From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AA4A0CAC587 for ; Thu, 11 Sep 2025 18:27:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1PEqqMkQCCsIIK80US5++EkJbtoh1psej63veCBFsh0=; b=mIebumGSpcao1b1NJCmJ3WcIEy 06s2CZkFEbEncUmtV0T0E+ZOUt1nZw1rweYeHbrXCPy2Gbs58uke8DGCs5AXqFIbV1A67RWd3Wt4q YFrrLcJ1TliP/LY/XdTxVXWdbR/4TSCGmDlfh9mj+XWw2UvDBYdW/302N7IWHkusMT+PcOWM5VEca RUwx+7a5+H3/QkuagxEDdEFT7nVcLtg34WSLPBjaOfXvuYIH2rx3/S1wRmJ6R8lhh2BR1S9qz25gl SJbhSRMdMlsXIcdatnupw0taPT7z7Kg1aXTXIV1VvW67V7A9rdviF6yQ4ZheNW1cHE5pjW5t7tweU g9IWNhiQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwm1H-00000004jLf-0b3E; Thu, 11 Sep 2025 18:27:43 +0000 Received: from out-189.mta1.migadu.com ([95.215.58.189]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwm1E-00000004jK4-2a9e for linux-arm-kernel@lists.infradead.org; Thu, 11 Sep 2025 18:27:42 +0000 Date: Thu, 11 Sep 2025 11:27:23 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757615256; 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=1PEqqMkQCCsIIK80US5++EkJbtoh1psej63veCBFsh0=; b=m66MoVbHAakOQHxhknbRV0aEtrzLIl0zCY5MZnXw/n2GB/8mMD2z8KI6sr7j6Zg2VMz5fZ LrEYbqoS2fE1sJyLz+JwXmPOOsVm1xe52j/yNKp+vJUnkU92KRcLd/H0qB2d1zMQk7NV3/ 0LIJakGffNrD7vjzin8Tacb4DAiuocM= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Jack Thomson Cc: maz@kernel.org, pbonzini@redhat.com, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, shuah@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, isaku.yamahata@intel.com, roypat@amazon.co.uk, kalyazin@amazon.co.uk, jackabt@amazon.com Subject: Re: [PATCH 1/6] KVM: arm64: Add __gmem_abort and __user_mem_abort Message-ID: References: <20250911134648.58945-1-jackabt.amazon@gmail.com> <20250911134648.58945-2-jackabt.amazon@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250911134648.58945-2-jackabt.amazon@gmail.com> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250911_112740_875951_ECD238BE X-CRM114-Status: UNSURE ( 8.60 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Jack, On Thu, Sep 11, 2025 at 02:46:43PM +0100, Jack Thomson wrote: > From: Jack Thomson > > Adding __gmem_abort and __user_mem_abort that preserve -EAGAIN results. > These will be used by the pre-fault implementation which needs to retry > on -EAGAIN. -EAGAIN is a pretty clear signal that another vCPU has faulted on this memory and is in the middle of installing a mapping. Why bother with retrying? If we conceptually treat this thing as a synthetic stage-2 abort then it should use the same EAGAIN handling as a literal stage-2 abort. Thanks, Oliver