From: Maxim Levitsky <mlevitsk@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Li RongQing <lirongqing@baidu.com>
Subject: Re: [PATCH 19/19] Revert "KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu"
Date: Wed, 31 Aug 2022 10:03:43 +0300 [thread overview]
Message-ID: <ad4986e64a02fbd75d4b3f0199fae546e2cea2c6.camel@redhat.com> (raw)
In-Reply-To: <fd349966a87ef3cb93fe1670e91cf6d2142ed442.camel@redhat.com>
On Wed, 2022-08-31 at 09:07 +0300, Maxim Levitsky wrote:
> On Wed, 2022-08-31 at 00:35 +0000, Sean Christopherson wrote:
> > Turns out that some warnings exist for good reasons. Restore the warning
> > in avic_vcpu_load() that guards against calling avic_vcpu_load() on a
> > running vCPU now that KVM avoids doing so when switching between x2APIC
> > and xAPIC. The entire point of the WARN is to highlight that KVM should
> > not be reloading an AVIC.
> >
> > Opportunistically convert the WARN_ON() to WARN_ON_ONCE() to avoid
> > spamming the kernel if it does fire.
> >
> > This reverts commit c0caeee65af3944b7b8abbf566e7cc1fae15c775.
> >
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> > arch/x86/kvm/svm/avic.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> > index b2033a56010c..3c300113d40b 100644
> > --- a/arch/x86/kvm/svm/avic.c
> > +++ b/arch/x86/kvm/svm/avic.c
> > @@ -1080,6 +1080,7 @@ void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> > return;
> >
> > entry = READ_ONCE(*(svm->avic_physical_id_cache));
> > + WARN_ON_ONCE(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK);
> >
> > entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
> > entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);
>
> Note that this warning was removed because it would trigger wheh x2avic code would switch
> between xapic and x2apic.
>
> I do agree 100% that this warning is useful.
Ah I see that you fixed the apic reloading to not trigger this code,
need more coffee - in this case this patch makes lot of sense.
I'll review it again when I review rest of the patches in the patch series.
Best regards,
Maxim Levitsky
>
> Best regards,
> Maxim Levitsky
prev parent reply other threads:[~2022-08-31 7:03 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-31 0:34 [PATCH 00/19] KVM: x86: AVIC and local APIC fixes+cleanups Sean Christopherson
2022-08-31 0:34 ` [PATCH 01/19] KVM: SVM: Process ICR on AVIC IPI delivery failure due to invalid target Sean Christopherson
2022-08-31 9:18 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 02/19] KVM: SVM: Don't put/load AVIC when setting virtual APIC mode Sean Christopherson
2022-08-31 9:24 ` Maxim Levitsky
2022-08-31 16:33 ` Sean Christopherson
2022-08-31 0:34 ` [PATCH 03/19] Revert "KVM: SVM: Introduce hybrid-AVIC mode" Sean Christopherson
2022-08-31 5:59 ` Maxim Levitsky
2022-08-31 6:45 ` Maxim Levitsky
2022-08-31 16:29 ` Sean Christopherson
2022-08-31 17:46 ` Maxim Levitsky
2022-08-31 17:58 ` Jim Mattson
2022-08-31 18:01 ` Maxim Levitsky
2022-08-31 19:12 ` Sean Christopherson
2022-09-01 10:25 ` Maxim Levitsky
2022-09-01 11:47 ` Jim Mattson
2022-09-01 13:29 ` Sean Christopherson
2022-09-01 13:53 ` Sean Christopherson
2022-09-01 15:08 ` Sean Christopherson
2022-08-31 16:19 ` Sean Christopherson
2022-08-31 17:47 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 04/19] KVM: SVM: Replace "avic_mode" enum with "x2avic_enabled" boolean Sean Christopherson
2022-08-31 9:36 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 05/19] KVM: SVM: Compute dest based on sender's x2APIC status for AVIC kick Sean Christopherson
2022-08-31 9:38 ` Maxim Levitsky
2022-09-01 2:56 ` Li,Rongqing
2022-08-31 0:34 ` [PATCH 06/19] KVM: SVM: Get x2APIC logical dest bitmap from ICRH[15:0], not ICHR[31:16] Sean Christopherson
2022-08-31 6:09 ` Maxim Levitsky
2022-08-31 9:43 ` Maxim Levitsky
2022-08-31 16:35 ` Sean Christopherson
2022-08-31 18:18 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 07/19] KVM: SVM: Drop buggy and redundant AVIC "single logical dest" check Sean Christopherson
2022-08-31 6:19 ` Maxim Levitsky
2022-08-31 16:37 ` Sean Christopherson
2022-08-31 18:10 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 08/19] KVM: SVM: Remove redundant cluster calculation that also creates a shadow Sean Christopherson
2022-08-31 10:19 ` Maxim Levitsky
2022-09-01 20:02 ` Sean Christopherson
2022-08-31 0:34 ` [PATCH 09/19] KVM: SVM: Drop duplicate calcuation of AVIC/x2AVIC "logical index" Sean Christopherson
2022-08-31 0:34 ` [PATCH 10/19] KVM: SVM: Document that vCPU ID == APIC ID in AVIC kick fastpatch Sean Christopherson
2022-08-31 10:22 ` Maxim Levitsky
2022-08-31 16:16 ` Sean Christopherson
2022-08-31 17:49 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 11/19] KVM: SVM: Add helper to perform final AVIC "kick" of single vCPU Sean Christopherson
2022-08-31 10:25 ` Maxim Levitsky
2022-08-31 15:08 ` Sean Christopherson
2022-08-31 18:12 ` Maxim Levitsky
2022-08-31 0:34 ` [PATCH 12/19] KVM: x86: Disable APIC logical map if logical ID covers multiple MDAs Sean Christopherson
2022-08-31 13:23 ` Maxim Levitsky
2022-08-31 0:35 ` [PATCH 13/19] KVM: x86: Disable APIC logical map if vCPUs are aliased in logical mode Sean Christopherson
2022-08-31 13:24 ` Maxim Levitsky
2022-08-31 0:35 ` [PATCH 14/19] KVM: x86: Honor architectural behavior for aliased 8-bit APIC IDs Sean Christopherson
2022-08-31 13:37 ` Maxim Levitsky
2022-08-31 16:41 ` Sean Christopherson
2022-08-31 17:51 ` Maxim Levitsky
2022-08-31 0:35 ` [PATCH 15/19] KVM: x86: Explicitly skip optimized logical map setup if vCPU's LDR==0 Sean Christopherson
2022-08-31 13:41 ` Maxim Levitsky
2022-08-31 16:47 ` Sean Christopherson
2022-08-31 0:35 ` [PATCH 16/19] KVM: x86: Explicitly track all possibilities for APIC map's logical modes Sean Christopherson
2022-08-31 13:43 ` Maxim Levitsky
2022-08-31 16:56 ` Sean Christopherson
2022-08-31 17:53 ` Maxim Levitsky
2022-09-16 18:58 ` Sean Christopherson
2022-08-31 18:42 ` Maxim Levitsky
2022-08-31 19:17 ` Sean Christopherson
2022-08-31 0:35 ` [PATCH 17/19] KVM: SVM: Handle multiple logical targets in AVIC kick fastpath Sean Christopherson
2022-08-31 13:57 ` Maxim Levitsky
2022-08-31 18:19 ` Sean Christopherson
2022-08-31 18:25 ` Maxim Levitsky
2022-08-31 0:35 ` [PATCH 18/19] KVM: SVM: Ignore writes to Remote Read Data on AVIC write traps Sean Christopherson
2022-08-31 10:40 ` Maxim Levitsky
2022-08-31 0:35 ` [PATCH 19/19] Revert "KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu" Sean Christopherson
2022-08-31 6:07 ` Maxim Levitsky
2022-08-31 7:03 ` Maxim Levitsky [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=ad4986e64a02fbd75d4b3f0199fae546e2cea2c6.camel@redhat.com \
--to=mlevitsk@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lirongqing@baidu.com \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=suravee.suthikulpanit@amd.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 NNTP newsgroup(s).