linux-kernel - Re: [PATCH v6 00/12] SVM cleanup and INVPCID feature support

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Date:   Fri, 22 Jan 2021 19:52:17 -0600
From:   Babu Moger <babu.moger@....com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        kvm list <kvm@...r.kernel.org>, Joerg Roedel <joro@...tes.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Makarand Sonare <makarandsonare@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH v6 00/12] SVM cleanup and INVPCID feature support



On 1/21/21 5:51 PM, Babu Moger wrote:
> 
> 
> On 1/20/21 9:10 PM, Babu Moger wrote:
>>
>>
>> On 1/20/21 3:45 PM, Babu Moger wrote:
>>>
>>>
>>> On 1/20/21 3:14 PM, Jim Mattson wrote:
>>>> On Tue, Jan 19, 2021 at 3:45 PM Babu Moger <babu.moger@....com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 1/19/21 5:01 PM, Jim Mattson wrote:
>>>>>> On Mon, Sep 14, 2020 at 11:33 AM Babu Moger <babu.moger@....com> wrote:
>>>>>>
>>>>>>> Thanks Paolo. Tested Guest/nested guest/kvm units tests. Everything works
>>>>>>> as expected.
>>>>>>
>>>>>> Debian 9 does not like this patch set. As a kvm guest, it panics on a
>>>>>> Milan CPU unless booted with 'nopcid'. Gmail mangles long lines, so
>>>>>> please see the attached kernel log snippet. Debian 10 is fine, so I
>>>>>> assume this is a guest bug.
>>>>>>
>>>>>
>>>>> We had an issue with PCID feature earlier. This was showing only with SEV
>>>>> guests. It is resolved recently. Do you think it is not related that?
>>>>> Here are the patch set.
>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fkvm%2F160521930597.32054.4906933314022910996.stgit%40bmoger-ubuntu%2F&amp;data=04%7C01%7CBabu.Moger%40amd.com%7C3009e5f7f32b4dbd4aee08d8bdc045c9%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637467980841376327%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=%2Bva7em372XD7uaCrSy3UBH6a9n8xaTTXWCAlA3gJX78%3D&amp;reserved=0
>>>>
>>>> The Debian 9 release we tested is not an SEV guest.
>>> ok. I have not tested Debian 9 before. I will try now. Will let you know
>>> how it goes. thanks
>>>
>>
>> I have reproduced the issue locally. Will investigate. thanks
>>
> Few updates.
> 1. Like Jim mentioned earlier, this appears to be guest kernel issue.
> Debian 9 runs the base kernel 4.9.0-14. Problem can be seen consistently
> with this kernel.
> 
> 2. This guest kernel(4.9.0-14) does not like the new feature INVPCID.
> 
> 3. System comes up fine when invpcid feature is disabled with the boot
> parameter "noinvpcid" and also with "nopcid". nopcid disables both pcid
> and invpcid.
> 
> 4. Upgraded the guest kernel to v5.0 and system comes up fine.
> 
> 5. Also system comes up fine with latest guest kernel 5.11.0-rc4.
> 
> I did not bisect further yet.
> Babu
> Thanks


Some more update:
 System comes up fine with kernel v4.9(checked out on upstream tag v4.9).
So, I am assuming this is something specific to Debian 4.9.0-14 kernel.

Note: I couldn't go back prior versions(v4.8 or earlier) due to compile
issues.
Thanks
Babu