Re: [PATCH v1 4/4] KVM: PPC: Book3S HV: migrate hot plugged memory

From: Laurent Dufour <redacted>

When a memory slot is hot plugged to a SVM, GFNs associated with that
memory slot automatically default to secure GFN. Hence migrate the
PFNs associated with these GFNs to device-PFNs.

uv_migrate_mem_slot() is called to achieve that. It will not call
UV_PAGE_IN since this request is ignored by the Ultravisor.
NOTE: Ultravisor does not trust any page content provided by
the Hypervisor, ones the VM turns secure.

Cc: Paul Mackerras <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Bharata B Rao <redacted>
Cc: Aneesh Kumar K.V <redacted>
Cc: Sukadev Bhattiprolu <redacted>
Cc: Laurent Dufour <redacted>
Cc: Thiago Jung Bauermann <redacted>
Cc: David Gibson <redacted>
Cc: Claudio Carvalho <redacted>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Ram Pai <redacted>
	(fixed merge conflicts. Modified the commit message)
Signed-off-by: Laurent Dufour <redacted>
---
  arch/powerpc/include/asm/kvm_book3s_uvmem.h |  4 ++++
  arch/powerpc/kvm/book3s_hv.c                | 11 +++++++----
  arch/powerpc/kvm/book3s_hv_uvmem.c          |  3 +--
  3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
index f0c5708..2ec2e5afb 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h

@@ -23,6 +23,7 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm,
  void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
  			     struct kvm *kvm, bool skip_page_out,
  			     bool purge_gfn);
+int uv_migrate_mem_slot(struct kvm *kvm, const struct kvm_memory_slot *memslot);
  #else
  static inline int kvmppc_uvmem_init(void)
  {

@@ -78,5 +79,8 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
  kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
  			struct kvm *kvm, bool skip_page_out,
  			bool purge_gfn) { }
+
+static int uv_migrate_mem_slot(struct kvm *kvm,
+		const struct kvm_memory_slot *memslot);
  #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 4c62bfe..604d062 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c

@@ -4516,13 +4516,16 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
  	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);
+		if (uv_register_mem_slot(kvm->arch.lpid,
+					 new->base_gfn << PAGE_SHIFT,
+					 new->npages * PAGE_SIZE,
+					 0, new->id))
+			return;
+		uv_migrate_mem_slot(kvm, new);
  		break;
  	case KVM_MR_DELETE:
  		uv_unregister_mem_slot(kvm->arch.lpid, old->id);
+		kvmppc_uvmem_drop_pages(old, kvm, true, true);

  		kvmppc_uvmem_slot_free(kvm, old);
  		break;
  	default:

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 36dda1d..1fa5f2a 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c

@@ -377,8 +377,7 @@ static int kvmppc_svm_migrate_page(struct vm_area_struct *vma,
  	return ret;
  }
  
-static int uv_migrate_mem_slot(struct kvm *kvm,
-		const struct kvm_memory_slot *memslot)
+int uv_migrate_mem_slot(struct kvm *kvm, const struct kvm_memory_slot *memslot)
  {
  	unsigned long gfn = memslot->base_gfn;
  	unsigned long end;