From patchwork Wed Dec 11 16:01:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Miko=C5=82aj_Lenczewski?= X-Patchwork-Id: 13903717 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 DAE6DE77180 for ; Wed, 11 Dec 2024 16:10:26 +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:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iEBINFMezgkT8kFwn0hqoIa1/VcW9GASEhKC5a7WGaY=; b=lOFt3kG2ImIY5lad1siiPSnT39 BqhpI4j/Lq3E2vmdeCqGcGEfTeajTzbt2iCuf6Z/PD4qFAz3kZVJmW6TolPdjBlJKeuIDQcyXsbqe L5sWjmwog2G8/cveiVgSosDNKGEGMi8t9vNUve2u8SjfWxVRnwKIbkUkwRkiQDlgoeeROe51sr7SI KwhNJoqu+M9Xd2DCrjn3q6CotS8fWafghttskm7mRrhXmsIdaZp5hfWEd4bvPxZhyEbnNjxIMpI5g 5FSQUu2UOKS036bdVv/k9V3kNQy5OmHj2TUwBEpwJxSoitHDOGpoGvR8Kprn+rrX5ZCYwDyjejslw AqtlIlEQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tLPHx-0000000FOzp-2Jaw; Wed, 11 Dec 2024 16:10:13 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tLPB8-0000000FNNL-0P6P for linux-arm-kernel@lists.infradead.org; Wed, 11 Dec 2024 16:03:11 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C32071713; Wed, 11 Dec 2024 08:03:37 -0800 (PST) Received: from mazurka.cambridge.arm.com (mazurka.cambridge.arm.com [10.1.196.66]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0CF63F5A1; Wed, 11 Dec 2024 08:03:07 -0800 (PST) From: =?utf-8?q?Miko=C5=82aj_Lenczewski?= To: ryan.roberts@arm.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: =?utf-8?q?Miko=C5=82aj_Lenczewski?= , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev Subject: [RESEND RFC PATCH v1 5/5] arm64/mm: Elide tlbi in contpte_convert() under BBML2 Date: Wed, 11 Dec 2024 16:01:41 +0000 Message-ID: <20241211160218.41404-6-miko.lenczewski@arm.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20241211160218.41404-1-miko.lenczewski@arm.com> References: <20241211160218.41404-1-miko.lenczewski@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241211_080310_174217_F6FD3A06 X-CRM114-Status: UNSURE ( 9.37 ) 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 If we support BBM level 2, we can potentially avoid an intermediate TLB invalidation, as hardware is capable of managing the TLB itself in this situation. Hardware will either silently clear out the offending entry, or will take a TLB Conflict Abort Exception. Note that such aborts should not occur on Arm hardware and indeed were not seen on any of the benchmarked systems. Eliding the invalidation results in a 12% improvement on a microbenchmark which targeted the worst case of contpte_convert(), which represents an 80% reduction in the overhead of contpte_convert(). Note also that this patch is pending review to ensure that it is architecturally valid, and we are working with Arm architects to validate this patch. Signed-off-by: MikoĊ‚aj Lenczewski --- arch/arm64/mm/contpte.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c index fc927be800ee..009690770415 100644 --- a/arch/arm64/mm/contpte.c +++ b/arch/arm64/mm/contpte.c @@ -72,9 +72,6 @@ static void contpte_convert(struct mm_struct *mm, unsigned long addr, __flush_tlb_range(&vma, start_addr, addr, PAGE_SIZE, true, 3); __set_ptes(mm, start_addr, start_ptep, pte, CONT_PTES); - - if (system_supports_bbml2()) - __flush_tlb_range(&vma, start_addr, addr, PAGE_SIZE, true, 3); } void __contpte_try_fold(struct mm_struct *mm, unsigned long addr,