Re: BUG with Win7 and user-return-notifier

Avi Kivity
2009-10-28T16:00:34Z

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On 10/28/2009 04:01 PM, Jan Kiszka wrote:
> Avi Kivity wrote:
>
>> On 10/27/2009 03:25 PM, Avi Kivity wrote:
>>
>>> On 10/27/2009 03:24 PM, Avi Kivity wrote:
>>>
>>>> Worked for me - getting to the initial prompt. Do you have
>>>>
>>>> CONFIG_USER_RETURN_NOTIFIER=y
>>>>
>>>> in your .config?
>>>>
>>>>
>>> If you do, send your own .config, will try to reproduce.
>>>
>>>
>> As I can't reproduce it, can you send a trace of what's going on?
>>
>> The kvm:kvm_msr and kvm:kvm_cr events should suffice to understand
>> what's going on. Please enlarge your buffer size (buffer_size_kb) so we
>> don't drop events.
>>
>>
> Find such a trace attached. I hope I caught all important events (there
> were tons of identical kvm_cr events before them which I cut off).
>

[you can get longer, more detailed traces by using
/sys/kernel/debug/tracing/trace instead of dmesg]

Oct 28 14:29:56 mchn012c kernel: qemu-sys-7200 0...1. 676996395us :
kvm_msr: msr_read c0000080 = 0x500
Oct 28 14:29:56 mchn012c kernel: qemu-sys-7200 0...1. 676996403us :
kvm_msr: msr_write c0000080 = 0xd01

So Windows is setting EFER.SCE and EFER.NX while in long mode -
perfectly reasonable. Can you rerun with the attached debug patch?

--
error compiling committee.c: too many arguments to function

[-- Attachment #2: efer-debug.patch --]
[-- Type: text/x-patch, Size: 1346 bytes --]

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 85f97d1..6bd6d2c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -590,6 +590,8 @@ static bool update_transition_efer(struct vcpu_vmx *vmx)
u64 guest_efer;
u64 ignore_bits;

+ printk("%s: efer_offset %d efer %llx\n",
+ __func__, efer_offset, vmx->vcpu.arch.shadow_efer);
if (efer_offset < 0)
return false;
guest_efer = vmx->vcpu.arch.shadow_efer;
@@ -606,10 +608,11 @@ static bool update_transition_efer(struct vcpu_vmx *vmx)
ignore_bits &= ~(u64)EFER_SCE;
#endif
if ((guest_efer & ~ignore_bits) == (host_efer & ~ignore_bits))
- return false;
+ return printk("%s: ignoring all bits\n", __func__), false;

guest_efer &= ~ignore_bits;
guest_efer |= host_efer & ignore_bits;
+ printk("%s: transition efer %llx\n", __func__, guest_efer);
vmx->guest_msrs[efer_offset].data = guest_efer;
return true;
}
@@ -928,8 +931,11 @@ static void setup_msrs(struct vcpu_vmx *vmx)
}
#endif
vmx->msr_offset_efer = index = __find_msr_index(vmx, MSR_EFER);
- if (index >= 0 && update_transition_efer(vmx))
+ if (index >= 0 && update_transition_efer(vmx)) {
+ printk("%s: marking efer for reload\n", __func__);
move_msr_up(vmx, index, save_nmsrs++);
+ } else
+ printk("%s: marking efer for no reload\n", __func__);

vmx->save_nmsrs = save_nmsrs;