I also faced problem in getting KVM CPU to run in FS mode. I figured that
the following changeset causes problems:
author Alexandru Dutu <[email protected]>
Sun Nov 23 18:01:08 2014 -0800 (2 weeks ago)
changeset 10554 fe2e2f06a7c8
I saw the hardware reason 0x80000021, but did not try to figure what was
going on wrong.
--
Nilay
On Mon, 8 Dec 2014, Gabe Black via gem5-dev wrote:
I'm pretty sure entering 64 bit mode is the same between AMD and Intel
CPUs. I vaguely remember there being some subtle page table difference
though, and gem5 is building the page tables in SE mode instead of the
kernel.
Gabe
On Mon, Dec 8, 2014 at 7:44 PM, Dutu, Alexandru via gem5-dev <
[email protected]> wrote:
Hi Mike,
trace-cmd is a very handy tool to get an overview of what the kvm kernel
module is doing before going into gdb. In extreme cases ftrace can be
useful as well.
What is the error that you are seeing? Is it still failing to enter
virtualized mode?
If that is the case and the hardware reason is 0x80000021, that seems to
be an unrecoverable exception (drivers/hv/hyperv_vmbus.h in linux kernel
source code). When running in SE mode, we are trying to bring the machine
state to full 64bit mode without going through legacy modes. It might be
that Intel machines have a different way of going to 64bit mode than AMD
machines (different CR4, different way of enabling 64bit mode page tables
etc.). I remember dealing with these issue for AMD platforms by going
through System Programming manual and making sure gem5 gets all the bits
right as there is not much the KVM kernel model will tell about the cause
of failure.
Best regards,
Alex
________________________________________
From: gem5-dev [[email protected]] on behalf of Gabe Black via
gem5-dev [[email protected]]
Sent: Monday, December 08, 2014 7:08 PM
To: gem5 Developer List
Subject: Re: [gem5-dev] x86 SE kvm functionality (AMD vs Intel)
I'm not an expert either, but I did have problems running KVM in SE mode on
an Intel CPU. I didn't look into it that much, but I think things failed in
the kernel somewhere. What might be happening is that the different vendors
hardware virtualization mechanisms are more or less picky about various
things. Something might be set up incorrectly, and one implementation gets
more upset about it than the other. I believe there are tools which will
help you determine whether your VM state is legal. Perhaps Andreas can tell
you more about those?
Gabe
On Mon, Dec 8, 2014 at 4:29 PM, mike upton via gem5-dev <[email protected]
wrote:
I have verified that x86 kvm works fine on AMD platforms, but fails on
Intel platforms.
Any hints about how to narrow down the cause (other than diving into gdb,
which I will do).
I am not an expert in KVM or how gem5 hooks up to libkvm.
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