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

[Laszlo Ersek]

Hi,

On 10/20/15 19:27, Janusz wrote:
> W dniu 15.10.2015 o 20:46, Laszlo Ersek pisze:
>> On 10/15/15 18:53, Kinney, Michael D wrote:
>>> Laszlo,
>>>
>>> There is already a PCD for this timeout that is used by CpuMpPei.
>>>
>>> gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
>>>
>>> I noticed that CpuDxe is using a hard coded AP timeout.  I think we should 
>>> just use this same PCD for both the PEI and DXE CPU module and then set it 
>>> for OVMF to the compatible value.
>> Perfect, thank you!
>>
>> (I notice the default in the DEC file is 5, which is half of what
>> the DXE driver hardcodes.)
>>
>> Now we only need a recommended (or experimental) value for it, and an
>> explanation why 100*1000 is no longer sufficient on KVM :)
>>
>> Thanks!
>> Laszlo
>>
>>
>>
> Laszlo,
> 
> I saw that there is already some change in ovmf for MicroSecondDelay
> https://github.com/tianocore/edk2/commit/1e410eadd80c328e66868263b3006a274ce81ae0
> Is that a fix for it? Because I tried it and it still doesn't work for
> me: https://bpaste.net/show/2514b51bf41f
> I still get internal error

I think you guys are now "mature enough OVMF users" to start employing
the correct terminology.

"edk2" (also spelled as "EDK II") is: "a modern, feature-rich,
cross-platform firmware development environment for the UEFI and PI
specifications".

The source tree contains a whole bunch of modules (drivers,
applications, libraries), organized into packages.

"OVMF" usually denotes a firmware binary built from one of the
OvmfPkg/OvmfPkg*.dsc "platform description files". Think of them as "top
level makefiles". The difference between them is the target architecture
(there's Ia32, X64, and Ia32X64 -- the last one means that the SEC and
PEI phases are 32-bit, whereas the DXE and later phases are 64-bit.) In
practice you'll only care about full X64.

Now, each of OvmfPkg/OvmfPkg*.dsc builds the following three kinds of
modules into the final binary:
- platform-independent modules from various top-level packages
- platform- (ie. Ia32/X64-) dependent modules from various top-level
  packages
- modules from under OvmfPkg that are specific to QEMU/KVM (and Xen, if
  you happen to use OVMF with Xen)

Now, when you reference a commit like 1e410ead above, you can look at
the diffstat, and decide if it is OvmfPkg-specific (third category
above) or not. Here you see UefiCpuPkg, which happens to be the second
category.

The important point is: please do *not* call any and all edk2 patches
"OVMF changes", indiscriminately. That's super confusing for people who
understand the above distinctions. Which now you do too. :)

Let me add that in edk2, patches that straddle top level packages are
generally forbidden -- you can't have a patch that modifies OvmfPkg and
UefiCpuPkg at the same time, modulo *very* rare exceptions. If a feature
or bugfix needs to touch several top-level packages, the series must be
built up carefully in stages.

Knowing all of the above, you can tell that the patch you referenced had
only *enabled* OvmfPkg to customize UefiCpuPkg, via
"PcdCpuApInitTimeOutInMicroSeconds". But for that customization to occur
actually, a small patch for OvmfPkg will be necessary too, in order to
set "PcdCpuApInitTimeOutInMicroSeconds" differently from the default.

I plan to send that patch soon. If you'd like to be CC'd, that's great
(reporting back with a Tested-by is even better!), but I'll need your
real name for that. (Or any name that looks like a real name.)

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

[Janusz]

W dniu 15.10.2015 o 20:46, Laszlo Ersek pisze:
> On 10/15/15 18:53, Kinney, Michael D wrote:
>> Laszlo,
>>
>> There is already a PCD for this timeout that is used by CpuMpPei.
>>
>>  gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
>>
>> I noticed that CpuDxe is using a hard coded AP timeout.  I think we should 
>> just use this same PCD for both the PEI and DXE CPU module and then set it 
>> for OVMF to the compatible value.
> Perfect, thank you!
>
> (I notice the default in the DEC file is 5, which is half of what
> the DXE driver hardcodes.)
>
> Now we only need a recommended (or experimental) value for it, and an
> explanation why 100*1000 is no longer sufficient on KVM :)
>
> Thanks!
> Laszlo
>
>
>
Laszlo,

I saw that there is already some change in ovmf for MicroSecondDelay
https://github.com/tianocore/edk2/commit/1e410eadd80c328e66868263b3006a274ce81ae0
Is that a fix for it? Because I tried it and it still doesn't work for
me: https://bpaste.net/show/2514b51bf41f
I still get internal error

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

[Laszlo Ersek]

On 10/16/15 05:05, Xiao Guangrong wrote:
> 
> 
> On 10/16/2015 12:18 AM, Laszlo Ersek wrote:
>> CC'ing Jordan and Chen Fan.
>>
>> On 10/15/15 09:10, Xiao Guangrong wrote:
>>>
>>>
>>> On 10/15/2015 02:58 PM, Janusz wrote:
 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

>>>
>>> Wow, it seems we have fixed the QEMU internal error now. :)
>>>
>>> Recurrently, Paolo has reverted some MTRR patches, was your test
>>> based on these reverted patches?
>>>
>>> The GPU passthrough issue may be related to vfio (not sure), Alex, do
>>> you have any idea?
>>>
>>> Laszlo, could you please check the root case is reasonable and fix it in
>>> OVMF if it's right?
>>
>> The code that you have found is in edk2's EFI_MP_SERVICES_PROTOCOL
>> implementation -- more closely, its initial CPU counter code --, from
>> edk2 git commit 533263ee5a7f. It is not specific to OVMF -- it is
>> generic edk2 code for Intel processors. (I'm CC'ing Jordan and Chen Fan
>> because they authored the patch in question.)
> 
> Okay, good to know it, i do not have much knowledge on edk2 and OVMF... :(
> 
>>
>> If VCPUs need more time to rendezvous than written in the code, on
>> recent KVM, then I think we should introduce a new FixedPCD in
>> UefiCpuPkg (practically: a compile time constant) for the timeout. Which
>> is not hard to do.
>>
>> However, we'll need two things:
>> - an idea about the concrete rendezvous timeout to set, from OvmfPkg
>>
>> - a *detailed* explanation / elaboration on your words:
>>
>>"KVM recent changes require zap all mappings if CR0.CD is changed,
>>that means the APs need more time to startup"
>>
>>Preferably with references to Linux kernel commits and the Intel SDM,
>>so that n00bs like me can get a fleeting idea. Do you mean that with
>>caching disabled, the APs execute their rendezvous code (from memory)
>>more slowly?
> 
> Kernel commit b18d5431acc causes the vCPUs need more time to startup
> as:
> - it zaps all the mappings for the guest memory in EPT or shadow page
>   table, it requires VM-exits to rebuild the mappings for all memory
>   access.
> 
> - if there is device passthrough-ed in guest and IOMMU lacks snooping
>   control feature, the memory will become UC after CR0.CD is set to 1.
> 
> And a generic factor is, if the guest has more vCPUs then more time is
> needed. That why the bug is hardly triggered on small vCPUs guest. I
> guess we need a self-adapting way to handle the case...

Thanks, this should be enough for composing a commit message.

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

[Janusz]

W dniu 15.10.2015 o 09:10, Xiao Guangrong pisze:
>
>
> On 10/15/2015 02:58 PM, Janusz wrote:
>> 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
>>
>
> Wow, it seems we have fixed the QEMU internal error now. :)
>
> Recurrently, Paolo has reverted some MTRR patches, was your test
> based on these reverted patches?
>
> The GPU passthrough issue may be related to vfio (not sure), Alex, do
> you have any idea?
>
> Laszlo, could you please check the root case is reasonable and fix it in
> OVMF if it's right?
>
> BTW, OVMF handles #UD with no trace - nothing is killed, and no call
> trace
> in the debug input...
>
Yes, reverted MTRR code is already in kernel I use - 4.3-r5+
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Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Janusz]

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

[Janusz]

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

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

[Laszlo Ersek]

CC'ing Jordan and Chen Fan.

On 10/15/15 09:10, Xiao Guangrong wrote:
> 
> 
> On 10/15/2015 02:58 PM, Janusz wrote:
>> 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
>>
> 
> Wow, it seems we have fixed the QEMU internal error now. :)
> 
> Recurrently, Paolo has reverted some MTRR patches, was your test
> based on these reverted patches?
> 
> The GPU passthrough issue may be related to vfio (not sure), Alex, do
> you have any idea?
> 
> Laszlo, could you please check the root case is reasonable and fix it in
> OVMF if it's right?

The code that you have found is in edk2's EFI_MP_SERVICES_PROTOCOL
implementation -- more closely, its initial CPU counter code --, from
edk2 git commit 533263ee5a7f. It is not specific to OVMF -- it is
generic edk2 code for Intel processors. (I'm CC'ing Jordan and Chen Fan
because they authored the patch in question.)

If VCPUs need more time to rendezvous than written in the code, on
recent KVM, then I think we should introduce a new FixedPCD in
UefiCpuPkg (practically: a compile time constant) for the timeout. Which
is not hard to do.

However, we'll need two things:
- an idea about the concrete rendezvous timeout to set, from OvmfPkg

- a *detailed* explanation / elaboration on your words:

  "KVM recent changes require zap all mappings if CR0.CD is changed,
  that means the APs need more time to startup"

  Preferably with references to Linux kernel commits and the Intel SDM,
  so that n00bs like me can get a fleeting idea. Do you mean that with
  caching disabled, the APs execute their rendezvous code (from memory)
  more slowly?

> BTW, OVMF handles #UD with no trace - nothing is killed, and no call trace
> in the debug input...

There *is* a trace (of any unexpected exception -- at least for the
BSP), but unfortunately its location is not intuitive.

The exception handler that is built into OVMF
("UefiCpuPkg/Library/CpuExceptionHandlerLib") is again generic edk2
code, and it prints the trace directly to the serial port, regardless of
the fact that OVMF's DebugLib instance logs explicit DEBUGs to the QEMU
debug port. (The latter can be directed to the serial port as well, if
you build OVMF with -D DEBUG_ON_SERIAL_PORT, but this is not relevant here.)

If you reproduce the issue while looking at the (virtual) serial port of
the guest, I trust you will get a register dump.

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

[Laszlo Ersek]

On 10/15/15 18:53, Kinney, Michael D wrote:
> Laszlo,
> 
> There is already a PCD for this timeout that is used by CpuMpPei.
> 
>   gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
> 
> I noticed that CpuDxe is using a hard coded AP timeout.  I think we should 
> just use this same PCD for both the PEI and DXE CPU module and then set it 
> for OVMF to the compatible value.

Perfect, thank you!

(I notice the default in the DEC file is 5, which is half of what
the DXE driver hardcodes.)

Now we only need a recommended (or experimental) value for it, and an
explanation why 100*1000 is no longer sufficient on KVM :)

Thanks!
Laszlo


> 
> Mike
> 
>> -Original Message-
>> From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of
>> Laszlo Ersek
>> Sent: Thursday, October 15, 2015 9:19 AM
>> To: Xiao Guangrong
>> Cc: k...@vger.kernel.org; Justen, Jordan L; edk2-de...@ml01.01.org; Alex
>> Williamson; Chen Fan; Paolo Bonzini; Wanpeng Li
>> Subject: Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is
>> completely disabled
>>
>> CC'ing Jordan and Chen Fan.
>>
>> On 10/15/15 09:10, Xiao Guangrong wrote:
>>>
>>>
>>> On 10/15/2015 02:58 PM, Janusz wrote:
>>>> 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 passt

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

[Janusz]

W dniu 14.10.2015 o 10:32, Xiao Guangrong pisze:
>
>
> On 10/14/2015 04:24 PM, Xiao Guangrong wrote:
>>
>>
>> On 10/14/2015 03:37 PM, Janusz wrote:
>>> I was able to run my virtual machine with this, but had very high cpu
>>> usage when something happen in it like booting system. once, my virtual
>>> machine hang and I couln't even get my mouse / keyboard back from qemu.
>>> When I did vga passthrough, I didn't get any video output, and cpu
>>> usage
>>> was also high. Tried it on 4.3
>>
>> Which tree are you using? Is it kvm tree?
>> Could you please work on queue brancn on current kvm tree based on
>> top commit 73917739334c6509: KVM: x86: fix SMI to halted VCPU.
>>
>> Hmm... interesting, this diff works on my box...
>
> Forgot to say that i built my test env following the instructions on
> kvm-wiki:
> http://www.linux-kvm.org/page/OVMF
>
> My test script is attached, and i will try to build the env like yours
> as much
> as possible...
I cloned git://git.kernel.org/pub/scm/virt/kvm/kvm.git 73917739334c6509
commit, but this is breaking my system...
Slim is not able to start i3, xdm is not killing X when I stop xdm, qemu
is not able to start when I don't use option -nographic
log from qemu on that kernel version:
xcb_connection_has_error() returned true
No protocol specified
Could not initialize SDL(No available video device) - exiting

On main kernel branch I don't have those problems.

I tried to run with -nographic, and tried pc-i440fx-2.1 but the same
problem as before, high cpu usage and no graphic on my GPU.
I don't know if that will help by this is my log from option -global
isa-debugcon.iobase=0x402 -debugcon file:fedora.ovmf.log:
https://bpaste.net/show/36c54dba68c2

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

[Janusz]

I was able to run my virtual machine with this, but had very high cpu
usage when something happen in it like booting system. once, my virtual
machine hang and I couln't even get my mouse / keyboard back from qemu.
When I did vga passthrough, I didn't get any video output, and cpu usage
was also high. Tried it on 4.3

W dniu 14.10.2015 o 05:58, Xiao Guangrong pisze:
>
> Janusz,
>
> Could you please try this:
>
> $ git diff
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 185fc16..bdd564f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4957,12 +4957,14 @@ static int handle_emulation_failure(struct
> kvm_vcpu *vcpu)
>
> ++vcpu->stat.insn_emulation_fail;
> trace_kvm_emulate_insn_failed(vcpu);
> +#if 0
> if (!is_guest_mode(vcpu) && kvm_x86_ops->get_cpl(vcpu) == 0) {
> vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
> vcpu->run->internal.suberror =
> KVM_INTERNAL_ERROR_EMULATION;
> vcpu->run->internal.ndata = 0;
> r = EMULATE_FAIL;
> }
> +#endif
> kvm_queue_exception(vcpu, UD_VECTOR);
>
> return r;
>
> To see if the issue still there?
>
>
> On 10/02/2015 10:38 PM, Janusz wrote:
>> W dniu 01.10.2015 o 16:18, Paolo Bonzini pisze:
>>>
>>> On 01/10/2015 16:12, Janusz wrote:
 Now, I can also add, that the problem is only when I allow VM to use
 more than one core, so with option  for example:
 -smp 8,cores=4,threads=2,sockets=1 and other combinations like -smp
 4,threads=1 its not working, and without it I am always running VM
 without problems

 Any ideas what can it be? or any idea what would help to find out what
 is causing this?
>>> I am going to send a revert of the patch tomorrow.
>>>
>>> Paolo
>> Thanks, but revert patch doesn't help, so something else is wrong here
>>

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

[Janusz]

W dniu 14.10.2015 o 11:13, Janusz pisze:
> W dniu 14.10.2015 o 10:32, Xiao Guangrong pisze:
>>
>> On 10/14/2015 04:24 PM, Xiao Guangrong wrote:
>>>
>>> On 10/14/2015 03:37 PM, Janusz wrote:
 I was able to run my virtual machine with this, but had very high cpu
 usage when something happen in it like booting system. once, my virtual
 machine hang and I couln't even get my mouse / keyboard back from qemu.
 When I did vga passthrough, I didn't get any video output, and cpu
 usage
 was also high. Tried it on 4.3
>>> Which tree are you using? Is it kvm tree?
>>> Could you please work on queue brancn on current kvm tree based on
>>> top commit 73917739334c6509: KVM: x86: fix SMI to halted VCPU.
>>>
>>> Hmm... interesting, this diff works on my box...
>> Forgot to say that i built my test env following the instructions on
>> kvm-wiki:
>> http://www.linux-kvm.org/page/OVMF
>>
>> My test script is attached, and i will try to build the env like yours
>> as much
>> as possible...
> I attach my script. I see that you are using pc-i440fx-2.1 - I use
> default, I think its pc-i440fx-2.4, tried 2.3 some time ago and I get
> the same problem. I will try with 2.1 after work
> I am using  master from main kernel  tree, will also try this tree you
> mentioned after work
I am sending this one more time, as my message was rejected by intel
servers because of attached script... Script:
https://bpaste.net/show/8467c3af8b18
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Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Janusz]

W dniu 14.10.2015 o 10:32, Xiao Guangrong pisze:
>
>
> On 10/14/2015 04:24 PM, Xiao Guangrong wrote:
>>
>>
>> On 10/14/2015 03:37 PM, Janusz wrote:
>>> I was able to run my virtual machine with this, but had very high cpu
>>> usage when something happen in it like booting system. once, my virtual
>>> machine hang and I couln't even get my mouse / keyboard back from qemu.
>>> When I did vga passthrough, I didn't get any video output, and cpu
>>> usage
>>> was also high. Tried it on 4.3
>>
>> Which tree are you using? Is it kvm tree?
>> Could you please work on queue brancn on current kvm tree based on
>> top commit 73917739334c6509: KVM: x86: fix SMI to halted VCPU.
>>
>> Hmm... interesting, this diff works on my box...
>
> Forgot to say that i built my test env following the instructions on
> kvm-wiki:
> http://www.linux-kvm.org/page/OVMF
>
> My test script is attached, and i will try to build the env like yours
> as much
> as possible...
I attach my script. I see that you are using pc-i440fx-2.1 - I use
default, I think its pc-i440fx-2.4, tried 2.3 some time ago and I get
the same problem. I will try with 2.1 after work
I am using  master from main kernel  tree, will also try this tree you
mentioned after work
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Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Laszlo Ersek]

On 10/14/15 10:32, Xiao Guangrong wrote:
> 
> 
> On 10/14/2015 04:24 PM, Xiao Guangrong wrote:
>>
>>
>> On 10/14/2015 03:37 PM, Janusz wrote:
>>> I was able to run my virtual machine with this, but had very high cpu
>>> usage when something happen in it like booting system. once, my virtual
>>> machine hang and I couln't even get my mouse / keyboard back from qemu.
>>> When I did vga passthrough, I didn't get any video output, and cpu usage
>>> was also high. Tried it on 4.3
>>
>> Which tree are you using? Is it kvm tree?
>> Could you please work on queue brancn on current kvm tree based on
>> top commit 73917739334c6509: KVM: x86: fix SMI to halted VCPU.
>>
>> Hmm... interesting, this diff works on my box...
> 
> Forgot to say that i built my test env following the instructions on
> kvm-wiki:
> http://www.linux-kvm.org/page/OVMF

Wow! Someone actually cares about the whitepaper. Thank you. :)

Laszlo

> 
> My test script is attached, and i will try to build the env like yours
> as much
> as possible...

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

[Janusz]

W dniu 01.10.2015 o 16:18, Paolo Bonzini pisze:
>
> On 01/10/2015 16:12, Janusz wrote:
>> Now, I can also add, that the problem is only when I allow VM to use
>> more than one core, so with option  for example:
>> -smp 8,cores=4,threads=2,sockets=1 and other combinations like -smp
>> 4,threads=1 its not working, and without it I am always running VM
>> without problems
>>
>> Any ideas what can it be? or any idea what would help to find out what
>> is causing this?
> I am going to send a revert of the patch tomorrow.
>
> Paolo
Thanks, but revert patch doesn't help, so something else is wrong here
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Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Paolo Bonzini]

On 01/10/2015 16:12, Janusz wrote:
> Now, I can also add, that the problem is only when I allow VM to use
> more than one core, so with option  for example:
> -smp 8,cores=4,threads=2,sockets=1 and other combinations like -smp
> 4,threads=1 its not working, and without it I am always running VM
> without problems
> 
> Any ideas what can it be? or any idea what would help to find out what
> is causing this?

I am going to send a revert of the patch tomorrow.

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

[Janusz]

Now, I can also add, that the problem is only when I allow VM to use
more than one core, so with option  for example:
-smp 8,cores=4,threads=2,sockets=1 and other combinations like -smp
4,threads=1 its not working, and without it I am always running VM
without problems

Any ideas what can it be? or any idea what would help to find out what
is causing this?


W dniu 21.09.2015 o 05:40, Xiao Guangrong pisze:
>
>
> On 09/21/2015 11:30 AM, Wanpeng Li wrote:
>> On 9/21/15 10:51 AM, Xiao Guangrong wrote:
>>>
>>> Thanks for your report and analysis, Janusz!
>>>
>>> On 09/19/2015 01:48 AM, Janusz wrote:
 W dniu 18.09.2015 o 12:07, Laszlo Ersek pisze:
> On 09/18/15 11:37, Janusz wrote:
>> Hello,
>>
>> I am writting about this patch that was posted by Xiao:
>> http://www.spinics.net/lists/kvm/msg119044.html and this:
>> http://www.spinics.net/lists/kvm/msg119045.html
>> I've tested both kernel 4.2 and 4.3 and problem still exists when
>> I use
>> OVMF - 100% cpu usage, VM resetting, while it works properly on
>> kernel 4.1
> My last (still current) request remains "please quirk it". See the
> end
> of ,
> and other messages in that subthread.
 when I saw message from Xiao that he posted patch for it and have seen
 this code in kernel sources (landed in 4.2-rc3) I though that the
 status
 is not "please quirk it" anymore
>
> I haven't been following kernel development, so maybe the quirk
> has not
> happened. No clue.
>
> ... "VM resetting" looks something different though; I've been
> under the
> impression that the pedantic (=unquirked) MTRR configuration didn't
> impact other things than speed. Janusz, maybe you could contribute
> with
> a host kernel bisection for the VM reset symptom.
 To be more exact - VM is mostly not starting or its starting after
 long
 time and then resetting it self at random time (but before system
 boots)
 or gets very high cpu usage or sometimes boots without problem (the
 least possible case scenario). When I start VM with -vga std, not with
 my gpu passthrough - in most of the time I get this:
 http://pastebin.com/raw.php?i=CKrNsueS
>>>
>>> It seems the behaviour is different with previous (previously, it
>>> can boot
>>> but slowly), right?
>>>
>>> The URL cat not be accessed, i do not know it's your web server
>>> issue or
>>> our networking issue.
>>>
>>
>> It can be accessed and dump as below:
>>
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> KVM internal error. Suberror: 1
>> emulation failure
>> EAX=bfefa000 EBX=0002 ECX= EDX=0600
>> ESI= EDI=3eb8 EBP= ESP=
>> EIP=000a EFL=00010086 [--S--P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
>> ES =0008   00c09300 DPL=0 DS   [-WA]
>> CS =0010   00c09b00 DPL=0 CS32 [-RA]
>> SS =0008   00c09300 DPL=0 DS   [-WA]
>> DS =0008   00c09300 DPL=0 DS   [-WA]
>> FS =0008   00c09300 DPL=0 DS   [-WA]
>> GS =0008   00c09300 DPL=0 DS   [-WA]
>> LDT=   8200 DPL=0 LDT
>> TR =   8b00 DPL=0 TSS32-busy
>> GDT= bfee87d8 003f
>> IDT=  
>> CR0=0033 CR2= CR3=bfefa000 CR4=0640
>> DR0= DR1= DR2=
>> DR3=
>> DR6=0ff0 DR7=0400
>> EFER=
>> Code=af af af af af af af af af af af af af af af af af af af af <00>
>> 00 00 00 00 00 00 00 00 00 00
>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> EAX=bfefa000 EBX=0002 ECX= EDX=0600
>> ESI= EDI=3eb8 EBP= ESP=
>> EIP=000a EFL=00010086 [--S--P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
>> ES =0008   00c09300 DPL=0 DS   [-WA]
>> CS =0010   00c09b00 DPL=0 CS32 [-RA]
>> SS =0008   00c09300 DPL=0 DS   [-WA]
>> DS =0008   00c09300 DPL=0 DS   [-WA]
>> FS =0008   00c09300 DPL=0 DS   [-WA]
>> GS =0008   00c09300 DPL=0 DS   [-WA]
>> LDT=   8200 DPL=0 LDT
>> TR =   8b00 DPL=0 TSS32-busy
>> GDT= bfee87d8 003f
>> IDT=  
>> CR0=0033 CR2= CR3=bfefa000 CR4=0640
>> DR0= DR1= DR2=
>> DR3=
>> DR6=0ff0 DR7=0400
>> EFER=
>> Code=af af af af af af af af af af af af af af af af af af af af 

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

[Paolo Bonzini]

On 18/09/2015 11:37, Janusz wrote:
> Hello,
> 
> I am writting about this patch that was posted by Xiao:
> http://www.spinics.net/lists/kvm/msg119044.html and this:
> http://www.spinics.net/lists/kvm/msg119045.html
> I've tested both kernel 4.2 and 4.3 and problem still exists when I use
> OVMF - 100% cpu usage, VM resetting, while it works properly on kernel 4.1

Is this an Intel or AMD CPU?

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

[Janusz]

W dniu 22.09.2015 o 10:59, Paolo Bonzini pisze:
>
> On 18/09/2015 11:37, Janusz wrote:
>> Hello,
>>
>> I am writting about this patch that was posted by Xiao:
>> http://www.spinics.net/lists/kvm/msg119044.html and this:
>> http://www.spinics.net/lists/kvm/msg119045.html
>> I've tested both kernel 4.2 and 4.3 and problem still exists when I use
>> OVMF - 100% cpu usage, VM resetting, while it works properly on kernel 4.1
> Is this an Intel or AMD CPU?
>
> Paolo
Intel i7 6700k
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Re: [edk2] KVM: MTRR: fix memory type handling if MTRR is completely disabled

[Janusz]

W dniu 21.09.2015 o 04:51, Xiao Guangrong pisze:
>
> Thanks for your report and analysis, Janusz!
>
> On 09/19/2015 01:48 AM, Janusz wrote:
>> W dniu 18.09.2015 o 12:07, Laszlo Ersek pisze:
>>> On 09/18/15 11:37, Janusz wrote:
 Hello,

 I am writting about this patch that was posted by Xiao:
 http://www.spinics.net/lists/kvm/msg119044.html and this:
 http://www.spinics.net/lists/kvm/msg119045.html
 I've tested both kernel 4.2 and 4.3 and problem still exists when I
 use
 OVMF - 100% cpu usage, VM resetting, while it works properly on
 kernel 4.1
>>> My last (still current) request remains "please quirk it". See the end
>>> of ,
>>> and other messages in that subthread.
>> when I saw message from Xiao that he posted patch for it and have seen
>> this code in kernel sources (landed in 4.2-rc3) I though that the status
>> is not "please quirk it" anymore
>>>
>>> I haven't been following kernel development, so maybe the quirk has not
>>> happened. No clue.
>>>
>>> ... "VM resetting" looks something different though; I've been under
>>> the
>>> impression that the pedantic (=unquirked) MTRR configuration didn't
>>> impact other things than speed. Janusz, maybe you could contribute with
>>> a host kernel bisection for the VM reset symptom.
>> To be more exact - VM is mostly not starting or its starting after long
>> time and then resetting it self at random time (but before system boots)
>> or gets very high cpu usage or sometimes boots without problem (the
>> least possible case scenario). When I start VM with -vga std, not with
>> my gpu passthrough - in most of the time I get this:
>> http://pastebin.com/raw.php?i=CKrNsueS
>
> It seems the behaviour is different with previous (previously, it can
> boot
> but slowly), right?
>
> The URL cat not be accessed, i do not know it's your web server issue or
> our networking issue.
>
>>
>> Result of bisect:
>>
>> git bisect start
>> # bad: [d770e558e21961ad6cfdf0ff7df0eb5d7d4f0754] Linux 4.2-rc1
>> git bisect bad d770e558e21961ad6cfdf0ff7df0eb5d7d4f0754
>> # good: [b953c0d234bc72e8489d3bf51a276c5c4ec85345] Linux 4.1
>> git bisect good b953c0d234bc72e8489d3bf51a276c5c4ec85345
>> # good: [4570a37169d4b44d316f40b2ccc681dc93fedc7b] Merge tag
>> 'sound-4.2-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
>> git bisect good 4570a37169d4b44d316f40b2ccc681dc93fedc7b
>> # good: [8d7804a2f03dbd34940fcb426450c730adf29dae] Merge tag
>> 'driver-core-4.2-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
>> git bisect good 8d7804a2f03dbd34940fcb426450c730adf29dae
>> # bad: [78c10e556ed904d5bfbd71e9cadd8ce8f25d6982] Merge branch
>> 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
>> git bisect bad 78c10e556ed904d5bfbd71e9cadd8ce8f25d6982
>> # good: [623f0e137c0fedb81bbf3d88be4ed300eee163da] Staging: lustre: fix
>> space before and after comma in dt_object.c
>> git bisect good 623f0e137c0fedb81bbf3d88be4ed300eee163da
>> # bad: [8c7febe83915332276cab49e89f6580bb963fb9a] Merge tag
>> 'tty-4.2-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
>> git bisect bad 8c7febe83915332276cab49e89f6580bb963fb9a
>> # good: [bcf5b92d9bbf0b7683199615f0f184e89fa486bc] staging: rtl8192e:
>> Remove rt_hi_throughput::ChnkOp
>> git bisect good bcf5b92d9bbf0b7683199615f0f184e89fa486bc
>> # good: [71eec4836b834b992e0cefeefc8b85efe4cb185b] drivers: PL011: allow
>> avoiding UART enabling/disabling
>> git bisect good 71eec4836b834b992e0cefeefc8b85efe4cb185b
>> # good: [49ef9c850154756cf2fbc50fd3804c44675d4633] staging: comedi:
>> me4000: rename 'thisboard' variables
>> git bisect good 49ef9c850154756cf2fbc50fd3804c44675d4633
>> # good: [2a4462418af771ef9f1f1d1532bcbb8799df842d] tty/serial: kill off
>> set_irq_flags usage
>> git bisect good 2a4462418af771ef9f1f1d1532bcbb8799df842d
>> # good: [6d43b0f482561ab421a91ebf59a51192d66cf8a7] Staging: sm750fb:
>> ddk750_swi2c.c: Insert spaces around operators
>> git bisect good 6d43b0f482561ab421a91ebf59a51192d66cf8a7
>> # good: [84e1eb83d0b9e0969a59b6848d718eaf71e98fcb] MAINTAINERS: tty: add
>> serial docs directory
>> git bisect good 84e1eb83d0b9e0969a59b6848d718eaf71e98fcb
>> # good: [53a20e9e378ecd52f0afa4b60f8f8c81b6f97c27] staging: wilc1000:
>> disable driver due to build warnings
>> git bisect good 53a20e9e378ecd52f0afa4b60f8f8c81b6f97c27
>> # good: [71206b9f8120eb513c621d4f31906577bb658df3] Doc:
>> serial-rs485.txt: update RS485 driver interface
>> git bisect good 71206b9f8120eb513c621d4f31906577bb658df3
>> # bad: [23908db413eccd77084b09c9b0a4451dfb0524c0] Merge tag
>> 'staging-4.2-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
>> git bisect bad 23908db413eccd77084b09c9b0a4451dfb0524c0
>> # first bad commit: [23908db413eccd77084b09c9b0a4451dfb0524c0] Merge tag
>> 'staging-4.2-rc1' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
>>
>
> The 

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

[Janusz]

Hello,

I am writting about this patch that was posted by Xiao:
http://www.spinics.net/lists/kvm/msg119044.html and this:
http://www.spinics.net/lists/kvm/msg119045.html
I've tested both kernel 4.2 and 4.3 and problem still exists when I use
OVMF - 100% cpu usage, VM resetting, while it works properly on kernel 4.1
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