From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 0DAF9261390 for ; Wed, 25 Jun 2025 12:53:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750856009; cv=none; b=mOY26UxIXFhQIv2zt/AtpHckEPQKwpyTcAN50e653PTh31dx7jmo5Moh2Kggq661jONwEFe/ttTYAkPVAlGT+3F2v28bLYtP2+h+GdaHChciBButarzwh3qIGwd4N2E/er/agmhN0vP4OC1x1UBeXu1RqDLboPd9AjtGeQdBAeU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750856009; c=relaxed/simple; bh=LyYQDcnXmGsVu73bpfzmTVDLBrEXLKs1lCcXT5WkdYU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ErfXmfHTdH1PGaGrZKAx0k+b2LXa3zZPepVKZgFmXk7KcnjB6sug5b8e90MUMrrrnm/oLyaUkHv7vIwP77EUDTwBtFSyu+B1SkR5zMhUngiIEOxYKqFOomFaeo7Fm+mINiV5dxpHcZh5XncZVtpUR0zloVsiyAy01oiC/QtBjlc= 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=OxtAGA5L; arc=none smtp.client-ip=209.85.214.201 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="OxtAGA5L" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2356ce55d33so25785695ad.0 for ; Wed, 25 Jun 2025 05:53:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1750856007; x=1751460807; 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=Qm9UdCmx0AUjdXCDjy0dtaSU1yfF/6cv13NPsG0xoPg=; b=OxtAGA5LpfPL2vRuPmjdvZ7zVnn59HhhsUiL8FIsXqJRLO9Cc5nrrTiy6F4g92OxJa zVPdPo0f1m5O4Ix5vHfhg2brORVyqSNuRdtOd0zFMedqOpFo+yLRuVZIkUPKZSgpFLUX 9aUQs75xPjeBX+95fV1qwEYZ0KuuieKZ/m1u0pecY419oQM+rdi65CQlA9XtvLiuyGkU H5Wtf9iLyjxLK9ZwPw8PFQAgIqOUqJjUowa9iFHaMcyfDFqrUo9KyEe7FojwSetAxYPX HRXxKA7vxeFSiFIJPQtfvM+z8BnT1eBVidaKnHYwBs72SVHVJEQbzaDYSXHOTOTSmRl0 9Q7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750856007; x=1751460807; 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=Qm9UdCmx0AUjdXCDjy0dtaSU1yfF/6cv13NPsG0xoPg=; b=ViirWEfi83gY1p9ZPdUqMfRvEURAJnBbYBhgn0Ppx4+9mxW9neE2OnxSV5kv0aaiOd cBI22XqO9qHER7GQqnSB89Q9b3SPQBw4I4VHONqWRIpSBWVQPfnFZl0S1iMNQaoWnk1J +Ps0CCF2J0kbiXKpNP2CLF6lYMwVn5JEejnPWEp8H0PyqtvsFS+YzxQKNHs6F/LIMdpm 0JD2p/0l5FeCHAEz+psSeCW5tyyWcI6huQrY6Bjylq4blF5lMvRisVF3WkQxtkBhhVLH DNgYGXukVbokNosTNgTDg9rhMEGshLClng2mWZMNrlWO5fyrYuwyQyBKzavd0ZBvXbz2 1akQ== X-Gm-Message-State: AOJu0Yzu2QT9U4iHkI1IANX4cDA1gHzk3hflZz2/uFcX9Pcgkz1CETpy WLF9rDwESfNvzklmZTc/l7t61523KftDTug74hoY/UcTvSrIoibO9WF6Ph0j1KjzXywQmrtHUGl EKe6xpw== X-Google-Smtp-Source: AGHT+IFkzNNA6kVoA+2D6FAE4AOHOnEwMQn/97TNwefolAE17lsZ+t6y3XTUeyFLF/Yx7w++6g2MSRnkPqg= X-Received: from plbmv13.prod.google.com ([2002:a17:903:b8d:b0:235:54f:4f12]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:2bcc:b0:235:5a9:976f with SMTP id d9443c01a7336-23824030ccdmr68655075ad.24.1750856007263; Wed, 25 Jun 2025 05:53:27 -0700 (PDT) Date: Wed, 25 Jun 2025 05:53:25 -0700 In-Reply-To: <20250610175424.209796-2-Neeraj.Upadhyay@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250610175424.209796-1-Neeraj.Upadhyay@amd.com> <20250610175424.209796-2-Neeraj.Upadhyay@amd.com> Message-ID: Subject: Re: [RFC PATCH v7 01/37] KVM: lapic: Remove __apic_test_and_{set|clear}_vector() From: Sean Christopherson To: Neeraj Upadhyay Cc: linux-kernel@vger.kernel.org, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, Thomas.Lendacky@amd.com, nikunj@amd.com, Santosh.Shukla@amd.com, Vasant.Hegde@amd.com, Suravee.Suthikulpanit@amd.com, David.Kaplan@amd.com, x86@kernel.org, hpa@zytor.com, peterz@infradead.org, pbonzini@redhat.com, kvm@vger.kernel.org, kirill.shutemov@linux.intel.com, huibo.wang@amd.com, naveen.rao@amd.com, francescolavra.fl@gmail.com, tiala@microsoft.com Content-Type: text/plain; charset="us-ascii" "KVM: x86:" for the scope. That goes for all of the relevant shortlogs. And for this one in particular, maybe something like: KVM: x86: Open code setting/clearing of bits in the ISR because seeing "Remove" in the shortlog reads like it's a straight deletion of code. On Tue, Jun 10, 2025, Neeraj Upadhyay wrote: > Remove __apic_test_and_set_vector() and __apic_test_and_clear_vector(), > because the _only_ register that's safe to modify with a non-atomic > operation is ISR, because KVM isn't running the vCPU, i.e. hardware can't > service an IRQ or process an EOI for the relevant (virtual) APIC. > > No functional change intended. > > Suggested-by: Sean Christopherson > [Neeraj: Add "inline" for apic_vector_to_isr()] > Signed-off-by: Neeraj Upadhyay > --- > Changes since v6: > > - New change. > > arch/x86/kvm/lapic.c | 19 +++++++------------ > 1 file changed, 7 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 73418dc0ebb2..11e57f351ce5 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -125,16 +125,6 @@ bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector) > apic_test_vector(vector, apic->regs + APIC_IRR); > } > > -static inline int __apic_test_and_set_vector(int vec, void *bitmap) > -{ > - return __test_and_set_bit(VEC_POS(vec), (bitmap) + REG_POS(vec)); > -} > - > -static inline int __apic_test_and_clear_vector(int vec, void *bitmap) > -{ > - return __test_and_clear_bit(VEC_POS(vec), (bitmap) + REG_POS(vec)); > -} > - > __read_mostly DEFINE_STATIC_KEY_FALSE(kvm_has_noapic_vcpu); > EXPORT_SYMBOL_GPL(kvm_has_noapic_vcpu); > > @@ -744,9 +734,14 @@ void kvm_apic_clear_irr(struct kvm_vcpu *vcpu, int vec) > } > EXPORT_SYMBOL_GPL(kvm_apic_clear_irr); > > +static inline void *apic_vector_to_isr(int vec, struct kvm_lapic *apic) Do not use "inline" for functions that are visible only to the local compilation unit. "inline" is just a hint, and modern compilers are smart enough to inline functions when appropriate without a hint. A longer explanation/rant here: https://lore.kernel.org/all/ZAdfX+S323JVWNZC@google.com Ignoring the existing code below, there's lots of crusty old code in KVM (that isn't "bad" per se, i.e. isn't worth fixing unless a prime opportunity arises). > +{ > + return apic->regs + APIC_ISR + REG_POS(vec); > +} > + > static inline void apic_set_isr(int vec, struct kvm_lapic *apic) > { > - if (__apic_test_and_set_vector(vec, apic->regs + APIC_ISR)) > + if (__test_and_set_bit(VEC_POS(vec), apic_vector_to_isr(vec, apic))) > return; > > /* > @@ -789,7 +784,7 @@ static inline int apic_find_highest_isr(struct kvm_lapic *apic) > > static inline void apic_clear_isr(int vec, struct kvm_lapic *apic) > { > - if (!__apic_test_and_clear_vector(vec, apic->regs + APIC_ISR)) > + if (!__test_and_clear_bit(VEC_POS(vec), apic_vector_to_isr(vec, apic))) > return; > > /* > -- > 2.34.1 >