Hi Christoffer,
Thank you!
1. Yeah, you are right. Right now i am just picking some stuffs from native kvm tool and pasting to my own code. But my ultimate goal is to build a process sandbox based on KVM/ARM, it hosts process rather than kernel, though i even don't know if it is possible, like those syscall relay stuffs. Anyway, yet to find better things to do for my research... :)
2. I checked the return value of mmap. Just being lazy and abbreviated the code. Sorry.
3. Actually i had an hvc instruction after "add r2, r1, r0", which should have caused a vm_exit. But since it didn't make any difference, i just got rid of it and thought the problem should be my guest image not getting run at all.
4. I asked how to detect a VM shutdown several days ago. And it seems that it involves power management devices emulation, which is complicated for me now. So the guest now just keeps executing... Any suggestion to let the guest exit itself?
5. I will definitely look into how to use KVM tracepoints and when you say printks, do you mean to insert some to kvm source code?
Thanks very much!
Tom.
On Fri, Nov 22, 2013 at 2:05 PM, Christoffer Dall <christoffer.dall@xxxxxxxxxx> wrote:
On Fri, Nov 22, 2013 at 01:47:17PM -0500, Zhuoqun Cheng wrote:one question would be why? You know there are already two such things
> Hi friends,
>
> I am working on a user level kvm tool based on KVM/ARM. Right now it is
> quite primitive. It creates a vm and loads a binary image to the address
> space of the vm, then runs the vcpu.
available right: kvm tool and qemu :)
>
> But the* problem* is it gets into KVM_RUN ioctl and is never able to get
> out of it.> kvm_inject_pabt */* Prefetch Abort on I/O address */ (this is the comment
> I use ftrace to trace the function calls and I see what is happening is:
>
> kvm_arch_vcpu_ioctl_run->
> handle_exit->
> exit_handler (which is kvm_handle_guest_abort)->
> in that if condition)*
>> is 1, it just keeps doing the* above loop*.
> Then it keeps returning 1 until back to kvm_arch_vcpu_ioctl, where there is
> a while loop checking if the return value is greater than 0. And since it
>
> I don't how it ended up *prefetching instructions from an I/O address*.
>
> The *arguments i used when calling ioctl*(KVM_SET_USER_MEMORY_REGION) is:
> .guest_phys_addr = 0x0000000080000000ULyou probably want to check the return value of mmap.
> .memory_size = 1024 * 1024
> .userspace_addr = mmap(NULL, ram_size, PROT_READ | PROT_WRITE,
> MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
>
> When *loading image*, i read a binary image to userspace address mapped to
> 0x0000000080000000UL. What the binary image does it just:yeah well, after this instruction who knows what happens....
> mov r0, #5
> mov r1, #4
> add r2, r1, r0
>
> And before running, i *set pc* to 0x0000000080000000UL. Then i run it.
>It means that you're not setting the PC properly or that the code you
> What did i do wrong? Can you offer me some hints?
>
end up executing quickly jumps to some location outside your VM RAM
region.
I cannot speculate as to what you're doing wrong, but if you look at the
tracepoints that KVM gives you it will tell you which address it is
entering for the VCPU and which address it exits on. That should give
you some hints as to what's going on.
printks will also be helpful - trace the execution of your code.
-Christoffer
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