Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Janusz <januszmk6@gmail.com>]

W dniu 15.10.2015 o 08:41, Xiao Guangrong pisze:
>
>
> On 10/15/2015 02:19 PM, Janusz wrote:
>> W dniu 15.10.2015 o 06:19, Xiao Guangrong pisze:
>>>
>>>
>>>
>>> Well, the bug may be not in KVM. When this bug happened, i saw OVMF
>>> only checked 1 CPU out, there is the log from OVMF's debug input:
>>>
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCD
>>>    Flushing GCDs
>>> Detect CPU count: 1
>>>
>>> So that the startup code has been freed however the APs are still
>>> running,
>>> i think that why we saw the vCPUs executed on unexpected address.
>>>
>>> After digging into OVMF's code, i noticed that BSP CPU waits for APs
>>> for a fixed timer period, however, KVM recent changes require zap all
>>> mappings if CR0.CD is changed, that means the APs need more time to
>>> startup.
>>>
>>> After following changes to OVMF, the bug is completely gone on my side:
>>>
>>> --- a/UefiCpuPkg/CpuDxe/ApStartup.c
>>> +++ b/UefiCpuPkg/CpuDxe/ApStartup.c
>>> @@ -454,7 +454,9 @@ StartApsStackless (
>>>     //
>>>     // Wait 100 milliseconds for APs to arrive at the ApEntryPoint
>>> routine
>>>     //
>>> -  MicroSecondDelay (100 * 1000);
>>> +  MicroSecondDelay (10 * 100 * 1000);
>>>
>>>     return EFI_SUCCESS;
>>>   }
>>>
>>> Janusz, could you please check this instead? You can switch to your
>>> previous kernel to do this test.
>>>
>>>
>> Ok, now first time when I started VM I was able to start system
>> successfully. When I turned it off and started it again, it restarted my
>> vm at system boot couple of times. Sometimes I also get very high cpu
>> usage for no reason. Also, I get less fps in GTA 5 than in kernel 4.1, I
>> get something like 30-55, but on 4.1 I get all the time 60 fps. This is
>> my new log: https://bpaste.net/show/61a122ad7fe5
>>
>
> Just confirm: the Qemu internal error did not appear any more, right?
Yes, when I reverted your first patch, switched to -vga std from -vga
none and didn't passthrough my GPU (case when I got this internal
error), vm started without problem. I even didn't get any VM restarts
like with passthrough