RE: [PATCH v6 00/12] SVM cleanup and INVPCID feature support

-----Original Message-----
From: Jim Mattson <redacted>
Sent: Tuesday, February 23, 2021 6:14 PM
To: Moger, Babu <Babu.Moger@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>; Vitaly Kuznetsov
[off-list ref]; Wanpeng Li [off-list ref]; kvm list
[off-list ref]; Joerg Roedel [off-list ref]; the arch/x86
maintainers [off-list ref]; LKML [off-list ref]; Ingo
Molnar [off-list ref]; Borislav Petkov [off-list ref]; H . Peter Anvin
[off-list ref]; Thomas Gleixner [off-list ref]; Makarand Sonare
[off-list ref]; Sean Christopherson [off-list ref]
Subject: Re: [PATCH v6 00/12] SVM cleanup and INVPCID feature support

Any updates? What should we be telling customers with Debian 9 guests? :-)

Found another problem with pcid feature om SVM. It is do with CR4 flags
reset during bootup. Problem was showing up with kexec loading on VM.
I am not sure if this is related to that. Will send the patch soon.

On Fri, Jan 22, 2021 at 5:52 PM Babu Moger [off-list ref] wrote:

quoted

On 1/21/21 5:51 PM, Babu Moger wrote:

quoted

On 1/20/21 9:10 PM, Babu Moger wrote:

quoted

On 1/20/21 3:45 PM, Babu Moger wrote:

quoted

On 1/20/21 3:14 PM, Jim Mattson wrote:

quoted

On Tue, Jan 19, 2021 at 3:45 PM Babu Moger [off-list ref]

wrote:

quoted

quoted

quoted

quoted

quoted

quoted

On 1/19/21 5:01 PM, Jim Mattson wrote:

quoted

On Mon, Sep 14, 2020 at 11:33 AM Babu Moger

[off-list ref] wrote:

quoted

quoted

quoted

quoted

quoted

quoted

quoted

quoted

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?

quoted

quoted

quoted

quoted

quoted

quoted

Here are the patch set.
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%

2Flore.kernel.org%2Fkvm%2F160521930597.32054.4906933314022910996

quoted

quoted

quoted

quoted

quoted

quoted

.stgit%40bmoger-

ubuntu%2F&data=04%7C01%7Cbabu.moger%40amd.co

quoted

quoted

quoted

quoted

quoted

quoted

m%7C9558672ca21c4f6c2d5308d8d85919dc%7C3dd8961fe4884e608e11a82d9

quoted

quoted

quoted

quoted

quoted

quoted

94e183d%7C0%7C0%7C637497224490455772%7CUnknown%7CTWFpbGZsb3d8
eyJ

quoted

quoted

quoted

quoted

quoted

quoted

WIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%

quoted

quoted

quoted

quoted

quoted

quoted

7C1000&sdata=4QzTNHaYllwPd1U0kumq75dpwp7Rg0ZXsSQ631jMeqs%3D
&

quoted

quoted

quoted

quoted

quoted

quoted

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