NOVA : Intel IO ports and Guest Unrestricted mode.

[avinash singh]

Hi Udo,

Thanks for your reply.  When I run my test cases on real physical hardware
I can run it through properly and also run in unrestricted guest mode.
Looks like Nested VT on Qemu_KVM environment is buggy. Anyway thanks for
looking into this problem and giving nice thought.

Regards
Avinash.



On Mon, Nov 11, 2013 at 5:27 PM, Udo Steinberg <udo at ...121...> wrote:

> On Fri, 8 Nov 2013 12:30:10 +0530 avinash singh (AS) wrote:
>
> AS> However, I also modified my test program to delegate IO ports upfront
> AS> before launching vcpu.  But I still get vcpu_ioaccess_handler invoked.
> AS> Please see below,
>
> In line 347, there is the following piece of code:
>
> bool success = utcb_main->append_item(Io_crd(0, ORDER_64k), HOTSPOT,
> MAP_FROM_KERNEL, false);
>
> I added "false" at the end to make the difference explicit. When running
> that piece of code I'm getting the following output:
>
> NOVA Microhypervisor v6-d5b54fa (x86_32): Sep  5 2013 16:18:28 [gcc 4.9.0]
>
> [ 0] CORE:0:0:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 3] CORE:0:3:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 1] CORE:0:1:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 7] CORE:0:3:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 5] CORE:0:1:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 4] CORE:0:0:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 6] CORE:0:2:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 2] CORE:0:2:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
>  Hello world
> All Portal created!
> runcpuid addr 0x02001000
> eip is initialized
> 0x00001000
> cs 0x02000000
> npt fault handler ..
>  host_adddr 0x01001000
> got cpuid intercept!
> IOACCES invoked
> IP 0x00001007
> dx 0x000003f8
> IOACCES invoked
> IP 0x00001007
> dx 0x000003f8
> IOACCESS: Duplicate Request...
> [ 0] Killed EC:0xc0011a00 SC:0xc0013500 V:0xd CS:0x1b EIP:0x1001717
> CR2:0x0 ERR:0x0 (PT not found)
> [ 0] Killed EC:0xc0011b00 SC:0xc0013500 V:0x1e CR0:0x10031 CR3:0x0 CR4:0x0
> (IPC Abort)
>
>
> As expected, I/O accesses cause VM exits because the G-bit has not been
> set.
>
> So then I've changed line 347 as follows:
>
> bool success = utcb_main->append_item(Io_crd(0, ORDER_64k), HOTSPOT,
> MAP_FROM_KERNEL, true);
>
> and I'm getting the following output:
>
> NOVA Microhypervisor v6-d5b54fa (x86_32): Sep  5 2013 16:18:28 [gcc 4.9.0]
>
> [ 0] CORE:0:0:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 4] CORE:0:0:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 2] CORE:0:2:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 6] CORE:0:2:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 3] CORE:0:3:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 5] CORE:0:1:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 7] CORE:0:3:1 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> [ 1] CORE:0:1:0 6:3c:3:1 [10] Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
>  Hello world
> All Portal created!
> runcpuid addr 0x02001000
> eip is initialized
> 0x00001000
> cs 0x02000000
> npt fault handler ..
>  host_adddr 0x01001000
> got cpuid intercept!
> Egot cpuid intercept!
> [ 0] Killed EC:0xc0012b00 SC:0xc0014500 V:0xc CR0:0x10031 CR3:0x0 CR4:0x0
> (PT not found)
>
> The EC is killed due to an unhandled HLT VM exit, which is expected. As you
> can see, there are no I/O exits and everything works as expected. Also note
> that the 'E' from startup.s line 46 is being printed to serial line in
> front
> of the CPUID output.
>
> AS> I am not sure what is wrong here. Because same logic works for AMD
> process.
> AS> Please could you just see main.cc if something is I am doing wrong
> there.
> AS> Goal is to run cpuid ad oubt instruction in guest mode with paging
> disabled
> AS> and protected mode bit on.
>
> I believe the problem is that you run NOVA as a nested hypervisor under KVM
> and if KVM is not virtualizing VMX correctly, then you get these kind of
> problems. Can you try running your tests on bare hardware (as I did) to see
> if they work correctly there?
>
> AS> > AS> My question is, does NOVA kernel supports to run intel cpu in
> AS> > AS> unrestricted guest mode? or is there any trick to do that so.
> Please
> AS> > AS> help me if I am missing something.
> AS> >
> AS> > NOVA automatically enables unrestricted guest if the CPU supports
> it. The
> AS> > feature is supported on processors based on the Westmere or newer
> AS> > microarchitectures. Unrestricted guest will be disabled, if the user
> AS>
> AS> [ 0] VMCS:0x017ef000 REV:0x11e57ed0 EPT:0 URG:0 VNMI:1 VPID:0
> AS> [ 0] CORE:0:0:0 6:f:b:0 [1] Intel(R) Core(TM)2 Duo CPU     T7700  @
> 2.40GHz
>
> First of all, the VMCS revision identifier looks really odd. Secondly, the
> virtual CPU claims not to support EPT or unrestricted guest, as you can see
> from the EPT and URG fields both showing a 0. This means KVM is not
> emulating EPT/URG support and thus NOVA cannot enable it. Again, running
> the
> test on bare hardware may be a better idea, because you rule out KVM as a
> potential source of bugs.
>
> Let me know what else you find out.
>
> Cheers,
> Udo
>



-- 
Avinash Singh
Gurgaon, Mob: 7838884449
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