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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8qt1IvNA0h427goTdW6RyILD07m/tG4A0536pVBT7JI=; b=gL6ARXa63kjpeUMlTS/T3O8c6 +21x0oPiKYUlAEajahmBvj5h+2Jo9pBB3JBX8qnMlX1O+mjD+SlPlfFlbYoHIqLCXGtEHizuQQNzB k3YCApBViM3yH4zig/mFUENDWnrywWcZtp5jVVM3KvAPTLa+wRCq084KiJesPAkaf0QSp7SDJg/kj qMtgfK3k2WhzwG5JoloBPCaS97CPIGSgo+pGklB1qLdwsvv2XzcmpgQJOG6WSNl+qVIO6f9oSr6g4 kj/qcga2wsu+RNflzZS3R/25wZFGIB3EFJZWRjnm8piL9x5UcI/fy43mJ7ObFizF9S89c13tyPeEU kie3ePytw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lKeHQ-00B37Z-JB; Fri, 12 Mar 2021 09:40:24 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lKeHK-00B36z-Ql for linux-arm-kernel@lists.infradead.org; Fri, 12 Mar 2021 09:40:20 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3961E64FDD; Fri, 12 Mar 2021 09:40:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615542017; bh=IhMRNUcJYwCkDReHSF76lISid/6+vJxJRq5TrqpWgk8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FttZZGnGm4GqH4u+TmUc57P5wbD6izysvvsuuknHB0t9tFFQ2cQUyxJP/LmMkMDPj pBaaPhflRrPTYmpAiwT0ngHHanDpHmZPoRs7X+JJnQ9lmsdsaUrapQE8/wHB66L3Hu aVesI5HypLmSPbqdaaWqDr25iEvI5DhjopJJ0hEA3yEeNosk9xaawcrEhTcWRKRiSJ byZmtWoB7mUSOf5wgOLjHY3cp9Q9veMVqbG3NIvjswUAA8acTGGr0x/S3V/DniQx4j 0+d4EafNVWpjsvT9E+2S9Uv0D5JTLHwiVdzh+eQOaEL5QjPeEq0Xn9UUd3EPKbRAWz EWOc5VUiGsXxg== Date: Fri, 12 Mar 2021 09:40:09 +0000 From: Will Deacon To: Quentin Perret Cc: catalin.marinas@arm.com, maz@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, android-kvm@google.com, linux-kernel@vger.kernel.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, tabba@google.com, mark.rutland@arm.com, dbrazdil@google.com, mate.toth-pal@arm.com, seanjc@google.com, robh+dt@kernel.org, ardb@kernel.org Subject: Re: [PATCH v4 30/34] KVM: arm64: Add kvm_pgtable_stage2_find_range() Message-ID: <20210312094009.GC32016@willie-the-truck> References: <20210310175751.3320106-1-qperret@google.com> <20210310175751.3320106-31-qperret@google.com> <20210311190406.GB31586@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210312_094019_253245_7F4ABB92 X-CRM114-Status: GOOD ( 19.41 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Mar 12, 2021 at 05:32:13AM +0000, Quentin Perret wrote: > On Thursday 11 Mar 2021 at 19:04:07 (+0000), Will Deacon wrote: > > On Wed, Mar 10, 2021 at 05:57:47PM +0000, Quentin Perret wrote: > > > + for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) { > > > + granule = kvm_granule_size(level); > > > + start = ALIGN_DOWN(addr, granule); > > > + end = start + granule; > > > + > > > + if (!kvm_level_support_block_mappings(level)) > > > + continue; > > > + > > > + if (start < range->start || range->end < end) > > > + continue; > > > + > > > + /* > > > + * Check the presence of existing mappings with incompatible > > > + * permissions within the current block range, and try one level > > > + * deeper if one is found. > > > + */ > > > + ret = kvm_pgtable_walk(pgt, start, granule, &check_perm_walker); > > > + if (ret != -EEXIST) > > > + break; > > > + } > > > > Can you write this as a: > > > > do { > > ... > > } while (level < KVM_PGTABLE_MAX_LEVELS && ret == -EEXIST); > > > > loop? > > I tried it but found it a little less pretty -- the pre-assignment of > level and the increment at the end make it really feel like a for loop > to me: > > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -1098,26 +1098,23 @@ int kvm_pgtable_stage2_find_range(struct kvm_pgtable *pgt, u64 addr, > return ret; > attr &= KVM_PTE_LEAF_S2_COMPAT_MASK; > > - for (level = pgt->start_level; level < KVM_PGTABLE_MAX_LEVELS; level++) { > + ret = -EEXIST; > + level = pgt->start_level; > + do { > granule = kvm_granule_size(level); > start = ALIGN_DOWN(addr, granule); > end = start + granule; > > - if (!kvm_level_support_block_mappings(level)) > - continue; > - > - if (start < range->start || range->end < end) > - continue; Urgh, yes, sorry, I hadn't appreciated what a mess it causes for these guys. Stick with the 'for' loop. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel