From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: Madhavan Srinivasan <maddy@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org,
Nicholas Piggin <npiggin@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
"Ritesh Harjani (IBM)" <ritesh.list@gmail.com>,
kvm-ppc@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Gautam Menghani <gautam@linux.ibm.com>,
Harsh Prateek Bora <harshpb@linux.ibm.com>,
R Nageswara Sastry <rnsastry@linux.ibm.com>,
Alexander Graf <agraf@suse.de>,
linux-hardening@vger.kernel.org, stable@vger.kernel.org,
Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH v2 2/3] KVM: PPC: Book3S HV: Add preempt_disable() around virtual-mode HPTE bit-lock users
Date: Tue, 6 Oct 2026 08:31:21 +0530 [thread overview]
Message-ID: <ad91f624-ea6f-441f-995e-14fd4fd30ebe@linux.ibm.com> (raw)
In-Reply-To: <20261005234024.20213ac7-78-amachhiw@linux.ibm.com>
On 10/5/26 11:57 PM, Amit Machhiwal wrote:
> Hi Shrikanth,
>
> Thanks for the review. Please find my responses inline below.
>
>> I don't like this sprinkling of preempt disable/enable.
>> Is there not a way to embedd this in try_lock_hpte/unlock_hpte?
>
> I understand the scattering of preempt_disable()/preempt_enable() looks ugly.
> But there are two blockers for that approach:
>
> 1. The real-mode hcall dispatch table (hcall_real_table in
> book3s_hv_rmhandlers.S) calls kvmppc_h_enter(), kvmppc_h_remove(),
> kvmppc_h_bulk_remove() and others in book3s_hv_rm_mmu.c, which all call
> try_lock_hpte() from real mode. Adding preempt_disable() inside
> try_lock_hpte() would affect those real-mode callers, which brings us to your
> second point.
>
Fair enough.
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
next prev parent reply other threads:[~2026-10-06 3:01 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 17:37 [PATCH v2 0/3] KVM: PPC: Fixes for Book3S HV HPT locking and paired-single decoding Amit Machhiwal
2026-09-30 17:37 ` [PATCH v2 1/3] KVM: PPC: Book3S HV: Add SRCU protection for virtual-mode HPT hcalls Amit Machhiwal
2026-09-30 17:37 ` [PATCH v2 2/3] KVM: PPC: Book3S HV: Add preempt_disable() around virtual-mode HPTE bit-lock users Amit Machhiwal
2026-10-05 14:28 ` Shrikanth Hegde
2026-10-05 18:27 ` Amit Machhiwal
2026-10-06 3:01 ` Shrikanth Hegde [this message]
2026-09-30 17:37 ` [PATCH v2 3/3] KVM: PPC: Fix get_d_signext() 12-bit displacement for paired-single D-form Amit Machhiwal
2026-10-06 3:27 ` Shrikanth Hegde
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