The RTAS call ibm,get-dynamic-sensor-state is used to get the
sensor state identified by the location code and the sensor
token. The librtas library provides an API
rtas_get_dynamic_sensor() which uses /dev/mem access for work
area allocation but is restricted under system lockdown.
This patch provides an interface with new ioctl
PAPR_DYNAMIC_SENSOR_IOC_GET to the papr-indices character
driver which executes this HCALL and copies the sensor state
in the user specified ioctl buffer.
Refer PAPR 7.3.19 ibm,get-dynamic-sensor-state for more
information on this RTAS call.
- User input parameters to the RTAS call: location code string
and the sensor token
Expose these interfaces to user space with a /dev/papr-indices
character device using the following programming model:
int fd = open("/dev/papr-indices", O_RDWR);
int ret = ioctl(fd, PAPR_DYNAMIC_SENSOR_IOC_GET,
struct papr_indices_io_block)
- The user space specifies input parameters in
papr_indices_io_block struct
- Returned state for the specified sensor is copied to
papr_indices_io_block.dynamic_param.state
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Tested-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250416225743.596462-6-haren@linux.ibm.com
The RTAS call ibm,set-dynamic-indicator is used to set the new
indicator state identified by a location code. The current
implementation uses rtas_set_dynamic_indicator() API provided by
librtas library which allocates RMO buffer and issue this RTAS
call in the user space. But /dev/mem access by the user space
is prohibited under system lockdown.
This patch provides an interface with new ioctl
PAPR_DYNAMIC_INDICATOR_IOC_SET to the papr-indices character
driver and expose this interface to the user space that is
compatible with lockdown.
Refer PAPR 7.3.18 ibm,set-dynamic-indicator for more
information on this RTAS call.
- User input parameters to the RTAS call: location code
string, indicator token and new state
Expose these interfaces to user space with a /dev/papr-indices
character device using the following programming model:
int fd = open("/dev/papr-indices", O_RDWR);
int ret = ioctl(fd, PAPR_DYNAMIC_INDICATOR_IOC_SET,
struct papr_indices_io_block)
- The user space passes input parameters in papr_indices_io_block
struct
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Tested-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250416225743.596462-5-haren@linux.ibm.com
The RTAS call ibm,get-indices is used to obtain indices and
location codes for a specified indicator or sensor token. The
current implementation uses rtas_get_indices() API provided by
librtas library which allocates RMO buffer and issue this RTAS
call in the user space. But writable mapping /dev/mem access by
the user space is prohibited under system lockdown.
To overcome the restricted access in the user space, the kernel
provide interfaces to collect indices data from the hypervisor.
This patch adds papr-indices character driver and expose standard
interfaces such as open / ioctl/ read to user space in ways that
are compatible with lockdown.
PAPR (2.13 7.3.17 ibm,get-indices RTAS Call) describes the
following steps to retrieve all indices data:
- User input parameters to the RTAS call: sensor or indicator,
and indice type
- ibm,get-indices is sequence RTAS call which means has to issue
multiple times to get the entire list of indicators or sensors
of a particular type. The hypervisor expects the first RTAS call
with the sequence 1 and the subsequent calls with the sequence
number returned from the previous calls.
- The OS may not interleave calls to ibm,get-indices for different
indicator or sensor types. Means other RTAS calls with different
type should not be issued while the previous type sequence is in
progress. So collect the entire list of indices and copied to
buffer BLOB during ioctl() and expose this buffer to the user
space with the file descriptor.
- The hypervisor fills the work area with a specific format but
does not return the number of bytes written to the buffer.
Instead of parsing the data for each call to determine the data
length, copy the work area size (RTAS_GET_INDICES_BUF_SIZE) to
the buffer. Return work-area size of data to the user space for
each read() call.
Expose these interfaces to user space with a /dev/papr-indices
character device using the following programming model:
int devfd = open("/dev/papr-indices", O_RDONLY);
int fd = ioctl(devfd, PAPR_INDICES_IOC_GET,
struct papr_indices_io_block)
- Collect all indices data for the specified token to the buffer
char *buf = malloc(RTAS_GET_INDICES_BUF_SIZE);
length = read(fd, buf, RTAS_GET_INDICES_BUF_SIZE)
- RTAS_GET_INDICES_BUF_SIZE of data is returned to the user
space.
- The user space retrieves the indices and their location codes
from the buffer
- Should issue multiple read() calls until reaches the end of
BLOB buffer.
The read() should use the file descriptor obtained from ioctl to
get the data that is exposed to file descriptor. Implemented
support in librtas (rtas_get_indices()) for this new ABI for
system lockdown.
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Tested-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250416225743.596462-4-haren@linux.ibm.com
