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KVM: Move memslot deletion to helper function
Move memslot deletion into its own routine so that the success path for other memslot updates does not need to use kvm_free_memslot(), i.e. can explicitly destroy the dirty bitmap when necessary. This paves the way for dropping @dont from kvm_free_memslot(), i.e. all callers now pass NULL for @dont. Add a comment above the code to make a copy of the existing memslot prior to deletion, it is not at all obvious that the pointer will become stale during sorting and/or installation of new memslots. Note, kvm_arch_commit_memory_region() allows an architecture to free resources when moving a memslot or changing its flags, e.g. x86 frees its arch specific memslot metadata during commit_memory_region(). Acked-by: Christoffer Dall <christoffer.dall@arm.com> Tested-by: Christoffer Dall <christoffer.dall@arm.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -1043,6 +1043,27 @@ out_slots:
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return r;
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return r;
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}
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}
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static int kvm_delete_memslot(struct kvm *kvm,
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const struct kvm_userspace_memory_region *mem,
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struct kvm_memory_slot *old, int as_id)
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{
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struct kvm_memory_slot new;
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int r;
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if (!old->npages)
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return -EINVAL;
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memset(&new, 0, sizeof(new));
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new.id = old->id;
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r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE);
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if (r)
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return r;
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kvm_free_memslot(kvm, old, NULL);
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return 0;
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}
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/*
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/*
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* Allocate some memory and give it an address in the guest physical address
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* Allocate some memory and give it an address in the guest physical address
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* space.
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* space.
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@ -1092,7 +1113,17 @@ int __kvm_set_memory_region(struct kvm *kvm,
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if (npages > KVM_MEM_MAX_NR_PAGES)
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if (npages > KVM_MEM_MAX_NR_PAGES)
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return -EINVAL;
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return -EINVAL;
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new = old = *slot;
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/*
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* Make a full copy of the old memslot, the pointer will become stale
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* when the memslots are re-sorted by update_memslots(), and the old
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* memslot needs to be referenced after calling update_memslots(), e.g.
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* to free its resources and for arch specific behavior.
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*/
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old = *slot;
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if (!mem->memory_size)
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return kvm_delete_memslot(kvm, mem, &old, as_id);
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new = old;
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new.id = id;
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new.id = id;
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new.base_gfn = base_gfn;
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new.base_gfn = base_gfn;
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@ -1100,10 +1131,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
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new.flags = mem->flags;
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new.flags = mem->flags;
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new.userspace_addr = mem->userspace_addr;
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new.userspace_addr = mem->userspace_addr;
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if (npages) {
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if (!old.npages) {
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if (!old.npages)
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change = KVM_MR_CREATE;
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change = KVM_MR_CREATE;
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else { /* Modify an existing slot. */
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} else { /* Modify an existing slot. */
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if ((new.userspace_addr != old.userspace_addr) ||
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if ((new.userspace_addr != old.userspace_addr) ||
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(npages != old.npages) ||
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(npages != old.npages) ||
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((new.flags ^ old.flags) & KVM_MEM_READONLY))
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((new.flags ^ old.flags) & KVM_MEM_READONLY))
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@ -1116,14 +1146,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
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else /* Nothing to change. */
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else /* Nothing to change. */
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return 0;
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return 0;
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}
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}
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} else {
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if (!old.npages)
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return -EINVAL;
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change = KVM_MR_DELETE;
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new.base_gfn = 0;
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new.flags = 0;
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}
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if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
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if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
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/* Check for overlaps */
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/* Check for overlaps */
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@ -1145,17 +1167,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
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return r;
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return r;
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}
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}
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/* actual memory is freed via old in kvm_free_memslot below */
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if (change == KVM_MR_DELETE) {
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new.dirty_bitmap = NULL;
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memset(&new.arch, 0, sizeof(new.arch));
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}
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r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
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r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
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if (r)
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if (r)
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goto out_bitmap;
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goto out_bitmap;
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kvm_free_memslot(kvm, &old, &new);
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if (old.dirty_bitmap && !new.dirty_bitmap)
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kvm_destroy_dirty_bitmap(&old);
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return 0;
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return 0;
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out_bitmap:
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out_bitmap:
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