[Xen-devel] problem in using MSR in the hypervisor

[Long Wang <longwang.longwang@xxxxxxxxx>]

I added code in the hypervisor to manipulate MSR. Here is my code in
emulate_privileged_op() in the Xen hypervisor:

....
        // for WRMSR
        case MSR_P4_IQ_PERFCTR0:
        case MSR_P4_IQ_CCCR0:
        case MSR_P4_CRU_ESCR0:
        case MSR_P4_IQ_PERFCTR2:
        case MSR_P4_IQ_CCCR2:
        case MSR_P4_CRU_ESCR1:
            wrmsr_safe(regs->ecx, eax, edx);
            break;
......
        // for RDMSR
        case MSR_P4_IQ_PERFCTR0:
        case MSR_P4_IQ_CCCR0:
        case MSR_P4_CRU_ESCR0:
        case MSR_P4_IQ_PERFCTR2:
        case MSR_P4_IQ_CCCR2:
        case MSR_P4_CRU_ESCR1:
                printk("the_cs = 0x%x\n", the_cs);
                __asm__ volatile(
                          "mov %%cs, %0\n"
                          :"=r"(the_cs)
                          :
                );
                printk("the_cs = 0x%x\n", the_cs);
                rdmsr_safe(regs->ecx, regs->eax, regs->edx);
            break;


The wrmsr_safe() and rdmsr_safe() trigger a general protection fault,
and the value read from the msr is 0. But I printed out the cs
descriptor, and found the CPL is 0. Why there is a general protection
fault here? How can I fix this?

thanks,
long

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel