catalog_read() implements the read interface for the sysfs file
/sys/bus/event_source/devices/hv_24x7/interface/catalog
It essentially takes a buffer, an offset and count as parameters
to the read() call. It makes a hypervisor call to read a specific
page from the catalog and copy the required bytes into the given
buffer. Each call to catalog_read() returns at most one 4K page.
Given these requirements, we should be able to simplify the
catalog_read().
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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