kern/54847: xsetbv value has uint16_t type instead of uint64_t

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>Number:         54847
>Category:       kern
>Synopsis:       xsetbv value has uint16_t type instead of uint64_t
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jan 09 15:45:00 +0000 2020
>Originator:     Alexey
>Release:        Found by reading the code
>Organization:
>Environment:
Found by reading the code
>Description:
vmx_exit_xsetbv in nvmm_x86_vmx.c is called when a guest executes xsetbv instruction. It sets the value from EDX:EAX to xcr0 register. The value 
is 64 bit long, but in the handler it has uint16_t type:

   1691 	uint16_t val;

The value is used as if it were 64 bits (that's right):
   1694 
   1695 	val = (cpudata->gprs[NVMM_X64_GPR_RDX] << 32) |
   1696 	    (cpudata->gprs[NVMM_X64_GPR_RAX] & 0xFFFFFFFF);

>How-To-Repeat:
Found by reading the code
>Fix:
Change the declaration of val to
   1691 	uint64_t val;