KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 391 insertions, 0 deletions

diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
new file mode 100644
index 000000000..075f38a67
--- /dev/null
+++ b/drivers/crypto/atmel-ecc.c
@@ -0,0 +1,391 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip / Atmel ECC (I2C) driver.
+ *
+ * Copyright (c) 2017, Microchip Technology Inc.
+ * Author: Tudor Ambarus
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <crypto/internal/kpp.h>
+#include <crypto/ecdh.h>
+#include <crypto/kpp.h>
+#include "atmel-i2c.h"
+
+static struct atmel_ecc_driver_data driver_data;
+
+/**
+ * struct atmel_ecdh_ctx - transformation context
+ * @client: I2C client device
+ * @fallback: ECDH fallback used for caller-provided private keys
+ * @public_key: cached public key for the device-generated private key
+ * @do_fallback: true when ECDH operations should use @fallback
+ *
+ * The caller must not invoke set_secret() while generate_public_key()
+ * or compute_shared_secret() are in flight.
+ */
+struct atmel_ecdh_ctx {
+	struct i2c_client *client;
+	struct crypto_kpp *fallback;
+	const u8 *public_key;
+	bool do_fallback;
+};
+
+static void atmel_ecdh_done(struct atmel_i2c_work_data *work_data, void *areq,
+			    int status)
+{
+	struct kpp_request *req = areq;
+	struct atmel_i2c_cmd *cmd = &work_data->cmd;
+	size_t copied, n_sz;
+
+	if (status)
+		goto free_work_data;
+
+	/* copy only as much as requested, capped at 32 bytes */
+	n_sz = min(ATMEL_ECC_NIST_P256_N_SIZE, req->dst_len);
+
+	/* copy the shared secret */
+	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, n_sz),
+				     &cmd->data[RSP_DATA_IDX], n_sz);
+	if (copied != n_sz)
+		status = -EINVAL;
+
+free_work_data:
+	kfree_sensitive(work_data);
+	kpp_request_complete(req, status);
+}
+
+/*
+ * If no private key is provided, generate one in the device and cache
+ * the corresponding public key. The generated private key never leaves
+ * the device.
+ */
+static int atmel_ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
+				 unsigned int len)
+{
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+	struct atmel_i2c_cmd *cmd;
+	void *public_key;
+	struct ecdh params;
+	int ret = -ENOMEM;
+
+	kfree(ctx->public_key);
+	ctx->public_key = NULL;
+	ctx->do_fallback = false;
+
+	if (crypto_ecdh_decode_key(buf, len, &params) < 0) {
+		dev_err(&ctx->client->dev, "crypto_ecdh_decode_key failed\n");
+		return -EINVAL;
+	}
+
+	if (params.key_size) {
+		ret = crypto_kpp_set_secret(ctx->fallback, buf, len);
+		ctx->do_fallback = !ret;
+		return ret;
+	}
+
+	cmd = kmalloc_obj(*cmd);
+	if (!cmd)
+		return -ENOMEM;
+
+	public_key = kmalloc(ATMEL_ECC_PUBKEY_SIZE, GFP_KERNEL);
+	if (!public_key)
+		goto free_cmd;
+
+	atmel_i2c_init_genkey_cmd(cmd, DATA_SLOT_2);
+
+	ret = atmel_i2c_send_receive(ctx->client, cmd);
+	if (ret) {
+		kfree(public_key);
+		goto free_cmd;
+	}
+
+	memcpy(public_key, &cmd->data[RSP_DATA_IDX], ATMEL_ECC_PUBKEY_SIZE);
+	ctx->public_key = public_key;
+
+free_cmd:
+	kfree(cmd);
+	return ret;
+}
+
+static int atmel_ecdh_generate_public_key(struct kpp_request *req)
+{
+	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+	size_t copied, nbytes;
+
+	if (ctx->do_fallback) {
+		kpp_request_set_tfm(req, ctx->fallback);
+		return crypto_kpp_generate_public_key(req);
+	}
+
+	if (!ctx->public_key)
+		return -EINVAL;
+
+	/* copy only as much as requested, capped at 64 bytes */
+	nbytes = min(ATMEL_ECC_PUBKEY_SIZE, req->dst_len);
+
+	/* public key was saved at private key generation */
+	copied = sg_copy_from_buffer(req->dst,
+				     sg_nents_for_len(req->dst, nbytes),
+				     ctx->public_key, nbytes);
+	if (copied != nbytes)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int atmel_ecdh_compute_shared_secret(struct kpp_request *req)
+{
+	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+	struct atmel_i2c_work_data *work_data;
+	gfp_t gfp;
+	int ret;
+
+	if (ctx->do_fallback) {
+		kpp_request_set_tfm(req, ctx->fallback);
+		return crypto_kpp_compute_shared_secret(req);
+	}
+
+	if (!ctx->public_key)
+		return -EINVAL;
+
+	/* A P-256 public key must contain two 32-byte coordinates */
+	if (req->src_len != ATMEL_ECC_PUBKEY_SIZE)
+		return -EINVAL;
+
+	gfp = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ? GFP_KERNEL :
+							     GFP_ATOMIC;
+
+	work_data = kmalloc_obj(*work_data, gfp);
+	if (!work_data)
+		return -ENOMEM;
+
+	work_data->ctx = ctx;
+	work_data->client = ctx->client;
+
+	ret = atmel_i2c_init_ecdh_cmd(&work_data->cmd, req->src);
+	if (ret)
+		goto free_work_data;
+
+	atmel_i2c_enqueue(work_data, atmel_ecdh_done, req);
+
+	return -EINPROGRESS;
+
+free_work_data:
+	kfree(work_data);
+	return ret;
+}
+
+static struct i2c_client *atmel_ecc_i2c_client_alloc(void)
+{
+	struct atmel_i2c_client_priv *i2c_priv, *min_i2c_priv = NULL;
+	struct i2c_client *client = ERR_PTR(-ENODEV);
+	int min_tfm_cnt = INT_MAX;
+	int tfm_cnt;
+
+	spin_lock(&driver_data.i2c_list_lock);
+
+	if (list_empty(&driver_data.i2c_client_list)) {
+		spin_unlock(&driver_data.i2c_list_lock);
+		return ERR_PTR(-ENODEV);
+	}
+
+	list_for_each_entry(i2c_priv, &driver_data.i2c_client_list,
+			    i2c_client_list_node) {
+		tfm_cnt = atomic_read(&i2c_priv->tfm_count);
+		if (tfm_cnt < min_tfm_cnt) {
+			min_tfm_cnt = tfm_cnt;
+			min_i2c_priv = i2c_priv;
+		}
+		if (!min_tfm_cnt)
+			break;
+	}
+
+	if (min_i2c_priv) {
+		atomic_inc(&min_i2c_priv->tfm_count);
+		client = min_i2c_priv->client;
+	}
+
+	spin_unlock(&driver_data.i2c_list_lock);
+
+	return client;
+}
+
+static void atmel_ecc_i2c_client_free(struct i2c_client *client)
+{
+	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
+
+	atomic_dec(&i2c_priv->tfm_count);
+}
+
+static int atmel_ecdh_init_tfm(struct crypto_kpp *tfm)
+{
+	const char *alg = kpp_alg_name(tfm);
+	struct crypto_kpp *fallback;
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+
+	ctx->client = atmel_ecc_i2c_client_alloc();
+	if (IS_ERR(ctx->client)) {
+		pr_err("tfm - i2c_client binding failed\n");
+		return PTR_ERR(ctx->client);
+	}
+
+	fallback = crypto_alloc_kpp(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
+	if (IS_ERR(fallback)) {
+		dev_err(&ctx->client->dev, "Failed to allocate transformation for '%s': %ld\n",
+			alg, PTR_ERR(fallback));
+		atmel_ecc_i2c_client_free(ctx->client);
+		return PTR_ERR(fallback);
+	}
+
+	crypto_kpp_set_flags(fallback, crypto_kpp_get_flags(tfm));
+	ctx->fallback = fallback;
+
+	return 0;
+}
+
+static void atmel_ecdh_exit_tfm(struct crypto_kpp *tfm)
+{
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+
+	kfree(ctx->public_key);
+	crypto_free_kpp(ctx->fallback);
+	atmel_ecc_i2c_client_free(ctx->client);
+}
+
+static unsigned int atmel_ecdh_max_size(struct crypto_kpp *tfm)
+{
+	struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
+
+	return crypto_kpp_maxsize(ctx->fallback);
+}
+
+static struct kpp_alg atmel_ecdh_nist_p256 = {
+	.set_secret = atmel_ecdh_set_secret,
+	.generate_public_key = atmel_ecdh_generate_public_key,
+	.compute_shared_secret = atmel_ecdh_compute_shared_secret,
+	.init = atmel_ecdh_init_tfm,
+	.exit = atmel_ecdh_exit_tfm,
+	.max_size = atmel_ecdh_max_size,
+	.base = {
+		.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
+		.cra_name = "ecdh-nist-p256",
+		.cra_driver_name = "atmel-ecdh",
+		.cra_priority = ATMEL_ECC_PRIORITY,
+		.cra_module = THIS_MODULE,
+		.cra_ctxsize = sizeof(struct atmel_ecdh_ctx),
+	},
+};
+
+static int atmel_ecc_probe(struct i2c_client *client)
+{
+	struct atmel_i2c_client_priv *i2c_priv;
+	int ret;
+
+	ret = atmel_i2c_probe(client);
+	if (ret)
+		return ret;
+
+	i2c_priv = i2c_get_clientdata(client);
+
+	spin_lock(&driver_data.i2c_list_lock);
+	list_add_tail(&i2c_priv->i2c_client_list_node,
+		      &driver_data.i2c_client_list);
+	spin_unlock(&driver_data.i2c_list_lock);
+
+	ret = crypto_register_kpp(&atmel_ecdh_nist_p256);
+	if (ret) {
+		spin_lock(&driver_data.i2c_list_lock);
+		list_del(&i2c_priv->i2c_client_list_node);
+		spin_unlock(&driver_data.i2c_list_lock);
+
+		dev_err(&client->dev, "%s alg registration failed\n",
+			atmel_ecdh_nist_p256.base.cra_driver_name);
+	} else {
+		dev_info(&client->dev, "atmel ecc algorithms registered in /proc/crypto\n");
+	}
+
+	return ret;
+}
+
+static void atmel_ecc_remove(struct i2c_client *client)
+{
+	struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client);
+
+	/* Return EBUSY if i2c client already allocated. */
+	if (atomic_read(&i2c_priv->tfm_count)) {
+		/*
+		 * After we return here, the memory backing the device is freed.
+		 * That happens no matter what the return value of this function
+		 * is because in the Linux device model there is no error
+		 * handling for unbinding a driver.
+		 * If there is still some action pending, it probably involves
+		 * accessing the freed memory.
+		 */
+		dev_emerg(&client->dev, "Device is busy, expect memory corruption.\n");
+		return;
+	}
+
+	crypto_unregister_kpp(&atmel_ecdh_nist_p256);
+
+	spin_lock(&driver_data.i2c_list_lock);
+	list_del(&i2c_priv->i2c_client_list_node);
+	spin_unlock(&driver_data.i2c_list_lock);
+}
+
+static const struct of_device_id atmel_ecc_dt_ids[] = {
+	{ .compatible = "atmel,atecc508a", },
+	{ .compatible = "atmel,atecc608b", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, atmel_ecc_dt_ids);
+
+static const struct i2c_device_id atmel_ecc_id[] = {
+	{ .name = "atecc508a" },
+	{ .name = "atecc608b" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, atmel_ecc_id);
+
+static struct i2c_driver atmel_ecc_driver = {
+	.driver = {
+		.name	= "atmel-ecc",
+		.of_match_table = atmel_ecc_dt_ids,
+	},
+	.probe		= atmel_ecc_probe,
+	.remove		= atmel_ecc_remove,
+	.id_table	= atmel_ecc_id,
+};
+
+static int __init atmel_ecc_init(void)
+{
+	spin_lock_init(&driver_data.i2c_list_lock);
+	INIT_LIST_HEAD(&driver_data.i2c_client_list);
+	return i2c_add_driver(&atmel_ecc_driver);
+}
+
+static void __exit atmel_ecc_exit(void)
+{
+	atmel_i2c_flush_queue();
+	i2c_del_driver(&atmel_ecc_driver);
+}
+
+module_init(atmel_ecc_init);
+module_exit(atmel_ecc_exit);
+
+MODULE_AUTHOR("Tudor Ambarus");
+MODULE_DESCRIPTION("Microchip / Atmel ECC (I2C) driver");
+MODULE_LICENSE("GPL v2");