[GIT PULL 06/11] s390/uvdevice: Add info IOCTL

Janosch Frank
2023-06-21T15:35:22Z

Add an IOCTL that allows userspace to find out which IOCTLs the uvdevice
supports without trial and error.

Explicitly expose the IOCTL nr for the request types.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20230615100533.3996107-3-seiden@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20230615100533.3996107-3-seiden@linux.ibm.com>
---
arch/s390/include/uapi/asm/uvdevice.h | 42 ++++++++++++++-
drivers/s390/char/Kconfig | 2 +-
drivers/s390/char/uvdevice.c | 77 ++++++++++++++++++++++++---
3 files changed, 112 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/uapi/asm/uvdevice.h b/arch/s390/include/uapi/asm/uvdevice.h
index 10a5ac918e02..9d9b684836c2 100644
--- a/arch/s390/include/uapi/asm/uvdevice.h
+++ b/arch/s390/include/uapi/asm/uvdevice.h
@@ -32,6 +32,33 @@ struct uvio_attest {
__u16 reserved136; /* 0x0136 */
};

+/**
+ * uvio_uvdev_info - Information of supported functions
+ * @supp_uvio_cmds - supported IOCTLs by this device
+ * @supp_uv_cmds - supported UVCs corresponding to the IOCTL
+ *
+ * UVIO request to get information about supported request types by this
+ * uvdevice and the Ultravisor. Everything is output. Bits are in LSB0
+ * ordering. If the bit is set in both, @supp_uvio_cmds and @supp_uv_cmds, the
+ * uvdevice and the Ultravisor support that call.
+ *
+ * Note that bit 0 (UVIO_IOCTL_UVDEV_INFO_NR) is always zero for `supp_uv_cmds`
+ * as there is no corresponding UV-call.
+ */
+struct uvio_uvdev_info {
+ /*
+ * If bit `n` is set, this device supports the IOCTL with nr `n`.
+ */
+ __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
+ * or guest). The value is only valid if the corresponding bit in
+ * @supp_uvio_cmds is set as well.
+ */
+ __u64 supp_uv_cmds;
+};
+
/*
* The following max values define an upper length for the IOCTL in/out buffers.
* However, they do not represent the maximum the Ultravisor allows which is
@@ -46,6 +73,19 @@ struct uvio_attest {
#define UVIO_DEVICE_NAME "uv"
#define UVIO_TYPE_UVC 'u'

-#define UVIO_IOCTL_ATT _IOWR(UVIO_TYPE_UVC, 0x01, struct uvio_ioctl_cb)
+enum UVIO_IOCTL_NR {
+ UVIO_IOCTL_UVDEV_INFO_NR = 0x00,
+ UVIO_IOCTL_ATT_NR,
+ /* must be the last entry */
+ 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_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)

#endif /* __S390_ASM_UVDEVICE_H */
diff --git a/drivers/s390/char/Kconfig b/drivers/s390/char/Kconfig
index 80c4e5101c97..8a03af5ee5b3 100644
--- a/drivers/s390/char/Kconfig
+++ b/drivers/s390/char/Kconfig
@@ -96,7 +96,7 @@ config SCLP_OFB
config S390_UV_UAPI
def_tristate m
prompt "Ultravisor userspace API"
- depends on S390
+ depends on S390 && (KVM || PROTECTED_VIRTUALIZATION_GUEST)
help
Selecting exposes parts of the UV interface to userspace
by providing a misc character device at /dev/uv.
diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c
index 1d40457c7b10..7d7866be389b 100644
--- a/drivers/s390/char/uvdevice.c
+++ b/drivers/s390/char/uvdevice.c
@@ -32,6 +32,52 @@
#include <asm/uvdevice.h>
#include <asm/uv.h>

+#define BIT_UVIO_INTERNAL U32_MAX
+/* Mapping from IOCTL-nr to UVC-bit */
+static const u32 ioctl_nr_to_uvc_bit[] __initconst = {
+ [UVIO_IOCTL_UVDEV_INFO_NR] = BIT_UVIO_INTERNAL,
+ [UVIO_IOCTL_ATT_NR] = BIT_UVC_CMD_RETR_ATTEST,
+};
+
+static_assert(ARRAY_SIZE(ioctl_nr_to_uvc_bit) == UVIO_IOCTL_NUM_IOCTLS);
+
+static struct uvio_uvdev_info uvdev_info = {
+ .supp_uvio_cmds = GENMASK_ULL(UVIO_IOCTL_NUM_IOCTLS - 1, 0),
+};
+
+static void __init set_supp_uv_cmds(unsigned long *supp_uv_cmds)
+{
+ int i;
+
+ for (i = 0; i < UVIO_IOCTL_NUM_IOCTLS; i++) {
+ if (ioctl_nr_to_uvc_bit[i] == BIT_UVIO_INTERNAL)
+ continue;
+ if (!test_bit_inv(ioctl_nr_to_uvc_bit[i], uv_info.inst_calls_list))
+ continue;
+ __set_bit(i, supp_uv_cmds);
+ }
+}
+
+/**
+ * uvio_uvdev_info() - get information about the uvdevice
+ *
+ * @uv_ioctl: ioctl control block
+ *
+ * Lists all IOCTLs that are supported by this uvdevice
+ */
+static int uvio_uvdev_info(struct uvio_ioctl_cb *uv_ioctl)
+{
+ void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
+
+ if (uv_ioctl->argument_len < sizeof(uvdev_info))
+ return -EINVAL;
+ if (copy_to_user(user_buf_arg, &uvdev_info, sizeof(uvdev_info)))
+ return -EFAULT;
+
+ uv_ioctl->uv_rc = UVC_RC_EXECUTED;
+ return 0;
+}
+
static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb,
u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest)
{
@@ -185,8 +231,19 @@ static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl)
return ret;
}

-static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp)
+static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp,
+ unsigned long cmd)
{
+ u8 nr = _IOC_NR(cmd);
+
+ if (_IOC_DIR(cmd) != (_IOC_READ | _IOC_WRITE))
+ return -ENOIOCTLCMD;
+ if (_IOC_TYPE(cmd) != UVIO_TYPE_UVC)
+ return -ENOIOCTLCMD;
+ if (nr >= UVIO_IOCTL_NUM_IOCTLS)
+ return -ENOIOCTLCMD;
+ if (_IOC_SIZE(cmd) != sizeof(*ioctl))
+ return -ENOIOCTLCMD;
if (copy_from_user(ioctl, argp, sizeof(*ioctl)))
return -EFAULT;
if (ioctl->flags != 0)
@@ -194,7 +251,7 @@ static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *a
if (memchr_inv(ioctl->reserved14, 0, sizeof(ioctl->reserved14)))
return -EINVAL;

- return 0;
+ return nr;
}

/*
@@ -205,12 +262,17 @@ static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
void __user *argp = (void __user *)arg;
struct uvio_ioctl_cb uv_ioctl = { };
long ret;
+ int nr;

- switch (cmd) {
- case UVIO_IOCTL_ATT:
- ret = uvio_copy_and_check_ioctl(&uv_ioctl, argp);
- if (ret)
- return ret;
+ nr = uvio_copy_and_check_ioctl(&uv_ioctl, argp, cmd);
+ if (nr < 0)
+ return nr;
+
+ switch (nr) {
+ case UVIO_IOCTL_UVDEV_INFO_NR:
+ ret = uvio_uvdev_info(&uv_ioctl);
+ break;
+ case UVIO_IOCTL_ATT_NR:
ret = uvio_attestation(&uv_ioctl);
break;
default:
@@ -245,6 +307,7 @@ static void __exit uvio_dev_exit(void)

static int __init uvio_dev_init(void)
{
+ set_supp_uv_cmds((unsigned long *)&uvdev_info.supp_uv_cmds);
return misc_register(&uvio_dev_miscdev);
}

--
2.41.0