Subject: Re: [PATCH v8 2/8] kvmppc: Movement of pages between normal and secure memory

From: Sukadev Bhattiprolu <[email-masked]>
Date: Tue, 17 Sep 2019 16:31:39 -0700

In the subject line s/Movement of/Move/? Some minor comments below.

Bharata B Rao [[email-masked]] wrote:

> Manage migration of pages betwen normal and secure memory of secure
> guest by implementing 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.
> Whenever a page belonging to the guest becomes secure, a page from
> this private device memory is used to represent and track that secure
> page on the HV side. The movement of pages between normal and secure
> memory is done via migrate_vma_pages() using UV_PAGE_IN and
> UV_PAGE_OUT ucalls.
> 
> Signed-off-by: Bharata B Rao <[email-masked]>
> ---
>  arch/powerpc/include/asm/hvcall.h           |   4 +
>  arch/powerpc/include/asm/kvm_book3s_uvmem.h |  29 ++
>  arch/powerpc/include/asm/kvm_host.h         |  12 +
>  arch/powerpc/include/asm/ultravisor-api.h   |   2 +
>  arch/powerpc/include/asm/ultravisor.h       |  14 +
>  arch/powerpc/kvm/Makefile                   |   3 +
>  arch/powerpc/kvm/book3s_hv.c                |  19 +
>  arch/powerpc/kvm/book3s_hv_uvmem.c          | 431 ++++++++++++++++++++
>  8 files changed, 514 insertions(+)
>  create mode 100644 arch/powerpc/include/asm/kvm_book3s_uvmem.h
>  create mode 100644 arch/powerpc/kvm/book3s_hv_uvmem.c
> 
> diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
> index 11112023e327..2595d0144958 100644
> --- a/arch/powerpc/include/asm/hvcall.h
> +++ b/arch/powerpc/include/asm/hvcall.h
> @@ -342,6 +342,10 @@
>  #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_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
> new file mode 100644
> index 000000000000..9603c2b48d67
> --- /dev/null
> +++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.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
> +unsigned long kvmppc_h_svm_page_in(struct kvm *kvm,
> +				   unsigned long gra,
> +				   unsigned long flags,
> +				   unsigned long page_shift);
> +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 81cd221ccc04..16633ad3be45 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -869,4 +869,16 @@ 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
> +int kvmppc_uvmem_init(void);
> +void kvmppc_uvmem_free(void);
> +#else
> +static inline int kvmppc_uvmem_init(void)
> +{
> +	return 0;
> +}
> +
> +static inline void kvmppc_uvmem_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 6a0f9c74f959..1cd1f595fd81 100644
> --- a/arch/powerpc/include/asm/ultravisor-api.h
> +++ b/arch/powerpc/include/asm/ultravisor-api.h
> @@ -25,5 +25,7 @@
>  /* 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 d7aa97aa7834..0fc4a974b2e8 100644
> --- a/arch/powerpc/include/asm/ultravisor.h
> +++ b/arch/powerpc/include/asm/ultravisor.h
> @@ -31,4 +31,18 @@ static inline int uv_register_pate(u64 lpid, u64 dw0, u64 dw1)
>  	return ucall_norets(UV_WRITE_PATE, lpid, dw0, dw1);
>  }
> 
> +static inline int uv_page_in(u64 lpid, u64 src_ra, u64 dst_gpa, u64 flags,
> +			     u64 page_shift)
> +{
> +	return ucall_norets(UV_PAGE_IN, 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)
> +{
> +	return ucall_norets(UV_PAGE_OUT, lpid, dst_ra, src_gpa, flags,
> +			    page_shift);
> +}
> +
>  #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
> index 4c67cc79de7c..2bfeaa13befb 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-$(CONFIG_PPC_UV) += \
> +	book3s_hv_uvmem.o
> +
>  kvm-hv-$(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 cde3f5a4b3e4..c5404db8f0cd 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -72,6 +72,8 @@
>  #include <asm/xics.h>
>  #include <asm/xive.h>
>  #include <asm/hw_breakpoint.h>
> +#include <asm/kvm_host.h>
> +#include <asm/kvm_book3s_uvmem.h>
> 
>  #include "book3s.h"
> 
> @@ -1075,6 +1077,18 @@ 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;
>  	}
> @@ -5523,11 +5537,16 @@ static int kvmppc_book3s_init_hv(void)
>  			no_mixing_hpt_and_radix = true;
>  	}
> 
> +	r = kvmppc_uvmem_init();
> +	if (r < 0)
> +		pr_err("KVM-HV: kvmppc_uvmem_init failed %d\n", r);
> +
>  	return r;
>  }
> 
>  static void kvmppc_book3s_exit_hv(void)
>  {
> +	kvmppc_uvmem_free();
>  	kvmppc_free_host_rm_ops();
>  	if (kvmppc_radix_possible())
>  		kvmppc_radix_exit();
> diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
> new file mode 100644
> index 000000000000..a1eccb065ba9
> --- /dev/null
> +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
> @@ -0,0 +1,431 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Secure pages management: Migration of pages between normal and secure
> + * memory of KVM guests.
> + *
> + * Copyright 2018 Bharata B Rao, IBM Corp. <[email-masked]>
> + */
> +
> +/*
> + * A pseries guest can be run as 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).
> + *
> + * The page-in or page-out requests from UV will come to HV as hcalls and
> + * HV will call back into UV via ultracalls to satisfy these page requests.
> + *
> + * Private ZONE_DEVICE memory equal to the amount of secure memory
> + * available in the platform for running secure guests is hotplugged.
> + * Whenever a page belonging to the guest becomes secure, a page from this
> + * private device memory is used to represent and track that secure page
> + * on the HV side.
> + *
> + * For each page that gets moved into secure memory, a device PFN is used
> + * on the HV side and migration PTE corresponding to that PFN would be
> + * populated in the QEMU page tables. Device PFNs are stored in the rmap
> + * array. Whenever a guest page becomes secure, device 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 since the same rmap array is used differently by nested
> + * guests, a secure guest can't have further nested guests.
> + */
> +
> +#include <linux/pagemap.h>
> +#include <linux/migrate.h>
> +#include <linux/kvm_host.h>
> +#include <asm/ultravisor.h>
> +
> +static struct dev_pagemap kvmppc_uvmem_pgmap;
> +static unsigned long *kvmppc_uvmem_pfn_bitmap;
> +static DEFINE_SPINLOCK(kvmppc_uvmem_pfn_lock);
> +
> +struct kvmppc_uvmem_page_pvt {
> +	unsigned long *rmap;
> +	unsigned int lpid;
> +	unsigned long gpa;
> +};
> +
> +/*
> + * Get a free device PFN from the pool
> + *
> + * Called when a normal page is moved to secure memory (UV_PAGE_IN). Device
> + * 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 corresponding guest
> + * page has become secure, and is not mapped on the HV side.
> + *
> + * NOTE: lock_rmap() could be used to prevent concurrent page-in and
> + * page-out on the same GPA.
> + */
> +static struct page *kvmppc_uvmem_get_page(unsigned long *rmap,

do static functions/helpers also need the kvmppc_ prefix?

> +					  unsigned long gpa, unsigned int lpid)
> +{
> +	struct page *dpage = NULL;
> +	unsigned long bit, uvmem_pfn;
> +	struct kvmppc_uvmem_page_pvt *pvt;
> +	unsigned long pfn_last, pfn_first;
> +
> +	pfn_first = kvmppc_uvmem_pgmap.res.start >> PAGE_SHIFT;
> +	pfn_last = pfn_first +
> +		   (resource_size(&kvmppc_uvmem_pgmap.res) >> PAGE_SHIFT);
> +
> +	spin_lock(&kvmppc_uvmem_pfn_lock);
> +	bit = find_first_zero_bit(kvmppc_uvmem_pfn_bitmap,
> +				  pfn_last - pfn_first);
> +	if (bit >= (pfn_last - pfn_first))
> +		goto out;
> +	bitmap_set(kvmppc_uvmem_pfn_bitmap, bit, 1);
> +
> +	uvmem_pfn = bit + pfn_first;
> +	dpage = pfn_to_page(uvmem_pfn);
> +	if (!trylock_page(dpage))
> +		goto out_clear;
> +
> +	pvt = kzalloc(sizeof(*pvt), GFP_KERNEL);
> +	if (!pvt)
> +		goto out_unlock;

Minor: Can this allocation be outside the lock? I guess it would change
the order of cleanup at the end of the function.

> +	spin_unlock(&kvmppc_uvmem_pfn_lock);
> +
> +	*rmap = uvmem_pfn | KVMPPC_RMAP_UVMEM_PFN;
> +	pvt->rmap = rmap;
> +	pvt->gpa = gpa;
> +	pvt->lpid = lpid;
> +	dpage->zone_device_data = pvt;
> +
> +	get_page(dpage);
> +	return dpage;
> +
> +out_unlock:
> +	unlock_page(dpage);
> +out_clear:
> +	bitmap_clear(kvmppc_uvmem_pfn_bitmap, uvmem_pfn - pfn_first, 1);

Reuse variable 'bit'  here?

> +out:
> +	spin_unlock(&kvmppc_uvmem_pfn_lock);
> +	return NULL;
> +}
> +
> +/*
> + * Alloc a PFN from private device memory pool and copy page from normal
> + * memory to secure memory using UV_PAGE_IN uvcall.
> + */
> +static int
> +kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
> +		   unsigned long end, unsigned long *rmap,
> +		   unsigned long gpa, unsigned int lpid,
> +		   unsigned long page_shift)
> +{
> +	unsigned long src_pfn, dst_pfn = 0;
> +	struct migrate_vma mig;
> +	struct page *spage;
> +	unsigned long pfn;
> +	struct page *dpage;
> +	int ret = 0;
> +
> +	memset(&mig, 0, sizeof(mig));
> +	mig.vma = vma;
> +	mig.start = start;
> +	mig.end = end;
> +	mig.src = &src_pfn;
> +	mig.dst = &dst_pfn;
> +
> +	ret = migrate_vma_setup(&mig);
> +	if (ret)
> +		return ret;
> +
> +	spage = migrate_pfn_to_page(*mig.src);
> +	pfn = *mig.src >> MIGRATE_PFN_SHIFT;
> +	if (!spage || !(*mig.src & MIGRATE_PFN_MIGRATE)) {
> +		ret = 0;

Do we want to return success here (and have caller return H_SUCCESS) if
we can't find the source page?

> +		goto out_finalize;
> +	}
> +
> +	dpage = kvmppc_uvmem_get_page(rmap, gpa, lpid);
> +	if (!dpage) {
> +		ret = -1;
> +		goto out_finalize;
> +	}
> +
> +	if (spage)
> +		uv_page_in(lpid, pfn << page_shift, gpa, 0, page_shift);
> +
> +	*mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
> +	migrate_vma_pages(&mig);

Nit: blank line here

> +out_finalize:
> +	migrate_vma_finalize(&mig);
> +	return ret;
> +}
> +
> +/*
> + * H_SVM_PAGE_IN: 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 start, end;
> +	struct vm_area_struct *vma;
> +	int srcu_idx;
> +	unsigned long gfn = gpa >> page_shift;
> +	struct kvm_memory_slot *slot;
> +	unsigned long *rmap;
> +	int ret;
> +
> +	if (page_shift != PAGE_SHIFT)
> +		return H_P3;
> +
> +	if (flags)
> +		return H_P2;
> +
> +	ret = H_PARAMETER;
> +	srcu_idx = srcu_read_lock(&kvm->srcu);
> +	down_read(&kvm->mm->mmap_sem);
> +	slot = gfn_to_memslot(kvm, gfn);
> +	if (!slot)
> +		goto out;
> +
> +	rmap = &slot->arch.rmap[gfn - slot->base_gfn];
> +	start = gfn_to_hva(kvm, gfn);
> +	if (kvm_is_error_hva(start))
> +		goto out;
> +
> +	if (kvmppc_rmap_type(rmap) == KVMPPC_RMAP_UVMEM_PFN)
> +		goto out;
> +
> +	end = start + (1UL << page_shift);
> +	vma = find_vma_intersection(kvm->mm, start, end);
> +	if (!vma || vma->vm_start > start || vma->vm_end < end)
> +		goto out;
> +
> +	if (!kvmppc_svm_page_in(vma, start, end, rmap, gpa, kvm->arch.lpid,
> +				page_shift))
> +		ret = H_SUCCESS;
> +out:
> +	up_read(&kvm->mm->mmap_sem);
> +	srcu_read_unlock(&kvm->srcu, srcu_idx);
> +	return ret;
> +}
> +
> +/*
> + * Provision a new page on HV side and copy over the contents
> + * from secure memory using UV_PAGE_OUT uvcall.
> + */
> +static int
> +kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start,
> +		    unsigned long end, unsigned long page_shift)
> +{
> +	unsigned long src_pfn, dst_pfn = 0;
> +	struct migrate_vma mig;
> +	struct page *dpage, *spage;
> +	struct kvmppc_uvmem_page_pvt *pvt;
> +	unsigned long pfn;
> +	int ret = U_SUCCESS;
> +
> +	memset(&mig, 0, sizeof(mig));
> +	mig.vma = vma;
> +	mig.start = start;
> +	mig.end = end;
> +	mig.src = &src_pfn;
> +	mig.dst = &dst_pfn;
> +
> +	ret = migrate_vma_setup(&mig);
> +	if (ret)
> +		return ret;
> +
> +	spage = migrate_pfn_to_page(*mig.src);
> +	if (!spage || !(*mig.src & MIGRATE_PFN_MIGRATE))
> +		goto out_finalize;
> +
> +	if (!is_zone_device_page(spage))
> +		goto out_finalize;
> +
> +	dpage = alloc_page_vma(GFP_HIGHUSER, vma, start);
> +	if (!dpage) {
> +		ret = -1;
> +		goto out_finalize;
> +	}
> +
> +	lock_page(dpage);
> +	pvt = spage->zone_device_data;
> +	pfn = page_to_pfn(dpage);
> +
> +	ret = uv_page_out(pvt->lpid, pfn << page_shift, pvt->gpa, 0,
> +			  page_shift);
> +
> +	if (ret == U_SUCCESS)
> +		*mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
> +	else {
> +		unlock_page(dpage);
> +		__free_page(dpage);
> +		goto out_finalize;
> +	}
> +
> +	migrate_vma_pages(&mig);

Nit: a blank line here

> +out_finalize:
> +	migrate_vma_finalize(&mig);
> +	return ret;
> +}
> +
> +/*
> + * Fault handler callback when HV touches any page that has been

 Nit: s/callback/callback. Called /

> + * moved to secure memory, we ask UV to give back the page by
> + * issuing UV_PAGE_OUT uvcall.
> + *
> + * This eventually results in dropping of device PFN and the newly
> + * provisioned page/PFN gets populated in QEMU page tables.
> + */
> +static vm_fault_t kvmppc_uvmem_migrate_to_ram(struct vm_fault *vmf)
> +{
> +	if (kvmppc_svm_page_out(vmf->vma, vmf->address,
> +				vmf->address + PAGE_SIZE, PAGE_SHIFT))
> +		return VM_FAULT_SIGBUS;
> +	else
> +		return 0;
> +}
> +
> +/*
> + * Release the device PFN back to the pool
> + *
> + * Gets called when secure page becomes a normal page during H_SVM_PAGE_OUT.
> + */
> +static void kvmppc_uvmem_page_free(struct page *page)
> +{
> +	unsigned long pfn = page_to_pfn(page) -
> +			(kvmppc_uvmem_pgmap.res.start >> PAGE_SHIFT);
> +	struct kvmppc_uvmem_page_pvt *pvt;
> +
> +	spin_lock(&kvmppc_uvmem_pfn_lock);
> +	bitmap_clear(kvmppc_uvmem_pfn_bitmap, pfn, 1);
> +	spin_unlock(&kvmppc_uvmem_pfn_lock);
> +
> +	pvt = page->zone_device_data;
> +	page->zone_device_data = NULL;
> +	*pvt->rmap = 0;
> +	kfree(pvt);
> +}
> +
> +static const struct dev_pagemap_ops kvmppc_uvmem_ops = {
> +	.page_free = kvmppc_uvmem_page_free,
> +	.migrate_to_ram	= kvmppc_uvmem_migrate_to_ram,
> +};
> +
> +/*
> + * H_SVM_PAGE_OUT: 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 start, end;
> +	struct vm_area_struct *vma;
> +	int srcu_idx;
> +	int ret;
> +
> +	if (page_shift != PAGE_SHIFT)
> +		return H_P3;
> +
> +	if (flags)
> +		return H_P2;
> +
> +	ret = H_PARAMETER;
> +	srcu_idx = srcu_read_lock(&kvm->srcu);
> +	down_read(&kvm->mm->mmap_sem);
> +	start = gfn_to_hva(kvm, gpa >> page_shift);
> +	if (kvm_is_error_hva(start))
> +		goto out;
> +
> +	end = start + (1UL << page_shift);
> +	vma = find_vma_intersection(kvm->mm, start, end);
> +	if (!vma || vma->vm_start > start || vma->vm_end < end)
> +		goto out;
> +
> +	if (!kvmppc_svm_page_out(vma, start, end, page_shift))
> +		ret = H_SUCCESS;
> +out:
> +	up_read(&kvm->mm->mmap_sem);
> +	srcu_read_unlock(&kvm->srcu, srcu_idx);
> +	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_compatible_node(NULL, NULL, "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;
> +}
> +
> +int kvmppc_uvmem_init(void)
> +{
> +	int ret = 0;
> +	unsigned long size;
> +	struct resource *res;
> +	void *addr;
> +	unsigned long pfn_last, pfn_first;
> +
> +	size = kvmppc_get_secmem_size();
> +	if (!size) {
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	res = request_free_mem_region(&iomem_resource, size, "kvmppc_uvmem");
> +	if (IS_ERR(res)) {
> +		ret = PTR_ERR(res);
> +		goto out;
> +	}
> +
> +	kvmppc_uvmem_pgmap.type = MEMORY_DEVICE_PRIVATE;
> +	kvmppc_uvmem_pgmap.res = *res;
> +	kvmppc_uvmem_pgmap.ops = &kvmppc_uvmem_ops;
> +	addr = memremap_pages(&kvmppc_uvmem_pgmap, NUMA_NO_NODE);
> +	if (IS_ERR(addr)) {
> +		ret = PTR_ERR(addr);
> +		goto out_free_region;
> +	}
> +
> +	pfn_first = res->start >> PAGE_SHIFT;
> +	pfn_last = pfn_first + (resource_size(res) >> PAGE_SHIFT);
> +	kvmppc_uvmem_pfn_bitmap = kcalloc(BITS_TO_LONGS(pfn_last - pfn_first),
> +					  sizeof(unsigned long), GFP_KERNEL);
> +	if (!kvmppc_uvmem_pfn_bitmap) {
> +		ret = -ENOMEM;
> +		goto out_unmap;
> +	}
> +
> +	pr_info("KVMPPC-UVMEM: Secure Memory size 0x%lx\n", size);
> +	return ret;
> +out_unmap:
> +	memunmap_pages(&kvmppc_uvmem_pgmap);
> +out_free_region:
> +	release_mem_region(res->start, size);
> +out:
> +	return ret;
> +}
> +
> +void kvmppc_uvmem_free(void)
> +{
> +	memunmap_pages(&kvmppc_uvmem_pgmap);
> +	release_mem_region(kvmppc_uvmem_pgmap.res.start,
> +			   resource_size(&kvmppc_uvmem_pgmap.res));
> +	kfree(kvmppc_uvmem_pfn_bitmap);
> +}
> -- 
> 2.21.0