From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta0.migadu.com (out-183.mta0.migadu.com [91.218.175.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 82A8A171E5F for ; Tue, 6 Aug 2024 22:59:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722985174; cv=none; b=d5t4TsvOpWSa6ZkRvr1MeYmJm0A5YoSuUlUqGKC88hfCjPzvevNfaNkGoEhspftlEq9Lr8S4IfQpuQghYzFzcD5Z1usD5mcnDYjSS5vg0iuR524kRwFIjSLZB/iVYcz5VQJHQW5sSTzx0r9D/UwpHaDy2gi+dwDKaaGO8mvlBpA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722985174; c=relaxed/simple; bh=ds9pqJh7H9fMOWP6se75ivaqlkU29QAObaWXCWyWx9M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=N8vRzIt3lDneEhySfFDbzKWCxa6k2VcDRAu7Brhf6Zv0AbeIlIIndRSCPpPZig0dXGVrcDG5iw1qnuvjv5aRk9pjTG+gbpTqY7SVQxWL86+bTZz5/eId7ptqJT25/mPiHpjBW8kXUCJy+P7RfJ70w9Ff27zhmY1/OQqiNCwGmxM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=t9OqXWrr; arc=none smtp.client-ip=91.218.175.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="t9OqXWrr" Date: Tue, 6 Aug 2024 15:59:26 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1722985170; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=czRgRDeRzLrqBrQivBvizwUbT0h+w1TNXUGWQtXg8MQ=; b=t9OqXWrr8NixYPqY6nc80jW99/6NeLrV2HCWr6yUBunDx7UPLELnjrVzzN4qoVfPhsxF6V L6OSjGitosA6JNlL/hEacVd+VrB9M1fL3dtNs6ZO646Z7Wh8G5DUU5Z+ZEnbcF90hyMc3C hjA1wKcVQKSff/vgqIJ2ORksr/t65Uc= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Sean Christopherson Cc: Marc Zyngier , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Steve Rutherford Subject: Re: [PATCH 0/2] KVM: Protect vCPU's PID with a rwlock Message-ID: References: <20240802200136.329973-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240802200136.329973-1-seanjc@google.com> X-Migadu-Flow: FLOW_OUT On Fri, Aug 02, 2024 at 01:01:34PM -0700, Sean Christopherson wrote: > Protect vcpu->pid with a rwlock instead of RCU, so that running a vCPU > with a different task doesn't require a full RCU synchronization, which > can introduce a non-trivial amount of jitter, especially on large systems. > > I've had this mini-series sitting around for ~2 years, pretty much as-is. > I could have sworn past me thought there was a flaw in using a rwlock, and > so I never posted it, but for the life of me I can't think of any issues. > > Extra eyeballs would be much appreciated. Besides the nitpicks: Acked-by: Oliver Upton -- Thanks, Oliver