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From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Li RongQing <lirongqing@baidu.com>
Subject: Re: [PATCH 08/19] KVM: SVM: Remove redundant cluster calculation that also creates a shadow
Date: Thu, 1 Sep 2022 20:02:53 +0000	[thread overview]
Message-ID: <YxEP7ZBRIuFWhnYJ@google.com> (raw)
In-Reply-To: <7281e42323b53a016cf8545b7a4547d70d87efce.camel@redhat.com>

On Wed, Aug 31, 2022, Maxim Levitsky wrote:
> On Wed, 2022-08-31 at 00:34 +0000, Sean Christopherson wrote:
> > Drop the redundant "cluster" calculation and its horrific shadowing in
> > the x2avic logical mode path.  The "cluster" that is declared at an outer
> > scope is derived using the exact same calculation and has performed the
> > left-shift.
> 
> Actually I think we should just revert the commit 
> 'KVM: SVM: Use target APIC ID to complete x2AVIC IRQs when possible'
> 
> 
> I know that the patch that intially introduced the the avic_kick_target_vcpus_fast had
> x2apic/x2avic code, and then it was split to avoid adding x2avic code before it was merged,
> resulting in this patch to add the x2apic specific code.
> 
> But when I fixed most issues of avic_kick_target_vcpus_fast in my 
> 'KVM: x86: SVM: fix avic_kick_target_vcpus_fast', I added back x2apic code because
> it was just natural to do since I had to calculate cluster/bitmap masks anyway.
> 
> I expected this patch to be dropped because of this but I guess it was not noticed,
> or patches were merged in the wrong order.
> 
> This is the reason of shadowing, duplicate calculations/etc.

Ooooh, I completely missed that x2AVIC was already supported.  I saw the code, but
between the fixing the first bug and unwinding everything everything else I didn't
see that the end result ended up being a full revert.

So yeah, a full revert is definitely in order.

Thanks!

  reply	other threads:[~2022-09-01 20:03 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 [this message]
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

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