Re: [GSOC] Implement hardware nested page table support for vkernels

[Mihai Carabas <mihai.carabas@xxxxxxxxx>]

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Hello,

This week I've been trying to execute a vmlaunch on the HOST in order to
run a dummy guest in VMX non-root operation. There were a lot of vmlaunch
errors due to consistency checks on the VMCS area of the HOST. With the
help of Bochs simulator (thanks to vsrinivas) I found out what bit was
wrong and the vmlaunch doesn't fail anymore. However, after the vmlaunch I
get immediatly a vmexit, which announce me that the guest consistency check
failed (Error 33 from the "Table C-1. Basic Exit Reason", Intel 3c manual).
Now I'm investigating this problem.

The HOST state is saved/loaded from the VMCS area on a vmlaunch, and on
vmexit the host is acting OK, means that all stuff restored are in order.
At the beginning there was a problem because I didn't set correctly the
IDTR base address and after a vmlaunch my CPU didn't handle the interrupts
anymore and caused the HOST failure.

This week, I've also had a long discussion with Dillon regarding the
vkernels and the type of guest we will be running. We are trying to do
something else than the vast majority does: run a "user-space" program in
guest mode of the virtualization extension, rather than a kernel.

Also there will be some design issues to solve: the user-space programs of
the vkernel run in other "execution contexts" than the vkernel thread
itself (through the vmspace_ctl syscall). So we would need two VMCS areas
for each vkernel thread. I will discuss this issues with Venkatesh more
this week.

Thanks,
Mihai

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<div dir=3D"ltr">Hello,<div><br></div><div>This week I&#39;ve been trying t=
o execute a vmlaunch on the HOST in order to run a dummy guest in VMX non-r=
oot operation. There were a lot of vmlaunch errors due to consistency check=
s on the VMCS area of the HOST. With the help of Bochs simulator (thanks to=
 vsrinivas) I found out what bit was wrong and the vmlaunch doesn&#39;t fai=
l anymore. However, after the vmlaunch I get immediatly a vmexit, which ann=
ounce me that the guest consistency check failed (Error 33 from the &quot;T=
able C-1. Basic Exit Reason&quot;, Intel 3c manual). Now I&#39;m investigat=
ing this problem.</div>
<div><br></div><div>The HOST state is saved/loaded from the VMCS area on a =
vmlaunch, and on vmexit the host is acting OK, means that all stuff restore=
d are in order. At the beginning there was a problem because I didn&#39;t s=
et correctly the IDTR base address and after a vmlaunch my CPU didn&#39;t h=
andle the interrupts anymore and caused the HOST failure.</div>
<div><br></div><div>This week, I&#39;ve also had a long discussion with Dil=
lon regarding the vkernels and the type of guest we will be running. We are=
 trying to do something else than the vast majority does: run a &quot;user-=
space&quot; program in guest mode of the virtualization extension, rather t=
han a kernel.</div>
<div><br></div><div>Also there will be some design issues to solve: the use=
r-space programs of the vkernel run in other &quot;execution contexts&quot;=
 than the vkernel thread itself (through the vmspace_ctl syscall). So we wo=
uld need two VMCS areas for each vkernel thread. I will discuss this issues=
 with Venkatesh more this week.</div>
<div><br></div><div>Thanks,</div><div>Mihai</div></div>

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