x86_msr_xcall(9) - NetBSD Manual Pages

X86_MSR_XCALL(9)     NetBSD/x86 Kernel Developer's Manual     X86_MSR_XCALL(9)


NAME

     x86_msr_xcall -- MSR specific cross-call


SYNOPSIS

     #include <x86/cpu_msr.h>

     void
     x86_msr_xcall(void *arg1, void *arg1);


DESCRIPTION

     The x86_msr_xcall() function provides a x86-specific IPI handler suitable
     for use with the xcall(9) interface.  It can be used to ensure that a
     given MSR call is executed on all processors.  The prototype follows the
     xcfunc_t function pointer type and the opaque arg1 pointer is casted to
     the following structure:

           struct msr_rw_info {
                   int             msr_read;
                   int             msr_type;
                   uint64_t        msr_value;
                   uint64_t        msr_mask;
           };

     This structure must be filled prior to the call.  Two fields are compul-
     sory: msr_type is used as the address of the MSR and msr_value is the
     value to be written.  If msr_read is not zero, x86_msr_xcall() will first
     read from msr_type and then clear the mask specified in msr_mask before
     the write operation.


EXAMPLES

     The following example writes a value zero to the MSR_THERM_CONTROL model-
     specific register on all processors in the system:

           struct msr_rw_info msr;
           uint64_t xc;

           msr.msr_value = 0;
           msr.msr_read = true;
           msr.msr_type = MSR_THERM_CONTROL;
           msr.msr_mask = 0x1e;

           xc = xc_broadcast(0, (xcfunc_t)x86_msr_xcall, &msr, NULL);
           xc_wait(xc);


SEE ALSO

     x86/rdmsr(9), xcall(9)

NetBSD 9.1                     February 17, 2017                    NetBSD 9.1