From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Tue, 21 Jan 2020 22:31:50 +0000 Subject: [PATCH v5 12/19] KVM: Move memslot deletion to helper function Message-Id: <20200121223157.15263-13-sean.j.christopherson@intel.com> List-Id: References: <20200121223157.15263-1-sean.j.christopherson@intel.com> In-Reply-To: <20200121223157.15263-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Paolo Bonzini Cc: Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall , Peter Xu , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= 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 Tested-by: Christoffer Dall Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 73 +++++++++++++++++++++++++++------------------ 1 file changed, 44 insertions(+), 29 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 69d6158cb405..5ae2dd6d9993 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1042,6 +1042,27 @@ static int kvm_set_memslot(struct kvm *kvm, return r; } +static int kvm_delete_memslot(struct kvm *kvm, + const struct kvm_userspace_memory_region *mem, + struct kvm_memory_slot *old, int as_id) +{ + struct kvm_memory_slot new; + int r; + + if (!old->npages) + return -EINVAL; + + memset(&new, 0, sizeof(new)); + new.id = old->id; + + r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE); + if (r) + return r; + + kvm_free_memslot(kvm, old, NULL); + return 0; +} + /* * Allocate some memory and give it an address in the guest physical address * space. @@ -1091,7 +1112,15 @@ int __kvm_set_memory_region(struct kvm *kvm, if (npages > KVM_MEM_MAX_NR_PAGES) return -EINVAL; - new = old = *slot; + /* + * Make a full copy of the old memslot, the pointer will become stale + * when the memslots are re-sorted by update_memslots(). + */ + old = *slot; + if (!mem->memory_size) + return kvm_delete_memslot(kvm, mem, &old, as_id); + + new = old; new.id = id; new.base_gfn = base_gfn; @@ -1099,29 +1128,20 @@ int __kvm_set_memory_region(struct kvm *kvm, new.flags = mem->flags; new.userspace_addr = mem->userspace_addr; - if (npages) { - if (!old.npages) - change = KVM_MR_CREATE; - else { /* Modify an existing slot. */ - if ((new.userspace_addr != old.userspace_addr) || - (npages != old.npages) || - ((new.flags ^ old.flags) & KVM_MEM_READONLY)) - return -EINVAL; - - if (base_gfn != old.base_gfn) - change = KVM_MR_MOVE; - else if (new.flags != old.flags) - change = KVM_MR_FLAGS_ONLY; - else /* Nothing to change. */ - return 0; - } - } else { - if (!old.npages) + if (!old.npages) { + change = KVM_MR_CREATE; + } else { /* Modify an existing slot. */ + if ((new.userspace_addr != old.userspace_addr) || + (npages != old.npages) || + ((new.flags ^ old.flags) & KVM_MEM_READONLY)) return -EINVAL; - change = KVM_MR_DELETE; - new.base_gfn = 0; - new.flags = 0; + if (base_gfn != old.base_gfn) + change = KVM_MR_MOVE; + else if (new.flags != old.flags) + change = KVM_MR_FLAGS_ONLY; + else /* Nothing to change. */ + return 0; } if ((change = KVM_MR_CREATE) || (change = KVM_MR_MOVE)) { @@ -1144,17 +1164,12 @@ int __kvm_set_memory_region(struct kvm *kvm, return r; } - /* 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)); - } - r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change); if (r) goto out_bitmap; - kvm_free_memslot(kvm, &old, &new); + if (old.dirty_bitmap && !new.dirty_bitmap) + kvm_destroy_dirty_bitmap(&old); return 0; out_bitmap: -- 2.24.1