ra, u64 dst_gpa, u64 flags,
+			     u64 page_shift)
+{
+	unsigned long retbuf[UCALL_BUFSIZE];
+
+	return ucall(UV_PAGE_IN, retbuf, lpid, src_ra, dst_gpa, flags,
+		     page_shift);
+}
+
+static inline int uv_page_out(u64 lpid, u64 dst_ra, u64 src_gpa, u64 flags,
+			      u64 page_shift)
+{
+	unsigned long retbuf[UCALL_BUFSIZE];
+
+	return ucall(UV_PAGE_OUT, retbuf, lpid, dst_ra, src_gpa, flags,
+		     page_shift);
+}
 #endif /* !__ASSEMBLY__ */
 
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
index 4c67cc79de7c..d1a79fb5f806 100644
--- a/arch/powerpc/kvm/Makefile
+++ b/arch/powerpc/kvm/Makefile
@@ -71,6 +71,9 @@ kvm-hv-y += \
 	book3s_64_mmu_radix.o \
 	book3s_hv_nested.o
 
+kvm-hv-$(CONFIG_PPC_UV) += \
+	book3s_hv_hmm.o
+
 kvm-hv-$(CONFIG_PPC_TRANSACTIONAL_MEM) += \
 	book3s_hv_tm.o
 
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index a104743291a9..8ee66aa0da58 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -75,6 +75,8 @@
 #include <asm/xics.h>
 #include <asm/xive.h>
 #include <asm/hw_breakpoint.h>
+#include <asm/kvm_host.h>
+#include <asm/kvm_book3s_hmm.h>
 
 #include "book3s.h"
 
@@ -1083,6 +1085,18 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
 					 kvmppc_get_gpr(vcpu, 5),
 					 kvmppc_get_gpr(vcpu, 6));
 		break;
+	case H_SVM_PAGE_IN:
+		ret = kvmppc_h_svm_page_in(vcpu->kvm,
+					   kvmppc_get_gpr(vcpu, 4),
+					   kvmppc_get_gpr(vcpu, 5),
+					   kvmppc_get_gpr(vcpu, 6));
+		break;
+	case H_SVM_PAGE_OUT:
+		ret = kvmppc_h_svm_page_out(vcpu->kvm,
+					    kvmppc_get_gpr(vcpu, 4),
+					    kvmppc_get_gpr(vcpu, 5),
+					    kvmppc_get_gpr(vcpu, 6));
+		break;
 	default:
 		return RESUME_HOST;
 	}
@@ -5501,11 +5515,16 @@ static int kvmppc_book3s_init_hv(void)
 			no_mixing_hpt_and_radix = true;
 	}
 
+	r = kvmppc_hmm_init();
+	if (r < 0)
+		pr_err("KVM-HV: kvmppc_hmm_init failed %d\n", r);
+
 	return r;
 }
 
 static void kvmppc_book3s_exit_hv(void)
 {
+	kvmppc_hmm_free();
 	kvmppc_free_host_rm_ops();
 	if (kvmppc_radix_possible())
 		kvmppc_radix_exit();
diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c b/arch/powerpc/kvm/book3s_hv_hmm.c
new file mode 100644
index 000000000000..cd34323888b6
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv_hmm.c
@@ -0,0 +1,482 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HMM driver to manage page migration between normal and secure
+ * memory.
+ *
+ * Based on Jérôme Glisse's HMM dummy driver.
+ *
+ * Copyright 2018 Bharata B Rao, IBM Corp. <bharata@linux.ibm.com>
+ */
+
+/*
+ * A pseries guest can be run as a secure guest on Ultravisor-enabled
+ * POWER platforms. On such platforms, this driver will be used to manage
+ * the movement of guest pages between the normal memory managed by
+ * hypervisor (HV) and secure memory managed by Ultravisor (UV).
+ *
+ * Private ZONE_DEVICE memory equal to the amount of secure memory
+ * available in the platform for running secure guests is created
+ * via a HMM device. The movement of pages between normal and secure
+ * memory is done by ->alloc_and_copy() callback routine of migrate_vma().
+ *
+ * The page-in or page-out requests from UV will come to HV as hcalls and
+ * HV will call back into UV via uvcalls to satisfy these page requests.
+ *
+ * For each page that gets moved into secure memory, a HMM PFN is used
+ * on the HV side and HMM migration PTE corresponding to that PFN would be
+ * populated in the QEMU page tables. HMM PFNs are stored in the rmap
+ * array. Whenever a guest page becomes secure, HMM PFN allocated for
+ * the same will be populated in the corresponding slot in the rmap
+ * array. The overloading of rmap array's usage which otherwise is
+ * used primarily by HPT guests means that this feature (secure
+ * guest on PEF platforms) is available only for Radix MMU guests.
+ * Also the same rmap array is used differently by nested HPT guests.
+ * Hence a secure guest can't have nested guests.
+ */
+
+#include <linux/hmm.h>
+#include <linux/kvm_host.h>
+#include <linux/sched/mm.h>
+#include <asm/ultravisor.h>
+
+struct kvmppc_hmm_device {
+	struct hmm_device *device;
+	struct hmm_devmem *devmem;
+	unsigned long *pfn_bitmap;
+};
+
+static struct kvmppc_hmm_device kvmppc_hmm;
+spinlock_t kvmppc_hmm_lock;
+
+struct kvmppc_hmm_page_pvt {
+	unsigned long *rmap;
+	unsigned int lpid;
+	unsigned long gpa;
+};
+
+struct kvmppc_hmm_migrate_args {
+	unsigned long *rmap;
+	unsigned int lpid;
+	unsigned long gpa;
+	unsigned long page_shift;
+};
+
+/*
+ * Bits 60:56 in the rmap entry will be used to identify the
+ * different uses/functions of rmap. This definition with move
+ * to a proper header when all other functions are defined.
+ */
+#define KVMPPC_PFN_HMM		(0x2ULL << 56)
+
+static inline bool kvmppc_is_hmm_pfn(unsigned long pfn)
+{
+	return !!(pfn & KVMPPC_PFN_HMM);
+}
+
+/*
+ * Get a free HMM PFN from the pool
+ *
+ * Called when a normal page is moved to secure memory (UV_PAGE_IN). HMM
+ * PFN will be used to keep track of the secure page on HV side.
+ *
+ * @rmap here is the slot in the rmap array that corresponds to @gpa.
+ * Thus a non-zero rmap entry indicates that the corresonding guest
+ * page has become secure, is not mapped on the HV side.
+ *
+ * NOTE: In this and subsequent functions, we pass around and access
+ * individual elements of kvm_memory_slot->arch.rmap[] without any
+ * protection. Should we use lock_rmap() here?
+ */
+static struct page *kvmppc_hmm_get_page(unsigned long *rmap,
+					unsigned long gpa, unsigned int lpid)
+{
+	struct page *dpage = NULL;
+	unsigned long bit, hmm_pfn;
+	unsigned long nr_pfns = kvmppc_hmm.devmem->pfn_last -
+				kvmppc_hmm.devmem->pfn_first;
+	unsigned long flags;
+	struct kvmppc_hmm_page_pvt *pvt;
+
+	if (kvmppc_is_hmm_pfn(*rmap))
+		return NULL;
+
+	spin_lock_irqsave(&kvmppc_hmm_lock, flags);
+	bit = find_first_zero_bit(kvmppc_hmm.pfn_bitmap, nr_pfns);
+	if (bit >= nr_pfns)
+		goto out;
+
+	bitmap_set(kvmppc_hmm.pfn_bitmap, bit, 1);
+	hmm_pfn = bit + kvmppc_hmm.devmem->pfn_first;
+	dpage = pfn_to_page(hmm_pfn);
+
+	if (!trylock_page(dpage))
+		goto out_clear;
+
+	*rmap = hmm_pfn | KVMPPC_PFN_HMM;
+	pvt = kzalloc(sizeof(*pvt), GFP_ATOMIC);
+	if (!pvt)
+		goto out_unlock;
+	pvt->rmap = rmap;
+	pvt->gpa = gpa;
+	pvt->lpid = lpid;
+	hmm_devmem_page_set_drvdata(dpage, (unsigned long)pvt);
+	spin_unlock_irqrestore(&kvmppc_hmm_lock, flags);
+
+	get_page(dpage);
+	return dpage;
+
+out_unlock:
+	unlock_page(dpage);
+out_clear:
+	bitmap_clear(kvmppc_hmm.pfn_bitmap,
+		     hmm_pfn - kvmppc_hmm.devmem->pfn_first, 1);
+out:
+	spin_unlock_irqrestore(&kvmppc_hmm_lock, flags);
+	return NULL;
+}
+
+/*
+ * Release the HMM PFN back to the pool
+ *
+ * Called when secure page becomes a normal page during UV_PAGE_OUT.
+ */
+static void kvmppc_hmm_put_page(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long flags;
+	struct kvmppc_hmm_page_pvt *pvt;
+
+	spin_lock_irqsave(&kvmppc_hmm_lock, flags);
+	pvt = (struct kvmppc_hmm_page_pvt *)hmm_devmem_page_get_drvdata(page);
+	hmm_devmem_page_set_drvdata(page, 0);
+
+	bitmap_clear(kvmppc_hmm.pfn_bitmap,
+		     pfn - kvmppc_hmm.devmem->pfn_first, 1);
+	*(pvt->rmap) = 0;
+	spin_unlock_irqrestore(&kvmppc_hmm_lock, flags);
+	kfree(pvt);
+}
+
+/*
+ * migrate_vma() callback to move page from normal memory to secure memory.
+ *
+ * We don't capture the return value of uv_page_in() here because when
+ * UV asks for a page and then fails to copy it over, we don't care.
+ */
+static void
+kvmppc_hmm_migrate_alloc_and_copy(struct vm_area_struct *vma,
+				  const unsigned long *src_pfn,
+				  unsigned long *dst_pfn,
+				  unsigned long start,
+				  unsigned long end,
+				  void *private)
+{
+	struct kvmppc_hmm_migrate_args *args = private;
+	struct page *spage = migrate_pfn_to_page(*src_pfn);
+	unsigned long pfn = *src_pfn >> MIGRATE_PFN_SHIFT;
+	struct page *dpage;
+
+	*dst_pfn = 0;
+	if (!(*src_pfn & MIGRATE_PFN_MIGRATE))
+		return;
+
+	dpage = kvmppc_hmm_get_page(args->rmap, args->gpa, args->lpid);
+	if (!dpage)
+		return;
+
+	if (spage)
+		uv_page_in(args->lpid, pfn << args->page_shift,
+			   args->gpa, 0, args->page_shift);
+
+	*dst_pfn = migrate_pfn(page_to_pfn(dpage)) |
+		    MIGRATE_PFN_DEVICE | MIGRATE_PFN_LOCKED;
+}
+
+/*
+ * This migrate_vma() callback is typically used to updated device
+ * page tables after successful migration. We have nothing to do here.
+ *
+ * Also as we don't care if UV successfully copied over the page in
+ * kvmppc_hmm_migrate_alloc_and_copy(), we don't bother to check
+ * dst_pfn for any errors here.
+ */
+static void
+kvmppc_hmm_migrate_finalize_and_map(struct vm_area_struct *vma,
+				    const unsigned long *src_pfn,
+				    const unsigned long *dst_pfn,
+				    unsigned long start,
+				    unsigned long end,
+				    void *private)
+{
+}
+
+static const struct migrate_vma_ops kvmppc_hmm_migrate_ops = {
+	.alloc_and_copy = kvmppc_hmm_migrate_alloc_and_copy,
+	.finalize_and_map = kvmppc_hmm_migrate_finalize_and_map,
+};
+
+/*
+ * Move page from normal memory to secure memory.
+ */
+unsigned long
+kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
+		     unsigned long flags, unsigned long page_shift)
+{
+	unsigned long addr, end;
+	unsigned long src_pfn, dst_pfn;
+	struct kvmppc_hmm_migrate_args args;
+	struct vm_area_struct *vma;
+	int srcu_idx;
+	unsigned long gfn = gpa >> page_shift;
+	struct kvm_memory_slot *slot;
+	unsigned long *rmap;
+	int ret = H_SUCCESS;
+
+	if (page_shift != PAGE_SHIFT)
+		return H_P3;
+
+	if (flags)
+		return H_P2;
+
+	down_read(&kvm->mm->mmap_sem);
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	slot = gfn_to_memslot(kvm, gfn);
+	rmap = &slot->arch.rmap[gfn - slot->base_gfn];
+	addr = gfn_to_hva(kvm, gpa >> page_shift);
+	if (kvm_is_error_hva(addr)) {
+		ret = H_PARAMETER;
+		goto out;
+	}
+
+	end = addr + (1UL << page_shift);
+	vma = find_vma_intersection(kvm->mm, addr, end);
+	if (!vma || vma->vm_start > addr || vma->vm_end < end) {
+		ret = H_PARAMETER;
+		goto out;
+	}
+
+	args.rmap = rmap;
+	args.lpid = kvm->arch.lpid;
+	args.gpa = gpa;
+	args.page_shift = page_shift;
+	ret = migrate_vma(&kvmppc_hmm_migrate_ops, vma, addr, end,
+			  &src_pfn, &dst_pfn, &args);
+	if (ret < 0)
+		ret = H_PARAMETER;
+out:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	up_read(&kvm->mm->mmap_sem);
+	return ret;
+}
+
+/*
+ * We drop the HMM PFN here, provision a new page and populate
+ * the same in QEMU page tables.
+ */
+static void
+kvmppc_hmm_fault_migrate_alloc_and_copy(struct vm_area_struct *vma,
+					const unsigned long *src_pfn,
+					unsigned long *dst_pfn,
+					unsigned long start,
+					unsigned long end,
+					void *private)
+{
+	struct page *dpage, *spage;
+	struct kvmppc_hmm_page_pvt *pvt;
+	unsigned long pfn;
+	int ret = U_SUCCESS;
+
+	*dst_pfn = MIGRATE_PFN_ERROR;
+	spage = migrate_pfn_to_page(*src_pfn);
+	if (!spage || !(*src_pfn & MIGRATE_PFN_MIGRATE))
+		return;
+	if (!is_zone_device_page(spage))
+		return;
+	dpage = hmm_vma_alloc_locked_page(vma, start);
+	if (!dpage)
+		return;
+	pvt = (struct kvmppc_hmm_page_pvt *)
+	       hmm_devmem_page_get_drvdata(spage);
+
+	pfn = page_to_pfn(dpage);
+	ret = uv_page_out(pvt->lpid, pfn << PAGE_SHIFT,
+			  pvt->gpa, 0, PAGE_SHIFT);
+	if (ret = U_SUCCESS)
+		*dst_pfn = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
+}
+
+/*
+ * We have nothing to do here.
+ */
+static void
+kvmppc_hmm_fault_migrate_finalize_and_map(struct vm_area_struct *vma,
+					  const unsigned long *src_pfn,
+					  const unsigned long *dst_pfn,
+					  unsigned long start,
+					  unsigned long end,
+					  void *private)
+{
+}
+
+static const struct migrate_vma_ops kvmppc_hmm_fault_migrate_ops = {
+	.alloc_and_copy = kvmppc_hmm_fault_migrate_alloc_and_copy,
+	.finalize_and_map = kvmppc_hmm_fault_migrate_finalize_and_map,
+};
+
+/*
+ * Fault handler callback when HV touches any page that has been
+ * moved to secure memory, we ask UV to give back the page by
+ * issuing a UV_PAGE_OUT uvcall.
+ */
+static vm_fault_t kvmppc_hmm_devmem_fault(struct hmm_devmem *devmem,
+					  struct vm_area_struct *vma,
+					  unsigned long addr,
+					  const struct page *page,
+					  unsigned int flags,
+					  pmd_t *pmdp)
+{
+	unsigned long end = addr + PAGE_SIZE;
+	unsigned long src_pfn, dst_pfn = 0;
+
+	if (migrate_vma(&kvmppc_hmm_fault_migrate_ops, vma, addr, end,
+			&src_pfn, &dst_pfn, NULL))
+		return VM_FAULT_SIGBUS;
+	if (dst_pfn = MIGRATE_PFN_ERROR)
+		return VM_FAULT_SIGBUS;
+	return 0;
+}
+
+static void kvmppc_hmm_devmem_free(struct hmm_devmem *devmem,
+				   struct page *page)
+{
+	kvmppc_hmm_put_page(page);
+}
+
+static const struct hmm_devmem_ops kvmppc_hmm_devmem_ops = {
+	.free = kvmppc_hmm_devmem_free,
+	.fault = kvmppc_hmm_devmem_fault,
+};
+
+/*
+ * Move page from secure memory to normal memory.
+ */
+unsigned long
+kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gpa,
+		      unsigned long flags, unsigned long page_shift)
+{
+	unsigned long addr, end;
+	struct vm_area_struct *vma;
+	unsigned long src_pfn, dst_pfn = 0;
+	int srcu_idx;
+	int ret = H_SUCCESS;
+
+	if (page_shift != PAGE_SHIFT)
+		return H_P3;
+
+	if (flags)
+		return H_P2;
+
+	down_read(&kvm->mm->mmap_sem);
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	addr = gfn_to_hva(kvm, gpa >> page_shift);
+	if (kvm_is_error_hva(addr)) {
+		ret = H_PARAMETER;
+		goto out;
+	}
+
+	end = addr + (1UL << page_shift);
+	vma = find_vma_intersection(kvm->mm, addr, end);
+	if (!vma || vma->vm_start > addr || vma->vm_end < end) {
+		ret = H_PARAMETER;
+		goto out;
+	}
+	ret = migrate_vma(&kvmppc_hmm_fault_migrate_ops, vma, addr, end,
+			  &src_pfn, &dst_pfn, NULL);
+	if (ret < 0)
+		ret = H_PARAMETER;
+out:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	up_read(&kvm->mm->mmap_sem);
+	return ret;
+}
+
+static u64 kvmppc_get_secmem_size(void)
+{
+	struct device_node *np;
+	int i, len;
+	const __be32 *prop;
+	u64 size = 0;
+
+	np = of_find_node_by_path("/ibm,ultravisor/ibm,uv-firmware");
+	if (!np)
+		goto out;
+
+	prop = of_get_property(np, "secure-memory-ranges", &len);
+	if (!prop)
+		goto out_put;
+
+	for (i = 0; i < len / (sizeof(*prop) * 4); i++)
+		size += of_read_number(prop + (i * 4) + 2, 2);
+
+out_put:
+	of_node_put(np);
+out:
+	return size;
+}
+
+static int kvmppc_hmm_pages_init(void)
+{
+	unsigned long nr_pfns = kvmppc_hmm.devmem->pfn_last -
+				kvmppc_hmm.devmem->pfn_first;
+
+	kvmppc_hmm.pfn_bitmap = kcalloc(BITS_TO_LONGS(nr_pfns),
+					 sizeof(unsigned long), GFP_KERNEL);
+	if (!kvmppc_hmm.pfn_bitmap)
+		return -ENOMEM;
+
+	spin_lock_init(&kvmppc_hmm_lock);
+
+	return 0;
+}
+
+int kvmppc_hmm_init(void)
+{
+	int ret = 0;
+	unsigned long size;
+
+	size = kvmppc_get_secmem_size();
+	if (!size) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	kvmppc_hmm.device = hmm_device_new(NULL);
+	if (IS_ERR(kvmppc_hmm.device)) {
+		ret = PTR_ERR(kvmppc_hmm.device);
+		goto out;
+	}
+
+	kvmppc_hmm.devmem = hmm_devmem_add(&kvmppc_hmm_devmem_ops,
+					   &kvmppc_hmm.device->device, size);
+	if (IS_ERR(kvmppc_hmm.devmem)) {
+		ret = PTR_ERR(kvmppc_hmm.devmem);
+		goto out_device;
+	}
+	ret = kvmppc_hmm_pages_init();
+	if (ret < 0)
+		goto out_device;
+
+	pr_info("KVMPPC-HMM: Secure Memory size 0x%lx\n", size);
+	return ret;
+
+out_device:
+	hmm_device_put(kvmppc_hmm.device);
+out:
+	return ret;
+}
+
+void kvmppc_hmm_free(void)
+{
+	kfree(kvmppc_hmm.pfn_bitmap);
+	hmm_device_put(kvmppc_hmm.device);
+}
-- 
2.21.0