The problem is in hypervisor checking definitely. I deeper debugged the
code, I met vmcall instruction execution. This means EFAULT is coming from
hypervisor.
Best Regards,
Rockosov Dmitry
2016-08-22 18:09 GMT+03:00 Dmitry Rockosov <rocko...@gmail.com>:
> Hello Tamas,
>
> Thank you for the answer!
>
> I installed the same xen source code (4.7.0) as on dom0 to domU, built
> dist-tools, installed xen-tools, updated rc.d configuration and rebooted.
> IOCTL channel to privcmd driver is working fine, but all requests to
> hypervisor like hvm_get_param, translate_foreign_address,
> altp2m_vcpu_enable_notify return EFAULT errno (Bad access).
>
> Just for experiment I wrote below code in usermode:
> ===================================
> ...
> rc = xc_hvm_param_get(xch, DOMID_SELF, HVM_PARAM_CONSOLE_PFN, &value);
> if (rc < 0) {
> PERROR("Fail to get CONSOLE PFN HVM PARAM\n");
> goto exit;
> }
> DPRINTF("CONSOLE PFN == %llx", (unsigned long long)value);
> ...
> ===================================
>
> and below code in kernelmode:
> ===================================
> ...
> printk(KERN_INFO "We are in Xen domain HVM = %d\n", xen_hvm_domain());
> err = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &value);
> printk(KERN_INFO "err = %d\n", err);
> printk(KERN_INFO "CONSOLE PFN = %llx\n", value);
> ...
> ===================================
>
> In the usermode I got an error:
> ===================================
> Fail to get CONSOLE PFN HVM PARAM
> : Bad address
> ===================================
>
> In the kernelmode code executed fine:
> ===================================
> [23261.230188] We are in Xen domain HVM = 1
> [23261.307840] err = 0
> [23261.352587] CONSOLE PFN = fefff
> ===================================
>
> Looks like usermode wrappers don't support many requests to hypervisor,
> right?
>
> Best Regards,
> Rockosov Dmitry
>
> 2016-08-21 20:27 GMT+03:00 Tamas K Lengyel <tamas.k.leng...@gmail.com>:
>
>> Hi Dmitry,
>> as long as you are testing with a HVM Linux guest you should be able
>> to just compile the Xen tools in the guest and then use libxc from
>> within the guest to issue that hypercall via
>> xc_altp2m_set_vcpu_enable_notify. You will need to load a couple Xen
>> related kernel-modules for it to work (like xen-privcmd). Let us know
>> if you got it working!
>>
>> Cheers,
>> Tamas
>>
>> On Fri, Aug 19, 2016 at 1:19 PM, Dmitry Rockosov <rocko...@gmail.com>
>> wrote:
>> > Hello Xen Team!
>> >
>> > Does anybody have any code examples of HVMOP_altp2m_vcpu_enable_notify?
>> >
>> > I want to fully test #VE, VMFUNC and EPTP Switching VM Function 0 in
>> Xen,
>> > but doesn't have any documentations/examples for it.
>> > I tried xen-access test from tools/tests/xen-access, but looks like it
>> > doesn't use VMFUNC and #VE, it simply changes VMCS entries with
>> vmwrite, w/o
>> > VMFUNC 0 (EPTP Switching).
>> >
>> > Thanks in advance!
>> >
>> > Best Regards,
>> > Rockosov Dmitry
>> >
>> > _______________________________________________
>> > Xen-devel mailing list
>> > Xen-devel@lists.xen.org
>> > https://lists.xen.org/xen-devel
>> >
>>
>
>
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