We are going unmap guest pages from direct mapping and cannot rely on it for guest memory access. Use temporary kmap_atomic()-style mapping to access guest memory.
Signed-off-by: Kirill A. Shutemov <[email protected]> --- virt/kvm/kvm_main.c | 57 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 55 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 07d45da5d2aa..63282def3760 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2258,17 +2258,45 @@ static int next_segment(unsigned long len, int offset) return len; } +static pte_t **guest_map_ptes; +static struct vm_struct *guest_map_area; + +static void *map_page_atomic(struct page *page) +{ + pte_t *pte; + void *vaddr; + + preempt_disable(); + pte = guest_map_ptes[smp_processor_id()]; + vaddr = guest_map_area->addr + smp_processor_id() * PAGE_SIZE; + set_pte(pte, mk_pte(page, PAGE_KERNEL)); + return vaddr; +} + +static void unmap_page_atomic(void *vaddr) +{ + pte_t *pte = guest_map_ptes[smp_processor_id()]; + set_pte(pte, __pte(0)); + __flush_tlb_one_kernel((unsigned long)vaddr); + preempt_enable(); +} + int copy_from_guest(void *data, unsigned long hva, int len) { int offset = offset_in_page(hva); struct page *page; int npages, seg; + void *vaddr; while ((seg = next_segment(len, offset)) != 0) { npages = get_user_pages_unlocked(hva, 1, &page, FOLL_KVM); if (npages != 1) return -EFAULT; - memcpy(data, page_address(page) + offset, seg); + + vaddr = map_page_atomic(page); + memcpy(data, vaddr + offset, seg); + unmap_page_atomic(vaddr); + put_page(page); len -= seg; hva += seg; @@ -2283,13 +2311,18 @@ int copy_to_guest(unsigned long hva, const void *data, int len) int offset = offset_in_page(hva); struct page *page; int npages, seg; + void *vaddr; while ((seg = next_segment(len, offset)) != 0) { npages = get_user_pages_unlocked(hva, 1, &page, FOLL_WRITE | FOLL_KVM); if (npages != 1) return -EFAULT; - memcpy(page_address(page) + offset, data, seg); + + vaddr = map_page_atomic(page); + memcpy(vaddr + offset, data, seg); + unmap_page_atomic(vaddr); + put_page(page); len -= seg; hva += seg; @@ -4921,6 +4954,18 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, if (r) goto out_free; + if (VM_KVM_PROTECTED) { + guest_map_ptes = kmalloc_array(num_possible_cpus(), + sizeof(pte_t *), GFP_KERNEL); + if (!guest_map_ptes) + goto out_unreg; + + guest_map_area = alloc_vm_area(PAGE_SIZE * num_possible_cpus(), + guest_map_ptes); + if (!guest_map_ptes) + goto out_unreg; + } + kvm_chardev_ops.owner = module; kvm_vm_fops.owner = module; kvm_vcpu_fops.owner = module; @@ -4944,6 +4989,10 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, return 0; out_unreg: + if (guest_map_area) + free_vm_area(guest_map_area); + if (guest_map_ptes) + kfree(guest_map_ptes); kvm_async_pf_deinit(); out_free: kmem_cache_destroy(kvm_vcpu_cache); @@ -4965,6 +5014,10 @@ EXPORT_SYMBOL_GPL(kvm_init); void kvm_exit(void) { + if (guest_map_area) + free_vm_area(guest_map_area); + if (guest_map_ptes) + kfree(guest_map_ptes); debugfs_remove_recursive(kvm_debugfs_dir); misc_deregister(&kvm_dev); kmem_cache_destroy(kvm_vcpu_cache); -- 2.26.2
