Re: [Qemu-devel] [edk2] OVMF hung on qemu 1.6.0 with KVM

[Gary Ching-Pang Lin]

On Fri, Aug 30, 2013 at 02:04:40AM +1000, Bruce Rogers wrote:
>  >>> On 8/29/2013 at 02:23 AM, Gary Ching-Pang Lin <address@hidden> wrote: 
> > On Wed, Aug 28, 2013 at 02:55:26PM +0200, Andreas Färber wrote:
> >> Am 28.08.2013 14:10, schrieb Laszlo Ersek:
> >> > On 08/28/13 13:49, Andreas Färber wrote:
> >> >> Am 28.08.2013 13:45, schrieb Laszlo Ersek:
> >> >>> (qemu-devel CC'd)
> >> >>>
> >> >>> On 08/28/13 12:35, Gary Ching-Pang Lin wrote:
> >> >>>> Hi,
> >> >>>>
> >> >>>> I recently updated qemu to 1.6.0 and found OVMF just showed a blank
> >> >>>> screen when kvm was enabled. I tried to dump OVMF log with the
> >> >>>> following commond but nothing was stored in debug.log.
> >> >>>>
> >> >>>> qemu-system-x86_64 -s -enable-kvm -bios OVMF.fd -debugcon 
> >> >>>> file:debug.log -global 
> > isa-debugcon.iobase=0x402
> >> >>>>
> >> >>>> The kvm trace was recorded with "trace-cmd record -b 20000 -e kvm"
> >> >>>> and uploaded to the following link:
> >> >>>> 
> > https://docs.google.com/file/d/0B9hbtlc_aK_gcGh2TDZLUVlzWWc/edit?usp=sharing
> >> >>>>
> >> >>>> I found a similar case with kernel < 3.9, but I already upgraded linux
> >> >>>> kernel to 3.10.5, so this may be another bug.
> >> >>>
> >> >>> Well, the usual first response in cases like this is...
> >> >>>
> >> >>> Can you bisect qemu? :)
> >> >>
> >> >> We had a similar report:
> >> >> https://bugzilla.novell.com/show_bug.cgi?id=835895
> >> > 
> >> > Well that's sorta the same report, considering you and Gary both work
> >> > for SUSE, and the Novell BZ seems to imply the build in question was 
> > Gary's:
> >> > 
> >> >> qemu 1.6.0 fails to run the tianocore firmware
> >> >> (home:gary_lin:UEFI/OVMF) properly. This worked with previous qemu
> >> >         ^^^^^^^^
> >> >> versions:
> >> > 
> >> > :)
> >> 
> >> Different reporters, so who knows if the setups are the same. ;)
> >> 
> >> >> git-bisect said:
> >> >> 235e8982ad393e5611cb892df54881c872eea9e1 is the first bad commit
> >> >> 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.)
> >> >>
> >> >>     v7:
> >> >>      * Update for readable => romd_mode rename (5f9a5ea1)
> >> >>
> >> >>     Signed-off-by: Jordan Justen <address@hidden>
> >> >>     Reviewed-by: Xiao Guangrong <address@hidden> (v4)
> >> >>     Reviewed-by: Paolo Bonzini <address@hidden> (v5)
> >> >>     Message-id: address@hidden
> >> >>     Signed-off-by: Anthony Liguori <address@hidden>
> >> >>
> >> >>
> >> >> Any hints or patches welcome. :)
> >> > 
> >> > Hm. LP 1212402 <https://bugs.launchpad.net/qemu/+bug/1212402> probably
> >> > concerns the "similar case with kernel < 3.9" mentioned by Gary, and is
> >> > likely not revelant here.
> >> > 
> >> > 
> >> > Gary & Ludwig, can you confirm that your OVMF build includes SVN r14494?
> >> > 
> >> > Author: Jordan Justen <address@hidden>
> >> > Date:   Thu Jul 18 22:51:27 2013 +0000
> >> > 
> >> >     OvmfPkg/Sec: Build identity mapped pages in RAM for X64
> >> > 
> >> >     This is based on MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c.
> >> > 
> >> >     Previously we would run using page tables built into the
> >> >     firmware device.
> >> > 
> >> >     If a flash memory is available, it is unsafe for the page
> >> >     tables to be stored in memory since the processor may try
> >> >     to write to the page table data structures.
> >> > 
> >> >     Additionally, when KVM ROM support is enabled for the
> >> >     firmware device, then PEI fails to boot when the page
> >> >     tables are in the firmware device.
> >> 
> >> https://build.opensuse.org/package/show/Virtualization/OVMF
> >> is at r14547 and that one works for me.
> >> 
> >> Gary/Ludwig, can you confirm that this is resolved?
> >>
> > I still got the black screen even with OVMF r14547 or r14608. I also
> > tried kernel 3.10.9 and 3.11-rc7, but no luck.
> > 
> > Reverting the KVM_MEM_READONLY patch works for me, but the OVMF patch
> > somehow didn't work.
> > 
> > Thanks,
> > 
> > Gary Lin
> 
> I tried this out, and I get the black screen as well when ept=n, but it boots
> successfully to the efi shell when ept=y.
> 
> Gary, what does 'cat /sys/module/kvm_intel/parameters/ept' report on your
> failing machine?
>
I think this is the root cause. My machine doesn't support ept.

Gary Lin