Re: [Qemu-devel] QEMU aborts since "kvm: support using KVM_MEM_READONLY flag for regions"

[Jordan Justen]

This should be fixed by Xiao's "fix double free the memslot in
kvm_set_phys_mem" patch.

On Mon, Jun 3, 2013 at 10:23 AM, Peter Wu <address@hidden> wrote:
> Hi,
>
> With the current git source (f10acc8b38d65a66ffa0588a036489d7fa6a593e),
> `qemu-system-x86_64 -enable-kvm` fails to run with the following error:
>
>     kvm_set_phys_mem: error unregistering overlapping slot: Invalid argument
>
> After this message, qemu aborts. Reverting the following commit on top of
> master makes the bug go away. Removing the `-enable-kvm` option also
> allows QEMU to operate, but without KVM.
>
> commit 235e8982ad393e5611cb892df54881c872eea9e1
> Author: Jordan Justen <address@hidden>
> Date:   Wed May 29 01:27:26 2013 -0700
>
>     kvm: support using KVM_MEM_READONLY flag for regions
>
>     For readonly memory regions and rom devices in romd_mode,
>     we make use of the KVM_MEM_READONLY. A slot that uses
>     KVM_MEM_READONLY can be read from and code can execute from the
>     region, but writes will exit to qemu.
>
>     For rom devices with !romd_mode, we force the slot to be
>     removed so reads or writes to the region will exit to qemu.
>     (Note that a memory region in this state is not executable
>     within kvm.)
>
> QEMU was built using GCC 4.8.0, runs on Arch Linux 64-bit with a
> custom kernel, Linux 3.9.1. CPU: i5-460M. A backtrace is provided
> on the bottom of this message. If you need more details, please ask.
>
> Regards,
> Peter
>
> #0  0x00007ffff1a251c9 in raise () from /usr/lib/libc.so.6
> #1  0x00007ffff1a265c8 in abort () from /usr/lib/libc.so.6
> #2  0x00005555557dd84d in kvm_set_phys_mem (section=0x7fffe6fdca00, 
> add=false) at /tmp/qemu/kvm-all.c:715
> #3  0x00005555557e132c in address_space_update_topology_pass (address@hidden 
> <address_space_memory>, address@hidden, old_view=..., new_view=...) at 
> /tmp/qemu/memory.c:725
> #4  0x00005555557e1f13 in address_space_update_topology (as=0x5555564dae00 
> <address_space_memory>) at /tmp/qemu/memory.c:761
> #5  memory_region_transaction_commit () at /tmp/qemu/memory.c:786
> #6  0x00005555557dfa42 in access_with_adjusted_size (address@hidden, 
> address@hidden, size=1, access_size_min=<optimized out>, 
> access_size_max=<optimized out>,
>     address@hidden <memory_region_write_accessor>, address@hidden) at 
> /tmp/qemu/memory.c:399
> #7  0x00005555557e0f77 in memory_region_iorange_write (iorange=<optimized 
> out>, offset=2, width=1, data=51) at /tmp/qemu/memory.c:475
> #8  0x00005555557de562 in kvm_handle_io (count=1, size=1, direction=1, 
> data=<optimized out>, port=3326) at /tmp/qemu/kvm-all.c:1507
> #9  kvm_cpu_exec (address@hidden) at /tmp/qemu/kvm-all.c:1659
> #10 0x000055555578da05 in qemu_kvm_cpu_thread_fn (arg=0x55555656f750) at 
> /tmp/qemu/cpus.c:759
> #11 0x00007ffff6280dd2 in start_thread () from /usr/lib/libpthread.so.0
> #12 0x00007ffff1ad5cdd in clone () from /usr/lib/libc.so.6
>
>