From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 B422E1AB6CD for ; Mon, 11 Nov 2024 18:56:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731351363; cv=none; b=lAXot3kQcoRv5u96e463dTpDXHxzSH6MLLplyMI5xQZRClGBjCha/5ipopElzdu557BUcpNQzzbLe0Xzn1GOEd2x5SY91hn51st85V9xKSrVEvoRw07OYsJvhqPabnGn1dGJBdApP7LoOAX/W361SBJjwpMAVjD0alEG1ol8usE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731351363; c=relaxed/simple; bh=IzlA191a9sOuuFmY6lyNEPM6Jabl7789VNit+P8V6po=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=DP7c2XNEgV7S2UQTFplTctNK8BeJj8FKEWR8+66NszNSMfLHpo7cM/IFwhbdLt9HYV+Gj8RR7+OhbntJbQQBgoRyi5t9vkhV3j76iKnYVeBHLoJ1wx5edekdoSyYpfaINY7pyhbflNmlEz2jor6b0W6M8G5apYxvYG56Cos8ZkU= 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=O2AZ9Adi; arc=none smtp.client-ip=209.85.216.74 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="O2AZ9Adi" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2e2ca4fb175so5050924a91.3 for ; Mon, 11 Nov 2024 10:56:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1731351361; x=1731956161; 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=enwYhWXEIuiTV/4/95gHLx0rhJypDLeqYQRs0TBOSwI=; b=O2AZ9Adi5KpMW7TjB8YDFuQqrTeASg0eoPMlYTKGQyPwmEOIUKPdhWTFgKSEhJQ3n3 utRVC+gynAewU3E0bO7uynlVId/MgDp7WARdcE8SISlkRBMIlRN4ArfqAS03zs0h/sZx dLHSeDkDwNWXHYNaP66UFRfb4KFDsDfeRqA2sFlP8tsBw0DKCPQVdM+YDUD6VDvE35Vg u49J0zLk4u9OOlWRwMXth0rX2jjo2IV2ixZwWVRDm9/GgRZRGArrenEmbBtbVI8Qb5mL gc9EItbr5Cp9pnFYS/iAMPSCBQ80C+dV6xjYnwhAD/aaCM3PFCSpaePZAlGaqpiG1cZS aIFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1731351361; x=1731956161; 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=enwYhWXEIuiTV/4/95gHLx0rhJypDLeqYQRs0TBOSwI=; b=A5sDg2wPXfBYwZqdDs/B9u/7f55XqkverQRYOLEVQ+y/c8XF8wHQGUYE5mLBqDTZ5G RHUGLZg9Xuug6WMDrw/9zdyUCrFVFSnI0PF54AGwuso2Cx1LIdRCFWfutd5NP0MoD+cD V4JUzduKwwb8o7lrA3T+7MKJ7cWblHhhX1eDFavUdE9hm9zHRvvCx+3fbJo5NdM8ZG4O 9r4h4ORikp3RMoTSAfcjU9NdDAP4wlZY+4XGsa0uIxT6xpcCaSNU68inOGQvC0mF2nGs 4Q34YtFLvS0vQxgFAz9yyTGUsgxbTUem23N4OA8cYXW/SOmGQyZLr+Ke5OM/AJ4iBQSZ Wq0Q== X-Forwarded-Encrypted: i=1; AJvYcCWwoy6i7F/sVjT/2y+EmvCLvla0lgW/B810TlUa+7PMyJSKUbx6ZIsINuzmF/v4atiwGS0=@vger.kernel.org X-Gm-Message-State: AOJu0Yy2uU7f19bIzNIrs1LfJfzn8sG8PPBZ/juDRYZhy8JMYljxs3J+ aw38OO/yaWnjSVC8XQmW29b79ayX7ui9FnVrxd+K/nJX+p91hUULJPaJU4UGef2w0iScyxHvhnX b/w== X-Google-Smtp-Source: AGHT+IEh6ifB12+o7Taest8u41nLOGFUh/dt/hht3n4wmwT2C1a8L6d290cW+MnMzxatdYpxjKvvorfGs1M= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:9d:3983:ac13:c240]) (user=seanjc job=sendgmr) by 2002:a17:90b:5103:b0:2e2:da81:40c1 with SMTP id 98e67ed59e1d1-2e9e4aaa353mr28a91.1.1731351360398; Mon, 11 Nov 2024 10:56:00 -0800 (PST) Date: Mon, 11 Nov 2024 10:55:59 -0800 In-Reply-To: <20241111183935.8550-1-advaitdhamorikar@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241111183935.8550-1-advaitdhamorikar@gmail.com> Message-ID: Subject: Re: [PATCH-next] KVM: x86/tdp_mmu: Fix redundant u16 compared to 0 From: Sean Christopherson To: Advait Dhamorikar Cc: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, anupnewsmail@gmail.com Content-Type: text/plain; charset="us-ascii" On Tue, Nov 12, 2024, Advait Dhamorikar wrote: > An unsigned value can never be negative, > so this test will always evaluate the same way. > `_as_id` a u16 is compared to 0. Please wrap changelogs at ~75 characters. > Signed-off-by: Advait Dhamorikar > --- > arch/x86/kvm/mmu/tdp_mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 4508d868f1cd..b4e7b6a264d6 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -153,7 +153,7 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, > for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \ > ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ > _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \ > - if (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) { \ > + if (kvm_mmu_page_as_id(_root) != _as_id) { \ NAK, the comparison is necessary as kvm_tdp_mmu_zap_leafs() deliberately invokes for_each_valid_tdp_mmu_root_yield_safe() => __for_each_tdp_mmu_root_yield_safe() with -1 to iterate over all address spaces. And I don't want to drop the check for __for_each_tdp_mmu_root(), even though there aren't any _current_ users that pass -1, as I want to keep the iterators symmetrical.