[PATCH v6 0/5] Migrate non-migrated pages of a SVM.

[PATCH v6 0/5] Migrate non-migrated pages of a SVM.

[Ram Pai]

The time to switch a VM to Secure-VM, increases by the size of the VM.
A 100GB VM takes about 7minutes. This is unacceptable.  This linear
increase is caused by a suboptimal behavior by the Ultravisor and the
Hypervisor.  The Ultravisor unnecessarily migrates all the GFN of the
VM from normal-memory to secure-memory. It has to just migrate the
necessary and sufficient GFNs.

However when the optimization is incorporated in the Ultravisor, the
Hypervisor starts misbehaving. The Hypervisor has a inbuilt assumption
that the Ultravisor will explicitly request to migrate, each and every
GFN of the VM. If only necessary and sufficient GFNs are requested for
migration, the Hypervisor continues to manage the remaining GFNs as
normal GFNs. This leads to memory corruption; manifested
consistently when the SVM reboots.

The same is true, when a memory slot is hotplugged into a SVM. The
Hypervisor expects the ultravisor to request migration of all GFNs to
secure-GFN.  But the hypervisor cannot handle any H_SVM_PAGE_IN
requests from the Ultravisor, done in the context of
UV_REGISTER_MEM_SLOT ucall.  This problem manifests as random errors
in the SVM, when a memory-slot is hotplugged.

This patch series automatically migrates the non-migrated pages of a
SVM, and thus solves the problem.

Testing: Passed rigorous testing using various sized SVMs.

Changelog:

v6:     . rearrangement of functions in book3s_hv_uvmem.c. No functional
		change.
	. decoupling this patch series from Laurent's memory-hotplug/unplug,
		since the memhotplug/unplug/hotplug/reboot test is failing.

v5:  .  This patch series includes Laurent's fix for memory hotplug/unplug
	  . drop pages first and then delete the memslot. Otherwise
	  	the memslot does not get cleanly deleted, causing
		problems during reboot.
	  . recreatable through the following set of commands
	     . device_add pc-dimm,id=dimm1,memdev=mem1
	     . device_del dimm1
	     . device_add pc-dimm,id=dimm1,memdev=mem1
	Further incorporates comments from Bharata:
	. fix for off-by-one while disabling migration.
	. code-reorganized to maximize sharing in init_start path
       		and in memory-hotplug path
	. locking adjustments in mass-page migration during H_SVM_INIT_DONE.
	. improved recovery on error paths.
	. additional comments in the code for better understanding.
	. removed the retry-on-migration-failure code.
	. re-added the initial patch that adjust some prototype to overcome
	   a git problem, where it messes up the code context. Had
		accidently dropped the patch in the last version.

v4:  .  Incorported Bharata's comments:
	- Optimization -- replace write mmap semaphore with read mmap semphore.
	- disable page-merge during memory hotplug.
	- rearranged the patches. consolidated the page-migration-retry logic
		in a single patch.

v3: . Optimized the page-migration retry-logic. 
    . Relax and relinquish the cpu regularly while bulk migrating
    	the non-migrated pages. This issue was causing soft-lockups.
	Fixed it.
    . Added a new patch, to retry page-migration a couple of times
    	before returning H_BUSY in H_SVM_PAGE_IN. This issue was
	seen a few times in a 24hour continuous reboot test of the SVMs.

v2: . fixed a bug observed by Laurent. The state of the GFN's associated
	with Secure-VMs were not reset during memslot flush.
    . Re-organized the code, for easier review.
    . Better description of the patch series.

v1: . fixed a bug observed by Bharata. Pages that where paged-in and later
	paged-out must also be skipped from migration during H_SVM_INIT_DONE.


Laurent Dufour (1):
  KVM: PPC: Book3S HV: migrate hot plugged memory

Ram Pai (4):
  KVM: PPC: Book3S HV: Fix function definition in book3s_hv_uvmem.c
  KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START
  KVM: PPC: Book3S HV: track the state GFNs associated with secure VMs
  KVM: PPC: Book3S HV: in H_SVM_INIT_DONE, migrate remaining normal-GFNs
    to secure-GFNs.

 Documentation/powerpc/ultravisor.rst        |   3 +
 arch/powerpc/include/asm/kvm_book3s_uvmem.h |  14 +
 arch/powerpc/kvm/book3s_hv.c                |  14 +-
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 498 +++++++++++++++++++++++-----
 4 files changed, 437 insertions(+), 92 deletions(-)

-- 
1.8.3.1

[PATCH v6 1/5] KVM: PPC: Book3S HV: Fix function definition in book3s_hv_uvmem.c

[Ram Pai]

Without this fix, git is confused. It generates wrong
function context for code changes in subsequent patches.
Weird, but true.

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclaudio@linux.ibm.com>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_uvmem.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 09d8119..e6f76bc 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -382,8 +382,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
  * 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,
+static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 		   unsigned long end, unsigned long gpa, struct kvm *kvm,
 		   unsigned long page_shift, bool *downgrade)
 {
@@ -450,8 +449,8 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
  * 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)
+static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa,
+		unsigned long page_shift)
 {
 
 	int ret = H_PARAMETER;
@@ -500,9 +499,9 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
  * 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,
-		     unsigned long flags, unsigned long page_shift)
+unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
+		unsigned long flags,
+		unsigned long page_shift)
 {
 	bool downgrade = false;
 	unsigned long start, end;
@@ -559,10 +558,10 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
  * 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 gpa)
+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 gpa)
 {
 	unsigned long src_pfn, dst_pfn = 0;
 	struct migrate_vma mig;
-- 
1.8.3.1

[PATCH v6 2/5] KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START

[Ram Pai]

Page-merging of pages in memory-slots associated with a Secure VM,
is disabled in H_SVM_PAGE_IN handler.

This operation should have been done the much earlier; the moment the VM
is initiated for secure-transition. Delaying this operation, increases
the probability for those pages to acquire new references , making it
impossible to migrate those pages in H_SVM_PAGE_IN handler.

Disable page-migration in H_SVM_INIT_START handling.

Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 Documentation/powerpc/ultravisor.rst |   1 +
 arch/powerpc/kvm/book3s_hv_uvmem.c   | 123 +++++++++++++++++++++++++----------
 2 files changed, 89 insertions(+), 35 deletions(-)

diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst
index df136c8..a1c8c37 100644
--- a/Documentation/powerpc/ultravisor.rst
+++ b/Documentation/powerpc/ultravisor.rst
@@ -895,6 +895,7 @@ Return values
     One of the following values:
 
 	* H_SUCCESS	 on success.
+        * H_STATE        if the VM is not in a position to switch to secure.
 
 Description
 ~~~~~~~~~~~
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index e6f76bc..533b608 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -211,10 +211,79 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
 	return false;
 }
 
+static int kvmppc_memslot_page_merge(struct kvm *kvm,
+		const struct kvm_memory_slot *memslot, bool merge)
+{
+	unsigned long gfn = memslot->base_gfn;
+	unsigned long end, start = gfn_to_hva(kvm, gfn);
+	int ret = 0;
+	struct vm_area_struct *vma;
+	int merge_flag = (merge) ? MADV_MERGEABLE : MADV_UNMERGEABLE;
+
+	if (kvm_is_error_hva(start))
+		return H_STATE;
+
+	end = start + (memslot->npages << PAGE_SHIFT);
+
+	mmap_write_lock(kvm->mm);
+	do {
+		vma = find_vma_intersection(kvm->mm, start, end);
+		if (!vma) {
+			ret = H_STATE;
+			break;
+		}
+		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
+			  merge_flag, &vma->vm_flags);
+		if (ret) {
+			ret = H_STATE;
+			break;
+		}
+		start = vma->vm_end;
+	} while (end > vma->vm_end);
+
+	mmap_write_unlock(kvm->mm);
+	return ret;
+}
+
+static void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+		const struct kvm_memory_slot *memslot)
+{
+	uv_unregister_mem_slot(kvm->arch.lpid, memslot->id);
+	kvmppc_uvmem_slot_free(kvm, memslot);
+	kvmppc_memslot_page_merge(kvm, memslot, true);
+}
+
+static int kvmppc_uvmem_memslot_create(struct kvm *kvm,
+		const struct kvm_memory_slot *memslot)
+{
+	int ret = H_PARAMETER;
+
+	if (kvmppc_memslot_page_merge(kvm, memslot, false))
+		return ret;
+
+	if (kvmppc_uvmem_slot_init(kvm, memslot))
+		goto out1;
+
+	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;
+	}
+	return 0;
+out:
+	kvmppc_uvmem_slot_free(kvm, memslot);
+out1:
+	kvmppc_memslot_page_merge(kvm, memslot, true);
+	return ret;
+}
+
 unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 {
 	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
+	struct kvm_memory_slot *memslot, *m;
 	int ret = H_SUCCESS;
 	int srcu_idx;
 
@@ -232,23 +301,24 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 		return H_AUTHORITY;
 
 	srcu_idx = srcu_read_lock(&kvm->srcu);
+
+	/* register the memslot */
 	slots = kvm_memslots(kvm);
 	kvm_for_each_memslot(memslot, slots) {
-		if (kvmppc_uvmem_slot_init(kvm, memslot)) {
-			ret = H_PARAMETER;
-			goto out;
-		}
-		ret = uv_register_mem_slot(kvm->arch.lpid,
-					   memslot->base_gfn << PAGE_SHIFT,
-					   memslot->npages * PAGE_SIZE,
-					   0, memslot->id);
-		if (ret < 0) {
-			kvmppc_uvmem_slot_free(kvm, memslot);
-			ret = H_PARAMETER;
-			goto out;
+		ret = kvmppc_uvmem_memslot_create(kvm, memslot);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		slots = kvm_memslots(kvm);
+		kvm_for_each_memslot(m, slots) {
+			if (m == memslot)
+				break;
+			kvmppc_uvmem_memslot_delete(kvm, memslot);
 		}
 	}
-out:
+
 	srcu_read_unlock(&kvm->srcu, srcu_idx);
 	return ret;
 }
@@ -384,7 +454,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
  */
 static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 		   unsigned long end, unsigned long gpa, struct kvm *kvm,
-		   unsigned long page_shift, bool *downgrade)
+		   unsigned long page_shift)
 {
 	unsigned long src_pfn, dst_pfn = 0;
 	struct migrate_vma mig;
@@ -400,18 +470,6 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 	mig.src = &src_pfn;
 	mig.dst = &dst_pfn;
 
-	/*
-	 * We come here with mmap_lock write lock held just for
-	 * ksm_madvise(), otherwise we only need read mmap_lock.
-	 * Hence downgrade to read lock once ksm_madvise() is done.
-	 */
-	ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
-			  MADV_UNMERGEABLE, &vma->vm_flags);
-	mmap_write_downgrade(kvm->mm);
-	*downgrade = true;
-	if (ret)
-		return ret;
-
 	ret = migrate_vma_setup(&mig);
 	if (ret)
 		return ret;
@@ -503,7 +561,6 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 		unsigned long flags,
 		unsigned long page_shift)
 {
-	bool downgrade = false;
 	unsigned long start, end;
 	struct vm_area_struct *vma;
 	int srcu_idx;
@@ -524,7 +581,7 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 
 	ret = H_PARAMETER;
 	srcu_idx = srcu_read_lock(&kvm->srcu);
-	mmap_write_lock(kvm->mm);
+	mmap_read_lock(kvm->mm);
 
 	start = gfn_to_hva(kvm, gfn);
 	if (kvm_is_error_hva(start))
@@ -540,16 +597,12 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 	if (!vma || vma->vm_start > start || vma->vm_end < end)
 		goto out_unlock;
 
-	if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift,
-				&downgrade))
+	if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift))
 		ret = H_SUCCESS;
 out_unlock:
 	mutex_unlock(&kvm->arch.uvmem_lock);
 out:
-	if (downgrade)
-		mmap_read_unlock(kvm->mm);
-	else
-		mmap_write_unlock(kvm->mm);
+	mmap_read_unlock(kvm->mm);
 	srcu_read_unlock(&kvm->srcu, srcu_idx);
 	return ret;
 }
-- 
1.8.3.1

[PATCH v6 3/5] KVM: PPC: Book3S HV: track the state GFNs associated with secure VMs

[Ram Pai]

During the life of SVM, its GFNs transition through normal, secure and
shared states. Since the kernel does not track GFNs that are shared, it
is not possible to disambiguate a shared GFN from a GFN whose PFN has
not yet been migrated to a secure-PFN. Also it is not possible to
disambiguate a secure-GFN from a GFN whose GFN has been pagedout from
the ultravisor.

The ability to identify the state of a GFN is needed to skip migration
of its PFN to secure-PFN during ESM transition.

The code is re-organized to track the states of a GFN as explained
below.

************************************************************************
 1. States of a GFN
    ---------------
 The GFN can be in one of the following states.

 (a) Secure - The GFN is secure. The GFN is associated with
 	a Secure VM, the contents of the GFN is not accessible
 	to the Hypervisor.  This GFN can be backed by a secure-PFN,
 	or can be backed by a normal-PFN with contents encrypted.
 	The former is true when the GFN is paged-in into the
 	ultravisor. The latter is true when the GFN is paged-out
 	of the ultravisor.

 (b) Shared - The GFN is shared. The GFN is associated with a
 	a secure VM. The contents of the GFN is accessible to
 	Hypervisor. This GFN is backed by a normal-PFN and its
 	content is un-encrypted.

 (c) Normal - The GFN is a normal. The GFN is associated with
 	a normal VM. The contents of the GFN is accesible to
 	the Hypervisor. Its content is never encrypted.

 2. States of a VM.
    ---------------

 (a) Normal VM:  A VM whose contents are always accessible to
 	the hypervisor.  All its GFNs are normal-GFNs.

 (b) Secure VM: A VM whose contents are not accessible to the
 	hypervisor without the VM's consent.  Its GFNs are
 	either Shared-GFN or Secure-GFNs.

 (c) Transient VM: A Normal VM that is transitioning to secure VM.
 	The transition starts on successful return of
 	H_SVM_INIT_START, and ends on successful return
 	of H_SVM_INIT_DONE. This transient VM, can have GFNs
 	in any of the three states; i.e Secure-GFN, Shared-GFN,
 	and Normal-GFN.	The VM never executes in this state
 	in supervisor-mode.

 3. Memory slot State.
    ------------------
  	The state of a memory slot mirrors the state of the
  	VM the memory slot is associated with.

 4. VM State transition.
    --------------------

  A VM always starts in Normal Mode.

  H_SVM_INIT_START moves the VM into transient state. During this
  time the Ultravisor may request some of its GFNs to be shared or
  secured. So its GFNs can be in one of the three GFN states.

  H_SVM_INIT_DONE moves the VM entirely from transient state to
  secure-state. At this point any left-over normal-GFNs are
  transitioned to Secure-GFN.

  H_SVM_INIT_ABORT moves the transient VM back to normal VM.
  All its GFNs are moved to Normal-GFNs.

  UV_TERMINATE transitions the secure-VM back to normal-VM. All
  the secure-GFN and shared-GFNs are tranistioned to normal-GFN
  Note: The contents of the normal-GFN is undefined at this point.

 5. GFN state implementation:
    -------------------------

 Secure GFN is associated with a secure-PFN; also called uvmem_pfn,
 when the GFN is paged-in. Its pfn[] has KVMPPC_GFN_UVMEM_PFN flag
 set, and contains the value of the secure-PFN.
 It is associated with a normal-PFN; also called mem_pfn, when
 the GFN is pagedout. Its pfn[] has KVMPPC_GFN_MEM_PFN flag set.
 The value of the normal-PFN is not tracked.

 Shared GFN is associated with a normal-PFN. Its pfn[] has
 KVMPPC_UVMEM_SHARED_PFN flag set. The value of the normal-PFN
 is not tracked.

 Normal GFN is associated with normal-PFN. Its pfn[] has
 no flag set. The value of the normal-PFN is not tracked.

 6. Life cycle of a GFN
    --------------------
 --------------------------------------------------------------
 |        |     Share  |  Unshare | SVM       |H_SVM_INIT_DONE|
 |        |operation   |operation | abort/    |               |
 |        |            |          | terminate |               |
 -------------------------------------------------------------
 |        |            |          |           |               |
 | Secure |     Shared | Secure   |Normal     |Secure         |
 |        |            |          |           |               |
 | Shared |     Shared | Secure   |Normal     |Shared         |
 |        |            |          |           |               |
 | Normal |     Shared | Secure   |Normal     |Secure         |
 --------------------------------------------------------------

 7. Life cycle of a VM
    --------------------
 --------------------------------------------------------------------
 |         |  start    |  H_SVM_  |H_SVM_   |H_SVM_     |UV_SVM_    |
 |         |  VM       |INIT_START|INIT_DONE|INIT_ABORT |TERMINATE  |
 |         |           |          |         |           |           |
 --------- ----------------------------------------------------------
 |         |           |          |         |           |           |
 | Normal  | Normal    | Transient|Error    |Error      |Normal     |
 |         |           |          |         |           |           |
 | Secure  |   Error   | Error    |Error    |Error      |Normal     |
 |         |           |          |         |           |           |
 |Transient|   N/A     | Error    |Secure   |Normal     |Normal     |
 --------------------------------------------------------------------

************************************************************************

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclaudio@linux.ibm.com>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org

Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/kvm/book3s_hv_uvmem.c | 191 +++++++++++++++++++++++++++++++++----
 1 file changed, 172 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 533b608..1b2b029 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -98,7 +98,127 @@
 static unsigned long *kvmppc_uvmem_bitmap;
 static DEFINE_SPINLOCK(kvmppc_uvmem_bitmap_lock);
 
-#define KVMPPC_UVMEM_PFN	(1UL << 63)
+/*
+ * States of a GFN
+ * ---------------
+ * The GFN can be in one of the following states.
+ *
+ * (a) Secure - The GFN is secure. The GFN is associated with
+ *	a Secure VM, the contents of the GFN is not accessible
+ *	to the Hypervisor.  This GFN can be backed by a secure-PFN,
+ *	or can be backed by a normal-PFN with contents encrypted.
+ *	The former is true when the GFN is paged-in into the
+ *	ultravisor. The latter is true when the GFN is paged-out
+ *	of the ultravisor.
+ *
+ * (b) Shared - The GFN is shared. The GFN is associated with a
+ *	a secure VM. The contents of the GFN is accessible to
+ *	Hypervisor. This GFN is backed by a normal-PFN and its
+ *	content is un-encrypted.
+ *
+ * (c) Normal - The GFN is a normal. The GFN is associated with
+ *	a normal VM. The contents of the GFN is accesible to
+ *	the Hypervisor. Its content is never encrypted.
+ *
+ * States of a VM.
+ * ---------------
+ *
+ * Normal VM:  A VM whose contents are always accessible to
+ *	the hypervisor.  All its GFNs are normal-GFNs.
+ *
+ * Secure VM: A VM whose contents are not accessible to the
+ *	hypervisor without the VM's consent.  Its GFNs are
+ *	either Shared-GFN or Secure-GFNs.
+ *
+ * Transient VM: A Normal VM that is transitioning to secure VM.
+ *	The transition starts on successful return of
+ *	H_SVM_INIT_START, and ends on successful return
+ *	of H_SVM_INIT_DONE. This transient VM, can have GFNs
+ *	in any of the three states; i.e Secure-GFN, Shared-GFN,
+ *	and Normal-GFN.	The VM never executes in this state
+ *	in supervisor-mode.
+ *
+ * Memory slot State.
+ * -----------------------------
+ *	The state of a memory slot mirrors the state of the
+ *	VM the memory slot is associated with.
+ *
+ * VM State transition.
+ * --------------------
+ *
+ *  A VM always starts in Normal Mode.
+ *
+ *  H_SVM_INIT_START moves the VM into transient state. During this
+ *  time the Ultravisor may request some of its GFNs to be shared or
+ *  secured. So its GFNs can be in one of the three GFN states.
+ *
+ *  H_SVM_INIT_DONE moves the VM entirely from transient state to
+ *  secure-state. At this point any left-over normal-GFNs are
+ *  transitioned to Secure-GFN.
+ *
+ *  H_SVM_INIT_ABORT moves the transient VM back to normal VM.
+ *  All its GFNs are moved to Normal-GFNs.
+ *
+ *  UV_TERMINATE transitions the secure-VM back to normal-VM. All
+ *  the secure-GFN and shared-GFNs are tranistioned to normal-GFN
+ *  Note: The contents of the normal-GFN is undefined at this point.
+ *
+ * GFN state implementation:
+ * -------------------------
+ *
+ * Secure GFN is associated with a secure-PFN; also called uvmem_pfn,
+ * when the GFN is paged-in. Its pfn[] has KVMPPC_GFN_UVMEM_PFN flag
+ * set, and contains the value of the secure-PFN.
+ * It is associated with a normal-PFN; also called mem_pfn, when
+ * the GFN is pagedout. Its pfn[] has KVMPPC_GFN_MEM_PFN flag set.
+ * The value of the normal-PFN is not tracked.
+ *
+ * Shared GFN is associated with a normal-PFN. Its pfn[] has
+ * KVMPPC_UVMEM_SHARED_PFN flag set. The value of the normal-PFN
+ * is not tracked.
+ *
+ * Normal GFN is associated with normal-PFN. Its pfn[] has
+ * no flag set. The value of the normal-PFN is not tracked.
+ *
+ * Life cycle of a GFN
+ * --------------------
+ *
+ * --------------------------------------------------------------
+ * |        |     Share  |  Unshare | SVM       |H_SVM_INIT_DONE|
+ * |        |operation   |operation | abort/    |               |
+ * |        |            |          | terminate |               |
+ * -------------------------------------------------------------
+ * |        |            |          |           |               |
+ * | Secure |     Shared | Secure   |Normal     |Secure         |
+ * |        |            |          |           |               |
+ * | Shared |     Shared | Secure   |Normal     |Shared         |
+ * |        |            |          |           |               |
+ * | Normal |     Shared | Secure   |Normal     |Secure         |
+ * --------------------------------------------------------------
+ *
+ * Life cycle of a VM
+ * --------------------
+ *
+ * --------------------------------------------------------------------
+ * |         |  start    |  H_SVM_  |H_SVM_   |H_SVM_     |UV_SVM_    |
+ * |         |  VM       |INIT_START|INIT_DONE|INIT_ABORT |TERMINATE  |
+ * |         |           |          |         |           |           |
+ * --------- ----------------------------------------------------------
+ * |         |           |          |         |           |           |
+ * | Normal  | Normal    | Transient|Error    |Error      |Normal     |
+ * |         |           |          |         |           |           |
+ * | Secure  |   Error   | Error    |Error    |Error      |Normal     |
+ * |         |           |          |         |           |           |
+ * |Transient|   N/A     | Error    |Secure   |Normal     |Normal     |
+ * --------------------------------------------------------------------
+ */
+
+#define KVMPPC_GFN_UVMEM_PFN	(1UL << 63)
+#define KVMPPC_GFN_MEM_PFN	(1UL << 62)
+#define KVMPPC_GFN_SHARED	(1UL << 61)
+#define KVMPPC_GFN_SECURE	(KVMPPC_GFN_UVMEM_PFN | KVMPPC_GFN_MEM_PFN)
+#define KVMPPC_GFN_FLAG_MASK	(KVMPPC_GFN_SECURE | KVMPPC_GFN_SHARED)
+#define KVMPPC_GFN_PFN_MASK	(~KVMPPC_GFN_FLAG_MASK)
 
 struct kvmppc_uvmem_slot {
 	struct list_head list;
@@ -106,11 +226,11 @@ struct kvmppc_uvmem_slot {
 	unsigned long base_pfn;
 	unsigned long *pfns;
 };
-
 struct kvmppc_uvmem_page_pvt {
 	struct kvm *kvm;
 	unsigned long gpa;
 	bool skip_page_out;
+	bool remove_gfn;
 };
 
 bool kvmppc_uvmem_available(void)
@@ -163,8 +283,8 @@ void kvmppc_uvmem_slot_free(struct kvm *kvm, const struct kvm_memory_slot *slot)
 	mutex_unlock(&kvm->arch.uvmem_lock);
 }
 
-static void kvmppc_uvmem_pfn_insert(unsigned long gfn, unsigned long uvmem_pfn,
-				    struct kvm *kvm)
+static void kvmppc_mark_gfn(unsigned long gfn, struct kvm *kvm,
+			unsigned long flag, unsigned long uvmem_pfn)
 {
 	struct kvmppc_uvmem_slot *p;
 
@@ -172,24 +292,41 @@ static void kvmppc_uvmem_pfn_insert(unsigned long gfn, unsigned long uvmem_pfn,
 		if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
 			unsigned long index = gfn - p->base_pfn;
 
-			p->pfns[index] = uvmem_pfn | KVMPPC_UVMEM_PFN;
+			if (flag == KVMPPC_GFN_UVMEM_PFN)
+				p->pfns[index] = uvmem_pfn | flag;
+			else
+				p->pfns[index] = flag;
 			return;
 		}
 	}
 }
 
-static void kvmppc_uvmem_pfn_remove(unsigned long gfn, struct kvm *kvm)
+/* mark the GFN as secure-GFN associated with @uvmem pfn device-PFN. */
+static void kvmppc_gfn_secure_uvmem_pfn(unsigned long gfn,
+			unsigned long uvmem_pfn, struct kvm *kvm)
 {
-	struct kvmppc_uvmem_slot *p;
+	kvmppc_mark_gfn(gfn, kvm, KVMPPC_GFN_UVMEM_PFN, uvmem_pfn);
+}
 
-	list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
-		if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
-			p->pfns[gfn - p->base_pfn] = 0;
-			return;
-		}
-	}
+/* mark the GFN as secure-GFN associated with a memory-PFN. */
+static void kvmppc_gfn_secure_mem_pfn(unsigned long gfn, struct kvm *kvm)
+{
+	kvmppc_mark_gfn(gfn, kvm, KVMPPC_GFN_MEM_PFN, 0);
 }
 
+/* mark the GFN as a shared GFN. */
+static void kvmppc_gfn_shared(unsigned long gfn, struct kvm *kvm)
+{
+	kvmppc_mark_gfn(gfn, kvm, KVMPPC_GFN_SHARED, 0);
+}
+
+/* mark the GFN as a non-existent GFN. */
+static void kvmppc_gfn_remove(unsigned long gfn, struct kvm *kvm)
+{
+	kvmppc_mark_gfn(gfn, kvm, 0, 0);
+}
+
+/* return true, if the GFN is a secure-GFN backed by a secure-PFN */
 static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
 				    unsigned long *uvmem_pfn)
 {
@@ -199,10 +336,10 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
 		if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
 			unsigned long index = gfn - p->base_pfn;
 
-			if (p->pfns[index] & KVMPPC_UVMEM_PFN) {
+			if (p->pfns[index] & KVMPPC_GFN_UVMEM_PFN) {
 				if (uvmem_pfn)
 					*uvmem_pfn = p->pfns[index] &
-						     ~KVMPPC_UVMEM_PFN;
+						     KVMPPC_GFN_PFN_MASK;
 				return true;
 			} else
 				return false;
@@ -354,6 +491,7 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 
 		mutex_lock(&kvm->arch.uvmem_lock);
 		if (!kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) {
+			kvmppc_gfn_remove(gfn, kvm);
 			mutex_unlock(&kvm->arch.uvmem_lock);
 			continue;
 		}
@@ -361,6 +499,7 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 		uvmem_page = pfn_to_page(uvmem_pfn);
 		pvt = uvmem_page->zone_device_data;
 		pvt->skip_page_out = skip_page_out;
+		pvt->remove_gfn = true;
 		mutex_unlock(&kvm->arch.uvmem_lock);
 
 		pfn = gfn_to_pfn(kvm, gfn);
@@ -430,7 +569,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
 		goto out_clear;
 
 	uvmem_pfn = bit + pfn_first;
-	kvmppc_uvmem_pfn_insert(gpa >> PAGE_SHIFT, uvmem_pfn, kvm);
+	kvmppc_gfn_secure_uvmem_pfn(gpa >> PAGE_SHIFT, uvmem_pfn, kvm);
 
 	pvt->gpa = gpa;
 	pvt->kvm = kvm;
@@ -525,6 +664,11 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa,
 		uvmem_page = pfn_to_page(uvmem_pfn);
 		pvt = uvmem_page->zone_device_data;
 		pvt->skip_page_out = true;
+		/*
+		 * do not drop the GFN. It is a valid GFN
+		 * that is transitioned to a shared GFN.
+		 */
+		pvt->remove_gfn = false;
 	}
 
 retry:
@@ -538,12 +682,16 @@ static unsigned long kvmppc_share_page(struct kvm *kvm, unsigned long gpa,
 		uvmem_page = pfn_to_page(uvmem_pfn);
 		pvt = uvmem_page->zone_device_data;
 		pvt->skip_page_out = true;
+		pvt->remove_gfn = false; /* it continues to be a valid GFN */
 		kvm_release_pfn_clean(pfn);
 		goto retry;
 	}
 
-	if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0, page_shift))
+	if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0,
+				page_shift)) {
+		kvmppc_gfn_shared(gfn, kvm);
 		ret = H_SUCCESS;
+	}
 	kvm_release_pfn_clean(pfn);
 	mutex_unlock(&kvm->arch.uvmem_lock);
 out:
@@ -599,6 +747,7 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 
 	if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift))
 		ret = H_SUCCESS;
+
 out_unlock:
 	mutex_unlock(&kvm->arch.uvmem_lock);
 out:
@@ -707,7 +856,8 @@ static vm_fault_t kvmppc_uvmem_migrate_to_ram(struct vm_fault *vmf)
 /*
  * Release the device PFN back to the pool
  *
- * Gets called when secure page becomes a normal page during H_SVM_PAGE_OUT.
+ * Gets called when secure GFN tranistions from a secure-PFN
+ * to a normal PFN during H_SVM_PAGE_OUT.
  * Gets called with kvm->arch.uvmem_lock held.
  */
 static void kvmppc_uvmem_page_free(struct page *page)
@@ -722,7 +872,10 @@ static void kvmppc_uvmem_page_free(struct page *page)
 
 	pvt = page->zone_device_data;
 	page->zone_device_data = NULL;
-	kvmppc_uvmem_pfn_remove(pvt->gpa >> PAGE_SHIFT, pvt->kvm);
+	if (pvt->remove_gfn)
+		kvmppc_gfn_remove(pvt->gpa >> PAGE_SHIFT, pvt->kvm);
+	else
+		kvmppc_gfn_secure_mem_pfn(pvt->gpa >> PAGE_SHIFT, pvt->kvm);
 	kfree(pvt);
 }
 
-- 
1.8.3.1

[PATCH v6 4/5] KVM: PPC: Book3S HV: in H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs.

[Ram Pai]

The Ultravisor is expected to explicitly call H_SVM_PAGE_IN for all the
pages of the SVM before calling H_SVM_INIT_DONE. This causes a huge
delay in tranistioning the VM to SVM. The Ultravisor is only interested
in the pages that contain the kernel, initrd and other important data
structures. The rest contain throw-away content.

However if not all pages are requested by the Ultravisor, the Hypervisor
continues to consider the GFNs corresponding to the non-requested pages
as normal GFNs. This can lead to data-corruption and undefined behavior.

In H_SVM_INIT_DONE handler, move all the PFNs associated with the SVM's
GFNs to secure-PFNs. Skip the GFNs that are already Paged-in or Shared
or Paged-in followed by a Paged-out.

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Claudio Carvalho <cclaudio@linux.ibm.com>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 Documentation/powerpc/ultravisor.rst |   2 +
 arch/powerpc/kvm/book3s_hv_uvmem.c   | 154 ++++++++++++++++++++++++++++++-----
 2 files changed, 134 insertions(+), 22 deletions(-)

diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst
index a1c8c37..ba6b1bf 100644
--- a/Documentation/powerpc/ultravisor.rst
+++ b/Documentation/powerpc/ultravisor.rst
@@ -934,6 +934,8 @@ Return values
 	* H_UNSUPPORTED		if called from the wrong context (e.g.
 				from an SVM or before an H_SVM_INIT_START
 				hypercall).
+	* H_STATE		if the hypervisor could not successfully
+                                transition the VM to Secure VM.
 
 Description
 ~~~~~~~~~~~
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 1b2b029..a1664ae 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -93,6 +93,7 @@
 #include <asm/ultravisor.h>
 #include <asm/mman.h>
 #include <asm/kvm_ppc.h>
+#include <asm/kvm_book3s_uvmem.h>
 
 static struct dev_pagemap kvmppc_uvmem_pgmap;
 static unsigned long *kvmppc_uvmem_bitmap;
@@ -348,6 +349,41 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
 	return false;
 }
 
+/*
+ * starting from *gfn search for the next available GFN that is not yet
+ * transitioned to a secure GFN.  return the value of that GFN in *gfn.  If a
+ * GFN is found, return true, else return false
+ *
+ * Must be called with kvm->arch.uvmem_lock  held.
+ */
+static bool kvmppc_next_nontransitioned_gfn(const struct kvm_memory_slot *memslot,
+		struct kvm *kvm, unsigned long *gfn)
+{
+	struct kvmppc_uvmem_slot *p;
+	bool ret = false;
+	unsigned long i;
+
+	list_for_each_entry(p, &kvm->arch.uvmem_pfns, list)
+		if (*gfn >= p->base_pfn && *gfn < p->base_pfn + p->nr_pfns)
+			break;
+	if (!p)
+		return ret;
+	/*
+	 * The code below assumes, one to one correspondence between
+	 * kvmppc_uvmem_slot and memslot.
+	 */
+	for (i = *gfn; i < p->base_pfn + p->nr_pfns; i++) {
+		unsigned long index = i - p->base_pfn;
+
+		if (!(p->pfns[index] & KVMPPC_GFN_FLAG_MASK)) {
+			*gfn = i;
+			ret = true;
+			break;
+		}
+	}
+	return ret;
+}
+
 static int kvmppc_memslot_page_merge(struct kvm *kvm,
 		const struct kvm_memory_slot *memslot, bool merge)
 {
@@ -460,16 +496,6 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 	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;
-	pr_info("LPID %d went secure\n", kvm->arch.lpid);
-	return H_SUCCESS;
-}
-
 /*
  * Drop device pages that we maintain for the secure guest
  *
@@ -588,12 +614,14 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
 }
 
 /*
- * Alloc a PFN from private device memory pool and copy page from normal
- * memory to secure memory using UV_PAGE_IN uvcall.
+ * Alloc a PFN from private device memory pool. If @pagein is true,
+ * 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 gpa, struct kvm *kvm,
-		   unsigned long page_shift)
+static int kvmppc_svm_page_in(struct vm_area_struct *vma,
+		unsigned long start,
+		unsigned long end, unsigned long gpa, struct kvm *kvm,
+		unsigned long page_shift,
+		bool pagein)
 {
 	unsigned long src_pfn, dst_pfn = 0;
 	struct migrate_vma mig;
@@ -624,11 +652,16 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 		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);
+	if (pagein) {
+		pfn = *mig.src >> MIGRATE_PFN_SHIFT;
+		spage = migrate_pfn_to_page(*mig.src);
+		if (spage) {
+			ret = uv_page_in(kvm->arch.lpid, pfn << page_shift,
+					gpa, 0, page_shift);
+			if (ret)
+				goto out_finalize;
+		}
+	}
 
 	*mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
 	migrate_vma_pages(&mig);
@@ -637,6 +670,80 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start,
 	return ret;
 }
 
+static int kvmppc_uv_migrate_mem_slot(struct kvm *kvm,
+		const struct kvm_memory_slot *memslot)
+{
+	unsigned long gfn = memslot->base_gfn;
+	struct vm_area_struct *vma;
+	unsigned long start, end;
+	int ret = 0;
+
+	mmap_read_lock(kvm->mm);
+	mutex_lock(&kvm->arch.uvmem_lock);
+	while (kvmppc_next_nontransitioned_gfn(memslot, kvm, &gfn)) {
+		ret = H_STATE;
+		start = gfn_to_hva(kvm, gfn);
+		if (kvm_is_error_hva(start))
+			break;
+
+		end = start + (1UL << PAGE_SHIFT);
+		vma = find_vma_intersection(kvm->mm, start, end);
+		if (!vma || vma->vm_start > start || vma->vm_end < end)
+			break;
+
+		ret = kvmppc_svm_page_in(vma, start, end,
+				(gfn << PAGE_SHIFT), kvm, PAGE_SHIFT, false);
+		if (ret) {
+			ret = H_STATE;
+			break;
+		}
+
+		/* relinquish the cpu if needed */
+		cond_resched();
+	}
+	mutex_unlock(&kvm->arch.uvmem_lock);
+	mmap_read_unlock(kvm->mm);
+	return ret;
+}
+
+unsigned long kvmppc_h_svm_init_done(struct kvm *kvm)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	int srcu_idx;
+	long ret = H_SUCCESS;
+
+	if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+		return H_UNSUPPORTED;
+
+	/* migrate any unmoved normal pfn to device pfns*/
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+	slots = kvm_memslots(kvm);
+	kvm_for_each_memslot(memslot, slots) {
+		ret = kvmppc_uv_migrate_mem_slot(kvm, memslot);
+		if (ret) {
+			/*
+			 * The pages will remain transitioned.
+			 * Its the callers responsibility to
+			 * terminate the VM, which will undo
+			 * all state of the VM. Till then
+			 * this VM is in a erroneous state.
+			 * Its KVMPPC_SECURE_INIT_DONE will
+			 * remain unset.
+			 */
+			ret = H_STATE;
+			goto out;
+		}
+	}
+
+	kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE;
+	pr_info("LPID %d went secure\n", kvm->arch.lpid);
+
+out:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+	return ret;
+}
+
 /*
  * Shares the page with HV, thus making it a normal page.
  *
@@ -745,8 +852,11 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa,
 	if (!vma || vma->vm_start > start || vma->vm_end < end)
 		goto out_unlock;
 
-	if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift))
-		ret = H_SUCCESS;
+	if (kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift,
+				true))
+		goto out_unlock;
+
+	ret = H_SUCCESS;
 
 out_unlock:
 	mutex_unlock(&kvm->arch.uvmem_lock);
-- 
1.8.3.1

[PATCH v6 5/5] KVM: PPC: Book3S HV: migrate hot plugged memory

[Ram Pai]

From: Laurent Dufour <ldufour@linux.ibm.com>

When a memory slot is hot plugged to a SVM, PFNs associated with the
GFNs in that slot must be migrated to the secure-PFNs, aka device-PFNs.

Call kvmppc_uv_migrate_mem_slot() to accomplish this.
Disable page-merge for all pages in the memory slot.

Reviewed-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[rearranged the code, and modified the commit log]
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
 arch/powerpc/include/asm/kvm_book3s_uvmem.h | 14 ++++++++++++++
 arch/powerpc/kvm/book3s_hv.c                | 14 ++++++--------
 arch/powerpc/kvm/book3s_hv_uvmem.c          | 23 +++++++++++++++++++----
 3 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index 9cb7d8b..0a63194 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -23,6 +23,10 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
 unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm);
 void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 			     struct kvm *kvm, bool skip_page_out);
+int kvmppc_uvmem_memslot_create(struct kvm *kvm,
+		const struct kvm_memory_slot *new);
+void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+		const struct kvm_memory_slot *old);
 #else
 static inline int kvmppc_uvmem_init(void)
 {
@@ -82,5 +86,15 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
 static inline void
 kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
 			struct kvm *kvm, bool skip_page_out) { }
+
+static inline int  kvmppc_uvmem_memslot_create(struct kvm *kvm,
+		const struct kvm_memory_slot *new)
+{
+	return H_UNSUPPORTED;
+}
+
+static inline void  kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+		const struct kvm_memory_slot *old) { }
+
 #endif /* CONFIG_PPC_UV */
 #endif /* __ASM_KVM_BOOK3S_UVMEM_H__ */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index d331b46..a93bc65 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4515,16 +4515,14 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
 
 	switch (change) {
 	case KVM_MR_CREATE:
-		if (kvmppc_uvmem_slot_init(kvm, new))
-			return;
-		uv_register_mem_slot(kvm->arch.lpid,
-				     new->base_gfn << PAGE_SHIFT,
-				     new->npages * PAGE_SIZE,
-				     0, new->id);
+		/*
+		 * @TODO kvmppc_uvmem_memslot_create() can fail and
+		 * return error. Fix this.
+		 */
+		kvmppc_uvmem_memslot_create(kvm, new);
 		break;
 	case KVM_MR_DELETE:
-		uv_unregister_mem_slot(kvm->arch.lpid, old->id);
-		kvmppc_uvmem_slot_free(kvm, old);
+		kvmppc_uvmem_memslot_delete(kvm, old);
 		break;
 	default:
 		/* TODO: Handle KVM_MR_MOVE */
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index a1664ae..5b917ea 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -418,7 +418,7 @@ static int kvmppc_memslot_page_merge(struct kvm *kvm,
 	return ret;
 }
 
-static void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
+static void __kvmppc_uvmem_memslot_delete(struct kvm *kvm,
 		const struct kvm_memory_slot *memslot)
 {
 	uv_unregister_mem_slot(kvm->arch.lpid, memslot->id);
@@ -426,7 +426,7 @@ static void kvmppc_uvmem_memslot_delete(struct kvm *kvm,
 	kvmppc_memslot_page_merge(kvm, memslot, true);
 }
 
-static int kvmppc_uvmem_memslot_create(struct kvm *kvm,
+static int __kvmppc_uvmem_memslot_create(struct kvm *kvm,
 		const struct kvm_memory_slot *memslot)
 {
 	int ret = H_PARAMETER;
@@ -478,7 +478,7 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 	/* register the memslot */
 	slots = kvm_memslots(kvm);
 	kvm_for_each_memslot(memslot, slots) {
-		ret = kvmppc_uvmem_memslot_create(kvm, memslot);
+		ret = __kvmppc_uvmem_memslot_create(kvm, memslot);
 		if (ret)
 			break;
 	}
@@ -488,7 +488,7 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
 		kvm_for_each_memslot(m, slots) {
 			if (m == memslot)
 				break;
-			kvmppc_uvmem_memslot_delete(kvm, memslot);
+			__kvmppc_uvmem_memslot_delete(kvm, memslot);
 		}
 	}
 
@@ -1057,6 +1057,21 @@ int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
 	return (ret == U_SUCCESS) ? RESUME_GUEST : -EFAULT;
 }
 
+int kvmppc_uvmem_memslot_create(struct kvm *kvm, const struct kvm_memory_slot *new)
+{
+	int ret = __kvmppc_uvmem_memslot_create(kvm, new);
+
+	if (!ret)
+		ret = kvmppc_uv_migrate_mem_slot(kvm, new);
+
+	return ret;
+}
+
+void kvmppc_uvmem_memslot_delete(struct kvm *kvm, const struct kvm_memory_slot *old)
+{
+	__kvmppc_uvmem_memslot_delete(kvm, old);
+}
+
 static u64 kvmppc_get_secmem_size(void)
 {
 	struct device_node *np;
-- 
1.8.3.1

Re: [PATCH v6 0/5] Migrate non-migrated pages of a SVM.

[Paul Mackerras]

On Mon, Jul 27, 2020 at 11:07:13AM -0700, Ram Pai wrote:
> The time to switch a VM to Secure-VM, increases by the size of the VM.
> A 100GB VM takes about 7minutes. This is unacceptable.  This linear
> increase is caused by a suboptimal behavior by the Ultravisor and the
> Hypervisor.  The Ultravisor unnecessarily migrates all the GFN of the
> VM from normal-memory to secure-memory. It has to just migrate the
> necessary and sufficient GFNs.
> 
> However when the optimization is incorporated in the Ultravisor, the
> Hypervisor starts misbehaving. The Hypervisor has a inbuilt assumption
> that the Ultravisor will explicitly request to migrate, each and every
> GFN of the VM. If only necessary and sufficient GFNs are requested for
> migration, the Hypervisor continues to manage the remaining GFNs as
> normal GFNs. This leads to memory corruption; manifested
> consistently when the SVM reboots.
> 
> The same is true, when a memory slot is hotplugged into a SVM. The
> Hypervisor expects the ultravisor to request migration of all GFNs to
> secure-GFN.  But the hypervisor cannot handle any H_SVM_PAGE_IN
> requests from the Ultravisor, done in the context of
> UV_REGISTER_MEM_SLOT ucall.  This problem manifests as random errors
> in the SVM, when a memory-slot is hotplugged.
> 
> This patch series automatically migrates the non-migrated pages of a
> SVM, and thus solves the problem.
> 
> Testing: Passed rigorous testing using various sized SVMs.

Thanks, series applied to my kvm-ppc-next branch and pull request sent.

Paul.