[PATCH v9 0/8] KVM: PPC: Driver to manage pages of secure guest

[PATCH v9 0/8] KVM: PPC: Driver to manage pages of secure guest

[Bharata B Rao]

[The main change in this version is the introduction of new
locking to prevent concurrent page-in and page-out calls. More
details about this are present in patch 2/8]

Hi,

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.
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(). The reverse movement is driven
via pagemap_ops.migrate_to_ram().

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.

These patches are against hmm.git
(https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/log/?h=hmm)

plus

Claudio Carvalho's base ultravisor enablement patches that are present
in Michael Ellerman's tree
(https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/log/?h=topic/ppc-kvm)

These patches along with Claudio's above patches are required to
run secure pseries guests on KVM. This patchset is based on hmm.git
because hmm.git has migrate_vma cleanup and not-device memremap_pages
patchsets that are required by this patchset.

Changes in v9
=============
- Prevent concurrent page-in and page-out calls.
- Ensure device PFNs are allocated for zero-pages that are sent to UV.
- Failure to migrate a page during page-in will now return error via
  hcall.
- Address review comments by Suka
- Misc cleanups

v8: https://lore.kernel.org/linux-mm/20190910082946.7849-2-bharata@linux.ibm.com/T/

Anshuman Khandual (1):
  KVM: PPC: Ultravisor: Add PPC_UV config option

Bharata B Rao (6):
  KVM: PPC: Move pages between normal and secure memory
  KVM: PPC: Shared pages support for secure guests
  KVM: PPC: H_SVM_INIT_START and H_SVM_INIT_DONE hcalls
  KVM: PPC: Handle memory plug/unplug to secure VM
  KVM: PPC: Radix changes for secure guest
  KVM: PPC: Support reset of secure guest

Suraj Jitindar Singh (1):
  KVM: PPC: Book3S HV: Define usage types for rmap array in guest
    memslot

 Documentation/virt/kvm/api.txt              |  19 +
 arch/powerpc/Kconfig                        |  17 +
 arch/powerpc/include/asm/hvcall.h           |   9 +
 arch/powerpc/include/asm/kvm_book3s_uvmem.h |  48 ++
 arch/powerpc/include/asm/kvm_host.h         |  57 +-
 arch/powerpc/include/asm/kvm_ppc.h          |   2 +
 arch/powerpc/include/asm/ultravisor-api.h   |   6 +
 arch/powerpc/include/asm/ultravisor.h       |  36 ++
 arch/powerpc/kvm/Makefile                   |   3 +
 arch/powerpc/kvm/book3s_64_mmu_radix.c      |  22 +
 arch/powerpc/kvm/book3s_hv.c                | 122 ++++
 arch/powerpc/kvm/book3s_hv_rm_mmu.c         |   2 +-
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 673 ++++++++++++++++++++
 arch/powerpc/kvm/powerpc.c                  |  12 +
 include/uapi/linux/kvm.h                    |   1 +
 15 files changed, 1024 insertions(+), 5 deletions(-)
 create mode 100644 arch/powerpc/include/asm/kvm_book3s_uvmem.h
 create mode 100644 arch/powerpc/kvm/book3s_hv_uvmem.c

-- 
2.21.0

[PATCH v9 1/8] KVM: PPC: Book3S HV: Define usage types for rmap array in guest memslot

[Bharata B Rao]

From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

The rmap array in the guest memslot is an array of size number of guest
pages, allocated at memslot creation time. Each rmap entry in this array
is used to store information about the guest page to which it
corresponds. For example for a hpt guest it is used to store a lock bit,
rc bits, a present bit and the index of a hpt entry in the guest hpt
which maps this page. For a radix guest which is running nested guests
it is used to store a pointer to a linked list of nested rmap entries
which store the nested guest physical address which maps this guest
address and for which there is a pte in the shadow page table.

As there are currently two uses for the rmap array, and the potential
for this to expand to more in the future, define a type field (being the
top 8 bits of the rmap entry) to be used to define the type of the rmap
entry which is currently present and define two values for this field
for the two current uses of the rmap array.

Since the nested case uses the rmap entry to store a pointer, define
this type as having the two high bits set as is expected for a pointer.
Define the hpt entry type as having bit 56 set (bit 7 IBM bit ordering).

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
		[Added rmap type KVMPPC_RMAP_UVMEM_PFN]
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 arch/powerpc/include/asm/kvm_host.h | 28 ++++++++++++++++++++++++----
 arch/powerpc/kvm/book3s_hv_rm_mmu.c |  2 +-
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 4bb552d639b8..81cd221ccc04 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -232,11 +232,31 @@ struct revmap_entry {
 };
 
 /*
- * We use the top bit of each memslot->arch.rmap entry as a lock bit,
- * and bit 32 as a present flag.  The bottom 32 bits are the
- * index in the guest HPT of a HPTE that points to the page.
+ * The rmap array of size number of guest pages is allocated for each memslot.
+ * This array is used to store usage specific information about the guest page.
+ * Below are the encodings of the various possible usage types.
  */
-#define KVMPPC_RMAP_LOCK_BIT	63
+/* Free bits which can be used to define a new usage */
+#define KVMPPC_RMAP_TYPE_MASK	0xff00000000000000
+#define KVMPPC_RMAP_NESTED	0xc000000000000000	/* Nested rmap array */
+#define KVMPPC_RMAP_HPT		0x0100000000000000	/* HPT guest */
+#define KVMPPC_RMAP_UVMEM_PFN	0x0200000000000000	/* Secure GPA */
+
+static inline unsigned long kvmppc_rmap_type(unsigned long *rmap)
+{
+	return (*rmap & KVMPPC_RMAP_TYPE_MASK);
+}
+
+/*
+ * rmap usage definition for a hash page table (hpt) guest:
+ * 0x0000080000000000	Lock bit
+ * 0x0000018000000000	RC bits
+ * 0x0000000100000000	Present bit
+ * 0x00000000ffffffff	HPT index bits
+ * The bottom 32 bits are the index in the guest HPT of a HPTE that points to
+ * the page.
+ */
+#define KVMPPC_RMAP_LOCK_BIT	43
 #define KVMPPC_RMAP_RC_SHIFT	32
 #define KVMPPC_RMAP_REFERENCED	(HPTE_R_R << KVMPPC_RMAP_RC_SHIFT)
 #define KVMPPC_RMAP_PRESENT	0x100000000ul
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 63e0ce91e29d..7186c65c61c9 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -99,7 +99,7 @@ void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev,
 	} else {
 		rev->forw = rev->back = pte_index;
 		*rmap = (*rmap & ~KVMPPC_RMAP_INDEX) |
-			pte_index | KVMPPC_RMAP_PRESENT;
+			pte_index | KVMPPC_RMAP_PRESENT | KVMPPC_RMAP_HPT;
 	}
 	unlock_rmap(rmap);
 }
-- 
2.21.0

[PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Bharata B Rao]

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 <bharata@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h           |   4 +
 arch/powerpc/include/asm/kvm_book3s_uvmem.h |  29 ++
 arch/powerpc/include/asm/kvm_host.h         |  13 +
 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                |  20 +
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 481 ++++++++++++++++++++
 8 files changed, 566 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..a2e7502346a3 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -336,6 +336,7 @@ struct kvm_arch {
 #endif
 	struct kvmppc_ops *kvm_ops;
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+	struct mutex uvmem_lock;
 	struct mutex mmu_setup_lock;	/* nests inside vcpu mutexes */
 	u64 l1_ptcr;
 	int max_nested_lpid;
@@ -869,4 +870,16 @@ 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..ef532cce85f9 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;
 	}
@@ -4769,6 +4783,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 	char buf[32];
 	int ret;
 
+	mutex_init(&kvm->arch.uvmem_lock);
 	mutex_init(&kvm->arch.mmu_setup_lock);
 
 	/* Allocate the guest's logical partition ID */
@@ -5523,11 +5538,16 @@ 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..312f0fedde0b
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -0,0 +1,481 @@
+// 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. <bharata@linux.ibm.com>
+ */
+
+/*
+ * 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.
+ */
+
+/*
+ * Notes on locking
+ *
+ * kvm->arch.uvmem_lock is a per-guest lock that prevents concurrent
+ * page-in and page-out requests for the same GPA. Concurrent accesses
+ * can either come via UV (guest vCPUs requesting for same page)
+ * or when HV and guest simultaneously access the same page.
+ * This mutex serializes the migration of page from HV(normal) to
+ * UV(secure) and vice versa. So the serialization points are around
+ * migrate_vma routines and page-in/out routines.
+ *
+ * It would have been desirable to use lock_rmap() which essentially
+ * is spinlock at guest PFN granularity. However migrate_vma_pages() and
+ * helpers can sleep and hence using spinlock across these routines is not
+ * possible. This first attempt uses a per-guest mutex though per-guest-PFN
+ * mutex would have been ideal and preferrable.
+ *
+ * Per-guest mutex comes with a cost though. Mainly it serializes the
+ * fault path as page-out can occur when HV faults on accessing secure
+ * guest pages. Currently UV issues page-in requests for all the guest
+ * PFNs one at a time during early boot (UV_ESM uvcall), so this is
+ * not a cause for concern. Also currently the number of page-outs caused
+ * by HV touching secure pages is very very low. If an when UV supports
+ * overcommitting, then we might see concurrent guest driven page-outs.
+ *
+ * Locking order
+ *
+ * 1. srcu_read_lock(&kvm->srcu) - Protects KVM memslots
+ * 2. down_read(&kvm->mm->mmap_sem) - find_vma, migrate_vma_pages and helpers
+ * 3. mutex_lock(&kvm->arch.uvmem_lock) - protects read/writes to rmap[] slots
+ *					thus acting as sync-points for
+ *					page-in/out
+ */
+
+#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;
+	struct kvm *kvm;
+	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.
+ * An rmap entry of type KVMPPC_RMAP_UVMEM_PFN indicates that the
+ * corresponding guest page has become secure, and is not mapped on
+ * the HV side.
+ *
+ * Called with kvm->arch.uvmem_lock held
+ */
+static struct page *kvmppc_uvmem_get_page(unsigned long *rmap,
+					  unsigned long gpa, struct kvm *kvm)
+{
+	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);
+	spin_unlock(&kvmppc_uvmem_pfn_lock);
+
+	pvt = kzalloc(sizeof(*pvt), GFP_KERNEL);
+	if (!pvt)
+		goto out_clear;
+
+	uvmem_pfn = bit + pfn_first;
+	dpage = pfn_to_page(uvmem_pfn);
+	*rmap = uvmem_pfn | KVMPPC_RMAP_UVMEM_PFN;
+	pvt->rmap = rmap;
+	pvt->gpa = gpa;
+	pvt->kvm = kvm;
+	dpage->zone_device_data = pvt;
+
+	get_page(dpage);
+	lock_page(dpage);
+	return dpage;
+out_clear:
+	spin_lock(&kvmppc_uvmem_pfn_lock);
+	bitmap_clear(kvmppc_uvmem_pfn_bitmap, bit, 1);
+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, struct kvm *kvm,
+		   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;
+
+	if (!(*mig.src & MIGRATE_PFN_MIGRATE)) {
+		ret = -1;
+		goto out_finalize;
+	}
+
+	dpage = kvmppc_uvmem_get_page(rmap, gpa, kvm);
+	if (!dpage) {
+		ret = -1;
+		goto out_finalize;
+	}
+
+	pfn = *mig.src >> MIGRATE_PFN_SHIFT;
+	spage = migrate_pfn_to_page(*mig.src);
+	if (spage)
+		uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0,
+			   page_shift);
+
+	*mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+	migrate_vma_pages(&mig);
+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;
+
+	start = gfn_to_hva(kvm, gfn);
+	if (kvm_is_error_hva(start))
+		goto out;
+
+	rmap = &slot->arch.rmap[gfn - slot->base_gfn];
+	mutex_lock(&kvm->arch.uvmem_lock);
+	/* Fail the page-in request of an already paged-in page */
+	if (kvmppc_rmap_type(rmap) == KVMPPC_RMAP_UVMEM_PFN)
+		goto out_unlock;
+
+	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_unlock;
+
+	if (!kvmppc_svm_page_in(vma, start, end, rmap, gpa, kvm, page_shift))
+		ret = H_SUCCESS;
+out_unlock:
+	mutex_unlock(&kvm->arch.uvmem_lock);
+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,
+		    struct kvm *kvm, unsigned long *rmap)
+{
+	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;
+
+	mutex_lock(&kvm->arch.uvmem_lock);
+	/* The requested page is already paged-out, nothing to do */
+	if (kvmppc_rmap_type(rmap) != KVMPPC_RMAP_UVMEM_PFN)
+		goto out;
+
+	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->kvm->arch.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);
+out_finalize:
+	migrate_vma_finalize(&mig);
+out:
+	mutex_unlock(&kvm->arch.uvmem_lock);
+	return ret;
+}
+
+/*
+ * Fault handler callback that gets called when HV touches any page that
+ * has been 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)
+{
+	struct kvmppc_uvmem_page_pvt *pvt = vmf->page->zone_device_data;
+
+	if (kvmppc_svm_page_out(vmf->vma, vmf->address,
+				vmf->address + PAGE_SIZE, PAGE_SHIFT,
+				pvt->kvm, pvt->rmap))
+		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.
+ * Gets called with kvm->arch.uvmem_lock held.
+ */
+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 gfn = gpa >> page_shift;
+	struct kvm_memory_slot *slot;
+	unsigned long *rmap;
+	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, gfn);
+	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;
+
+	slot = gfn_to_memslot(kvm, gfn);
+	rmap = &slot->arch.rmap[gfn - slot->base_gfn];
+	if (!kvmppc_svm_page_out(vma, start, end, page_shift, kvm, rmap))
+		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

[PATCH v9 3/8] KVM: PPC: Shared pages support for secure guests

[Bharata B Rao]

A secure guest will share some of its pages with hypervisor (Eg. virtio
bounce buffers etc). Support sharing of pages between hypervisor and
ultravisor.

Shared page is reachable via both HV and UV side page tables. Once a
secure page is converted to shared page, the device page that represents
the secure page is unmapped from the HV side page tables.

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h  |  3 ++
 arch/powerpc/kvm/book3s_hv_uvmem.c | 86 ++++++++++++++++++++++++++++--
 2 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 2595d0144958..4e98dd992bd1 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -342,6 +342,9 @@
 #define H_TLB_INVALIDATE	0xF808
 #define H_COPY_TOFROM_GUEST	0xF80C
 
+/* Flags for H_SVM_PAGE_IN */
+#define H_PAGE_IN_SHARED        0x1
+
 /* Platform-specific hcalls used by the Ultravisor */
 #define H_SVM_PAGE_IN		0xEF00
 #define H_SVM_PAGE_OUT		0xEF04
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 312f0fedde0b..5e5b5a3e9eec 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -19,7 +19,10 @@
  * 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.
+ * on the HV side. Some pages (like virtio buffers, VPA pages etc) are
+ * shared between UV and HV. However such pages aren't represented by
+ * device private memory and mappings to shared memory exist in both
+ * UV and HV page tables.
  *
  * 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
@@ -80,6 +83,7 @@ struct kvmppc_uvmem_page_pvt {
 	unsigned long *rmap;
 	struct kvm *kvm;
 	unsigned long gpa;
+	bool skip_page_out;
 };
 
 /*
@@ -190,8 +194,70 @@ kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 	return ret;
 }
 
+/*
+ * Shares the page with HV, thus making it a normal page.
+ *
+ * - If the page is already secure, then provision a new page and share
+ * - If the page is a normal page, share the existing page
+ *
+ * In the former case, uses dev_pagemap_ops.migrate_to_ram handler
+ * to unmap the device page from QEMU's page tables.
+ */
+static unsigned long
+kvmppc_share_page(struct kvm *kvm, unsigned long gpa, unsigned long page_shift)
+{
+
+	int ret = H_PARAMETER;
+	struct page *uvmem_page;
+	struct kvmppc_uvmem_page_pvt *pvt;
+	unsigned long pfn;
+	unsigned long *rmap;
+	struct kvm_memory_slot *slot;
+	unsigned long gfn = gpa >> page_shift;
+	int srcu_idx;
+
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	slot = gfn_to_memslot(kvm, gfn);
+	if (!slot)
+		goto out;
+
+	rmap = &slot->arch.rmap[gfn - slot->base_gfn];
+	mutex_lock(&kvm->arch.uvmem_lock);
+	if (kvmppc_rmap_type(rmap) == KVMPPC_RMAP_UVMEM_PFN) {
+		uvmem_page = pfn_to_page(*rmap & ~KVMPPC_RMAP_UVMEM_PFN);
+		pvt = uvmem_page->zone_device_data;
+		pvt->skip_page_out = true;
+	}
+
+retry:
+	mutex_unlock(&kvm->arch.uvmem_lock);
+	pfn = gfn_to_pfn(kvm, gfn);
+	if (is_error_noslot_pfn(pfn))
+		goto out;
+
+	mutex_lock(&kvm->arch.uvmem_lock);
+	if (kvmppc_rmap_type(rmap) == KVMPPC_RMAP_UVMEM_PFN) {
+		uvmem_page = pfn_to_page(*rmap & ~KVMPPC_RMAP_UVMEM_PFN);
+		pvt = uvmem_page->zone_device_data;
+		pvt->skip_page_out = true;
+		kvm_release_pfn_clean(pfn);
+		goto retry;
+	}
+
+	if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0, page_shift))
+		ret = H_SUCCESS;
+	kvm_release_pfn_clean(pfn);
+	mutex_unlock(&kvm->arch.uvmem_lock);
+out:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	return ret;
+}
+
 /*
  * H_SVM_PAGE_IN: Move page from normal memory to secure memory.
+ *
+ * H_PAGE_IN_SHARED flag makes the page shared which means that the same
+ * memory in is visible from both UV and HV.
  */
 unsigned long
 kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
@@ -208,9 +274,12 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 	if (page_shift != PAGE_SHIFT)
 		return H_P3;
 
-	if (flags)
+	if (flags & ~H_PAGE_IN_SHARED)
 		return H_P2;
 
+	if (flags & H_PAGE_IN_SHARED)
+		return kvmppc_share_page(kvm, gpa, page_shift);
+
 	ret = H_PARAMETER;
 	srcu_idx = srcu_read_lock(&kvm->srcu);
 	down_read(&kvm->mm->mmap_sem);
@@ -292,8 +361,17 @@ kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start,
 	pvt = spage->zone_device_data;
 	pfn = page_to_pfn(dpage);
 
-	ret = uv_page_out(pvt->kvm->arch.lpid, pfn << page_shift,
-			  pvt->gpa, 0, page_shift);
+	/*
+	 * This function is used in two cases:
+	 * - When HV touches a secure page, for which we do UV_PAGE_OUT
+	 * - When a secure page is converted to shared page, we *get*
+	 *   the page to essentially unmap the device page. In this
+	 *   case we skip page-out.
+	 */
+	if (!pvt->skip_page_out)
+		ret = uv_page_out(pvt->kvm->arch.lpid, pfn << page_shift,
+				  pvt->gpa, 0, page_shift);
+
 	if (ret == U_SUCCESS)
 		*mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
 	else {
-- 
2.21.0

[PATCH v9 4/8] KVM: PPC: H_SVM_INIT_START and H_SVM_INIT_DONE hcalls

[Bharata B Rao]

H_SVM_INIT_START: Initiate securing a VM
H_SVM_INIT_DONE: Conclude securing a VM

As part of H_SVM_INIT_START, register all existing memslots with
the UV. H_SVM_INIT_DONE call by UV informs HV that transition of
the guest to secure mode is complete.

These two states (transition to secure mode STARTED and transition
to secure mode COMPLETED) are recorded in kvm->arch.secure_guest.
Setting these states will cause the assembly code that enters the
guest to call the UV_RETURN ucall instead of trying to enter the
guest directly.

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h           |  2 ++
 arch/powerpc/include/asm/kvm_book3s_uvmem.h | 12 ++++++++
 arch/powerpc/include/asm/kvm_host.h         |  4 +++
 arch/powerpc/include/asm/ultravisor-api.h   |  1 +
 arch/powerpc/include/asm/ultravisor.h       |  7 +++++
 arch/powerpc/kvm/book3s_hv.c                |  7 +++++
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 34 +++++++++++++++++++++
 7 files changed, 67 insertions(+)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 4e98dd992bd1..13bd870609c3 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -348,6 +348,8 @@
 /* Platform-specific hcalls used by the Ultravisor */
 #define H_SVM_PAGE_IN		0xEF00
 #define H_SVM_PAGE_OUT		0xEF04
+#define H_SVM_INIT_START	0xEF08
+#define H_SVM_INIT_DONE		0xEF0C
 
 /* Values for 2nd argument to H_SET_MODE */
 #define H_SET_MODE_RESOURCE_SET_CIABR		1
diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index 9603c2b48d67..fc924ef00b91 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -11,6 +11,8 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
 				    unsigned long gra,
 				    unsigned long flags,
 				    unsigned long page_shift);
+unsigned long kvmppc_h_svm_init_start(struct kvm *kvm);
+unsigned long kvmppc_h_svm_init_done(struct kvm *kvm);
 #else
 static inline unsigned long
 kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gra,
@@ -25,5 +27,15 @@ kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gra,
 {
 	return H_UNSUPPORTED;
 }
+
+static inline unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
+{
+	return H_UNSUPPORTED;
+}
+
+static inline unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
+{
+	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 a2e7502346a3..726d35eb3bfe 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -281,6 +281,10 @@ struct kvm_hpt_info {
 
 struct kvm_resize_hpt;
 
+/* Flag values for kvm_arch.secure_guest */
+#define KVMPPC_SECURE_INIT_START 0x1 /* H_SVM_INIT_START has been called */
+#define KVMPPC_SECURE_INIT_DONE  0x2 /* H_SVM_INIT_DONE completed */
+
 struct kvm_arch {
 	unsigned int lpid;
 	unsigned int smt_mode;		/* # vcpus per virtual core */
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index 1cd1f595fd81..c578d9b13a56 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -25,6 +25,7 @@
 /* opcodes */
 #define UV_WRITE_PATE			0xF104
 #define UV_RETURN			0xF11C
+#define UV_REGISTER_MEM_SLOT		0xF120
 #define UV_PAGE_IN			0xF128
 #define UV_PAGE_OUT			0xF12C
 
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index 0fc4a974b2e8..58ccf5e2d6bb 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -45,4 +45,11 @@ static inline int uv_page_out(u64 lpid, u64 dst_ra, u64 src_gpa, u64 flags,
 			    page_shift);
 }
 
+static inline int uv_register_mem_slot(u64 lpid, u64 start_gpa, u64 size,
+				       u64 flags, u64 slotid)
+{
+	return ucall_norets(UV_REGISTER_MEM_SLOT, lpid, start_gpa,
+			    size, flags, slotid);
+}
+
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index ef532cce85f9..3ba27fed3018 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1089,6 +1089,13 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
 					    kvmppc_get_gpr(vcpu, 5),
 					    kvmppc_get_gpr(vcpu, 6));
 		break;
+	case H_SVM_INIT_START:
+		ret = kvmppc_h_svm_init_start(vcpu->kvm);
+		break;
+	case H_SVM_INIT_DONE:
+		ret = kvmppc_h_svm_init_done(vcpu->kvm);
+		break;
+
 	default:
 		return RESUME_HOST;
 	}
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 5e5b5a3e9eec..074549e312b4 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -86,6 +86,40 @@ struct kvmppc_uvmem_page_pvt {
 	bool skip_page_out;
 };
 
+unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	int ret = H_SUCCESS;
+	int srcu_idx;
+
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	slots = kvm_memslots(kvm);
+	kvm_for_each_memslot(memslot, slots) {
+		ret = uv_register_mem_slot(kvm->arch.lpid,
+					   memslot->base_gfn << PAGE_SHIFT,
+					   memslot->npages * PAGE_SIZE,
+					   0, memslot->id);
+		if (ret < 0) {
+			ret = H_PARAMETER;
+			goto out;
+		}
+	}
+	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_START;
+out:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	return ret;
+}
+
+unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
+{
+	if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+		return H_UNSUPPORTED;
+
+	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
+	return H_SUCCESS;
+}
+
 /*
  * Get a free device PFN from the pool
  *
-- 
2.21.0

[PATCH v9 5/8] KVM: PPC: Handle memory plug/unplug to secure VM

[Bharata B Rao]

Register the new memslot with UV during plug and unregister
the memslot during unplug.

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 arch/powerpc/include/asm/ultravisor-api.h |  1 +
 arch/powerpc/include/asm/ultravisor.h     |  5 +++++
 arch/powerpc/kvm/book3s_hv.c              | 21 +++++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index c578d9b13a56..46b1ee381695 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -26,6 +26,7 @@
 #define UV_WRITE_PATE			0xF104
 #define UV_RETURN			0xF11C
 #define UV_REGISTER_MEM_SLOT		0xF120
+#define UV_UNREGISTER_MEM_SLOT		0xF124
 #define UV_PAGE_IN			0xF128
 #define UV_PAGE_OUT			0xF12C
 
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index 58ccf5e2d6bb..719c0c3930b9 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -52,4 +52,9 @@ static inline int uv_register_mem_slot(u64 lpid, u64 start_gpa, u64 size,
 			    size, flags, slotid);
 }
 
+static inline int uv_unregister_mem_slot(u64 lpid, u64 slotid)
+{
+	return ucall_norets(UV_UNREGISTER_MEM_SLOT, lpid, slotid);
+}
+
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3ba27fed3018..c5320cc0a534 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -74,6 +74,7 @@
 #include <asm/hw_breakpoint.h>
 #include <asm/kvm_host.h>
 #include <asm/kvm_book3s_uvmem.h>
+#include <asm/ultravisor.h>
 
 #include "book3s.h"
 
@@ -4517,6 +4518,26 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
 	if (change == KVM_MR_FLAGS_ONLY && kvm_is_radix(kvm) &&
 	    ((new->flags ^ old->flags) & KVM_MEM_LOG_DIRTY_PAGES))
 		kvmppc_radix_flush_memslot(kvm, old);
+	/*
+	 * If UV hasn't yet called H_SVM_INIT_START, don't register memslots.
+	 */
+	if (!kvm->arch.secure_guest)
+		return;
+
+	switch (change) {
+	case KVM_MR_CREATE:
+		uv_register_mem_slot(kvm->arch.lpid,
+				     new->base_gfn << PAGE_SHIFT,
+				     new->npages * PAGE_SIZE,
+				     0, new->id);
+		break;
+	case KVM_MR_DELETE:
+		uv_unregister_mem_slot(kvm->arch.lpid, old->id);
+		break;
+	default:
+		/* TODO: Handle KVM_MR_MOVE */
+		break;
+	}
 }
 
 /*
-- 
2.21.0

[PATCH v9 6/8] KVM: PPC: Radix changes for secure guest

[Bharata B Rao]

- After the guest becomes secure, when we handle a page fault of a page
  belonging to SVM in HV, send that page to UV via UV_PAGE_IN.
- Whenever a page is unmapped on the HV side, inform UV via UV_PAGE_INVAL.
- Ensure all those routines that walk the secondary page tables of
  the guest don't do so in case of secure VM. For secure guest, the
  active secondary page tables are in secure memory and the secondary
  page tables in HV are freed when guest becomes secure.

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 arch/powerpc/include/asm/kvm_host.h       | 12 ++++++++++++
 arch/powerpc/include/asm/ultravisor-api.h |  1 +
 arch/powerpc/include/asm/ultravisor.h     |  5 +++++
 arch/powerpc/kvm/book3s_64_mmu_radix.c    | 22 ++++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv_uvmem.c        | 20 ++++++++++++++++++++
 5 files changed, 60 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 726d35eb3bfe..c0c6603ddd6b 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -877,6 +877,8 @@ 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);
+bool kvmppc_is_guest_secure(struct kvm *kvm);
+int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa);
 #else
 static inline int kvmppc_uvmem_init(void)
 {
@@ -884,6 +886,16 @@ static inline int kvmppc_uvmem_init(void)
 }
 
 static inline void kvmppc_uvmem_free(void) {}
+
+static inline bool kvmppc_is_guest_secure(struct kvm *kvm)
+{
+	return false;
+}
+
+static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa)
+{
+	return -EFAULT;
+}
 #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 46b1ee381695..cf200d4ce703 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -29,5 +29,6 @@
 #define UV_UNREGISTER_MEM_SLOT		0xF124
 #define UV_PAGE_IN			0xF128
 #define UV_PAGE_OUT			0xF12C
+#define UV_PAGE_INVAL			0xF138
 
 #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index 719c0c3930b9..b333241bbe4c 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -57,4 +57,9 @@ static inline int uv_unregister_mem_slot(u64 lpid, u64 slotid)
 	return ucall_norets(UV_UNREGISTER_MEM_SLOT, lpid, slotid);
 }
 
+static inline int uv_page_inval(u64 lpid, u64 gpa, u64 page_shift)
+{
+	return ucall_norets(UV_PAGE_INVAL, lpid, gpa, page_shift);
+}
+
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 2d415c36a61d..93ad34e63045 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -19,6 +19,8 @@
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/pte-walk.h>
+#include <asm/ultravisor.h>
+#include <asm/kvm_host.h>
 
 /*
  * Supported radix tree geometry.
@@ -915,6 +917,9 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	if (!(dsisr & DSISR_PRTABLE_FAULT))
 		gpa |= ea & 0xfff;
 
+	if (kvmppc_is_guest_secure(kvm))
+		return kvmppc_send_page_to_uv(kvm, gpa & PAGE_MASK);
+
 	/* Get the corresponding memslot */
 	memslot = gfn_to_memslot(kvm, gfn);
 
@@ -972,6 +977,11 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 	unsigned long gpa = gfn << PAGE_SHIFT;
 	unsigned int shift;
 
+	if (kvmppc_is_guest_secure(kvm)) {
+		uv_page_inval(kvm->arch.lpid, gpa, PAGE_SIZE);
+		return 0;
+	}
+
 	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
 	if (ptep && pte_present(*ptep))
 		kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
@@ -989,6 +999,9 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 	int ref = 0;
 	unsigned long old, *rmapp;
 
+	if (kvmppc_is_guest_secure(kvm))
+		return ref;
+
 	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
 	if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
 		old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
@@ -1013,6 +1026,9 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 	unsigned int shift;
 	int ref = 0;
 
+	if (kvmppc_is_guest_secure(kvm))
+		return ref;
+
 	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
 	if (ptep && pte_present(*ptep) && pte_young(*ptep))
 		ref = 1;
@@ -1030,6 +1046,9 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
 	int ret = 0;
 	unsigned long old, *rmapp;
 
+	if (kvmppc_is_guest_secure(kvm))
+		return ret;
+
 	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
 	if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
 		ret = 1;
@@ -1082,6 +1101,9 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
 	unsigned long gpa;
 	unsigned int shift;
 
+	if (kvmppc_is_guest_secure(kvm))
+		return;
+
 	gpa = memslot->base_gfn << PAGE_SHIFT;
 	spin_lock(&kvm->mmu_lock);
 	for (n = memslot->npages; n; --n) {
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 074549e312b4..9250d1917a45 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -86,6 +86,11 @@ struct kvmppc_uvmem_page_pvt {
 	bool skip_page_out;
 };
 
+bool kvmppc_is_guest_secure(struct kvm *kvm)
+{
+	return (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE);
+}
+
 unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 {
 	struct kvm_memslots *slots;
@@ -512,6 +517,21 @@ kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gpa,
 	return ret;
 }
 
+int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa)
+{
+	unsigned long pfn;
+	int ret;
+
+	pfn = gfn_to_pfn(kvm, gpa >> PAGE_SHIFT);
+	if (is_error_noslot_pfn(pfn))
+		return -EFAULT;
+
+	ret = uv_page_in(kvm->arch.lpid, pfn << PAGE_SHIFT, gpa, 0, PAGE_SHIFT);
+	kvm_release_pfn_clean(pfn);
+
+	return (ret == U_SUCCESS) ? RESUME_GUEST : -EFAULT;
+}
+
 static u64 kvmppc_get_secmem_size(void)
 {
 	struct device_node *np;
-- 
2.21.0

[PATCH v9 7/8] KVM: PPC: Support reset of secure guest

[Bharata B Rao]

Add support for reset of secure guest via a new ioctl KVM_PPC_SVM_OFF.
This ioctl will be issued by QEMU during reset and includes the
the following steps:

- Ask UV to terminate the guest via UV_SVM_TERMINATE ucall
- Unpin the VPA pages so that they can be migrated back to secure
  side when guest becomes secure again. This is required because
  pinned pages can't be migrated.
- Reinitialize guest's partitioned scoped page tables. These are
  freed when guest becomes secure (H_SVM_INIT_DONE)
- Release all device pages of the secure guest.

After these steps, guest is ready to issue UV_ESM call once again
to switch to secure mode.

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
	[Implementation of uv_svm_terminate() and its call from
	guest shutdown path]
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
	[Unpinning of VPA pages]
---
 Documentation/virt/kvm/api.txt              | 19 ++++++
 arch/powerpc/include/asm/kvm_book3s_uvmem.h |  7 ++
 arch/powerpc/include/asm/kvm_ppc.h          |  2 +
 arch/powerpc/include/asm/ultravisor-api.h   |  1 +
 arch/powerpc/include/asm/ultravisor.h       |  5 ++
 arch/powerpc/kvm/book3s_hv.c                | 74 +++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 60 +++++++++++++++++
 arch/powerpc/kvm/powerpc.c                  | 12 ++++
 include/uapi/linux/kvm.h                    |  1 +
 9 files changed, 181 insertions(+)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index 2d067767b617..8e7a02e547e9 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -4111,6 +4111,25 @@ Valid values for 'action':
 #define KVM_PMU_EVENT_ALLOW 0
 #define KVM_PMU_EVENT_DENY 1
 
+4.121 KVM_PPC_SVM_OFF
+
+Capability: basic
+Architectures: powerpc
+Type: vm ioctl
+Parameters: none
+Returns: 0 on successful completion,
+Errors:
+  EINVAL:    if ultravisor failed to terminate the secure guest
+  ENOMEM:    if hypervisor failed to allocate new radix page tables for guest
+
+This ioctl is used to turn off the secure mode of the guest or transition
+the guest from secure mode to normal mode. This is invoked when the guest
+is reset. This has no effect if called for a normal guest.
+
+This ioctl issues an ultravisor call to terminate the secure guest,
+unpins the VPA pages, reinitializes guest's partition scoped page
+tables and releases all the device pages that are used to track the
+secure pages by hypervisor.
 
 5. The kvm_run structure
 ------------------------
diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index fc924ef00b91..6b8cc8edd0ab 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -13,6 +13,8 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
 				    unsigned long page_shift);
 unsigned long kvmppc_h_svm_init_start(struct kvm *kvm);
 unsigned long kvmppc_h_svm_init_done(struct kvm *kvm);
+void kvmppc_uvmem_free_memslot_pfns(struct kvm *kvm,
+				    struct kvm_memslots *slots);
 #else
 static inline unsigned long
 kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gra,
@@ -37,5 +39,10 @@ static inline unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
 {
 	return H_UNSUPPORTED;
 }
+
+static inline void kvmppc_uvmem_free_memslot_pfns(struct kvm *kvm,
+						  struct kvm_memslots *slots)
+{
+}
 #endif /* CONFIG_PPC_UV */
 #endif /* __POWERPC_KVM_PPC_HMM_H__ */
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 2484e6a8f5ca..e4093d067354 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -177,6 +177,7 @@ extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
 extern int kvmppc_switch_mmu_to_hpt(struct kvm *kvm);
 extern int kvmppc_switch_mmu_to_radix(struct kvm *kvm);
 extern void kvmppc_setup_partition_table(struct kvm *kvm);
+extern int kvmppc_reinit_partition_table(struct kvm *kvm);
 
 extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
 				struct kvm_create_spapr_tce_64 *args);
@@ -321,6 +322,7 @@ struct kvmppc_ops {
 			       int size);
 	int (*store_to_eaddr)(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
 			      int size);
+	int (*svm_off)(struct kvm *kvm);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;
diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
index cf200d4ce703..3a27a0c0be05 100644
--- a/arch/powerpc/include/asm/ultravisor-api.h
+++ b/arch/powerpc/include/asm/ultravisor-api.h
@@ -30,5 +30,6 @@
 #define UV_PAGE_IN			0xF128
 #define UV_PAGE_OUT			0xF12C
 #define UV_PAGE_INVAL			0xF138
+#define UV_SVM_TERMINATE		0xF13C
 
 #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
index b333241bbe4c..754a37de646d 100644
--- a/arch/powerpc/include/asm/ultravisor.h
+++ b/arch/powerpc/include/asm/ultravisor.h
@@ -62,4 +62,9 @@ static inline int uv_page_inval(u64 lpid, u64 gpa, u64 page_shift)
 	return ucall_norets(UV_PAGE_INVAL, lpid, gpa, page_shift);
 }
 
+static inline int uv_svm_terminate(u64 lpid)
+{
+	return ucall_norets(UV_SVM_TERMINATE, lpid);
+}
+
 #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index c5320cc0a534..d0014ca8d66a 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2433,6 +2433,15 @@ static void unpin_vpa(struct kvm *kvm, struct kvmppc_vpa *vpa)
 					vpa->dirty);
 }
 
+static void unpin_vpa_reset(struct kvm *kvm, struct kvmppc_vpa *vpa)
+{
+	unpin_vpa(kvm, vpa);
+	vpa->gpa = 0;
+	vpa->pinned_addr = NULL;
+	vpa->dirty = false;
+	vpa->update_pending = 0;
+}
+
 static void kvmppc_core_vcpu_free_hv(struct kvm_vcpu *vcpu)
 {
 	spin_lock(&vcpu->arch.vpa_update_lock);
@@ -4593,6 +4602,22 @@ void kvmppc_setup_partition_table(struct kvm *kvm)
 	kvmhv_set_ptbl_entry(kvm->arch.lpid, dw0, dw1);
 }
 
+/*
+ * Called from KVM_PPC_SVM_OFF ioctl at guest reset time when secure
+ * guest is converted back to normal guest.
+ */
+int kvmppc_reinit_partition_table(struct kvm *kvm)
+{
+	int ret;
+
+	ret = kvmppc_init_vm_radix(kvm);
+	if (ret)
+		return ret;
+
+	kvmppc_setup_partition_table(kvm);
+	return 0;
+}
+
 /*
  * Set up HPT (hashed page table) and RMA (real-mode area).
  * Must be called with kvm->arch.mmu_setup_lock held.
@@ -4981,6 +5006,7 @@ static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
 		if (nesting_enabled(kvm))
 			kvmhv_release_all_nested(kvm);
 		kvm->arch.process_table = 0;
+		uv_svm_terminate(kvm->arch.lpid);
 		kvmhv_set_ptbl_entry(kvm->arch.lpid, 0, 0);
 	}
 	kvmppc_free_lpid(kvm->arch.lpid);
@@ -5422,6 +5448,53 @@ static int kvmhv_store_to_eaddr(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
 	return rc;
 }
 
+/*
+ *  IOCTL handler to turn off secure mode of guest
+ *
+ * - Issue ucall to terminate the guest on the UV side
+ * - Unpin the VPA pages (Enables these pages to be migrated back
+ *   when VM becomes secure again)
+ * - Recreate partition table as the guest is transitioning back to
+ *   normal mode
+ * - Release all device pages
+ */
+static int kvmhv_svm_off(struct kvm *kvm)
+{
+	struct kvm_vcpu *vcpu;
+	int srcu_idx;
+	int ret = 0;
+	int i;
+
+	if (!kvmppc_is_guest_secure(kvm))
+		return ret;
+
+	ret = uv_svm_terminate(kvm->arch.lpid);
+	if (ret != U_SUCCESS) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		spin_lock(&vcpu->arch.vpa_update_lock);
+		unpin_vpa_reset(kvm, &vcpu->arch.dtl);
+		unpin_vpa_reset(kvm, &vcpu->arch.slb_shadow);
+		unpin_vpa_reset(kvm, &vcpu->arch.vpa);
+		spin_unlock(&vcpu->arch.vpa_update_lock);
+	}
+
+	ret = kvmppc_reinit_partition_table(kvm);
+	if (ret)
+		goto out;
+
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
+		kvmppc_uvmem_free_memslot_pfns(kvm, __kvm_memslots(kvm, i));
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	kvm->arch.secure_guest = 0;
+out:
+	return ret;
+}
+
 static struct kvmppc_ops kvm_ops_hv = {
 	.get_sregs = kvm_arch_vcpu_ioctl_get_sregs_hv,
 	.set_sregs = kvm_arch_vcpu_ioctl_set_sregs_hv,
@@ -5464,6 +5537,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.enable_nested = kvmhv_enable_nested,
 	.load_from_eaddr = kvmhv_load_from_eaddr,
 	.store_to_eaddr = kvmhv_store_to_eaddr,
+	.svm_off = kvmhv_svm_off,
 };
 
 static int kvm_init_subcore_bitmap(void)
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 9250d1917a45..14494f6af949 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -74,6 +74,7 @@
 #include <linux/migrate.h>
 #include <linux/kvm_host.h>
 #include <asm/ultravisor.h>
+#include <asm/kvm_ppc.h>
 
 static struct dev_pagemap kvmppc_uvmem_pgmap;
 static unsigned long *kvmppc_uvmem_pfn_bitmap;
@@ -122,9 +123,68 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
 		return H_UNSUPPORTED;
 
 	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
+	if (kvm_is_radix(kvm)) {
+		kvmppc_free_radix(kvm);
+		pr_info("LPID %d went secure, freed HV side radix pgtables\n",
+			kvm->arch.lpid);
+	}
 	return H_SUCCESS;
 }
 
+/*
+ * Drop device pages that we maintain for the secure guest
+ *
+ * We first mark the pages to be skipped from UV_PAGE_OUT when there
+ * is HV side fault on these pages. Next we *get* these pages, forcing
+ * fault on them, do fault time migration to replace the device PTEs in
+ * QEMU page table with normal PTEs from newly allocated pages.
+ */
+static void kvmppc_uvmem_drop_pages(struct kvm_memory_slot *free,
+				   struct kvm *kvm)
+{
+	int i;
+	struct kvmppc_uvmem_page_pvt *pvt;
+	unsigned long pfn;
+
+	for (i = 0; i < free->npages; i++) {
+		unsigned long *rmap = &free->arch.rmap[i];
+		struct page *uvmem_page;
+
+		mutex_lock(&kvm->arch.uvmem_lock);
+		if (kvmppc_rmap_type(rmap) != KVMPPC_RMAP_UVMEM_PFN) {
+			mutex_unlock(&kvm->arch.uvmem_lock);
+			continue;
+		}
+
+		uvmem_page = pfn_to_page(*rmap & ~KVMPPC_RMAP_UVMEM_PFN);
+		pvt = uvmem_page->zone_device_data;
+		pvt->skip_page_out = true;
+		mutex_unlock(&kvm->arch.uvmem_lock);
+
+		pfn = gfn_to_pfn(kvm, pvt->gpa >> PAGE_SHIFT);
+		if (is_error_noslot_pfn(pfn))
+			continue;
+		kvm_release_pfn_clean(pfn);
+	}
+}
+
+/*
+ * Called from KVM_PPC_SVM_OFF ioctl when secure guest is reset
+ *
+ * UV has already cleaned up the guest, we release any device pages
+ * that we maintain
+ */
+void kvmppc_uvmem_free_memslot_pfns(struct kvm *kvm, struct kvm_memslots *slots)
+{
+	struct kvm_memory_slot *memslot;
+
+	if (!slots)
+		return;
+
+	kvm_for_each_memslot(memslot, slots)
+		kvmppc_uvmem_drop_pages(memslot, kvm);
+}
+
 /*
  * Get a free device PFN from the pool
  *
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 3e566c2e6066..3f7393177fba 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -31,6 +31,8 @@
 #include <asm/hvcall.h>
 #include <asm/plpar_wrappers.h>
 #endif
+#include <asm/ultravisor.h>
+#include <asm/kvm_host.h>
 
 #include "timing.h"
 #include "irq.h"
@@ -2410,6 +2412,16 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			r = -EFAULT;
 		break;
 	}
+	case KVM_PPC_SVM_OFF: {
+		struct kvm *kvm = filp->private_data;
+
+		r = 0;
+		if (!kvm->arch.kvm_ops->svm_off)
+			goto out;
+
+		r = kvm->arch.kvm_ops->svm_off(kvm);
+		break;
+	}
 	default: {
 		struct kvm *kvm = filp->private_data;
 		r = kvm->arch.kvm_ops->arch_vm_ioctl(filp, ioctl, arg);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 5e3f12d5359e..c2393a347680 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1332,6 +1332,7 @@ struct kvm_s390_ucas_mapping {
 #define KVM_PPC_GET_CPU_CHAR	  _IOR(KVMIO,  0xb1, struct kvm_ppc_cpu_char)
 /* Available with KVM_CAP_PMU_EVENT_FILTER */
 #define KVM_SET_PMU_EVENT_FILTER  _IOW(KVMIO,  0xb2, struct kvm_pmu_event_filter)
+#define KVM_PPC_SVM_OFF		  _IO(KVMIO,  0xb3)
 
 /* ioctl for vm fd */
 #define KVM_CREATE_DEVICE	  _IOWR(KVMIO,  0xe0, struct kvm_create_device)
-- 
2.21.0

[PATCH v9 8/8] KVM: PPC: Ultravisor: Add PPC_UV config option

[Bharata B Rao]

From: Anshuman Khandual <khandual@linux.vnet.ibm.com>

CONFIG_PPC_UV adds support for ultravisor.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[ Update config help and commit message ]
Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Reviewed-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
---
 arch/powerpc/Kconfig | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8dcd8820369..044838794112 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -448,6 +448,23 @@ config PPC_TRANSACTIONAL_MEM
 	help
 	  Support user-mode Transactional Memory on POWERPC.
 
+config PPC_UV
+	bool "Ultravisor support"
+	depends on KVM_BOOK3S_HV_POSSIBLE
+	select ZONE_DEVICE
+	select DEV_PAGEMAP_OPS
+	select DEVICE_PRIVATE
+	select MEMORY_HOTPLUG
+	select MEMORY_HOTREMOVE
+	default n
+	help
+	  This option paravirtualizes the kernel to run in POWER platforms that
+	  supports the Protected Execution Facility (PEF). On such platforms,
+	  the ultravisor firmware runs at a privilege level above the
+	  hypervisor.
+
+	  If unsure, say "N".
+
 config LD_HEAD_STUB_CATCH
 	bool "Reserve 256 bytes to cope with linker stubs in HEAD text" if EXPERT
 	depends on PPC64
-- 
2.21.0

Re: [PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Jason Gunthorpe]

On Wed, Sep 25, 2019 at 10:36:43AM +0530, Bharata B Rao 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 <bharata@linux.ibm.com>
>  arch/powerpc/include/asm/hvcall.h           |   4 +
>  arch/powerpc/include/asm/kvm_book3s_uvmem.h |  29 ++
>  arch/powerpc/include/asm/kvm_host.h         |  13 +
>  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                |  20 +
>  arch/powerpc/kvm/book3s_hv_uvmem.c          | 481 ++++++++++++++++++++
>  8 files changed, 566 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
> +++ 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
> +++ 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__

This is a strange sentinal for a header called kvm_book3s_uvmem.h

Jason

Re: [PATCH v9 0/8] KVM: PPC: Driver to manage pages of secure guest

[Jason Gunthorpe]

On Wed, Sep 25, 2019 at 10:36:41AM +0530, Bharata B Rao wrote:
> [The main change in this version is the introduction of new
> locking to prevent concurrent page-in and page-out calls. More
> details about this are present in patch 2/8]
> 
> Hi,
> 
> 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.
> 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(). The reverse movement is driven
> via pagemap_ops.migrate_to_ram().
> 
> 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.
> 
> These patches are against hmm.git
> (https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/log/?h=hmm)
> 
> plus
> 
> Claudio Carvalho's base ultravisor enablement patches that are present
> in Michael Ellerman's tree
> (https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/log/?h=topic/ppc-kvm)
> 
> These patches along with Claudio's above patches are required to
> run secure pseries guests on KVM. This patchset is based on hmm.git
> because hmm.git has migrate_vma cleanup and not-device memremap_pages
> patchsets that are required by this patchset.

FWIW this is all merged to Linus now and will be in rc1

Jason

Re: [PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Paul Mackerras]

On Wed, Sep 25, 2019 at 10:36:43AM +0530, Bharata B Rao 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.

As we discussed privately, but mentioning it here so there is a
record:  I am concerned about this structure

> +struct kvmppc_uvmem_page_pvt {
> +	unsigned long *rmap;
> +	struct kvm *kvm;
> +	unsigned long gpa;
> +};

which keeps a reference to the rmap.  The reference could become stale
if the memslot is deleted or moved, and nothing in the patch series
ensures that the stale references are cleaned up.

If it is possible to do without the long-term rmap reference, and
instead find the rmap via the memslots (with the srcu lock held) each
time we need the rmap, that would be safer, I think, provided that we
can sort out the lock ordering issues.

Paul.

Re: [PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Bharata B Rao]

On Fri, Oct 18, 2019 at 8:31 AM Paul Mackerras <paulus@ozlabs.org> wrote:
>
> On Wed, Sep 25, 2019 at 10:36:43AM +0530, Bharata B Rao 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.
>
> As we discussed privately, but mentioning it here so there is a
> record:  I am concerned about this structure
>
> > +struct kvmppc_uvmem_page_pvt {
> > +     unsigned long *rmap;
> > +     struct kvm *kvm;
> > +     unsigned long gpa;
> > +};
>
> which keeps a reference to the rmap.  The reference could become stale
> if the memslot is deleted or moved, and nothing in the patch series
> ensures that the stale references are cleaned up.

I will add code to release the device PFNs when memslot goes away. In
fact the early versions of the patchset had this, but it subsequently
got removed.

>
> If it is possible to do without the long-term rmap reference, and
> instead find the rmap via the memslots (with the srcu lock held) each
> time we need the rmap, that would be safer, I think, provided that we
> can sort out the lock ordering issues.

All paths except fault handler access rmap[] under srcu lock. Even in
case of fault handler, for those faults induced by us (shared page
handling, releasing device pfns), we do hold srcu lock. The difficult
case is when we fault due to HV accessing a device page. In this case
we come to fault hanler with mmap_sem already held and are not in a
position to take kvm srcu lock as that would lead to lock order
reversal. Given that we have pages mapped in still, I assume memslot
can't go away while we access rmap[], so think we should be ok here.

However if that sounds fragile, may be I can go back to my initial
design where we weren't using rmap[] to store device PFNs. That will
increase the memory usage but we give us an easy option to have
per-guest mutex to protect concurrent page-ins/outs/faults.

Regards,
Bharata.
-- 
http://raobharata.wordpress.com/

Re: [PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Paul Mackerras]

On Tue, Oct 22, 2019 at 11:59:35AM +0530, Bharata B Rao wrote:
> On Fri, Oct 18, 2019 at 8:31 AM Paul Mackerras <paulus@ozlabs.org> wrote:
> >
> > On Wed, Sep 25, 2019 at 10:36:43AM +0530, Bharata B Rao 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.
> >
> > As we discussed privately, but mentioning it here so there is a
> > record:  I am concerned about this structure
> >
> > > +struct kvmppc_uvmem_page_pvt {
> > > +     unsigned long *rmap;
> > > +     struct kvm *kvm;
> > > +     unsigned long gpa;
> > > +};
> >
> > which keeps a reference to the rmap.  The reference could become stale
> > if the memslot is deleted or moved, and nothing in the patch series
> > ensures that the stale references are cleaned up.
> 
> I will add code to release the device PFNs when memslot goes away. In
> fact the early versions of the patchset had this, but it subsequently
> got removed.
> 
> >
> > If it is possible to do without the long-term rmap reference, and
> > instead find the rmap via the memslots (with the srcu lock held) each
> > time we need the rmap, that would be safer, I think, provided that we
> > can sort out the lock ordering issues.
> 
> All paths except fault handler access rmap[] under srcu lock. Even in
> case of fault handler, for those faults induced by us (shared page
> handling, releasing device pfns), we do hold srcu lock. The difficult
> case is when we fault due to HV accessing a device page. In this case
> we come to fault hanler with mmap_sem already held and are not in a
> position to take kvm srcu lock as that would lead to lock order
> reversal. Given that we have pages mapped in still, I assume memslot
> can't go away while we access rmap[], so think we should be ok here.

The mapping of pages in userspace memory, and the mapping of userspace
memory to guest physical space, are two distinct things.  The memslots
describe the mapping of userspace addresses to guest physical
addresses, but don't say anything about what is mapped at those
userspace addresses.  So you can indeed get a page fault on a
userspace address at the same time that a memslot is being deleted
(even a memslot that maps that particular userspace address), because
removing the memslot does not unmap anything from userspace memory,
it just breaks the association between that userspace memory and guest
physical memory.  Deleting the memslot does unmap the pages from the
guest but doesn't unmap them from the userspace process (e.g. QEMU).

It is an interesting question what the semantics should be when a
memslot is deleted and there are pages of userspace currently paged
out to the device (i.e. the ultravisor).  One approach might be to say
that all those pages have to come back to the host before we finish
the memslot deletion, but that is probably not necessary; I think we
could just say that those pages are gone and can be replaced by zero
pages if they get accessed on the host side.  If userspace then unmaps
the corresponding region of the userspace memory map, we can then just
forget all those pages with very little work.

> However if that sounds fragile, may be I can go back to my initial
> design where we weren't using rmap[] to store device PFNs. That will
> increase the memory usage but we give us an easy option to have
> per-guest mutex to protect concurrent page-ins/outs/faults.

That sounds like it would be the best option, even if only in the
short term.  At least it would give us a working solution, even if
it's not the best performing solution.

Paul.

Re: [PATCH v9 2/8] KVM: PPC: Move pages between normal and secure memory

[Bharata B Rao]

On Wed, Oct 23, 2019 at 03:17:54PM +1100, Paul Mackerras wrote:
> On Tue, Oct 22, 2019 at 11:59:35AM +0530, Bharata B Rao wrote:
> The mapping of pages in userspace memory, and the mapping of userspace
> memory to guest physical space, are two distinct things.  The memslots
> describe the mapping of userspace addresses to guest physical
> addresses, but don't say anything about what is mapped at those
> userspace addresses.  So you can indeed get a page fault on a
> userspace address at the same time that a memslot is being deleted
> (even a memslot that maps that particular userspace address), because
> removing the memslot does not unmap anything from userspace memory,
> it just breaks the association between that userspace memory and guest
> physical memory.  Deleting the memslot does unmap the pages from the
> guest but doesn't unmap them from the userspace process (e.g. QEMU).
> 
> It is an interesting question what the semantics should be when a
> memslot is deleted and there are pages of userspace currently paged
> out to the device (i.e. the ultravisor).  One approach might be to say
> that all those pages have to come back to the host before we finish
> the memslot deletion, but that is probably not necessary; I think we
> could just say that those pages are gone and can be replaced by zero
> pages if they get accessed on the host side.  If userspace then unmaps
> the corresponding region of the userspace memory map, we can then just
> forget all those pages with very little work.

There are 5 scenarios currently where we are replacing the device mappings:

1. Guest reset
2. Memslot free (Memory unplug) (Not present in this version though)
3. Converting secure page to shared page
4. HV touching the secure page
5. H_SVM_INIT_ABORT hcall to abort SVM due to errors when transitioning
   to secure mode (Not present in this version)

In the first 3 cases, we don't need to get the page to HV from
the secure side and hence skip the page out. However currently we do
allocate fresh page and replace the mapping with the new one.
 
> > However if that sounds fragile, may be I can go back to my initial
> > design where we weren't using rmap[] to store device PFNs. That will
> > increase the memory usage but we give us an easy option to have
> > per-guest mutex to protect concurrent page-ins/outs/faults.
> 
> That sounds like it would be the best option, even if only in the
> short term.  At least it would give us a working solution, even if
> it's not the best performing solution.

Sure, will avoid using rmap[] in the next version.

Regards,
Bharata.