commit 6fc138d2278078990f597cb1f62fde9e5b458f96
author Izik Eidus <izike@qumranet.com> Tue Oct 09 19:20:39 2007 +0200
committer Avi Kivity <avi@qumranet.com> Wed Jan 30 17:52:51 2008 +0200
tree 176026316843a4e47b8271f0e84a03f8807ecb64
parent d77c26fce93d07802db97498959587eb9347b31d

KVM: Support assigning userspace memory to the guest

Instead of having the kernel allocate memory to the guest, let userspace
allocate it and pass the address to the kernel.

This is required for s390 support, but also enables features like memory
sharing and using hugetlbfs backed memory.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a1983d2..22b143f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -40,6 +40,7 @@
 #include <linux/anon_inodes.h>
 #include <linux/profile.h>
 #include <linux/kvm_para.h>
+#include <linux/pagemap.h>
 
 #include <asm/processor.h>
 #include <asm/msr.h>
@@ -300,19 +301,40 @@
 	return kvm;
 }
 
+static void kvm_free_userspace_physmem(struct kvm_memory_slot *free)
+{
+	int i;
+
+	for (i = 0; i < free->npages; ++i) {
+		if (free->phys_mem[i]) {
+			if (!PageReserved(free->phys_mem[i]))
+				SetPageDirty(free->phys_mem[i]);
+			page_cache_release(free->phys_mem[i]);
+		}
+	}
+}
+
+static void kvm_free_kernel_physmem(struct kvm_memory_slot *free)
+{
+	int i;
+
+	for (i = 0; i < free->npages; ++i)
+		if (free->phys_mem[i])
+			__free_page(free->phys_mem[i]);
+}
+
 /*
  * Free any memory in @free but not in @dont.
  */
 static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
 				  struct kvm_memory_slot *dont)
 {
-	int i;
-
 	if (!dont || free->phys_mem != dont->phys_mem)
 		if (free->phys_mem) {
-			for (i = 0; i < free->npages; ++i)
-				if (free->phys_mem[i])
-					__free_page(free->phys_mem[i]);
+			if (free->user_alloc)
+				kvm_free_userspace_physmem(free);
+			else
+				kvm_free_kernel_physmem(free);
 			vfree(free->phys_mem);
 		}
 	if (!dont || free->rmap != dont->rmap)
@@ -652,7 +674,9 @@
  * Discontiguous memory is allowed, mostly for framebuffers.
  */
 static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
-					  struct kvm_memory_region *mem)
+					  struct
+					  kvm_userspace_memory_region *mem,
+					  int user_alloc)
 {
 	int r;
 	gfn_t base_gfn;
@@ -728,11 +752,27 @@
 
 		memset(new.phys_mem, 0, npages * sizeof(struct page *));
 		memset(new.rmap, 0, npages * sizeof(*new.rmap));
-		for (i = 0; i < npages; ++i) {
-			new.phys_mem[i] = alloc_page(GFP_HIGHUSER
-						     | __GFP_ZERO);
-			if (!new.phys_mem[i])
+		if (user_alloc) {
+			unsigned long pages_num;
+
+			new.user_alloc = 1;
+			down_read(&current->mm->mmap_sem);
+
+			pages_num = get_user_pages(current, current->mm,
+						   mem->userspace_addr,
+						   npages, 1, 1, new.phys_mem,
+						   NULL);
+
+			up_read(&current->mm->mmap_sem);
+			if (pages_num != npages)
 				goto out_unlock;
+		} else {
+			for (i = 0; i < npages; ++i) {
+				new.phys_mem[i] = alloc_page(GFP_HIGHUSER
+							     | __GFP_ZERO);
+				if (!new.phys_mem[i])
+					goto out_unlock;
+			}
 		}
 	}
 
@@ -3108,11 +3148,29 @@
 		break;
 	case KVM_SET_MEMORY_REGION: {
 		struct kvm_memory_region kvm_mem;
+		struct kvm_userspace_memory_region kvm_userspace_mem;
 
 		r = -EFAULT;
 		if (copy_from_user(&kvm_mem, argp, sizeof kvm_mem))
 			goto out;
-		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_mem);
+		kvm_userspace_mem.slot = kvm_mem.slot;
+		kvm_userspace_mem.flags = kvm_mem.flags;
+		kvm_userspace_mem.guest_phys_addr = kvm_mem.guest_phys_addr;
+		kvm_userspace_mem.memory_size = kvm_mem.memory_size;
+		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem, 0);
+		if (r)
+			goto out;
+		break;
+	}
+	case KVM_SET_USER_MEMORY_REGION: {
+		struct kvm_userspace_memory_region kvm_userspace_mem;
+
+		r = -EFAULT;
+		if (copy_from_user(&kvm_userspace_mem, argp,
+						sizeof kvm_userspace_mem))
+			goto out;
+
+		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem, 1);
 		if (r)
 			goto out;
 		break;
@@ -3332,6 +3390,7 @@
 		case KVM_CAP_IRQCHIP:
 		case KVM_CAP_HLT:
 		case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
+		case KVM_CAP_USER_MEMORY:
 			r = 1;
 			break;
 		default: