I am working on a Linux kernel module to test Intel VMX operations.
And my module could 'vmlaunch' successfully in RHEL 6.8 (Linux-2.6.32-642).
But 'vmlaunch' failed in RHEL 7.1 (Linux-3.10.0).
Below is the failed log.
[ 178.857991] VM-instruction error: 0
[ 178.857993] Exit Reason: 0x0 (0)
[ 178.857996] Exit Qualif: 0
[ 178.858007] flags = 0x242
[ 178.858010] VMX-abort indicator = 0x0
And it shows, in eflags, Z bit is '1'.
But from above log, I could NOT get what cause 'vmlauch' failed.
And I don't know why it worked in Linux-2.6.32, but failed in Linux-3.10.0.
Here is main code around vmlaunch,
" vmlaunch \n"
" movl $-1, retval \n"
" pushf \n"
" pop %rax \n"
" movl %eax, saved_eflags \n"
" jmp over \n"
" \n"
"vmx_vmm: \n"
" movl $97, retval \n"
" popfq \n"
vmx_vmm is set to vm_host_rip, so once vm exits, host shall continue from here.
I got retval is setup to -1, not 97, so i think there is a failure in vmlaunch.
Thanks,
-Tao