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Sun, 01 Nov 2026 07:28:34 -0800 (PST) Received: from pve-server.rlab ([49.205.216.49]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1ac18458e07sm24862665c88.8.2026.11.01.07.28.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Nov 2026 07:28:34 -0800 (PST) From: "Ritesh Harjani (IBM)" To: linuxppc-dev@lists.ozlabs.org Cc: Madhavan Srinivasan , Venkat Rao Bagalkote , linux-kernel@vger.kernel.org, chleroy@kernel.org, Michael Ellerman , Nicholas Piggin , kvm@vger.kernel.org, Anushree Mathur , Harsh Prateek Bora , "Ritesh Harjani (IBM)" Subject: [PATCHv3 3/7] KVM: PPC: BookE: Don't call __ffs() on an empty pending_exceptions bitmap Date: Sun, 1 Nov 2026 20:58:08 +0530 Message-Id: <9d5d92e93197ea43468312c82417b2f24159cca6.1793546707.git.ritesh.list@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit kvmppc_core_check_exceptions() has the same pattern as the Book3S code: it starts the scan of the pending exception bitmap with __ffs(*pending) and is called from kvmppc_core_prepare_to_enter() on every guest entry, so it routinely passes 0 to __ffs(), which is undefined. To be safe here, let's use find_first_bit(), which returns the bitmap size when no bit is set. Signed-off-by: Ritesh Harjani (IBM) --- arch/powerpc/kvm/booke.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 13ad4cf5fa71..9794ee6f7204 100644 --- a/arch/powerpc/kvm/booke.c +++ b/arch/powerpc/kvm/booke.c @@ -692,7 +692,7 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu *vcpu) unsigned long *pending = &vcpu->arch.pending_exceptions; unsigned int priority; - priority = __ffs(*pending); + priority = find_first_bit(pending, BITS_PER_BYTE * sizeof(*pending)); while (priority < BOOKE_IRQPRIO_MAX) { if (kvmppc_booke_irqprio_deliver(vcpu, priority)) break; -- 2.39.5