Re: [PATCH v10 2/9] KVM: Introduce per-page memory attributes

Isaku Yamahata
2023-02-09T07:25:54Z

On Fri, Dec 02, 2022 at 02:13:40PM +0800,
Chao Peng <chao.p.peng@linux.intel.com> wrote:

> +static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm,
> + struct kvm_memory_attributes *attrs)
> +{
> + gfn_t start, end;
> + unsigned long i;
> + void *entry;
> + u64 supported_attrs = kvm_supported_mem_attributes(kvm);
> +
> + /* flags is currently not used. */
> + if (attrs->flags)
> + return -EINVAL;
> + if (attrs->attributes & ~supported_attrs)
> + return -EINVAL;
> + if (attrs->size == 0 || attrs->address + attrs->size < attrs->address)
> + return -EINVAL;
> + if (!PAGE_ALIGNED(attrs->address) || !PAGE_ALIGNED(attrs->size))
> + return -EINVAL;
> +
> + start = attrs->address >> PAGE_SHIFT;
> + end = (attrs->address + attrs->size - 1 + PAGE_SIZE) >> PAGE_SHIFT;
> +
> + entry = attrs->attributes ? xa_mk_value(attrs->attributes) : NULL;
> +
> + mutex_lock(&kvm->lock);
> + for (i = start; i < end; i++)
> + if (xa_err(xa_store(&kvm->mem_attr_array, i, entry,
> + GFP_KERNEL_ACCOUNT)))
> + break;
> + mutex_unlock(&kvm->lock);
> +
> + attrs->address = i << PAGE_SHIFT;
> + attrs->size = (end - i) << PAGE_SHIFT;
> +
> + return 0;
> +}
> +#endif /* CONFIG_HAVE_KVM_MEMORY_ATTRIBUTES */
> +

If memslot isn't private, it should return error if private attribute is set.
Something like following check is needed.

+ if (attrs->flags & KVM_MEM_PRIVATE) {
+ /* non-private memory slot doesn't allow KVM_MEM_PRIVATE */
+ for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
+ struct kvm_memslot_iter iter;
+ struct kvm_memslots *slots;
+
+ slots = __kvm_memslots(kvm, i);
+ kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
+ if (!kvm_slot_can_be_private(iter.slot)) {
+ mutex_unlock(&kvm->slots_lock);
+ return -EINVAL;
+ }
+ }
+ }
+ }
+

--
Isaku Yamahata <isaku.yamahata@gmail.com>