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

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Message-ID: <84f42bad-9fb0-8a76-7f9b-580898b634b9@amd.com>
Date:   Thu, 21 Jan 2021 17:51:11 -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 1/20/21 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