From f0d648bdf0a5bbc91da6099d5282f77996558ea4 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 12 Oct 2015 13:56:27 +0200 Subject: [PATCH] KVM: x86: map/unmap private slots in __x86_set_memory_region MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Otherwise, two copies (one of them never populated and thus bogus) are allocated for the regular and SMM address spaces. This breaks SMM with EPT but without unrestricted guest support, because the SMM copy of the identity page map is all zeros. By moving the allocation to the caller we also remove the last vestiges of kernel-allocated memory regions (not accessible anymore in userspace since commit b74a07beed0e, "KVM: Remove kernel-allocated memory regions", 2010-06-21); that is a nice bonus. Reported-by: Alexandre DERUMIER Cc: stable@vger.kernel.org Fixes: 9da0e4d5ac969909f6b435ce28ea28135a9cbd69 Reviewed-by: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 62 ++++++++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 32 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7bf8096f013d..3ac33f86c873 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7477,23 +7477,53 @@ void kvm_arch_sync_events(struct kvm *kvm) int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size) { int i, r; + u64 hva; + struct kvm_memslots *slots = kvm_memslots(kvm); + struct kvm_memory_slot *slot, old; /* Called with kvm->slots_lock held. */ if (WARN_ON(id >= KVM_MEM_SLOTS_NUM)) return -EINVAL; + slot = id_to_memslot(slots, id); + if (size) { + if (WARN_ON(slot->npages)) + return -EEXIST; + + /* + * MAP_SHARED to prevent internal slot pages from being moved + * by fork()/COW. + */ + hva = vm_mmap(NULL, 0, size, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, 0); + if (IS_ERR((void *)hva)) + return PTR_ERR((void *)hva); + } else { + if (!slot->npages) + return 0; + + hva = 0; + } + + old = *slot; for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { struct kvm_userspace_memory_region m; m.slot = id | (i << 16); m.flags = 0; m.guest_phys_addr = gpa; + m.userspace_addr = hva; m.memory_size = size; r = __kvm_set_memory_region(kvm, &m); if (r < 0) return r; } + if (!size) { + r = vm_munmap(old.userspace_addr, old.npages * PAGE_SIZE); + WARN_ON(r < 0); + } + return 0; } EXPORT_SYMBOL_GPL(__x86_set_memory_region); @@ -7623,27 +7653,6 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, const struct kvm_userspace_memory_region *mem, enum kvm_mr_change change) { - /* - * Only private memory slots need to be mapped here since - * KVM_SET_MEMORY_REGION ioctl is no longer supported. - */ - if ((memslot->id >= KVM_USER_MEM_SLOTS) && (change == KVM_MR_CREATE)) { - unsigned long userspace_addr; - - /* - * MAP_SHARED to prevent internal slot pages from being moved - * by fork()/COW. - */ - userspace_addr = vm_mmap(NULL, 0, memslot->npages * PAGE_SIZE, - PROT_READ | PROT_WRITE, - MAP_SHARED | MAP_ANONYMOUS, 0); - - if (IS_ERR((void *)userspace_addr)) - return PTR_ERR((void *)userspace_addr); - - memslot->userspace_addr = userspace_addr; - } - return 0; } @@ -7705,17 +7714,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, { int nr_mmu_pages = 0; - if (change == KVM_MR_DELETE && old->id >= KVM_USER_MEM_SLOTS) { - int ret; - - ret = vm_munmap(old->userspace_addr, - old->npages * PAGE_SIZE); - if (ret < 0) - printk(KERN_WARNING - "kvm_vm_ioctl_set_memory_region: " - "failed to munmap memory\n"); - } - if (!kvm->arch.n_requested_mmu_pages) nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm); -- 2.20.1