| Message ID | 20210210000259.635748-5-ben.widawsky@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | CXL 2.0 Support | expand |
On Tue, 9 Feb 2021 16:02:55 -0800 Ben Widawsky <ben.widawsky@intel.com> wrote: > Add a straightforward IOCTL that provides a mechanism for userspace to > query the supported memory device commands. CXL commands as they appear > to userspace are described as part of the UAPI kerneldoc. The command > list returned via this IOCTL will contain the full set of commands that > the driver supports, however, some of those commands may not be > available for use by userspace. > > Memory device commands first appear in the CXL 2.0 specification. They > are submitted through a mailbox mechanism specified also originally > specified in the CXL 2.0 specification. > > The send command allows userspace to issue mailbox commands directly to > the hardware. The list of available commands to send are the output of > the query command. The driver verifies basic properties of the command > and possibly inspect the input (or output) payload to determine whether > or not the command is allowed (or might taint the kernel). > > Reported-by: kernel test robot <lkp@intel.com> # bug in earlier revision > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > Reviewed-by: Dan Williams <dan.j.willams@intel.com> A bit of anti macro commentary below. Heavy use of them may make the code shorter, but I'd argue they make it harder to do review if you've not looked at a given bit of code for a while. Also there is a bit of documentation in here for flags that don't seem to exist (at this stage anyway) - may just be in the wrong patch. Jonathan > --- > .clang-format | 1 + > .../userspace-api/ioctl/ioctl-number.rst | 1 + > drivers/cxl/mem.c | 291 +++++++++++++++++- > include/uapi/linux/cxl_mem.h | 152 +++++++++ > 4 files changed, 443 insertions(+), 2 deletions(-) > create mode 100644 include/uapi/linux/cxl_mem.h > > diff --git a/.clang-format b/.clang-format > index 10dc5a9a61b3..3f11c8901b43 100644 > --- a/.clang-format > +++ b/.clang-format > @@ -109,6 +109,7 @@ ForEachMacros: > - 'css_for_each_child' > - 'css_for_each_descendant_post' > - 'css_for_each_descendant_pre' > + - 'cxl_for_each_cmd' > - 'device_for_each_child_node' > - 'dma_fence_chain_for_each' > - 'do_for_each_ftrace_op' > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst > index a4c75a28c839..6eb8e634664d 100644 > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst > @@ -352,6 +352,7 @@ Code Seq# Include File Comments > <mailto:michael.klein@puffin.lb.shuttle.de> > 0xCC 00-0F drivers/misc/ibmvmc.h pseries VMC driver > 0xCD 01 linux/reiserfs_fs.h > +0xCE 01-02 uapi/linux/cxl_mem.h Compute Express Link Memory Devices > 0xCF 02 fs/cifs/ioctl.c > 0xDB 00-0F drivers/char/mwave/mwavepub.h > 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/ > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > index 8bbd2495e237..ce65630bb75e 100644 > --- a/drivers/cxl/mem.c > +++ b/drivers/cxl/mem.c > @@ -1,5 +1,6 @@ > // SPDX-License-Identifier: GPL-2.0-only > /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ > +#include <uapi/linux/cxl_mem.h> > #include <linux/module.h> > #include <linux/mutex.h> > #include <linux/cdev.h> > @@ -39,6 +40,7 @@ > #define CXL_MAILBOX_TIMEOUT_MS (2 * HZ) > > enum opcode { > + CXL_MBOX_OP_INVALID = 0x0000, > CXL_MBOX_OP_IDENTIFY = 0x4000, > CXL_MBOX_OP_MAX = 0x10000 > }; > @@ -90,9 +92,57 @@ struct cxl_memdev { > static int cxl_mem_major; > static DEFINE_IDA(cxl_memdev_ida); > > +/** > + * struct cxl_mem_command - Driver representation of a memory device command > + * @info: Command information as it exists for the UAPI > + * @opcode: The actual bits used for the mailbox protocol > + * @flags: Set of flags reflecting the state of the command. > + * > + * * %CXL_CMD_FLAG_MANDATORY: Hardware must support this command. This flag is > + * only used internally by the driver for sanity checking. Doesn't seem to be defined yet. > + * > + * The cxl_mem_command is the driver's internal representation of commands that > + * are supported by the driver. Some of these commands may not be supported by > + * the hardware. The driver will use @info to validate the fields passed in by > + * the user then submit the @opcode to the hardware. > + * > + * See struct cxl_command_info. > + */ > +struct cxl_mem_command { > + struct cxl_command_info info; > + enum opcode opcode; > +}; > + > +#define CXL_CMD(_id, _flags, sin, sout) \ > + [CXL_MEM_COMMAND_ID_##_id] = { \ > + .info = { \ > + .id = CXL_MEM_COMMAND_ID_##_id, \ > + .flags = CXL_MEM_COMMAND_FLAG_##_flags, \ > + .size_in = sin, \ > + .size_out = sout, \ > + }, \ > + .opcode = CXL_MBOX_OP_##_id, \ > + } > + > +/* > + * This table defines the supported mailbox commands for the driver. This table > + * is made up of a UAPI structure. Non-negative values as parameters in the > + * table will be validated against the user's input. For example, if size_in is > + * 0, and the user passed in 1, it is an error. > + */ > +static struct cxl_mem_command mem_commands[] = { > + CXL_CMD(IDENTIFY, NONE, 0, 0x43), > +}; As below, I'm doubtful about the macro magic and would rather see the long hand version. It's a fwe more characters but I can immediately see if fields are in the right places etc and we can skip the 0 default values. static struct cxl_mem_command mem_commands[] = { [CXL_MEM_COMMAND_ID_IDENTIFY] = { .info = { .id = CXL_MEM_COMMAND_ID_IDENTIFY, .size_out = 0x43, }, .opcode = CXL_MBOX_OP_IDENTIFY, }, }; Still it's your driver and I guess I'll guess I can probably get my head around this macro.. > > diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h > new file mode 100644 > index 000000000000..f1f7e9f32ea5 > --- /dev/null > +++ b/include/uapi/linux/cxl_mem.h > @@ -0,0 +1,152 @@ > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > +/* > + * CXL IOCTLs for Memory Devices > + */ > + > +#ifndef _UAPI_CXL_MEM_H_ > +#define _UAPI_CXL_MEM_H_ > + > +#include <linux/types.h> > + > +/** > + * DOC: UAPI > + * > + * Not all of all commands that the driver supports are always available for use > + * by userspace. Userspace must check the results from the QUERY command in > + * order to determine the live set of commands. > + */ > + > +#define CXL_MEM_QUERY_COMMANDS _IOR(0xCE, 1, struct cxl_mem_query_commands) > +#define CXL_MEM_SEND_COMMAND _IOWR(0xCE, 2, struct cxl_send_command) > + > +#define CXL_CMDS \ > + ___C(INVALID, "Invalid Command"), \ > + ___C(IDENTIFY, "Identify Command"), \ > + ___C(MAX, "Last command") > + > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a > +enum { CXL_CMDS }; > + > +#undef ___C > +#define ___C(a, b) { b } > +static const struct { > + const char *name; > +} cxl_command_names[] = { CXL_CMDS }; > +#undef ___C Unless there are going to be a lot of these, I'd just write them out long hand as much more readable than the macro magic. enum { CXL_MEM_COMMAND_ID_INVALID, CXL_MEM_COMMAND_ID_IDENTIFY, CXL_MEM_COMMAND_ID_MAX }; static const struct { const char *name; } cxl_command_names[] = { [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, /* I hope you never need the Last command to exist in here as that sounds like a bug */ }; That's assuming I actually figured the macro fun out correctly. To my mind it's worth doing this stuff for 'lots' no so much for 3. > + > +/** > + * struct cxl_command_info - Command information returned from a query. > + * @id: ID number for the command. > + * @flags: Flags that specify command behavior. > + * > + * * %CXL_MEM_COMMAND_FLAG_KERNEL: This command is reserved for exclusive > + * kernel use. > + * * %CXL_MEM_COMMAND_FLAG_MUTEX: This command may require coordination with > + * the kernel in order to complete successfully. Doesn't correspond to the flags defined below. If introduced in a later patch then bring the docs in with the first use. > + * > + * @size_in: Expected input size, or -1 if variable length. > + * @size_out: Expected output size, or -1 if variable length. > + * > + * Represents a single command that is supported by both the driver and the > + * hardware. This is returned as part of an array from the query ioctl. The > + * following would be a command named "foobar" that takes a variable length > + * input and returns 0 bytes of output. Why give it a name? It's just an id! > + * > + * - @id = 10 > + * - @flags = CXL_MEM_COMMAND_FLAG_MUTEX That flag doesn't seem to be defined below. > + * - @size_in = -1 > + * - @size_out = 0 > + * > + * See struct cxl_mem_query_commands. > + */ > +struct cxl_command_info { > + __u32 id; > + > + __u32 flags; > +#define CXL_MEM_COMMAND_FLAG_NONE 0 > +#define CXL_MEM_COMMAND_FLAG_KERNEL BIT(0) > +#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(1, 0) > + > + __s32 size_in; > + __s32 size_out; > +}; > + > +/** > + * struct cxl_mem_query_commands - Query supported commands. > + * @n_commands: In/out parameter. When @n_commands is > 0, the driver will > + * return min(num_support_commands, n_commands). When @n_commands > + * is 0, driver will return the number of total supported commands. > + * @rsvd: Reserved for future use. > + * @commands: Output array of supported commands. This array must be allocated > + * by userspace to be at least min(num_support_commands, @n_commands) > + * > + * Allow userspace to query the available commands supported by both the driver, > + * and the hardware. Commands that aren't supported by either the driver, or the > + * hardware are not returned in the query. > + * > + * Examples: > + * > + * - { .n_commands = 0 } // Get number of supported commands > + * - { .n_commands = 15, .commands = buf } // Return first 15 (or less) > + * supported commands > + * > + * See struct cxl_command_info. > + */ > +struct cxl_mem_query_commands { > + /* > + * Input: Number of commands to return (space allocated by user) > + * Output: Number of commands supported by the driver/hardware > + * > + * If n_commands is 0, kernel will only return number of commands and > + * not try to populate commands[], thus allowing userspace to know how > + * much space to allocate > + */ > + __u32 n_commands; > + __u32 rsvd; > + > + struct cxl_command_info __user commands[]; /* out: supported commands */ > +}; > + > +/** > + * struct cxl_send_command - Send a command to a memory device. > + * @id: The command to send to the memory device. This must be one of the > + * commands returned by the query command. > + * @flags: Flags for the command (input). > + * @rsvd: Must be zero. > + * @retval: Return value from the memory device (output). > + * @in.size: Size of the payload to provide to the device (input). > + * @in.rsvd: Must be zero. > + * @in.payload: Pointer to memory for payload input (little endian order). Silly point, but perhaps distinguish it's the payload that is in little endian order not the pointer. (I obviously haven't had enough coffee today and missread it) > + * @out.size: Size of the payload received from the device (input/output). This > + * field is filled in by userspace to let the driver know how much > + * space was allocated for output. It is populated by the driver to > + * let userspace know how large the output payload actually was. > + * @out.rsvd: Must be zero. > + * @out.payload: Pointer to memory for payload output (little endian order). > + * > + * Mechanism for userspace to send a command to the hardware for processing. The > + * driver will do basic validation on the command sizes. In some cases even the > + * payload may be introspected. Userspace is required to allocate large > + * enough buffers for size_out which can be variable length in certain > + * situations. > + */ > +struct cxl_send_command { > + __u32 id; > + __u32 flags; > + __u32 rsvd; > + __u32 retval; > + > + struct { > + __s32 size; > + __u32 rsvd; > + __u64 payload; > + } in; > + > + struct { > + __s32 size; > + __u32 rsvd; > + __u64 payload; > + } out; > +}; > + > +#endif
On 21-02-10 18:45:40, Jonathan Cameron wrote: > On Tue, 9 Feb 2021 16:02:55 -0800 > Ben Widawsky <ben.widawsky@intel.com> wrote: > > > Add a straightforward IOCTL that provides a mechanism for userspace to > > query the supported memory device commands. CXL commands as they appear > > to userspace are described as part of the UAPI kerneldoc. The command > > list returned via this IOCTL will contain the full set of commands that > > the driver supports, however, some of those commands may not be > > available for use by userspace. > > > > Memory device commands first appear in the CXL 2.0 specification. They > > are submitted through a mailbox mechanism specified also originally > > specified in the CXL 2.0 specification. > > > > The send command allows userspace to issue mailbox commands directly to > > the hardware. The list of available commands to send are the output of > > the query command. The driver verifies basic properties of the command > > and possibly inspect the input (or output) payload to determine whether > > or not the command is allowed (or might taint the kernel). > > > > Reported-by: kernel test robot <lkp@intel.com> # bug in earlier revision > > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com> > > Reviewed-by: Dan Williams <dan.j.willams@intel.com> > > A bit of anti macro commentary below. Heavy use of them may make the code > shorter, but I'd argue they make it harder to do review if you've not looked > at a given bit of code for a while. > > Also there is a bit of documentation in here for flags that don't seem to > exist (at this stage anyway) - may just be in the wrong patch. > > Jonathan > > > > --- > > .clang-format | 1 + > > .../userspace-api/ioctl/ioctl-number.rst | 1 + > > drivers/cxl/mem.c | 291 +++++++++++++++++- > > include/uapi/linux/cxl_mem.h | 152 +++++++++ > > 4 files changed, 443 insertions(+), 2 deletions(-) > > create mode 100644 include/uapi/linux/cxl_mem.h > > > > diff --git a/.clang-format b/.clang-format > > index 10dc5a9a61b3..3f11c8901b43 100644 > > --- a/.clang-format > > +++ b/.clang-format > > @@ -109,6 +109,7 @@ ForEachMacros: > > - 'css_for_each_child' > > - 'css_for_each_descendant_post' > > - 'css_for_each_descendant_pre' > > + - 'cxl_for_each_cmd' > > - 'device_for_each_child_node' > > - 'dma_fence_chain_for_each' > > - 'do_for_each_ftrace_op' > > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst > > index a4c75a28c839..6eb8e634664d 100644 > > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst > > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst > > @@ -352,6 +352,7 @@ Code Seq# Include File Comments > > <mailto:michael.klein@puffin.lb.shuttle.de> > > 0xCC 00-0F drivers/misc/ibmvmc.h pseries VMC driver > > 0xCD 01 linux/reiserfs_fs.h > > +0xCE 01-02 uapi/linux/cxl_mem.h Compute Express Link Memory Devices > > 0xCF 02 fs/cifs/ioctl.c > > 0xDB 00-0F drivers/char/mwave/mwavepub.h > > 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/ > > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > > index 8bbd2495e237..ce65630bb75e 100644 > > --- a/drivers/cxl/mem.c > > +++ b/drivers/cxl/mem.c > > @@ -1,5 +1,6 @@ > > // SPDX-License-Identifier: GPL-2.0-only > > /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ > > +#include <uapi/linux/cxl_mem.h> > > #include <linux/module.h> > > #include <linux/mutex.h> > > #include <linux/cdev.h> > > @@ -39,6 +40,7 @@ > > #define CXL_MAILBOX_TIMEOUT_MS (2 * HZ) > > > > enum opcode { > > + CXL_MBOX_OP_INVALID = 0x0000, > > CXL_MBOX_OP_IDENTIFY = 0x4000, > > CXL_MBOX_OP_MAX = 0x10000 > > }; > > @@ -90,9 +92,57 @@ struct cxl_memdev { > > static int cxl_mem_major; > > static DEFINE_IDA(cxl_memdev_ida); > > > > +/** > > + * struct cxl_mem_command - Driver representation of a memory device command > > + * @info: Command information as it exists for the UAPI > > + * @opcode: The actual bits used for the mailbox protocol > > + * @flags: Set of flags reflecting the state of the command. > > + * > > + * * %CXL_CMD_FLAG_MANDATORY: Hardware must support this command. This flag is > > + * only used internally by the driver for sanity checking. > > Doesn't seem to be defined yet. > This slipped by me. The flags are entirely gone now. I found some other stale comments like references to "mbox_lock" that I'm also cleaning up. > > + * > > + * The cxl_mem_command is the driver's internal representation of commands that > > + * are supported by the driver. Some of these commands may not be supported by > > + * the hardware. The driver will use @info to validate the fields passed in by > > + * the user then submit the @opcode to the hardware. > > + * > > + * See struct cxl_command_info. > > + */ > > +struct cxl_mem_command { > > + struct cxl_command_info info; > > + enum opcode opcode; > > +}; > > + > > +#define CXL_CMD(_id, _flags, sin, sout) \ > > + [CXL_MEM_COMMAND_ID_##_id] = { \ > > + .info = { \ > > + .id = CXL_MEM_COMMAND_ID_##_id, \ > > + .flags = CXL_MEM_COMMAND_FLAG_##_flags, \ > > + .size_in = sin, \ > > + .size_out = sout, \ > > + }, \ > > + .opcode = CXL_MBOX_OP_##_id, \ > > + } > > + > > +/* > > + * This table defines the supported mailbox commands for the driver. This table > > + * is made up of a UAPI structure. Non-negative values as parameters in the > > + * table will be validated against the user's input. For example, if size_in is > > + * 0, and the user passed in 1, it is an error. > > + */ > > +static struct cxl_mem_command mem_commands[] = { > > + CXL_CMD(IDENTIFY, NONE, 0, 0x43), > > +}; > > As below, I'm doubtful about the macro magic and would rather see the > long hand version. It's a fwe more characters but I can immediately see if fields > are in the right places etc and we can skip the 0 default values. > > static struct cxl_mem_command mem_commands[] = { > [CXL_MEM_COMMAND_ID_IDENTIFY] = { > .info = { > .id = CXL_MEM_COMMAND_ID_IDENTIFY, > .size_out = 0x43, > }, > .opcode = CXL_MBOX_OP_IDENTIFY, > }, > }; > > Still it's your driver and I guess I'll guess I can probably get my head around > this macro.. > An unreleased version of this series did just that. Dan suggested the change. My original preference was your suggestion FWIW, but over time I've come to prefer this. We can drop flags now, and we could add more macros to make it a bit better: CXL_CMD_IN(FOO, 0x10) // we have none in the driver today CXL_CMD_OUT(IDENTIFY, 0x43) CXL_CMD_INOUT(GET_LSA, 0x8, ~0) > > > > diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h > > new file mode 100644 > > index 000000000000..f1f7e9f32ea5 > > --- /dev/null > > +++ b/include/uapi/linux/cxl_mem.h > > @@ -0,0 +1,152 @@ > > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > > +/* > > + * CXL IOCTLs for Memory Devices > > + */ > > + > > +#ifndef _UAPI_CXL_MEM_H_ > > +#define _UAPI_CXL_MEM_H_ > > + > > +#include <linux/types.h> > > + > > +/** > > + * DOC: UAPI > > + * > > + * Not all of all commands that the driver supports are always available for use > > + * by userspace. Userspace must check the results from the QUERY command in > > + * order to determine the live set of commands. > > + */ > > + > > +#define CXL_MEM_QUERY_COMMANDS _IOR(0xCE, 1, struct cxl_mem_query_commands) > > +#define CXL_MEM_SEND_COMMAND _IOWR(0xCE, 2, struct cxl_send_command) > > + > > +#define CXL_CMDS \ > > + ___C(INVALID, "Invalid Command"), \ > > + ___C(IDENTIFY, "Identify Command"), \ > > + ___C(MAX, "Last command") > > + > > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a > > +enum { CXL_CMDS }; > > + > > +#undef ___C > > +#define ___C(a, b) { b } > > +static const struct { > > + const char *name; > > +} cxl_command_names[] = { CXL_CMDS }; > > +#undef ___C > > Unless there are going to be a lot of these, I'd just write them out long hand > as much more readable than the macro magic. > > enum { > CXL_MEM_COMMAND_ID_INVALID, > CXL_MEM_COMMAND_ID_IDENTIFY, > CXL_MEM_COMMAND_ID_MAX > }; > > static const struct { > const char *name; > } cxl_command_names[] = { > [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, > [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, > /* I hope you never need the Last command to exist in here as that sounds like a bug */ > }; > > That's assuming I actually figured the macro fun out correctly. > To my mind it's worth doing this stuff for 'lots' no so much for 3. > > > + > > +/** > > + * struct cxl_command_info - Command information returned from a query. > > + * @id: ID number for the command. > > + * @flags: Flags that specify command behavior. > > + * > > + * * %CXL_MEM_COMMAND_FLAG_KERNEL: This command is reserved for exclusive > > + * kernel use. > > + * * %CXL_MEM_COMMAND_FLAG_MUTEX: This command may require coordination with > > + * the kernel in order to complete successfully. > Doesn't correspond to the flags defined below. If introduced in a later patch > then bring the docs in with the first use. > MUTEX should be gone. KERNEL is still there, and I will move it to later. > > + * > > + * @size_in: Expected input size, or -1 if variable length. > > + * @size_out: Expected output size, or -1 if variable length. > > + * > > + * Represents a single command that is supported by both the driver and the > > + * hardware. This is returned as part of an array from the query ioctl. The > > + * following would be a command named "foobar" that takes a variable length > > + * input and returns 0 bytes of output. > > Why give it a name? It's just an id! > At one point, name was part of the struct. Who reads comments anyway :P > > + * > > + * - @id = 10 > > + * - @flags = CXL_MEM_COMMAND_FLAG_MUTEX > > That flag doesn't seem to be defined below. > Yeah, stale comment... > > + * - @size_in = -1 > > + * - @size_out = 0 > > + * > > + * See struct cxl_mem_query_commands. > > + */ > > +struct cxl_command_info { > > + __u32 id; > > + > > + __u32 flags; > > +#define CXL_MEM_COMMAND_FLAG_NONE 0 > > +#define CXL_MEM_COMMAND_FLAG_KERNEL BIT(0) > > +#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(1, 0) > > + > > + __s32 size_in; > > + __s32 size_out; > > +}; > > + > > +/** > > + * struct cxl_mem_query_commands - Query supported commands. > > + * @n_commands: In/out parameter. When @n_commands is > 0, the driver will > > + * return min(num_support_commands, n_commands). When @n_commands > > + * is 0, driver will return the number of total supported commands. > > + * @rsvd: Reserved for future use. > > + * @commands: Output array of supported commands. This array must be allocated > > + * by userspace to be at least min(num_support_commands, @n_commands) > > + * > > + * Allow userspace to query the available commands supported by both the driver, > > + * and the hardware. Commands that aren't supported by either the driver, or the > > + * hardware are not returned in the query. > > + * > > + * Examples: > > + * > > + * - { .n_commands = 0 } // Get number of supported commands > > + * - { .n_commands = 15, .commands = buf } // Return first 15 (or less) > > + * supported commands > > + * > > + * See struct cxl_command_info. > > + */ > > +struct cxl_mem_query_commands { > > + /* > > + * Input: Number of commands to return (space allocated by user) > > + * Output: Number of commands supported by the driver/hardware > > + * > > + * If n_commands is 0, kernel will only return number of commands and > > + * not try to populate commands[], thus allowing userspace to know how > > + * much space to allocate > > + */ > > + __u32 n_commands; > > + __u32 rsvd; > > + > > + struct cxl_command_info __user commands[]; /* out: supported commands */ > > +}; > > + > > +/** > > + * struct cxl_send_command - Send a command to a memory device. > > + * @id: The command to send to the memory device. This must be one of the > > + * commands returned by the query command. > > + * @flags: Flags for the command (input). > > + * @rsvd: Must be zero. > > + * @retval: Return value from the memory device (output). > > + * @in.size: Size of the payload to provide to the device (input). > > + * @in.rsvd: Must be zero. > > + * @in.payload: Pointer to memory for payload input (little endian order). > > Silly point, but perhaps distinguish it's the payload that is in little endian order > not the pointer. (I obviously haven't had enough coffee today and missread it) > > > > + * @out.size: Size of the payload received from the device (input/output). This > > + * field is filled in by userspace to let the driver know how much > > + * space was allocated for output. It is populated by the driver to > > + * let userspace know how large the output payload actually was. > > + * @out.rsvd: Must be zero. > > + * @out.payload: Pointer to memory for payload output (little endian order). > > + * > > + * Mechanism for userspace to send a command to the hardware for processing. The > > + * driver will do basic validation on the command sizes. In some cases even the > > + * payload may be introspected. Userspace is required to allocate large > > + * enough buffers for size_out which can be variable length in certain > > + * situations. > > + */ > > +struct cxl_send_command { > > + __u32 id; > > + __u32 flags; > > + __u32 rsvd; > > + __u32 retval; > > + > > + struct { > > + __s32 size; > > + __u32 rsvd; > > + __u64 payload; > > + } in; > > + > > + struct { > > + __s32 size; > > + __u32 rsvd; > > + __u64 payload; > > + } out; > > +}; > > + > > +#endif >
On Wed, Feb 10, 2021 at 10:47 AM Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote: [..] > > +#define CXL_CMDS \ > > + ___C(INVALID, "Invalid Command"), \ > > + ___C(IDENTIFY, "Identify Command"), \ > > + ___C(MAX, "Last command") > > + > > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a > > +enum { CXL_CMDS }; > > + > > +#undef ___C > > +#define ___C(a, b) { b } > > +static const struct { > > + const char *name; > > +} cxl_command_names[] = { CXL_CMDS }; > > +#undef ___C > > Unless there are going to be a lot of these, I'd just write them out long hand > as much more readable than the macro magic. This macro magic isn't new to Linux it was introduced with ftrace: See "cpp tricks and treats": https://lwn.net/Articles/383362/ > > enum { > CXL_MEM_COMMAND_ID_INVALID, > CXL_MEM_COMMAND_ID_IDENTIFY, > CXL_MEM_COMMAND_ID_MAX > }; > > static const struct { > const char *name; > } cxl_command_names[] = { > [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, > [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, > /* I hope you never need the Last command to exist in here as that sounds like a bug */ > }; > > That's assuming I actually figured the macro fun out correctly. > To my mind it's worth doing this stuff for 'lots' no so much for 3. The list will continue to expand, and it eliminates the "did you remember to update cxl_command_names" review burden permanently.
On Wed, 10 Feb 2021 20:40:52 -0800 Dan Williams <dan.j.williams@intel.com> wrote: > On Wed, Feb 10, 2021 at 10:47 AM Jonathan Cameron > <Jonathan.Cameron@huawei.com> wrote: > [..] > > > +#define CXL_CMDS \ > > > + ___C(INVALID, "Invalid Command"), \ > > > + ___C(IDENTIFY, "Identify Command"), \ > > > + ___C(MAX, "Last command") > > > + > > > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a > > > +enum { CXL_CMDS }; > > > + > > > +#undef ___C > > > +#define ___C(a, b) { b } > > > +static const struct { > > > + const char *name; > > > +} cxl_command_names[] = { CXL_CMDS }; > > > +#undef ___C > > > > Unless there are going to be a lot of these, I'd just write them out long hand > > as much more readable than the macro magic. > > This macro magic isn't new to Linux it was introduced with ftrace: > > See "cpp tricks and treats": https://lwn.net/Articles/383362/ Yeah. I've dealt with that one a few times. It's very cleaver and compact but a PITA to debug build errors related to it. > > > > > enum { > > CXL_MEM_COMMAND_ID_INVALID, > > CXL_MEM_COMMAND_ID_IDENTIFY, > > CXL_MEM_COMMAND_ID_MAX > > }; > > > > static const struct { > > const char *name; > > } cxl_command_names[] = { > > [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, > > [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, > > /* I hope you never need the Last command to exist in here as that sounds like a bug */ > > }; > > > > That's assuming I actually figured the macro fun out correctly. > > To my mind it's worth doing this stuff for 'lots' no so much for 3. > > The list will continue to expand, and it eliminates the "did you > remember to update cxl_command_names" review burden permanently. How about a compromise. Add a comment giving how the first entry expands to avoid people (me at least :) having to think their way through it every time? Jonathan
On 21-02-11 10:06:46, Jonathan Cameron wrote: > On Wed, 10 Feb 2021 20:40:52 -0800 > Dan Williams <dan.j.williams@intel.com> wrote: > > > On Wed, Feb 10, 2021 at 10:47 AM Jonathan Cameron > > <Jonathan.Cameron@huawei.com> wrote: > > [..] > > > > +#define CXL_CMDS \ > > > > + ___C(INVALID, "Invalid Command"), \ > > > > + ___C(IDENTIFY, "Identify Command"), \ > > > > + ___C(MAX, "Last command") > > > > + > > > > +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a > > > > +enum { CXL_CMDS }; > > > > + > > > > +#undef ___C > > > > +#define ___C(a, b) { b } > > > > +static const struct { > > > > + const char *name; > > > > +} cxl_command_names[] = { CXL_CMDS }; > > > > +#undef ___C > > > > > > Unless there are going to be a lot of these, I'd just write them out long hand > > > as much more readable than the macro magic. > > > > This macro magic isn't new to Linux it was introduced with ftrace: > > > > See "cpp tricks and treats": https://lwn.net/Articles/383362/ > > Yeah. I've dealt with that one a few times. It's very cleaver and compact > but a PITA to debug build errors related to it. > > > > > > > > > enum { > > > CXL_MEM_COMMAND_ID_INVALID, > > > CXL_MEM_COMMAND_ID_IDENTIFY, > > > CXL_MEM_COMMAND_ID_MAX > > > }; > > > > > > static const struct { > > > const char *name; > > > } cxl_command_names[] = { > > > [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, > > > [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, > > > /* I hope you never need the Last command to exist in here as that sounds like a bug */ > > > }; > > > > > > That's assuming I actually figured the macro fun out correctly. > > > To my mind it's worth doing this stuff for 'lots' no so much for 3. > > > > The list will continue to expand, and it eliminates the "did you > > remember to update cxl_command_names" review burden permanently. > > How about a compromise. Add a comment giving how the first entry expands to > avoid people (me at least :) having to think their way through it every time? > > Jonathan > A minor tweak while here... diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h index 655fbfde97fd..dac0adb879ec 100644 --- a/include/uapi/linux/cxl_mem.h +++ b/include/uapi/linux/cxl_mem.h @@ -22,7 +22,7 @@ #define CXL_CMDS \ ___C(INVALID, "Invalid Command"), \ ___C(IDENTIFY, "Identify Command"), \ - ___C(MAX, "Last command") + ___C(MAX, "invalid / last command") #define ___C(a, b) CXL_MEM_COMMAND_ID_##a enum { CXL_CMDS }; @@ -32,6 +32,17 @@ enum { CXL_CMDS }; static const struct { const char *name; } cxl_command_names[] = { CXL_CMDS }; + +/* + * Here's how this actually breaks out: + * cxl_command_names[] = { + * [CXL_MEM_COMMAND_ID_INVALID] = { "Invalid Command" }, + * [CXL_MEM_COMMAND_ID_IDENTIFY] = { "Identify Comamnd" }, + * ... + * [CXL_MEM_COMMAND_ID_MAX] = { "invalid / last command" }, + * }; + */ +
On Tue, Feb 09, 2021 at 04:02:55PM -0800, Ben Widawsky wrote: > +static int handle_mailbox_cmd_from_user(struct cxl_memdev *cxlmd, > + const struct cxl_mem_command *cmd, > + u64 in_payload, u64 out_payload, > + struct cxl_send_command __user *s) > +{ > + struct cxl_mem *cxlm = cxlmd->cxlm; > + struct device *dev = &cxlmd->dev; > + struct mbox_cmd mbox_cmd = { > + .opcode = cmd->opcode, > + .size_in = cmd->info.size_in, > + }; > + s32 user_size_out; > + int rc; > + > + if (get_user(user_size_out, &s->out.size)) > + return -EFAULT; You have already copied it in. Never reread stuff from userland - it *can* change under you.
On 21-02-14 16:30:09, Al Viro wrote: > On Tue, Feb 09, 2021 at 04:02:55PM -0800, Ben Widawsky wrote: > > > +static int handle_mailbox_cmd_from_user(struct cxl_memdev *cxlmd, > > + const struct cxl_mem_command *cmd, > > + u64 in_payload, u64 out_payload, > > + struct cxl_send_command __user *s) > > +{ > > + struct cxl_mem *cxlm = cxlmd->cxlm; > > + struct device *dev = &cxlmd->dev; > > + struct mbox_cmd mbox_cmd = { > > + .opcode = cmd->opcode, > > + .size_in = cmd->info.size_in, > > + }; > > + s32 user_size_out; > > + int rc; > > + > > + if (get_user(user_size_out, &s->out.size)) > > + return -EFAULT; > > You have already copied it in. Never reread stuff from userland - it *can* > change under you. As it turns out, this is some leftover logic which doesn't need to exist at all, and I'm happy to change it. Thanks for reviewing. I wasn't familiar with this restriction though. For my edification could you explain how that could happen? Also, is this something that should go in the kdocs, because I don't see anything about this restriction there. Thanks. Ben
On Sun, Feb 14, 2021 at 03:14:56PM -0800, Ben Widawsky wrote: > On 21-02-14 16:30:09, Al Viro wrote: > > On Tue, Feb 09, 2021 at 04:02:55PM -0800, Ben Widawsky wrote: > > > > > +static int handle_mailbox_cmd_from_user(struct cxl_memdev *cxlmd, > > > + const struct cxl_mem_command *cmd, > > > + u64 in_payload, u64 out_payload, > > > + struct cxl_send_command __user *s) > > > +{ > > > + struct cxl_mem *cxlm = cxlmd->cxlm; > > > + struct device *dev = &cxlmd->dev; > > > + struct mbox_cmd mbox_cmd = { > > > + .opcode = cmd->opcode, > > > + .size_in = cmd->info.size_in, > > > + }; > > > + s32 user_size_out; > > > + int rc; > > > + > > > + if (get_user(user_size_out, &s->out.size)) > > > + return -EFAULT; > > > > You have already copied it in. Never reread stuff from userland - it *can* > > change under you. > > As it turns out, this is some leftover logic which doesn't need to exist at all, > and I'm happy to change it. Thanks for reviewing. > > I wasn't familiar with this restriction though. For my edification could you > explain how that could happen? Also, is this something that should go in the > kdocs, because I don't see anything about this restriction there. Er... You do realize that if two processes share memory, one can bloody well modify it while another is in the middle of syscall, right? Always could - even mmap(2) with MAP_SHARED is sufficient, same as shmat(2), or the wholesale sharing between POSIX threads, etc. And even on UP with no preemption you could bloody well have a structure that spans a page boundary, with the next page being mmapped and currently not present in memory. Then copy_from_user() would've copied the beginning, hit a page fault, try to read the next page from something slow and lose CPU. Letting the second process run and modify the already copied part. It has been possible since at least mid-80s, well before Linux. Anything in user memory can change under you, right in the middle of syscall. Always could. And there had been very real bugs along the lines of data being read twice, once for safety check, once for actual work. Something like get_user(len, &user_object->len); check that len is reasonable p = kmalloc(offsetof(struct foo, string[len]), GFP_KERNEL); copy_from_user(p, user_object, len); work with the copy, assuming that first p->len bytes of p->string[] are safe to use, find out that p->len is much greater than len since the userland data has changed between two fetches Some of those had been exploitable from the very beginning, some had become such on innocious-looking changes. For the sake of your sanity it's better to avoid such landmines. In some cases it's OK to read the data twice (e.g. in something like select(2)), but those cases are rare and seeing something of that sort is generally a big red flag on review. In almost all cases it's best avoided.
On Sun, Feb 14, 2021 at 11:50:12PM +0000, Al Viro wrote: > check that len is reasonable > p = kmalloc(offsetof(struct foo, string[len]), GFP_KERNEL); > copy_from_user(p, user_object, len); offsetof(struct foo, string[len]), that is
diff --git a/.clang-format b/.clang-format index 10dc5a9a61b3..3f11c8901b43 100644 --- a/.clang-format +++ b/.clang-format @@ -109,6 +109,7 @@ ForEachMacros: - 'css_for_each_child' - 'css_for_each_descendant_post' - 'css_for_each_descendant_pre' + - 'cxl_for_each_cmd' - 'device_for_each_child_node' - 'dma_fence_chain_for_each' - 'do_for_each_ftrace_op' diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst index a4c75a28c839..6eb8e634664d 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -352,6 +352,7 @@ Code Seq# Include File Comments <mailto:michael.klein@puffin.lb.shuttle.de> 0xCC 00-0F drivers/misc/ibmvmc.h pseries VMC driver 0xCD 01 linux/reiserfs_fs.h +0xCE 01-02 uapi/linux/cxl_mem.h Compute Express Link Memory Devices 0xCF 02 fs/cifs/ioctl.c 0xDB 00-0F drivers/char/mwave/mwavepub.h 0xDD 00-3F ZFCP device driver see drivers/s390/scsi/ diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c index 8bbd2495e237..ce65630bb75e 100644 --- a/drivers/cxl/mem.c +++ b/drivers/cxl/mem.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0-only /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ +#include <uapi/linux/cxl_mem.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/cdev.h> @@ -39,6 +40,7 @@ #define CXL_MAILBOX_TIMEOUT_MS (2 * HZ) enum opcode { + CXL_MBOX_OP_INVALID = 0x0000, CXL_MBOX_OP_IDENTIFY = 0x4000, CXL_MBOX_OP_MAX = 0x10000 }; @@ -90,9 +92,57 @@ struct cxl_memdev { static int cxl_mem_major; static DEFINE_IDA(cxl_memdev_ida); +/** + * struct cxl_mem_command - Driver representation of a memory device command + * @info: Command information as it exists for the UAPI + * @opcode: The actual bits used for the mailbox protocol + * @flags: Set of flags reflecting the state of the command. + * + * * %CXL_CMD_FLAG_MANDATORY: Hardware must support this command. This flag is + * only used internally by the driver for sanity checking. + * + * The cxl_mem_command is the driver's internal representation of commands that + * are supported by the driver. Some of these commands may not be supported by + * the hardware. The driver will use @info to validate the fields passed in by + * the user then submit the @opcode to the hardware. + * + * See struct cxl_command_info. + */ +struct cxl_mem_command { + struct cxl_command_info info; + enum opcode opcode; +}; + +#define CXL_CMD(_id, _flags, sin, sout) \ + [CXL_MEM_COMMAND_ID_##_id] = { \ + .info = { \ + .id = CXL_MEM_COMMAND_ID_##_id, \ + .flags = CXL_MEM_COMMAND_FLAG_##_flags, \ + .size_in = sin, \ + .size_out = sout, \ + }, \ + .opcode = CXL_MBOX_OP_##_id, \ + } + +/* + * This table defines the supported mailbox commands for the driver. This table + * is made up of a UAPI structure. Non-negative values as parameters in the + * table will be validated against the user's input. For example, if size_in is + * 0, and the user passed in 1, it is an error. + */ +static struct cxl_mem_command mem_commands[] = { + CXL_CMD(IDENTIFY, NONE, 0, 0x43), +}; + +#define cxl_for_each_cmd(cmd) \ + for ((cmd) = &mem_commands[0]; \ + ((cmd) - mem_commands) < ARRAY_SIZE(mem_commands); (cmd)++) + +#define cxl_cmd_count ARRAY_SIZE(mem_commands) + static int cxl_mem_wait_for_doorbell(struct cxl_mem *cxlm) { - const unsigned long start = jiffies; + unsigned long start = jiffies; unsigned long end = start; while (cxl_doorbell_busy(cxlm)) { @@ -313,6 +363,243 @@ static void cxl_mem_mbox_put(struct cxl_mem *cxlm) mutex_unlock(&cxlm->mbox_mutex); } +/** + * handle_mailbox_cmd_from_user() - Dispatch a mailbox command. + * @cxlmd: The CXL memory device to communicate with. + * @cmd: The validated command. + * @in_payload: Pointer to userspace's input payload. + * @out_payload: Pointer to userspace's output payload. + * @s: The command submitted by userspace. Has output fields. + * + * Return: + * * %0 - Mailbox transaction succeeded. + * * %-EFAULT - Something happened with copy_to/from_user. + * * %-ENOMEM - Couldn't allocate a bounce buffer. + * * %-EINTR - Mailbox acquisition interrupted. + * * %-E2BIG - Output payload would overrun user's buffer. + * + * Creates the appropriate mailbox command on behalf of a userspace request. + * Return value, size, and output payload are all copied out to @u. The + * parameters for the command must be validated before calling this function. + * + * A 0 return code indicates the command executed successfully, not that it was + * itself successful. IOW, the cmd->retval should always be checked if wanting + * to determine the actual result. + */ +static int handle_mailbox_cmd_from_user(struct cxl_memdev *cxlmd, + const struct cxl_mem_command *cmd, + u64 in_payload, u64 out_payload, + struct cxl_send_command __user *s) +{ + struct cxl_mem *cxlm = cxlmd->cxlm; + struct device *dev = &cxlmd->dev; + struct mbox_cmd mbox_cmd = { + .opcode = cmd->opcode, + .size_in = cmd->info.size_in, + }; + s32 user_size_out; + int rc; + + if (get_user(user_size_out, &s->out.size)) + return -EFAULT; + + if (cmd->info.size_out > 0) /* fixed size command */ + mbox_cmd.payload_out = kvzalloc(cmd->info.size_out, GFP_KERNEL); + else if (cmd->info.size_out < 0) /* variable */ + mbox_cmd.payload_out = kvzalloc(cxlm->payload_size, GFP_KERNEL); + + if (cmd->info.size_in) { + mbox_cmd.payload_in = kvzalloc(cmd->info.size_in, GFP_KERNEL); + if (!mbox_cmd.payload_in) { + rc = -ENOMEM; + goto out; + } + + if (copy_from_user(mbox_cmd.payload_in, + u64_to_user_ptr(in_payload), + cmd->info.size_in)) { + rc = -EFAULT; + goto out; + } + } + + rc = cxl_mem_mbox_get(cxlm); + if (rc) + goto out; + + dev_dbg(dev, + "Submitting %s command for user\n" + "\topcode: %x\n" + "\tsize: %ub\n", + cxl_command_names[cmd->info.id].name, mbox_cmd.opcode, + cmd->info.size_in); + + rc = cxl_mem_mbox_send_cmd(cxlm, &mbox_cmd); + cxl_mem_mbox_put(cxlm); + if (rc) + goto out; + + rc = put_user(mbox_cmd.return_code, &s->retval); + if (rc) + goto out; + + if (user_size_out < mbox_cmd.size_out) { + rc = -E2BIG; + goto out; + } + + if (mbox_cmd.size_out) { + if (copy_to_user(u64_to_user_ptr(out_payload), + mbox_cmd.payload_out, mbox_cmd.size_out)) { + rc = -EFAULT; + goto out; + } + } + + rc = put_user(mbox_cmd.size_out, &s->out.size); + +out: + kvfree(mbox_cmd.payload_in); + kvfree(mbox_cmd.payload_out); + return rc; +} + +/** + * cxl_validate_cmd_from_user() - Check fields for CXL_MEM_SEND_COMMAND. + * @cxlm: &struct cxl_mem device whose mailbox will be used. + * @send_cmd: &struct cxl_send_command copied in from userspace. + * @out_cmd: Sanitized and populated &struct cxl_mem_command. + * + * Return: + * * %0 - @out_cmd is ready to send. + * * %-ENOTTY - Invalid command specified. + * * %-EINVAL - Reserved fields or invalid values were used. + * * %-EPERM - Attempted to use a protected command. + * * %-ENOMEM - Input or output buffer wasn't sized properly. + * + * The result of this command is a fully validated command in @out_cmd that is + * safe to send to the hardware. + * + * See handle_mailbox_cmd_from_user() + */ +static int cxl_validate_cmd_from_user(struct cxl_mem *cxlm, + const struct cxl_send_command *send_cmd, + struct cxl_mem_command *out_cmd) +{ + const struct cxl_command_info *info; + struct cxl_mem_command *c; + + if (send_cmd->id == 0 || send_cmd->id >= CXL_MEM_COMMAND_ID_MAX) + return -ENOTTY; + + /* + * The user can never specify an input payload larger than + * hardware supports, but output can be arbitrarily large, + * simply write out as much data as the hardware provides. + */ + if (send_cmd->in.size > cxlm->payload_size) + return -EINVAL; + + if (send_cmd->flags & ~CXL_MEM_COMMAND_FLAG_MASK) + return -EINVAL; + + if (send_cmd->rsvd) + return -EINVAL; + + if (send_cmd->in.rsvd || send_cmd->out.rsvd) + return -EINVAL; + + /* Convert user's command into the internal representation */ + c = &mem_commands[send_cmd->id]; + info = &c->info; + + if (info->flags & CXL_MEM_COMMAND_FLAG_KERNEL) + return -EPERM; + + /* Check the input buffer is the expected size */ + if (info->size_in >= 0 && info->size_in != send_cmd->in.size) + return -ENOMEM; + + /* Check the output buffer is at least large enough */ + if (info->size_out >= 0 && send_cmd->out.size < info->size_out) + return -ENOMEM; + + /* Setting a few const fields here... */ + memcpy(out_cmd, c, sizeof(*c)); + out_cmd->info.size_in = send_cmd->in.size; + out_cmd->info.size_out = send_cmd->out.size; + + return 0; +} + +static int cxl_query_cmd(struct cxl_memdev *cxlmd, + struct cxl_mem_query_commands __user *q) +{ + struct device *dev = &cxlmd->dev; + struct cxl_mem_command *cmd; + u32 n_commands; + int j = 0; + + dev_dbg(dev, "Query IOCTL\n"); + + if (get_user(n_commands, &q->n_commands)) + return -EFAULT; + + /* returns the total number if 0 elements are requested. */ + if (n_commands == 0) + return put_user(cxl_cmd_count, &q->n_commands); + + /* + * otherwise, return max(n_commands, total commands) cxl_command_info + * structures. + */ + cxl_for_each_cmd(cmd) { + const struct cxl_command_info *info = &cmd->info; + + if (copy_to_user(&q->commands[j++], info, sizeof(*info))) + return -EFAULT; + + if (j == n_commands) + break; + } + + return 0; +} + +static int cxl_send_cmd(struct cxl_memdev *cxlmd, + struct cxl_send_command __user *s) +{ + struct device *dev = &cxlmd->dev; + struct cxl_send_command send; + struct cxl_mem_command c; + int rc; + + dev_dbg(dev, "Send IOCTL\n"); + + if (copy_from_user(&send, s, sizeof(send))) + return -EFAULT; + + rc = cxl_validate_cmd_from_user(cxlmd->cxlm, &send, &c); + if (rc) + return rc; + + return handle_mailbox_cmd_from_user(cxlmd, &c, send.in.payload, + send.out.payload, s); +} + +static long __cxl_memdev_ioctl(struct cxl_memdev *cxlmd, unsigned int cmd, + unsigned long arg) +{ + switch (cmd) { + case CXL_MEM_QUERY_COMMANDS: + return cxl_query_cmd(cxlmd, (void __user *)arg); + case CXL_MEM_SEND_COMMAND: + return cxl_send_cmd(cxlmd, (void __user *)arg); + default: + return -ENOTTY; + } +} + static long cxl_memdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -326,7 +613,7 @@ static long cxl_memdev_ioctl(struct file *file, unsigned int cmd, if (!percpu_ref_tryget_live(&cxlmd->ops_active)) return -ENXIO; - /* TODO: ioctl body */ + rc = __cxl_memdev_ioctl(cxlmd, cmd, arg); percpu_ref_put(&cxlmd->ops_active); diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h new file mode 100644 index 000000000000..f1f7e9f32ea5 --- /dev/null +++ b/include/uapi/linux/cxl_mem.h @@ -0,0 +1,152 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * CXL IOCTLs for Memory Devices + */ + +#ifndef _UAPI_CXL_MEM_H_ +#define _UAPI_CXL_MEM_H_ + +#include <linux/types.h> + +/** + * DOC: UAPI + * + * Not all of all commands that the driver supports are always available for use + * by userspace. Userspace must check the results from the QUERY command in + * order to determine the live set of commands. + */ + +#define CXL_MEM_QUERY_COMMANDS _IOR(0xCE, 1, struct cxl_mem_query_commands) +#define CXL_MEM_SEND_COMMAND _IOWR(0xCE, 2, struct cxl_send_command) + +#define CXL_CMDS \ + ___C(INVALID, "Invalid Command"), \ + ___C(IDENTIFY, "Identify Command"), \ + ___C(MAX, "Last command") + +#define ___C(a, b) CXL_MEM_COMMAND_ID_##a +enum { CXL_CMDS }; + +#undef ___C +#define ___C(a, b) { b } +static const struct { + const char *name; +} cxl_command_names[] = { CXL_CMDS }; +#undef ___C + +/** + * struct cxl_command_info - Command information returned from a query. + * @id: ID number for the command. + * @flags: Flags that specify command behavior. + * + * * %CXL_MEM_COMMAND_FLAG_KERNEL: This command is reserved for exclusive + * kernel use. + * * %CXL_MEM_COMMAND_FLAG_MUTEX: This command may require coordination with + * the kernel in order to complete successfully. + * + * @size_in: Expected input size, or -1 if variable length. + * @size_out: Expected output size, or -1 if variable length. + * + * Represents a single command that is supported by both the driver and the + * hardware. This is returned as part of an array from the query ioctl. The + * following would be a command named "foobar" that takes a variable length + * input and returns 0 bytes of output. + * + * - @id = 10 + * - @flags = CXL_MEM_COMMAND_FLAG_MUTEX + * - @size_in = -1 + * - @size_out = 0 + * + * See struct cxl_mem_query_commands. + */ +struct cxl_command_info { + __u32 id; + + __u32 flags; +#define CXL_MEM_COMMAND_FLAG_NONE 0 +#define CXL_MEM_COMMAND_FLAG_KERNEL BIT(0) +#define CXL_MEM_COMMAND_FLAG_MASK GENMASK(1, 0) + + __s32 size_in; + __s32 size_out; +}; + +/** + * struct cxl_mem_query_commands - Query supported commands. + * @n_commands: In/out parameter. When @n_commands is > 0, the driver will + * return min(num_support_commands, n_commands). When @n_commands + * is 0, driver will return the number of total supported commands. + * @rsvd: Reserved for future use. + * @commands: Output array of supported commands. This array must be allocated + * by userspace to be at least min(num_support_commands, @n_commands) + * + * Allow userspace to query the available commands supported by both the driver, + * and the hardware. Commands that aren't supported by either the driver, or the + * hardware are not returned in the query. + * + * Examples: + * + * - { .n_commands = 0 } // Get number of supported commands + * - { .n_commands = 15, .commands = buf } // Return first 15 (or less) + * supported commands + * + * See struct cxl_command_info. + */ +struct cxl_mem_query_commands { + /* + * Input: Number of commands to return (space allocated by user) + * Output: Number of commands supported by the driver/hardware + * + * If n_commands is 0, kernel will only return number of commands and + * not try to populate commands[], thus allowing userspace to know how + * much space to allocate + */ + __u32 n_commands; + __u32 rsvd; + + struct cxl_command_info __user commands[]; /* out: supported commands */ +}; + +/** + * struct cxl_send_command - Send a command to a memory device. + * @id: The command to send to the memory device. This must be one of the + * commands returned by the query command. + * @flags: Flags for the command (input). + * @rsvd: Must be zero. + * @retval: Return value from the memory device (output). + * @in.size: Size of the payload to provide to the device (input). + * @in.rsvd: Must be zero. + * @in.payload: Pointer to memory for payload input (little endian order). + * @out.size: Size of the payload received from the device (input/output). This + * field is filled in by userspace to let the driver know how much + * space was allocated for output. It is populated by the driver to + * let userspace know how large the output payload actually was. + * @out.rsvd: Must be zero. + * @out.payload: Pointer to memory for payload output (little endian order). + * + * Mechanism for userspace to send a command to the hardware for processing. The + * driver will do basic validation on the command sizes. In some cases even the + * payload may be introspected. Userspace is required to allocate large + * enough buffers for size_out which can be variable length in certain + * situations. + */ +struct cxl_send_command { + __u32 id; + __u32 flags; + __u32 rsvd; + __u32 retval; + + struct { + __s32 size; + __u32 rsvd; + __u64 payload; + } in; + + struct { + __s32 size; + __u32 rsvd; + __u64 payload; + } out; +}; + +#endif