From: Amit Machhiwal <amachhiw@linux.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org
Cc: Jordan Niethe <jniethe5@gmail.com>,
linux-kernel@vger.kernel.org, Nicholas Piggin <npiggin@gmail.com>,
Vaidyanathan Srinivasan <svaidy@linux.ibm.com>,
"Aneesh Kumar K . V" <aneesh.kumar@kernel.org>,
"Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
Vaibhav Jain <vaibhav@linux.ibm.com>
Subject: Re: Re: [PATCH v3] KVM: PPC: Book3S HV: Fix L2 guest reboot failure due to empty 'arch_compat'
Date: Wed, 7 Feb 2024 10:58:43 +0530 [thread overview]
Message-ID: <t5qjoir2gvckq6vscsi4zg66grkk3px24znzfrraaq32x5wea3@ogxxeqk5vrpu> (raw)
In-Reply-To: <87r0hp9a4z.fsf@mail.lhotse>
Hi Michael,
Thanks for looking into the patch and your comments.
On 2024/02/06 09:09 PM, Michael Ellerman wrote:
> Hi Amit,
>
> One comment below ...
>
> Amit Machhiwal <amachhiw@linux.ibm.com> writes:
> > Currently, rebooting a pseries nested qemu-kvm guest (L2) results in
> > below error as L1 qemu sends PVR value 'arch_compat' == 0 via
> > ppc_set_compat ioctl. This triggers a condition failure in
> > kvmppc_set_arch_compat() resulting in an EINVAL.
> ...
> >
> > diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > index 5378eb40b162..6042bdc70230 100644
> > --- a/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > +++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c
> > @@ -347,8 +348,26 @@ static int gs_msg_ops_vcpu_fill_info(struct kvmppc_gs_buff *gsb,
> > break;
> > }
> > case KVMPPC_GSID_LOGICAL_PVR:
> > - rc = kvmppc_gse_put_u32(gsb, iden,
> > - vcpu->arch.vcore->arch_compat);
> > + /*
> > + * Though 'arch_compat == 0' would mean the default
> > + * compatibility, arch_compat, being a Guest Wide
> > + * Element, cannot be filled with a value of 0 in GSB
> > + * as this would result into a kernel trap.
> > + * Hence, when `arch_compat == 0`, arch_compat should
> > + * default to L1's PVR.
> > + *
> > + * Rework this when PowerVM supports a value of 0
> > + * for arch_compat for KVM API v2.
> > + */
>
> Is there an actual plan that PowerVM will support this in future?
>
> If so, how will a future kernel know that it's running on a version of
> PowerVM that does support arch_compat == 0?
>
> Similarly how will we know when it's OK to drop support for this
> workaround?
I'm sending a v4 based on an off mailing list discussion.
>
> cheers
~Amit
prev parent reply other threads:[~2024-02-07 5:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-05 18:18 [PATCH v3] KVM: PPC: Book3S HV: Fix L2 guest reboot failure due to empty 'arch_compat' Amit Machhiwal
2024-02-06 10:09 ` Michael Ellerman
2024-02-07 5:28 ` Amit Machhiwal [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=t5qjoir2gvckq6vscsi4zg66grkk3px24znzfrraaq32x5wea3@ogxxeqk5vrpu \
--to=amachhiw@linux.ibm.com \
--cc=aneesh.kumar@kernel.org \
--cc=jniethe5@gmail.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=naveen.n.rao@linux.ibm.com \
--cc=npiggin@gmail.com \
--cc=svaidy@linux.ibm.com \
--cc=vaibhav@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).