From: Sean Christopherson <seanjc@google.com>
To: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH v4 01/26] KVM: SVM: Switch svm_copy_lbrs() to a macro
Date: Thu, 5 Feb 2026 16:59:25 -0800 [thread overview]
Message-ID: <aYU87QeMg8_kTM-G@google.com> (raw)
In-Reply-To: <20260115011312.3675857-2-yosry.ahmed@linux.dev>
On Thu, Jan 15, 2026, Yosry Ahmed wrote:
> In preparation for using svm_copy_lbrs() with 'struct vmcb_save_area'
> without a containing 'struct vmcb', and later even 'struct
> vmcb_save_area_cached', make it a macro. Pull the call to
> vmcb_mark_dirty() out to the callers.
>
> Macros are generally not preferred compared to functions, mainly due to
> type-safety. However, in this case it seems like having a simple macro
> copying a few fields is better than copy-pasting the same 5 lines of
> code in different places.
>
> On the bright side, pulling vmcb_mark_dirty() calls to the callers makes
> it clear that in one case, vmcb_mark_dirty() was being called on VMCB12.
> It is not architecturally defined for the CPU to clear arbitrary clean
> bits, and it is not needed, so drop that one call.
>
> Technically fixes the non-architectural behavior of setting the dirty
> bit on VMCB12.
Stop. Bundling. Things. Together.
/shakes fist angrily
I was absolutely not expecting a patch titled "KVM: SVM: Switch svm_copy_lbrs()
to a macro" to end with a Fixes tag, and I was *really* not expecting it to also
be Cc'd for stable.
At a glance, I genuinely can't tell if you added a Fixes to scope the backport,
or because of the dirty vmcb12 bits thing.
First fix the dirty behavior (and probably tag it for stable to avoid creating
an unnecessary backport conflict), then in a separate patch macrofy the helper.
Yeah, checkpatch will "suggest" that the stable@ patch should have Fixes, but
for us humans, that's _useful_ information, because it says "hey you, this is a
dependency for an upcoming fix!". As written, I look at this patch and go "huh?".
(and then I look at the next patch and it all makes sense).
next prev parent reply other threads:[~2026-02-06 0:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260115011312.3675857-1-yosry.ahmed@linux.dev>
2026-01-15 1:12 ` [PATCH v4 01/26] KVM: SVM: Switch svm_copy_lbrs() to a macro Yosry Ahmed
2026-02-06 0:59 ` Sean Christopherson [this message]
2026-02-06 1:12 ` Yosry Ahmed
2026-02-06 1:25 ` Sean Christopherson
2026-02-06 15:13 ` Yosry Ahmed
2026-02-06 15:54 ` Sean Christopherson
2026-01-15 1:12 ` [PATCH v4 02/26] KVM: SVM: Add missing save/restore handling of LBR MSRs Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 04/26] KVM: nSVM: Always inject a #GP if mapping VMCB12 fails on nested VMRUN Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 05/26] KVM: nSVM: Triple fault if mapping VMCB12 fails on nested #VMEXIT Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 06/26] KVM: nSVM: Triple fault if restore host CR3 " Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 07/26] KVM: nSVM: Drop nested_vmcb_check_{save/control}() wrappers Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 08/26] KVM: nSVM: Call enter_guest_mode() before switching to VMCB02 Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 09/26] KVM: nSVM: Make nested_svm_merge_msrpm() return an errno Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 10/26] KVM: nSVM: Call nested_svm_merge_msrpm() from enter_svm_guest_mode() Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 11/26] KVM: nSVM: Call nested_svm_init_mmu_context() before switching to VMCB02 Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 12/26] KVM: nSVM: Refactor minimal #VMEXIT handling out of nested_svm_vmexit() Yosry Ahmed
2026-01-15 1:12 ` [PATCH v4 13/26] KVM: nSVM: Unify handling of VMRUN failures with proper cleanup Yosry Ahmed
2026-02-06 0:47 ` Sean Christopherson
2026-02-06 15:40 ` Yosry Ahmed
2026-02-06 1:20 ` Sean Christopherson
2026-01-15 1:13 ` [PATCH v4 14/26] KVM: nSVM: Clear EVENTINJ field in VMCB12 on nested #VMEXIT Yosry Ahmed
2026-01-15 1:13 ` [PATCH v4 15/26] KVM: nSVM: Drop the non-architectural consistency check for NP_ENABLE Yosry Ahmed
2026-01-15 1:13 ` [PATCH v4 16/26] KVM: nSVM: Add missing consistency check for nCR3 validity Yosry Ahmed
2026-01-22 1:38 ` Yosry Ahmed
2026-01-15 1:13 ` [PATCH v4 17/26] KVM: nSVM: Add missing consistency check for hCR0.PG and NP_ENABLE Yosry Ahmed
2026-01-15 1:13 ` [PATCH v4 18/26] KVM: nSVM: Add missing consistency check for EFER, CR0, CR4, and CS Yosry Ahmed
2026-01-15 1:13 ` [PATCH v4 19/26] KVM: nSVM: Add missing consistency check for event_inj Yosry Ahmed
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