KVM: Portability: Split kvm_set_memory_region() to have an arch callout

Moving !user_alloc case to kvm_arch to avoid unnecessary
code logic in non-x86 platform.

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c
index 5a54e328088d..6abb2ed1a908 100644
--- a/drivers/kvm/x86.c
+++ b/drivers/kvm/x86.c
@@ -24,6 +24,7 @@
 #include <linux/fs.h>
 #include <linux/vmalloc.h>
 #include <linux/module.h>
+#include <linux/mman.h>
 
 #include <asm/uaccess.h>
 #include <asm/msr.h>
@@ -2637,3 +2638,53 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
         kvm_free_physmem(kvm);
         kfree(kvm);
 }
+
+int kvm_arch_set_memory_region(struct kvm *kvm,
+                                struct kvm_userspace_memory_region *mem,
+                                struct kvm_memory_slot old,
+                                int user_alloc)
+{
+        int npages = mem->memory_size >> PAGE_SHIFT;
+        struct kvm_memory_slot *memslot = &kvm->memslots[mem->slot];
+
+        /*To keep backward compatibility with older userspace,
+         *x86 needs to hanlde !user_alloc case.
+         */
+        if (!user_alloc) {
+                if (npages && !old.rmap) {
+                        down_write(&current->mm->mmap_sem);
+                        memslot->userspace_addr = do_mmap(NULL, 0,
+                                                     npages * PAGE_SIZE,
+                                                     PROT_READ | PROT_WRITE,
+                                                     MAP_SHARED | MAP_ANONYMOUS,
+                                                     0);
+                        up_write(&current->mm->mmap_sem);
+
+                        if (IS_ERR((void *)memslot->userspace_addr))
+                                return PTR_ERR((void *)memslot->userspace_addr);
+                } else {
+                        if (!old.user_alloc && old.rmap) {
+                                int ret;
+
+                                down_write(&current->mm->mmap_sem);
+                                ret = do_munmap(current->mm, old.userspace_addr,
+                                                old.npages * PAGE_SIZE);
+                                up_write(&current->mm->mmap_sem);
+                                if (ret < 0)
+                                        printk(KERN_WARNING
+                                       "kvm_vm_ioctl_set_memory_region: "
+                                       "failed to munmap memory\n");
+                        }
+                }
+        }
+
+        if (!kvm->n_requested_mmu_pages) {
+                unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
+                kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
+        }
+
+        kvm_mmu_slot_remove_write_access(kvm, mem->slot);
+        kvm_flush_remote_tlbs(kvm);
+
+        return 0;
+}