Kiselev, Sergey wrote:
> Hi,
>
> 1. When booting old Linux (RH7.1 based, 2.4.9, 32bit) guest on kvm-18,
> kvm userspace process crashes with 'Bus error' (last output on guest's
> screen is "Uncompressing Linux...").
> I did some debugging and found that kvm_readl() function calls
> ldl_phys() with address 0x9FFFD, so resulting double-word read crosses
> page boundary.
> After looking at qemu/exec.c it seems that ld*_phys and st*_phys
> functions not really care about crossing page boundary (even there is
> a comment sayng "warning: addr must be aligned"). So either
> qemu/exec.c should be updated to check such condition or (more logical
> place) qemu/qemu-kvm.c should take care of it.
>
> gdb backtrace:
> (gdb) bt
> #0 ldl_phys (addr=4093) at ../cpu-all.h:322
> #1 0x000000000047e08d in kvm_readl (opaque=0x9f, addr=159,
> data=0x2b63605a5030) at /srv/src/kvm-18/qemu/qemu-kvm.c:543
This is quite surprising. I agree that hacking kvm_readl() is the best fix.
> 2. After working-around the first issue, I have following problem: at
> some point of guest's Linux boot sequence (after running
> microcode_ctl, before running kudzu) following oops happens:
>
>
> Mar 27 12:10:39 itstl140 kernel: Code: 4c 8b 08 41 0f 18 09 48 8d 70
> d8 31 c0 e9 39 ff ff ff 48 63
> Mar 27 12:10:39 itstl140 kernel: RIP
> <ffffffff88366aa6>{:kvm:mmu_page_remove_parent_pte+225} RSP
> <ffff81014e34f938>
> Mar 27 12:10:39 itstl140 kernel: CR2: 000000030593a563
> I tried to disable both microcode_ctl and kudzu, in this case oops h
Strangely, I've seen this exact oops somewhere booting Windows XP in
safe mode. I haven't been able to reproduce it, though.
If this is reproducible, it may be debugged by turning on audit
(s/#undef AUDIT/#define AUDIT/ in mmu.c). Audit slows the guest down,
but is a little faster if you reduce the amount of guest memory. If
this is reproducible using a publicly available image, I may have a go
at it too.
--
error compiling committee.c: too many arguments to function
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