+static bool is_hva_registered(struct kvm *kvm, hva_t hva, size_t len)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct list_head *head = &sev->regions_list;
+	struct enc_region *i;
+
+	lockdep_assert_held(&kvm->lock);
+
+	list_for_each_entry(i, head, list) {
+		u64 start = i->uaddr;
+		u64 end = start + i->size;
+
+		if (start <= hva && end >= (hva + len))
+			return true;
+	}
+
+	return false;
+}

Since KVM_MEMORY_ENCRYPT_REG_REGION should be called for every memory region the user gives to kvm,
is the regions_list any different from kvm's memslots?

+
+static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	struct sev_data_snp_launch_update data = {0};
+	struct kvm_sev_snp_launch_update params;
+	unsigned long npages, pfn, n = 0;
+	int *error = &argp->error;
+	struct page **inpages;
+	int ret, i, level;
+	u64 gfn;
+
+	if (!sev_snp_guest(kvm))
+		return -ENOTTY;
+
+	if (!sev->snp_context)
+		return -EINVAL;
+
+	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
+		return -EFAULT;
+
+	/* Verify that the specified address range is registered. */
+	if (!is_hva_registered(kvm, params.uaddr, params.len))
+		return -EINVAL;
+
+	/*
+	 * The userspace memory is already locked so technically we don't
+	 * need to lock it again. Later part of the function needs to know
+	 * pfn so call the sev_pin_memory() so that we can get the list of
+	 * pages to iterate through.
+	 */
+	inpages = sev_pin_memory(kvm, params.uaddr, params.len, &npages, 1);
+	if (!inpages)
+		return -ENOMEM;

sev_pin_memory will call pin_user_pages() which fails for PFNMAP vmas that you
would get if you use memory allocated from an IO driver.
Using gfn_to_pfn instead will make this work with vmas backed by pages or raw
pfn mappings.




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