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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9509C38A2D for ; Mon, 24 Oct 2022 20:10:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233098AbiJXUKt (ORCPT ); Mon, 24 Oct 2022 16:10:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231968AbiJXUIh (ORCPT ); Mon, 24 Oct 2022 16:08:37 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96B0D8E79A; Mon, 24 Oct 2022 11:28:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=R2CozcFHwiChhVIqs9e1K7KGsaZbKqtzxGeJtPv9o4I=; b=kIseVJ2df1bajoZTbCM6NTSzk3 aAMcxXbtdOSJSoQJcJ5AwEtJfcHjIKlO54CzW1473JnXWY+4pbRjbCnbhZkHDnFMSYQI16SHsQ0Un C5HUIGuZI3Vj+yi1EJ73edNhXPpC7mWC/77d38X96cylJ45BjMRtPVupLNQ3MekhFWX1tMFRA/mik PidTxoEXuf4sxtY10c52U0iGpLcR889au95SDPugZ9kZ9aGB1BmsNG/p1Y3hezN49AE1g7PlzKIz6 fBFxfL+yAc8Z7lM8uL8Nrf82mLnCBBDMeXHT7NPasxJeFoithuIP6hPw4h5SOmwzH9LS46qQFYM9e zw2/RcCw==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1on1Hd-002Ta1-SO; Mon, 24 Oct 2022 17:30:41 +0000 Date: Mon, 24 Oct 2022 10:30:41 -0700 From: Christoph Hellwig To: Sreekanth Reddy Cc: Bart Van Assche , Salvatore Bonaccorso , "James E.J. Bottomley" , sathya.prakash@broadcom.com, suganath-prabu.subramani@broadcom.com, "Martin K. Petersen" , MPT-FusionLinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, adi@kriegisch.at Subject: Re: Report in downstream Debian: mpt3sas broken with xen dom0 with update to 5.10.149 in 5.10.y. Message-ID: References: <85ad4508-b979-c792-e92b-01bc16260dec@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 24, 2022 at 05:26:44PM +0530, Sreekanth Reddy wrote: > This issue is getting observed after having the below patch changes, > 2b9aba0c5d58e141e32bb1bb4c7cd91d19f075b8 scsi: mpt3sas: Fix return > value check of dma_get_required_mask() Looking at this commit it seems odd. dma_get_required_mask() should only be used as an optimization for hardware that actually benefits from a lower DMA Mask. That means either classic PCI that requires DAC cycles, or firmware architectures like aic7xxx that do need additional overhead. I don't think either is the case for mpt3sas, so I think (in addition to fixing up the Xen required mask), mpt3sas should do something like: diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c index 4e981ccaac4163..295942a8989780 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_base.c +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c @@ -2992,8 +2992,7 @@ _base_config_dma_addressing(struct MPT3SAS_ADAPTER *ioc, struct pci_dev *pdev) struct sysinfo s; u64 coherent_dma_mask, dma_mask; - if (ioc->is_mcpu_endpoint || sizeof(dma_addr_t) == 4 || - dma_get_required_mask(&pdev->dev) <= DMA_BIT_MASK(32)) { + if (ioc->is_mcpu_endpoint) { ioc->dma_mask = 32; coherent_dma_mask = dma_mask = DMA_BIT_MASK(32); /* Set 63 bit DMA mask for all SAS3 and SAS35 controllers */