[PATCH v4 0/6] s390/uv: Retrieve Secrets Ultravisor Call support

[PATCH v4 0/6] s390/uv: Retrieve Secrets Ultravisor Call support

[Steffen Eiden]

A new secret type (group) allows SE-guests to retrieve the secret value
from the UV secret store. All retrieved secrets (but plaintext) are
retrieved as a PCMKO-wrapped key so that they will never appear in
plaintext in the secure guest. Supported key/secret types are:
AES, AES-XTS, HMAC, and EC. Add support for an in-kernel API and an UAPI
to retrieve a previously added secret. If the Hardware supports it,
adding secrets works with the same infrastructure that is used by
associate secrets introduced with AP-pass-through support.

With this addition List Secret UVCs can report more-data now and may
expect a starting index different to zero. This requires the addition of
LIST_SECRET_EXT IOCTL that works the same as the non_EXT variant but
additionally accepts an index (u16) as input.

Since v3:
	* converted an accidental kernel-doc-comment to a normal
	  comment.
	* improved list_ext documentation

Since v2:
	* Simplify conditionals
	* Fix documentation issues
	* Simplify list_secrets()
	* Add r-b from Christoph

Since v1:
	* Add various r-b's
	* Fix nits and minor issues

Steffen Eiden (6):
  s390/boot/uv.c: Use a constant for more-data rc
  s390/uv: Retrieve UV secrets support
  s390/uvdevice: Add Retrieve Secret IOCTL
  s390/uvdevice: Increase indent in IOCTL definitions
  s390/uvdevice: Add List Secrets Ext IOCTL
  s390/uv: Retrieve UV secrets sysfs support

 arch/s390/boot/uv.c                   |   7 +-
 arch/s390/include/asm/uv.h            | 146 +++++++++++++++++++++++-
 arch/s390/include/uapi/asm/uvdevice.h |  36 +++---
 arch/s390/kernel/uv.c                 | 153 ++++++++++++++++++++++++-
 drivers/s390/char/uvdevice.c          | 156 +++++++++++++++++++++-----
 5 files changed, 444 insertions(+), 54 deletions(-)

-- 
2.45.2

[PATCH v4 1/6] s390/boot/uv.c: Use a constant for more-data rc

[Steffen Eiden]

Add a define for the UVC rc 0x0100 that indicates that a UV-call was
successful but may serve more data if called with a larger buffer
again.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/boot/uv.c        | 4 ++--
 arch/s390/include/asm/uv.h | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index 318e6ba95bfd..2a71e759dc42 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -22,8 +22,8 @@ void uv_query_info(void)
 	if (!test_facility(158))
 		return;
 
-	/* rc==0x100 means that there is additional data we do not process */
-	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != 0x100)
+	/* Ignore that there might be more data we do not process */
+	if (uv_call(0, (uint64_t)&uvcb) && uvcb.header.rc != UVC_RC_MORE_DATA)
 		return;
 
 	if (IS_ENABLED(CONFIG_KVM)) {
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 153d93468b77..94ff58336e8e 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -28,6 +28,7 @@
 #define UVC_RC_INV_STATE	0x0003
 #define UVC_RC_INV_LEN		0x0005
 #define UVC_RC_NO_RESUME	0x0007
+#define UVC_RC_MORE_DATA	0x0100
 #define UVC_RC_NEED_DESTROY	0x8000
 
 #define UVC_CMD_QUI			0x0001
-- 
2.45.2

[PATCH v4 2/6] s390/uv: Retrieve UV secrets support

[Steffen Eiden]

Provide a kernel API to retrieve secrets from the UV secret store.
Add two new functions:
* `uv_get_secret_metadata` - get metadata for a given secret identifier
* `uv_retrieve_secret` - get the secret value for the secret index

With those two functions one can extract the secret for a given secret
id, if the secret is retrievable.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 135 ++++++++++++++++++++++++++++++++++++-
 arch/s390/kernel/uv.c      | 129 ++++++++++++++++++++++++++++++++++-
 2 files changed, 261 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 94ff58336e8e..bc61cf3e689b 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -2,7 +2,7 @@
 /*
  * Ultravisor Interfaces
  *
- * Copyright IBM Corp. 2019, 2022
+ * Copyright IBM Corp. 2019, 2024
  *
  * Author(s):
  *	Vasily Gorbik <gor@linux.ibm.com>
@@ -62,6 +62,7 @@
 #define UVC_CMD_ADD_SECRET		0x1031
 #define UVC_CMD_LIST_SECRETS		0x1033
 #define UVC_CMD_LOCK_SECRETS		0x1034
+#define UVC_CMD_RETR_SECRET		0x1035
 
 /* Bits in installed uv calls */
 enum uv_cmds_inst {
@@ -95,6 +96,7 @@ enum uv_cmds_inst {
 	BIT_UVC_CMD_ADD_SECRET = 29,
 	BIT_UVC_CMD_LIST_SECRETS = 30,
 	BIT_UVC_CMD_LOCK_SECRETS = 31,
+	BIT_UVC_CMD_RETR_SECRET = 33,
 };
 
 enum uv_feat_ind {
@@ -318,7 +320,6 @@ struct uv_cb_dump_complete {
  * A common UV call struct for pv guests that contains a single address
  * Examples:
  * Add Secret
- * List Secrets
  */
 struct uv_cb_guest_addr {
 	struct uv_cb_header header;
@@ -327,6 +328,91 @@ struct uv_cb_guest_addr {
 	u64 reserved28[4];
 } __packed __aligned(8);
 
+#define UVC_RC_RETR_SECR_BUF_SMALL	0x0109
+#define UVC_RC_RETR_SECR_STORE_EMPTY	0x010f
+#define UVC_RC_RETR_SECR_INV_IDX	0x0110
+#define UVC_RC_RETR_SECR_INV_SECRET	0x0111
+
+struct uv_cb_retr_secr {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u16 secret_idx;
+	u16 reserved1a;
+	u32 buf_size;
+	u64 buf_addr;
+	u64 reserved28[4];
+}  __packed __aligned(8);
+
+struct uv_cb_list_secrets {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u8  reserved18[6];
+	u16 start_idx;
+	u64 list_addr;
+	u64 reserved28[4];
+} __packed __aligned(8);
+
+enum uv_secret_types {
+	UV_SECRET_INVAL = 0x0,
+	UV_SECRET_NULL = 0x1,
+	UV_SECRET_ASSOCIATION = 0x2,
+	UV_SECRET_PLAIN = 0x3,
+	UV_SECRET_AES_128 = 0x4,
+	UV_SECRET_AES_192 = 0x5,
+	UV_SECRET_AES_256 = 0x6,
+	UV_SECRET_AES_XTS_128 = 0x7,
+	UV_SECRET_AES_XTS_256 = 0x8,
+	UV_SECRET_HMAC_SHA_256 = 0x9,
+	UV_SECRET_HMAC_SHA_512 = 0xa,
+	/* 0x0b - 0x10 reserved */
+	UV_SECRET_ECDSA_P256 = 0x11,
+	UV_SECRET_ECDSA_P384 = 0x12,
+	UV_SECRET_ECDSA_P521 = 0x13,
+	UV_SECRET_ECDSA_ED25519 = 0x14,
+	UV_SECRET_ECDSA_ED448 = 0x15,
+};
+
+/**
+ * uv_secret_list_item_hdr - UV secret metadata.
+ * @index: Index of the secret in the secret list.
+ * @type: Type of the secret. See `enum uv_secret_types`.
+ * @length: Length of the stored secret.
+ */
+struct uv_secret_list_item_hdr {
+	u16 index;
+	u16 type;
+	u32 length;
+};
+
+#define UV_SECRET_ID_LEN 32
+/**
+ * uv_secret_list_item - UV secret entry.
+ * @hdr: The metadata of this secret.
+ * @id: The ID of this secret, not the secret itself.
+ */
+struct uv_secret_list_item {
+	struct uv_secret_list_item_hdr hdr;
+	u64 reserverd08;
+	u8 id[UV_SECRET_ID_LEN];
+};
+
+/**
+ * uv_secret_list - UV secret-metadata list.
+ * @num_secr_stored: Number of secrets stored in this list.
+ * @total_num_secrets: Number of secrets stored in the UV for this guest.
+ * @next_secret_idx: positive number if there are more secrets available or zero.
+ * @secrets: Up to 85 UV-secret metadata entries.
+ */
+struct uv_secret_list {
+	u16 num_secr_stored;
+	u16 total_num_secrets;
+	u16 next_secret_idx;
+	u16 reserved_06;
+	u64 reserved_08;
+	struct uv_secret_list_item secrets[85];
+} __packed __aligned(8);
+static_assert(sizeof(struct uv_secret_list) == PAGE_SIZE);
+
 static inline int __uv_call(unsigned long r1, unsigned long r2)
 {
 	int cc;
@@ -383,6 +469,47 @@ static inline int uv_cmd_nodata(u64 handle, u16 cmd, u16 *rc, u16 *rrc)
 	return cc ? -EINVAL : 0;
 }
 
+/**
+ *  uv_list_secrets() - Do a List Secrets UVC.
+ *
+ *  @buf: Buffer to write list into; size of one page.
+ *  @start_idx: The smallest index that should be included in the list.
+ *		For the fist invocation use 0.
+ *  @rc: Pointer to store the return code or NULL.
+ *  @rrc: Pointer to store the return reason code or NULL.
+ *
+ *  This function calls the List Secrets UVC. The result is written into `buf`,
+ *  that needs to be at least one page of writable memory.
+ *  `buf` consists of:
+ *  * %struct uv_secret_list_hdr
+ *  * %struct uv_secret_list_item (multiple)
+ *
+ *  For `start_idx` use _0_ for the first call. If there are more secrets available
+ *  but could not fit into the page then `rc` is `UVC_RC_MORE_DATA`.
+ *  In this case use `uv_secret_list_hdr.next_secret_idx` for `start_idx`.
+ *
+ *  Context: might sleep.
+ *
+ *  Return: The UVC condition code.
+ */
+static inline int uv_list_secrets(u8 *buf, u16 start_idx, u16 *rc, u16 *rrc)
+{
+	struct uv_cb_list_secrets uvcb = {
+		.header.len = sizeof(uvcb),
+		.header.cmd = UVC_CMD_LIST_SECRETS,
+		.start_idx = start_idx,
+		.list_addr = (u64)buf,
+	};
+	int cc = uv_call_sched(0, (u64)&uvcb);
+
+	if (rc)
+		*rc = uvcb.header.rc;
+	if (rrc)
+		*rrc = uvcb.header.rrc;
+
+	return cc;
+}
+
 struct uv_info {
 	unsigned long inst_calls_list[4];
 	unsigned long uv_base_stor_len;
@@ -469,6 +596,10 @@ static inline int uv_remove_shared(unsigned long addr)
 	return share(addr, UVC_CMD_REMOVE_SHARED_ACCESS);
 }
 
+int uv_get_secret_metadata(const u8 secret_id[UV_SECRET_ID_LEN],
+			   struct uv_secret_list_item_hdr *secret);
+int uv_retrieve_secret(u16 secret_idx, u8 *buf, size_t buf_size);
+
 extern int prot_virt_host;
 
 static inline int is_prot_virt_host(void)
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 9646f773208a..588caf5d4f0c 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -2,7 +2,7 @@
 /*
  * Common Ultravisor functions and initialization
  *
- * Copyright IBM Corp. 2019, 2020
+ * Copyright IBM Corp. 2019, 2024
  */
 #define KMSG_COMPONENT "prot_virt"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
@@ -787,3 +787,130 @@ static int __init uv_info_init(void)
 	return rc;
 }
 device_initcall(uv_info_init);
+
+/*
+ * Find the secret with the secret_id in the provided list.
+ *
+ * Context: might sleep.
+ */
+static int find_secret_in_page(const u8 secret_id[UV_SECRET_ID_LEN],
+			       const struct uv_secret_list *list,
+			       struct uv_secret_list_item_hdr *secret)
+{
+	u16 i;
+
+	for (i = 0; i < list->total_num_secrets; i++) {
+		if (memcmp(secret_id, list->secrets[i].id, UV_SECRET_ID_LEN) == 0) {
+			*secret = list->secrets[i].hdr;
+			return 0;
+		}
+	}
+	return -ENOENT;
+}
+
+/*
+ * Do the actual search for `uv_get_secret_metadata`.
+ *
+ * Context: might sleep.
+ */
+static int find_secret(const u8 secret_id[UV_SECRET_ID_LEN],
+		       struct uv_secret_list *list,
+		       struct uv_secret_list_item_hdr *secret)
+{
+	u16 start_idx = 0;
+	u16 list_rc;
+	int ret;
+
+	do {
+		uv_list_secrets((u8 *)list, start_idx, &list_rc, NULL);
+		if (list_rc != UVC_RC_EXECUTED && list_rc != UVC_RC_MORE_DATA) {
+			if (list_rc == UVC_RC_INV_CMD)
+				return -ENODEV;
+			else
+				return -EIO;
+		}
+		ret = find_secret_in_page(secret_id, list, secret);
+		if (ret == 0)
+			return ret;
+		start_idx = list->next_secret_idx;
+	} while (list_rc == UVC_RC_MORE_DATA && start_idx < list->next_secret_idx);
+
+	return -ENOENT;
+}
+
+/**
+ * uv_get_secret_metadata() - get secret metadata for a given secret id.
+ * @secret_id: search pattern.
+ * @secret: output data, containing the secret's metadata.
+ *
+ * Search for a secret with the given secret_id in the Ultravisor secret store.
+ *
+ * Context: might sleep.
+ *
+ * Return:
+ * * %0:	- Found entry; secret->idx and secret->type are valid.
+ * * %ENOENT	- No entry found.
+ * * %ENODEV:	- Not supported: UV not available or command not available.
+ * * %EIO:	- Other unexpected UV error.
+ */
+int uv_get_secret_metadata(const u8 secret_id[UV_SECRET_ID_LEN],
+			   struct uv_secret_list_item_hdr *secret)
+{
+	struct uv_secret_list *buf;
+	int rc;
+
+	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	rc = find_secret(secret_id, buf, secret);
+	kfree(buf);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(uv_get_secret_metadata);
+
+/**
+ * uv_retrieve_secret() - get the secret value for the secret index.
+ * @secret_idx: Secret index for which the secret should be retrieved.
+ * @buf: Buffer to store retrieved secret.
+ * @buf_size: Size of the buffer. The correct buffer size is reported as part of
+ * the result from `uv_get_secret_metadata`.
+ *
+ * Calls the Retrieve Secret UVC and translates the UV return code into an errno.
+ *
+ * Context: might sleep.
+ *
+ * Return:
+ * * %0		- Entry found; buffer contains a valid secret.
+ * * %ENOENT:	- No entry found or secret at the index is non-retrievable.
+ * * %ENODEV:	- Not supported: UV not available or command not available.
+ * * %EINVAL:	- Buffer too small for content.
+ * * %EIO:	- Other unexpected UV error.
+ */
+int uv_retrieve_secret(u16 secret_idx, u8 *buf, size_t buf_size)
+{
+	struct uv_cb_retr_secr uvcb = {
+		.header.len = sizeof(uvcb),
+		.header.cmd = UVC_CMD_RETR_SECRET,
+		.secret_idx = secret_idx,
+		.buf_addr = (u64)buf,
+		.buf_size = buf_size,
+	};
+
+	uv_call_sched(0, (u64)&uvcb);
+
+	switch (uvcb.header.rc) {
+	case UVC_RC_EXECUTED:
+		return 0;
+	case UVC_RC_INV_CMD:
+		return -ENODEV;
+	case UVC_RC_RETR_SECR_STORE_EMPTY:
+	case UVC_RC_RETR_SECR_INV_SECRET:
+	case UVC_RC_RETR_SECR_INV_IDX:
+		return -ENOENT;
+	case UVC_RC_RETR_SECR_BUF_SMALL:
+		return -EINVAL;
+	default:
+		return -EIO;
+	}
+}
+EXPORT_SYMBOL_GPL(uv_retrieve_secret);
-- 
2.45.2

[PATCH v4 3/6] s390/uvdevice: Add Retrieve Secret IOCTL

[Steffen Eiden]

Add a new IOCL number to support the new Retrieve Secret UVC for
user-space.
User-space provides the index of the secret (u16) to retrieve.
The uvdevice calls the Retrieve Secret UVC and copies the secret into
the provided buffer if it fits. To get the secret type, index, and size
user-space needs to call the List UVC first.

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/uapi/asm/uvdevice.h |  6 ++-
 drivers/s390/char/uvdevice.c          | 58 ++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h
index b9c2f14a6af3..2ee5bfc61800 100644
--- a/arch/s390/include/uapi/asm/uvdevice.h
+++ b/arch/s390/include/uapi/asm/uvdevice.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 /*
- *  Copyright IBM Corp. 2022
+ *  Copyright IBM Corp. 2022, 2024
  *  Author(s): Steffen Eiden <seiden@linux.ibm.com>
  */
 #ifndef __S390_ASM_UVDEVICE_H
@@ -71,6 +71,7 @@ struct uvio_uvdev_info {
 #define UVIO_ATT_ADDITIONAL_MAX_LEN	0x8000
 #define UVIO_ADD_SECRET_MAX_LEN		0x100000
 #define UVIO_LIST_SECRETS_LEN		0x1000
+#define UVIO_RETR_SECRET_MAX_LEN	0x2000
 
 #define UVIO_DEVICE_NAME "uv"
 #define UVIO_TYPE_UVC 'u'
@@ -81,6 +82,7 @@ enum UVIO_IOCTL_NR {
 	UVIO_IOCTL_ADD_SECRET_NR,
 	UVIO_IOCTL_LIST_SECRETS_NR,
 	UVIO_IOCTL_LOCK_SECRETS_NR,
+	UVIO_IOCTL_RETR_SECRET_NR,
 	/* must be the last entry */
 	UVIO_IOCTL_NUM_IOCTLS
 };
@@ -91,6 +93,7 @@ enum UVIO_IOCTL_NR {
 #define UVIO_IOCTL_ADD_SECRET	UVIO_IOCTL(UVIO_IOCTL_ADD_SECRET_NR)
 #define UVIO_IOCTL_LIST_SECRETS	UVIO_IOCTL(UVIO_IOCTL_LIST_SECRETS_NR)
 #define UVIO_IOCTL_LOCK_SECRETS	UVIO_IOCTL(UVIO_IOCTL_LOCK_SECRETS_NR)
+#define UVIO_IOCTL_RETR_SECRET	UVIO_IOCTL(UVIO_IOCTL_RETR_SECRET_NR)
 
 #define UVIO_SUPP_CALL(nr)	(1ULL << (nr))
 #define UVIO_SUPP_UDEV_INFO	UVIO_SUPP_CALL(UVIO_IOCTL_UDEV_INFO_NR)
@@ -98,5 +101,6 @@ enum UVIO_IOCTL_NR {
 #define UVIO_SUPP_ADD_SECRET	UVIO_SUPP_CALL(UVIO_IOCTL_ADD_SECRET_NR)
 #define UVIO_SUPP_LIST_SECRETS	UVIO_SUPP_CALL(UVIO_IOCTL_LIST_SECRETS_NR)
 #define UVIO_SUPP_LOCK_SECRETS	UVIO_SUPP_CALL(UVIO_IOCTL_LOCK_SECRETS_NR)
+#define UVIO_SUPP_RETR_SECRET	UVIO_SUPP_CALL(UVIO_IOCTL_RETR_SECRET_NR)
 
 #endif /* __S390_ASM_UVDEVICE_H */
diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c
index f598edc5f251..1f90976293e8 100644
--- a/drivers/s390/char/uvdevice.c
+++ b/drivers/s390/char/uvdevice.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- *  Copyright IBM Corp. 2022
+ *  Copyright IBM Corp. 2022, 2024
  *  Author(s): Steffen Eiden <seiden@linux.ibm.com>
  *
  *  This file provides a Linux misc device to give userspace access to some
@@ -40,6 +40,7 @@ static const u32 ioctl_nr_to_uvc_bit[] __initconst = {
 	[UVIO_IOCTL_ADD_SECRET_NR] = BIT_UVC_CMD_ADD_SECRET,
 	[UVIO_IOCTL_LIST_SECRETS_NR] = BIT_UVC_CMD_LIST_SECRETS,
 	[UVIO_IOCTL_LOCK_SECRETS_NR] = BIT_UVC_CMD_LOCK_SECRETS,
+	[UVIO_IOCTL_RETR_SECRET_NR] = BIT_UVC_CMD_RETR_ATTEST,
 };
 
 static_assert(ARRAY_SIZE(ioctl_nr_to_uvc_bit) == UVIO_IOCTL_NUM_IOCTLS);
@@ -379,6 +380,58 @@ static int uvio_lock_secrets(struct uvio_ioctl_cb *ioctl)
 	return 0;
 }
 
+/**
+ * uvio_retr_secret() - perform a retrieve secret UVC.
+ * @uv_ioctl: ioctl control block.
+ *
+ * uvio_retr_secret() performs the Retrieve Secret Ultravisor Call.
+ * The first two bytes of the argument specify the index of the secret to be
+ * retrieved. The retrieved secret is copied into the argument buffer if there
+ * is enough space.
+ * The argument length must be at least two bytes and at max 8192 bytes.
+ *
+ * Context: might sleep.
+ *
+ * Return: 0 on success or a negative error code on error.
+ */
+static int uvio_retr_secret(struct uvio_ioctl_cb *uv_ioctl)
+{
+	u16 __user *user_index = (u16 __user *)uv_ioctl->argument_addr;
+	struct uv_cb_retr_secr uvcb = {
+		.header.len = sizeof(uvcb),
+		.header.cmd = UVC_CMD_RETR_SECRET,
+	};
+	u32 buf_len = uv_ioctl->argument_len;
+	void *buf = NULL;
+	int ret;
+
+	if (buf_len > UVIO_RETR_SECRET_MAX_LEN || buf_len < sizeof(*user_index))
+		return -EINVAL;
+
+	buf = kvzalloc(buf_len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = -EFAULT;
+	if (get_user(uvcb.secret_idx, user_index))
+		goto err;
+
+	uvcb.buf_addr = (u64)buf;
+	uvcb.buf_size = buf_len;
+	uv_call_sched(0, (u64)&uvcb);
+
+	if (copy_to_user((__user void *)uv_ioctl->argument_addr, buf, buf_len))
+		goto err;
+
+	ret = 0;
+	uv_ioctl->uv_rc = uvcb.header.rc;
+	uv_ioctl->uv_rrc = uvcb.header.rrc;
+
+err:
+	kvfree_sensitive(buf, buf_len);
+	return ret;
+}
+
 static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp,
 				     unsigned long cmd)
 {
@@ -432,6 +485,9 @@ static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case UVIO_IOCTL_LOCK_SECRETS_NR:
 		ret = uvio_lock_secrets(&uv_ioctl);
 		break;
+	case UVIO_IOCTL_RETR_SECRET_NR:
+		ret = uvio_retr_secret(&uv_ioctl);
+		break;
 	default:
 		ret = -ENOIOCTLCMD;
 		break;
-- 
2.45.2

[PATCH v4 4/6] s390/uvdevice: Increase indent in IOCTL definitions

[Steffen Eiden]

Increase the indentations in the IOCTL defines so that we will not have
problems with upcoming, longer constant names.
While at it, fix a minor typo.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/uapi/asm/uvdevice.h | 30 +++++++++++++--------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h
index 2ee5bfc61800..4947f26ad9fb 100644
--- a/arch/s390/include/uapi/asm/uvdevice.h
+++ b/arch/s390/include/uapi/asm/uvdevice.h
@@ -52,7 +52,7 @@ struct uvio_uvdev_info {
 	__u64 supp_uvio_cmds;
 	/*
 	 * If bit `n` is set, the Ultravisor(UV) supports the UV-call
-	 * corresponding to the IOCTL with nr `n` in the calling contextx (host
+	 * corresponding to the IOCTL with nr `n` in the calling context (host
 	 * or guest).  The value is only valid if the corresponding bit in
 	 * @supp_uvio_cmds is set as well.
 	 */
@@ -87,20 +87,20 @@ enum UVIO_IOCTL_NR {
 	UVIO_IOCTL_NUM_IOCTLS
 };
 
-#define UVIO_IOCTL(nr)		_IOWR(UVIO_TYPE_UVC, nr, struct uvio_ioctl_cb)
-#define UVIO_IOCTL_UVDEV_INFO	UVIO_IOCTL(UVIO_IOCTL_UVDEV_INFO_NR)
-#define UVIO_IOCTL_ATT		UVIO_IOCTL(UVIO_IOCTL_ATT_NR)
-#define UVIO_IOCTL_ADD_SECRET	UVIO_IOCTL(UVIO_IOCTL_ADD_SECRET_NR)
-#define UVIO_IOCTL_LIST_SECRETS	UVIO_IOCTL(UVIO_IOCTL_LIST_SECRETS_NR)
-#define UVIO_IOCTL_LOCK_SECRETS	UVIO_IOCTL(UVIO_IOCTL_LOCK_SECRETS_NR)
-#define UVIO_IOCTL_RETR_SECRET	UVIO_IOCTL(UVIO_IOCTL_RETR_SECRET_NR)
+#define UVIO_IOCTL(nr)			_IOWR(UVIO_TYPE_UVC, nr, struct uvio_ioctl_cb)
+#define UVIO_IOCTL_UVDEV_INFO		UVIO_IOCTL(UVIO_IOCTL_UVDEV_INFO_NR)
+#define UVIO_IOCTL_ATT			UVIO_IOCTL(UVIO_IOCTL_ATT_NR)
+#define UVIO_IOCTL_ADD_SECRET		UVIO_IOCTL(UVIO_IOCTL_ADD_SECRET_NR)
+#define UVIO_IOCTL_LIST_SECRETS		UVIO_IOCTL(UVIO_IOCTL_LIST_SECRETS_NR)
+#define UVIO_IOCTL_LOCK_SECRETS		UVIO_IOCTL(UVIO_IOCTL_LOCK_SECRETS_NR)
+#define UVIO_IOCTL_RETR_SECRET		UVIO_IOCTL(UVIO_IOCTL_RETR_SECRET_NR)
 
-#define UVIO_SUPP_CALL(nr)	(1ULL << (nr))
-#define UVIO_SUPP_UDEV_INFO	UVIO_SUPP_CALL(UVIO_IOCTL_UDEV_INFO_NR)
-#define UVIO_SUPP_ATT		UVIO_SUPP_CALL(UVIO_IOCTL_ATT_NR)
-#define UVIO_SUPP_ADD_SECRET	UVIO_SUPP_CALL(UVIO_IOCTL_ADD_SECRET_NR)
-#define UVIO_SUPP_LIST_SECRETS	UVIO_SUPP_CALL(UVIO_IOCTL_LIST_SECRETS_NR)
-#define UVIO_SUPP_LOCK_SECRETS	UVIO_SUPP_CALL(UVIO_IOCTL_LOCK_SECRETS_NR)
-#define UVIO_SUPP_RETR_SECRET	UVIO_SUPP_CALL(UVIO_IOCTL_RETR_SECRET_NR)
+#define UVIO_SUPP_CALL(nr)		(1ULL << (nr))
+#define UVIO_SUPP_UDEV_INFO		UVIO_SUPP_CALL(UVIO_IOCTL_UDEV_INFO_NR)
+#define UVIO_SUPP_ATT			UVIO_SUPP_CALL(UVIO_IOCTL_ATT_NR)
+#define UVIO_SUPP_ADD_SECRET		UVIO_SUPP_CALL(UVIO_IOCTL_ADD_SECRET_NR)
+#define UVIO_SUPP_LIST_SECRETS		UVIO_SUPP_CALL(UVIO_IOCTL_LIST_SECRETS_NR)
+#define UVIO_SUPP_LOCK_SECRETS		UVIO_SUPP_CALL(UVIO_IOCTL_LOCK_SECRETS_NR)
+#define UVIO_SUPP_RETR_SECRET		UVIO_SUPP_CALL(UVIO_IOCTL_RETR_SECRET_NR)
 
 #endif /* __S390_ASM_UVDEVICE_H */
-- 
2.45.2

[PATCH v4 5/6] s390/uvdevice: Add List Secrets Ext IOCTL

[Steffen Eiden]

Add an extended List Secrets IOCTL. In contrast to the first list IOCTL
this accepts an index as the first two bytes of the provided page as an
input. This index is then taken as the index offset for the list UVC to
receive later entries for the list. While at it fix some kernel doc
issues with the list function.

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/uapi/asm/uvdevice.h |  4 ++
 drivers/s390/char/uvdevice.c          | 98 +++++++++++++++++++--------
 2 files changed, 74 insertions(+), 28 deletions(-)

diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h
index 4947f26ad9fb..1cfa4e17af03 100644
--- a/arch/s390/include/uapi/asm/uvdevice.h
+++ b/arch/s390/include/uapi/asm/uvdevice.h
@@ -72,6 +72,7 @@ struct uvio_uvdev_info {
 #define UVIO_ADD_SECRET_MAX_LEN		0x100000
 #define UVIO_LIST_SECRETS_LEN		0x1000
 #define UVIO_RETR_SECRET_MAX_LEN	0x2000
+#define UVIO_LIST_SECRETS_EXT_LEN	UVIO_LIST_SECRETS_LEN
 
 #define UVIO_DEVICE_NAME "uv"
 #define UVIO_TYPE_UVC 'u'
@@ -83,6 +84,7 @@ enum UVIO_IOCTL_NR {
 	UVIO_IOCTL_LIST_SECRETS_NR,
 	UVIO_IOCTL_LOCK_SECRETS_NR,
 	UVIO_IOCTL_RETR_SECRET_NR,
+	UVIO_IOCTL_LIST_SECRETS_EXT_NR,
 	/* must be the last entry */
 	UVIO_IOCTL_NUM_IOCTLS
 };
@@ -94,6 +96,7 @@ enum UVIO_IOCTL_NR {
 #define UVIO_IOCTL_LIST_SECRETS		UVIO_IOCTL(UVIO_IOCTL_LIST_SECRETS_NR)
 #define UVIO_IOCTL_LOCK_SECRETS		UVIO_IOCTL(UVIO_IOCTL_LOCK_SECRETS_NR)
 #define UVIO_IOCTL_RETR_SECRET		UVIO_IOCTL(UVIO_IOCTL_RETR_SECRET_NR)
+#define UVIO_IOCTL_LIST_SECRETS_EXT	UVIO_IOCTL(UVIO_IOCTL_LIST_SECRETS_EXT_NR)
 
 #define UVIO_SUPP_CALL(nr)		(1ULL << (nr))
 #define UVIO_SUPP_UDEV_INFO		UVIO_SUPP_CALL(UVIO_IOCTL_UDEV_INFO_NR)
@@ -102,5 +105,6 @@ enum UVIO_IOCTL_NR {
 #define UVIO_SUPP_LIST_SECRETS		UVIO_SUPP_CALL(UVIO_IOCTL_LIST_SECRETS_NR)
 #define UVIO_SUPP_LOCK_SECRETS		UVIO_SUPP_CALL(UVIO_IOCTL_LOCK_SECRETS_NR)
 #define UVIO_SUPP_RETR_SECRET		UVIO_SUPP_CALL(UVIO_IOCTL_RETR_SECRET_NR)
+#define UVIO_SUPP_LIST_SECRETS_EXT	UVIO_SUPP_CALL(UVIO_IOCTL_LIST_SECRETS_EXT_NR)
 
 #endif /* __S390_ASM_UVDEVICE_H */
diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c
index 1f90976293e8..18bae2d45bf6 100644
--- a/drivers/s390/char/uvdevice.c
+++ b/drivers/s390/char/uvdevice.c
@@ -41,6 +41,7 @@ static const u32 ioctl_nr_to_uvc_bit[] __initconst = {
 	[UVIO_IOCTL_LIST_SECRETS_NR] = BIT_UVC_CMD_LIST_SECRETS,
 	[UVIO_IOCTL_LOCK_SECRETS_NR] = BIT_UVC_CMD_LOCK_SECRETS,
 	[UVIO_IOCTL_RETR_SECRET_NR] = BIT_UVC_CMD_RETR_ATTEST,
+	[UVIO_IOCTL_LIST_SECRETS_EXT_NR] = BIT_UVC_CMD_LIST_SECRETS,
 };
 
 static_assert(ARRAY_SIZE(ioctl_nr_to_uvc_bit) == UVIO_IOCTL_NUM_IOCTLS);
@@ -297,8 +298,39 @@ static int uvio_add_secret(struct uvio_ioctl_cb *uv_ioctl)
 	return ret;
 }
 
-/** uvio_list_secrets() - perform a List Secret UVC
- * @uv_ioctl: ioctl control block
+/*
+ * The actual list(_ext) IOCTL.
+ * If list_ext is true, the first two bytes of the user buffer set the starting
+ * index of the list-UVC.
+ */
+static int list_secrets(struct uvio_ioctl_cb *uv_ioctl, bool list_ext)
+{
+	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
+	u16 __user *user_index = (u16 __user *)uv_ioctl->argument_addr;
+	u16 start_idx = 0;
+	u8 *secrets;
+	int ret = 0;
+
+	BUILD_BUG_ON(UVIO_LIST_SECRETS_LEN != PAGE_SIZE);
+	if (uv_ioctl->argument_len != UVIO_LIST_SECRETS_LEN)
+		return -EINVAL;
+	/* The extended call accepts an u16 index as input */
+	if (list_ext && get_user(start_idx, user_index))
+		return -EFAULT;
+	secrets = (u8 *)get_zeroed_page(GFP_KERNEL);
+	if (!secrets)
+		return -ENOMEM;
+	uv_list_secrets(secrets, start_idx, &uv_ioctl->uv_rc, &uv_ioctl->uv_rrc);
+	if (copy_to_user(user_buf_arg, secrets, UVIO_LIST_SECRETS_LEN))
+		ret = -EFAULT;
+
+	free_page((unsigned long)secrets);
+	return ret;
+}
+
+/**
+ * uvio_list_secrets() - perform a List Secret UVC.
+ * @uv_ioctl: ioctl control block.
  *
  * uvio_list_secrets() performs the List Secret Ultravisor Call. It verifies
  * that the given userspace argument address is valid and its size is sane.
@@ -312,37 +344,13 @@ static int uvio_add_secret(struct uvio_ioctl_cb *uv_ioctl)
  * command rc. This won't be fenced in the driver and does not result in a
  * negative return value.
  *
- * Context: might sleep
+ * Context: might sleep.
  *
  * Return: 0 on success or a negative error code on error.
  */
 static int uvio_list_secrets(struct uvio_ioctl_cb *uv_ioctl)
 {
-	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
-	struct uv_cb_guest_addr uvcb = {
-		.header.len = sizeof(uvcb),
-		.header.cmd = UVC_CMD_LIST_SECRETS,
-	};
-	void *secrets = NULL;
-	int ret = 0;
-
-	if (uv_ioctl->argument_len != UVIO_LIST_SECRETS_LEN)
-		return -EINVAL;
-
-	secrets = kvzalloc(UVIO_LIST_SECRETS_LEN, GFP_KERNEL);
-	if (!secrets)
-		return -ENOMEM;
-
-	uvcb.addr = (u64)secrets;
-	uv_call_sched(0, (u64)&uvcb);
-	uv_ioctl->uv_rc = uvcb.header.rc;
-	uv_ioctl->uv_rrc = uvcb.header.rrc;
-
-	if (copy_to_user(user_buf_arg, secrets, UVIO_LIST_SECRETS_LEN))
-		ret = -EFAULT;
-
-	kvfree(secrets);
-	return ret;
+	return list_secrets(uv_ioctl, false);
 }
 
 /** uvio_lock_secrets() - perform a Lock Secret Store UVC
@@ -432,6 +440,37 @@ static int uvio_retr_secret(struct uvio_ioctl_cb *uv_ioctl)
 	return ret;
 }
 
+/**
+ * uvio_list_secrets_ext() - perform a List Secret UVC with a starting index.
+ * @uv_ioctl: ioctl control block.
+ *
+ * uvio_list_secrets_ext() performs the List Secret Ultravisor Call. It verifies
+ * that the given userspace argument address is valid and its size is sane.
+ * Every other check is made by the Ultravisor (UV) and won't result in a
+ * negative return value. It builds the request, performs the UV-call, and
+ * copies the result to userspace.
+ *
+ * The argument specifies the location for the result of the UV-Call.
+ * The first two bytes of the argument specify the starting index of the list.
+ * This should be zero for the first IOCTL. If UV reports more data
+ * (rc UVC_RC_MORE_DATA) another list_ext IOCTL with a higher starting index
+ * shows the following entries of the secret list. Choose next_valid_index from
+ * the list header as starting index for the list in the following IOCTLs to
+ * get a continuous list without holes.
+ *
+ * If the List Secrets UV facility is not present, UV will return invalid
+ * command rc. This won't be fenced in the driver and does not result in a
+ * negative return value.
+ *
+ * Context: might sleep.
+ *
+ * Return: 0 on success or a negative error code on error.
+ */
+static int uvio_list_secrets_ext(struct uvio_ioctl_cb *uv_ioctl)
+{
+	return list_secrets(uv_ioctl, true);
+}
+
 static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp,
 				     unsigned long cmd)
 {
@@ -488,6 +527,9 @@ static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case UVIO_IOCTL_RETR_SECRET_NR:
 		ret = uvio_retr_secret(&uv_ioctl);
 		break;
+	case UVIO_IOCTL_LIST_SECRETS_EXT_NR:
+		ret = uvio_list_secrets_ext(&uv_ioctl);
+		break;
 	default:
 		ret = -ENOIOCTLCMD;
 		break;
-- 
2.45.2

[PATCH v4 6/6] s390/uv: Retrieve UV secrets sysfs support

[Steffen Eiden]

Reflect the updated content in the query information UVC to the sysfs at
/sys/firmware/query

* new UV-query sysfs entry for the maximum number of retrievable
  secrets the UV can store for one secure guest.
* new UV-query sysfs entry for the maximum number of association
  secrets the UV can store for one secure guest.
* max_secrets contains the sum of max association and max retrievable
  secrets.

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/boot/uv.c        |  3 ++-
 arch/s390/include/asm/uv.h | 10 ++++++----
 arch/s390/kernel/uv.c      | 24 +++++++++++++++++++++++-
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index 2a71e759dc42..4568e8f81dac 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -46,7 +46,8 @@ void uv_query_info(void)
 		uv_info.supp_add_secret_req_ver = uvcb.supp_add_secret_req_ver;
 		uv_info.supp_add_secret_pcf = uvcb.supp_add_secret_pcf;
 		uv_info.supp_secret_types = uvcb.supp_secret_types;
-		uv_info.max_secrets = uvcb.max_secrets;
+		uv_info.max_assoc_secrets = uvcb.max_assoc_secrets;
+		uv_info.max_retr_secrets = uvcb.max_retr_secrets;
 	}
 
 	if (test_bit_inv(BIT_UVC_CMD_SET_SHARED_ACCESS, (unsigned long *)uvcb.inst_calls_list) &&
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index bc61cf3e689b..371bbaf3dbe9 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -143,9 +143,10 @@ struct uv_cb_qui {
 	u64 reservedf0;				/* 0x00f0 */
 	u64 supp_add_secret_req_ver;		/* 0x00f8 */
 	u64 supp_add_secret_pcf;		/* 0x0100 */
-	u64 supp_secret_types;			/* 0x0180 */
-	u16 max_secrets;			/* 0x0110 */
-	u8 reserved112[0x120 - 0x112];		/* 0x0112 */
+	u64 supp_secret_types;			/* 0x0108 */
+	u16 max_assoc_secrets;			/* 0x0110 */
+	u16 max_retr_secrets;			/* 0x0112 */
+	u8 reserved114[0x120 - 0x114];		/* 0x0114 */
 } __packed __aligned(8);
 
 /* Initialize Ultravisor */
@@ -530,7 +531,8 @@ struct uv_info {
 	unsigned long supp_add_secret_req_ver;
 	unsigned long supp_add_secret_pcf;
 	unsigned long supp_secret_types;
-	unsigned short max_secrets;
+	unsigned short max_assoc_secrets;
+	unsigned short max_retr_secrets;
 };
 
 extern struct uv_info uv_info;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 588caf5d4f0c..d6079aa9b57b 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -696,12 +696,32 @@ static struct kobj_attribute uv_query_supp_secret_types_attr =
 static ssize_t uv_query_max_secrets(struct kobject *kobj,
 				    struct kobj_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "%d\n", uv_info.max_secrets);
+	return sysfs_emit(buf, "%d\n",
+			  uv_info.max_assoc_secrets + uv_info.max_retr_secrets);
 }
 
 static struct kobj_attribute uv_query_max_secrets_attr =
 	__ATTR(max_secrets, 0444, uv_query_max_secrets, NULL);
 
+static ssize_t uv_query_max_retr_secrets(struct kobject *kobj,
+					 struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", uv_info.max_retr_secrets);
+}
+
+static struct kobj_attribute uv_query_max_retr_secrets_attr =
+	__ATTR(max_retr_secrets, 0444, uv_query_max_retr_secrets, NULL);
+
+static ssize_t uv_query_max_assoc_secrets(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  char *buf)
+{
+	return sysfs_emit(buf, "%d\n", uv_info.max_assoc_secrets);
+}
+
+static struct kobj_attribute uv_query_max_assoc_secrets_attr =
+	__ATTR(max_assoc_secrets, 0444, uv_query_max_assoc_secrets, NULL);
+
 static struct attribute *uv_query_attrs[] = {
 	&uv_query_facilities_attr.attr,
 	&uv_query_feature_indications_attr.attr,
@@ -719,6 +739,8 @@ static struct attribute *uv_query_attrs[] = {
 	&uv_query_supp_add_secret_pcf_attr.attr,
 	&uv_query_supp_secret_types_attr.attr,
 	&uv_query_max_secrets_attr.attr,
+	&uv_query_max_assoc_secrets_attr.attr,
+	&uv_query_max_retr_secrets_attr.attr,
 	NULL,
 };
 
-- 
2.45.2

Re: [PATCH v4 2/6] s390/uv: Retrieve UV secrets support

[Christoph Schlameuss]

On Fri Oct 18, 2024 at 11:15 AM CEST, Steffen Eiden wrote:
> Provide a kernel API to retrieve secrets from the UV secret store.
> Add two new functions:
> * `uv_get_secret_metadata` - get metadata for a given secret identifier
> * `uv_retrieve_secret` - get the secret value for the secret index
>
> With those two functions one can extract the secret for a given secret
> id, if the secret is retrievable.
>
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

> ---
>  arch/s390/include/asm/uv.h | 135 ++++++++++++++++++++++++++++++++++++-
>  arch/s390/kernel/uv.c      | 129 ++++++++++++++++++++++++++++++++++-
>  2 files changed, 261 insertions(+), 3 deletions(-)

[...]

Re: [PATCH v4 2/6] s390/uv: Retrieve UV secrets support

[Janosch Frank]

On 10/18/24 11:15 AM, Steffen Eiden wrote:
> Provide a kernel API to retrieve secrets from the UV secret store.
> Add two new functions:
> * `uv_get_secret_metadata` - get metadata for a given secret identifier
> * `uv_retrieve_secret` - get the secret value for the secret index
> 
> With those two functions one can extract the secret for a given secret
> id, if the secret is retrievable.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
> ---

[...]

> +/**
> + * uv_secret_list_item_hdr - UV secret metadata.
> + * @index: Index of the secret in the secret list.
> + * @type: Type of the secret. See `enum uv_secret_types`.
> + * @length: Length of the stored secret.
> + */
> +struct uv_secret_list_item_hdr {
> +	u16 index;
> +	u16 type;
> +	u32 length;
> +};
> +
> +#define UV_SECRET_ID_LEN 32
> +/**
> + * uv_secret_list_item - UV secret entry.
> + * @hdr: The metadata of this secret.
> + * @id: The ID of this secret, not the secret itself.
> + */
> +struct uv_secret_list_item {
> +	struct uv_secret_list_item_hdr hdr;
> +	u64 reserverd08;
> +	u8 id[UV_SECRET_ID_LEN];
> +};

Are you skipping the size asserts since the list is asserted?
It might still make sense to pack them, no?

>   static inline int __uv_call(unsigned long r1, unsigned long r2)
>   {
>   	int cc;
> @@ -383,6 +469,47 @@ static inline int uv_cmd_nodata(u64 handle, u16 cmd, u16 *rc, u16 *rrc)
>   	return cc ? -EINVAL : 0;
>   }
>   
> +/**
> + *  uv_list_secrets() - Do a List Secrets UVC.
> + *
> + *  @buf: Buffer to write list into; size of one page.
> + *  @start_idx: The smallest index that should be included in the list.
> + *		For the fist invocation use 0.
> + *  @rc: Pointer to store the return code or NULL.
> + *  @rrc: Pointer to store the return reason code or NULL.
> + *
> + *  This function calls the List Secrets UVC. The result is written into `buf`,
> + *  that needs to be at least one page of writable memory.
> + *  `buf` consists of:
> + *  * %struct uv_secret_list_hdr
> + *  * %struct uv_secret_list_item (multiple)
> + *
> + *  For `start_idx` use _0_ for the first call. If there are more secrets available
> + *  but could not fit into the page then `rc` is `UVC_RC_MORE_DATA`.
> + *  In this case use `uv_secret_list_hdr.next_secret_idx` for `start_idx`.
> + *
> + *  Context: might sleep.
> + *
> + *  Return: The UVC condition code.
> + */
> +static inline int uv_list_secrets(u8 *buf, u16 start_idx, u16 *rc, u16 *rrc)
>

Why is buf (u8 *) if you have it as (struct uv_secret_list *) in 
find_secret()?

You have a second caller in list_secrets() but that can also be (struct 
uv_secret_list *) since copy_to_user() shouldn't care and you need to 
cast it anyway for alloc_page().

If you'd be passing buf as u64 and not as a pointer it would make sense 
but you're casting it to u64 here

Re: [PATCH v4 2/6] s390/uv: Retrieve UV secrets support

[Steffen Eiden]

On 10/22/24 2:16 PM, Janosch Frank wrote:
> On 10/18/24 11:15 AM, Steffen Eiden wrote:
>> Provide a kernel API to retrieve secrets from the UV secret store.
>> Add two new functions:
>> * `uv_get_secret_metadata` - get metadata for a given secret identifier
>> * `uv_retrieve_secret` - get the secret value for the secret index
>>
>> With those two functions one can extract the secret for a given secret
>> id, if the secret is retrievable.
>>
>> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
>> ---
> 
> [...]
> 
>> +/**
>> + * uv_secret_list_item_hdr - UV secret metadata.
>> + * @index: Index of the secret in the secret list.
>> + * @type: Type of the secret. See `enum uv_secret_types`.
>> + * @length: Length of the stored secret.
>> + */
>> +struct uv_secret_list_item_hdr {
>> +    u16 index;
>> +    u16 type;
>> +    u32 length;
>> +};
>> +
>> +#define UV_SECRET_ID_LEN 32
>> +/**
>> + * uv_secret_list_item - UV secret entry.
>> + * @hdr: The metadata of this secret.
>> + * @id: The ID of this secret, not the secret itself.
>> + */
>> +struct uv_secret_list_item {
>> +    struct uv_secret_list_item_hdr hdr;
>> +    u64 reserverd08;
>> +    u8 id[UV_SECRET_ID_LEN];
>> +};
> 
> Are you skipping the size asserts since the list is asserted?
yes.
> It might still make sense to pack them, no?
It is unnecessary to pack the struct as it is naturally aligned (at least on s390).
While, processing your comment I noticed I unnecessarily packed uv_secret_list as well.
Probably because nearly every struct in that header is (IMO unnecessarily) packed.
IIRC packing may restrict optimizations done by the compiler.

However, to stay consistent with the rest of that file I will pack this struct as well
(+ uv_secret_list_item_hdr). Those are not hot paths anyways.


> 
>>   static inline int __uv_call(unsigned long r1, unsigned long r2)
>>   {
>>       int cc;
>> @@ -383,6 +469,47 @@ static inline int uv_cmd_nodata(u64 handle, u16 cmd, u16 *rc, u16 *rrc)
>>       return cc ? -EINVAL : 0;
>>   }
>> +/**
>> + *  uv_list_secrets() - Do a List Secrets UVC.
>> + *
>> + *  @buf: Buffer to write list into; size of one page.
>> + *  @start_idx: The smallest index that should be included in the list.
>> + *        For the fist invocation use 0.
>> + *  @rc: Pointer to store the return code or NULL.
>> + *  @rrc: Pointer to store the return reason code or NULL.
>> + *
>> + *  This function calls the List Secrets UVC. The result is written into `buf`,
>> + *  that needs to be at least one page of writable memory.
>> + *  `buf` consists of:
>> + *  * %struct uv_secret_list_hdr
>> + *  * %struct uv_secret_list_item (multiple)
>> + *
>> + *  For `start_idx` use _0_ for the first call. If there are more secrets available
>> + *  but could not fit into the page then `rc` is `UVC_RC_MORE_DATA`.
>> + *  In this case use `uv_secret_list_hdr.next_secret_idx` for `start_idx`.
>> + *
>> + *  Context: might sleep.
>> + *
>> + *  Return: The UVC condition code.
>> + */
>> +static inline int uv_list_secrets(u8 *buf, u16 start_idx, u16 *rc, u16 *rrc)
>>
> 
> Why is buf (u8 *) if you have it as (struct uv_secret_list *) in find_secret()?
> 
> You have a second caller in list_secrets() but that can also be (struct uv_secret_list *) since copy_to_user() shouldn't care and you need to cast it anyway for alloc_page().
>
Yes, that makes sense. I'll change that to struct uv_secret_list *


> If you'd be passing buf as u64 and not as a pointer it would make sense but you're casting it to u64 here
> 
Thanks for the feedback.

Steffen