From: Avi Kivity <avi@redhat.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: KVM General <kvm@vger.kernel.org>
Subject: Re: Problem with KVM guest switching to x86 long mode
Date: Thu, 08 Apr 2010 21:36:03 +0300 [thread overview]
Message-ID: <4BBE2213.6020802@redhat.com> (raw)
In-Reply-To: <u2u84144f021004081126sf2f6c8f9s3f228bd455356ab0@mail.gmail.com>
On 04/08/2010 09:26 PM, Pekka Enberg wrote:
> Hi!
>
> I am working on a light-weight KVM userspace launcher for Linux and am
> bit stuck with a guest Linux kernel restarting when it tries to enter
> long mode.
>
> The register dump looks like this:
>
> penberg@tiger:~/vm$ ./kvm bzImage
> KVM exit reason: 8 ("KVM_EXIT_SHUTDOWN")
> Registers:
> rip: 00000000001000ed rsp: 00000000005d54b8 flags: 0000000000010046
> rax: 0000000080000001 rbx: 0000000001f2c000 rcx: 00000000c0000080
> rdx: 0000000000000000 rsi: 0000000000013670 rdi: 0000000002408000
> rbp: 0000000000100000 r8: 0000000000000000 r9: 0000000000000000
> r10: 0000000000000000 r11: 0000000000000000 r12: 0000000000000000
> r13: 0000000000000000 r14: 0000000000000000 r15: 0000000000000000
> cr0: 0000000080000011 cr2: 00000000001000ed cr3: 0000000002402000
> cr4: 0000000000000020 cr8: 0000000000000000
> Segment registers:
> register selector base limit type p dpl db s l g avl
> cs 0010 0000000000000000 ffffffff 0b 1 0 1 1 0 1 0
> ss 0018 0000000000000000 ffffffff 03 1 0 1 1 0 1 0
> ds 0018 0000000000000000 ffffffff 03 1 0 1 1 0 1 0
> es 0018 0000000000000000 ffffffff 03 1 0 1 1 0 1 0
> fs 0018 0000000000000000 ffffffff 03 1 0 1 1 0 1 0
> gs 0018 0000000000000000 ffffffff 03 1 0 1 1 0 1 0
> tr 0020 0000000000001000 00000067 0b 1 0 0 0 0 0 0
> ldt 0000 0000000000000000 ffffffff 00 0 0 0 0 0 0 0
>
These all look reasonable. Please add a gdtr dump and an idtr dump.
> 2b:* cb lret<-- trapping instruction
>
Post the two u32s at ss:rsp -> ss:rsp+8. That will tell us where the
guest is trying to return. Actually, from the dump:
1a: 6a 10 pushq $0x10
1c: 8d 85 00 02 00 00 lea 0x200(%rbp),%eax
22: 50 push %rax
it looks like you're returning to segment 0x10, this should be the word
at ss:rsp+4. So if you dump the 2 u32s at
gdtr.base+0x10..gdtr.base+0x18 we'll see if there's anything wrong with
the segment descriptor.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-04-08 18:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-08 18:26 Problem with KVM guest switching to x86 long mode Pekka Enberg
2010-04-08 18:36 ` Avi Kivity [this message]
2010-04-08 18:59 ` Pekka Enberg
2010-04-08 19:30 ` Avi Kivity
2010-04-11 6:30 ` Pekka Enberg
2010-04-11 9:16 ` Avi Kivity
2010-04-11 9:48 ` Pekka Enberg
2010-04-11 9:59 ` Avi Kivity
2010-04-11 10:02 ` Pekka Enberg
2010-04-11 11:48 ` Avi Kivity
2010-04-11 11:52 ` Pekka Enberg
2010-04-11 12:02 ` Avi Kivity
2010-04-11 12:04 ` Avi Kivity
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