From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31C0C223DC1 for ; Wed, 14 May 2025 23:21:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747264880; cv=none; b=h2Y1VWkT1qgG5YQ7+yAiCAJ3y0Z1FEFsyr40V4+gH5svrHGhWtmCOM0wWy/hHAC7InWz/pKnP2MUrU8uKVkb+RylPBCc9iexy0qZNK8aZRQyl6fmL+XhEwDCaKU1Mz++JCOxOTNZTMn66FrfcKaYy4xZEgmC7sI9nMEnOZaPoJ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747264880; c=relaxed/simple; bh=YEKXLYRf3Z91CVsnsWfdQ9wfCYW5gqK6f8e442q5Hiw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=dzJO3RWK9NUbQE6e3icys8cxAYeOvs6qfbKrx4so3sJ+B1w9Q8YWf0uqvim2q0csndRYDdC1o1UuaAV8V5QmHxoJhSovIdHlTyn/VIX3pgAeNSH0T5Rxd42XHnk4nOkpoCquWjAXexJrwfonjF5TjUEMQCI21NtPDd0UTqDXzq0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=xd7F1Oye; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="xd7F1Oye" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-b26cdc70befso159094a12.1 for ; Wed, 14 May 2025 16:21:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1747264878; x=1747869678; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0W5oRAU5Tx1bBNWhYqi9a+fsUdga8B/qghEhaqvlHzU=; b=xd7F1OyehJBJvB2ccUvc1pKbtQVY5d09+V8IxScIfm8ZLwDX9UjVOD56BcsIxCzNzn rOyIJsHArhieQweztEahZnvtMw/USUgm+zMrAaFzNUbNARnmgoiSfn0FNt3M7WU8WyUj m2itZn6ay/9gZwfo5OTyWFLWgI1rGPzRndG2NK8orSxQCGnavft5U0RgLQTOMRn64+8e LYmDrkJNfgyeIi42TES2rhHKsPnDzsVosuz/GhQ7KPWfa0UcSz/cXSB2LlL+z6Ua4/EZ KxiBo+q+aCJKIBGZkpU8dtKGBEl0Eetv3/wIEvqA85lixJW4B3dD6oNqCCNm7iVoupP8 O+Zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747264878; x=1747869678; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=0W5oRAU5Tx1bBNWhYqi9a+fsUdga8B/qghEhaqvlHzU=; b=WD78POxGNwyFyOHj93zHQA/5wGNcyf1TyfHJ/DJvqMNyuodlJ7wFN0GNkUFV5cKasI 9h4vjo5sSSQ3yj8mVU+UdoBKNSeJFCpSCWexpZr5Rmsl5EuojC8sseVCb3o0T21DHuvJ njtm2tBB97xiea4H595LRJXprv5LVm9uSfu6S8w/qUHoyuAYtY2ZUbQVjUdZqs65KJ7b l/QEsRvSLrB1mk/lXA1XS42wGIQ5vKRhPzN+bnSnde0jBUAqC0THC/xc9kUtvRW+wFlb jEX3ks5hCfkJAjylaO28FsB0GscPEuN97wnyQirk+WniQr5EWCrQqffJeOWQJL9c7r2b F95Q== X-Forwarded-Encrypted: i=1; AJvYcCWOH4CpNsCk7rcaTz8qKUoKav3M5DaxQfrAUsOv30Gttg+xsM4i6CqG4gzQNeJ00QpPol7+YJwA1iJdSmA=@vger.kernel.org X-Gm-Message-State: AOJu0Yzf0vBzDvqg7d+zOHbFrJPrC4dRLBNhjMwO4Ct8btHb0LW2ECY7 68uQ+/xhN4dm1AJCrncYyRNCGE4jpxjyMfloRWXVHMYveOmfE1UHLZtT3em1WLN1zVfClqIH2mo U7Q== X-Google-Smtp-Source: AGHT+IGTO73AIKyjnTSCUICJ5vVeiHlgCc/yVjvzHrQyDqfhwzwnQP3wljVXsvhihVqXHqt1ySm+522Vois= X-Received: from pjuj4.prod.google.com ([2002:a17:90a:d004:b0:2ff:852c:ceb8]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:564d:b0:2ef:31a9:95c6 with SMTP id 98e67ed59e1d1-30e2e5c3177mr9009619a91.14.1747264878446; Wed, 14 May 2025 16:21:18 -0700 (PDT) Date: Wed, 14 May 2025 16:21:16 -0700 In-Reply-To: <20250324173121.1275209-7-mizhang@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250324173121.1275209-1-mizhang@google.com> <20250324173121.1275209-7-mizhang@google.com> Message-ID: Subject: Re: [PATCH v4 06/38] x86/irq: Factor out common code for installing kvm irq handler From: Sean Christopherson To: Mingwei Zhang Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Paolo Bonzini , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Liang@google.com, Kan , "H. Peter Anvin" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Yongwei Ma , Xiong Zhang , Dapeng Mi , Jim Mattson , Sandipan Das , Zide Chen , Eranian Stephane , Shukla Manali , Nikunj Dadhania Content-Type: text/plain; charset="us-ascii" On Mon, Mar 24, 2025, Mingwei Zhang wrote: > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > index 385e3a5fc304..18cd418fe106 100644 > --- a/arch/x86/kernel/irq.c > +++ b/arch/x86/kernel/irq.c > @@ -312,16 +312,22 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_x86_platform_ipi) > static void dummy_handler(void) {} > static void (*kvm_posted_intr_wakeup_handler)(void) = dummy_handler; > > -void kvm_set_posted_intr_wakeup_handler(void (*handler)(void)) > +void x86_set_kvm_irq_handler(u8 vector, void (*handler)(void)) > { > - if (handler) > + if (!handler) > + handler = dummy_handler; > + > + if (vector == POSTED_INTR_WAKEUP_VECTOR && > + (handler == dummy_handler || > + kvm_posted_intr_wakeup_handler == dummy_handler)) > kvm_posted_intr_wakeup_handler = handler; > - else { > - kvm_posted_intr_wakeup_handler = dummy_handler; > + else > + WARN_ON_ONCE(1); > + > + if (handler == dummy_handler) Eww. Aside from the fact that the dummy_handler implementation is pointless overhead, I don't think KVM should own the IRQ vector. Given that perf owns the LVTPC, i.e. responsible for switching between NMI and the medited PMI IRQ, I think perf should also own the vector. KVM can then use the existing perf guest callbacks to wire up its PMI handler. And with that, this patch can be dropped.