[PATCH v5 09/19] KVM: Move setting of memslot into helper routine

Sean Christopherson
2020-01-21T22:32:07Z

Split out the core functionality of setting a memslot into a separate
helper in preparation for moving memslot deletion into its own routine.

Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
virt/kvm/kvm_main.c | 106 ++++++++++++++++++++++++++------------------
1 file changed, 63 insertions(+), 43 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fdf045a5d240..64f6c5d35260 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -982,6 +982,66 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
return old_memslots;
}

+static int kvm_set_memslot(struct kvm *kvm,
+ const struct kvm_userspace_memory_region *mem,
+ const struct kvm_memory_slot *old,
+ struct kvm_memory_slot *new, int as_id,
+ enum kvm_mr_change change)
+{
+ struct kvm_memory_slot *slot;
+ struct kvm_memslots *slots;
+ int r;
+
+ slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
+ if (!slots)
+ return -ENOMEM;
+ memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
+
+ if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
+ /*
+ * Note, the INVALID flag needs to be in the appropriate entry
+ * in the freshly allocated memslots, not in @old or @new.
+ */
+ slot = id_to_memslot(slots, old->id);
+ slot->flags |= KVM_MEMSLOT_INVALID;
+
+ /*
+ * We can re-use the old memslots, the only difference from the
+ * newly installed memslots is the invalid flag, which will get
+ * dropped by update_memslots anyway. We'll also revert to the
+ * old memslots if preparing the new memory region fails.
+ */
+ slots = install_new_memslots(kvm, as_id, slots);
+
+ /* From this point no new shadow pages pointing to a deleted,
+ * or moved, memslot will be created.
+ *
+ * validation of sp->gfn happens in:
+ * - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
+ * - kvm_is_visible_gfn (mmu_check_root)
+ */
+ kvm_arch_flush_shadow_memslot(kvm, slot);
+ }
+
+ r = kvm_arch_prepare_memory_region(kvm, new, mem, change);
+ if (r)
+ goto out_slots;
+
+ update_memslots(slots, new, change);
+ slots = install_new_memslots(kvm, as_id, slots);
+
+ kvm_arch_commit_memory_region(kvm, mem, old, new, change);
+
+ kvfree(slots);
+ return 0;
+
+out_slots:
+ if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
+ slots = install_new_memslots(kvm, as_id, slots);
+ kvfree(slots);
+ return r;
+}
+
/*
* Allocate some memory and give it an address in the guest physical address
* space.
@@ -998,7 +1058,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
unsigned long npages;
struct kvm_memory_slot *slot;
struct kvm_memory_slot old, new;
- struct kvm_memslots *slots;
int as_id, id;
enum kvm_mr_change change;

@@ -1085,58 +1144,19 @@ int __kvm_set_memory_region(struct kvm *kvm,
return r;
}

- slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
- if (!slots) {
- r = -ENOMEM;
- goto out_bitmap;
- }
- memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
-
- if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
- slot = id_to_memslot(slots, id);
- slot->flags |= KVM_MEMSLOT_INVALID;
-
- /*
- * We can re-use the old memslots, the only difference from the
- * newly installed memslots is the invalid flag, which will get
- * dropped by update_memslots anyway. We'll also revert to the
- * old memslots if preparing the new memory region fails.
- */
- slots = install_new_memslots(kvm, as_id, slots);
-
- /* From this point no new shadow pages pointing to a deleted,
- * or moved, memslot will be created.
- *
- * validation of sp->gfn happens in:
- * - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
- * - kvm_is_visible_gfn (mmu_check_root)
- */
- kvm_arch_flush_shadow_memslot(kvm, slot);
- }
-
- r = kvm_arch_prepare_memory_region(kvm, &new, mem, change);
- if (r)
- goto out_slots;
-
/* actual memory is freed via old in kvm_free_memslot below */
if (change == KVM_MR_DELETE) {
new.dirty_bitmap = NULL;
memset(&new.arch, 0, sizeof(new.arch));
}

- update_memslots(slots, &new, change);
- slots = install_new_memslots(kvm, as_id, slots);
-
- kvm_arch_commit_memory_region(kvm, mem, &old, &new, change);
+ r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
+ if (r)
+ goto out_bitmap;

kvm_free_memslot(kvm, &old, &new);
- kvfree(slots);
return 0;

-out_slots:
- if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
- slots = install_new_memslots(kvm, as_id, slots);
- kvfree(slots);
out_bitmap:
if (new.dirty_bitmap && !old.dirty_bitmap)
kvm_destroy_dirty_bitmap(&new);
--
2.24.1