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 F0BA3CD4851 for ; Tue, 12 May 2026 15:11:44 +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=vWXMLSbqiyEkH0k1UKJeayzUqXsbhd23PKmYFrT067Y=; b=prhkDcY8VyQfYTrsOSkDBZYQ/K JF5fQaQ92Ctx5HTbs+tE6M/Pj8kUcUjXfBcOUhjh+/7zHvKfQCcLjk/ZujxJ/lW7tkTQWrx98Dwt4 q35sgp8YF05SrB1v2UDhq4Qs9e8LcDJfNBsMtRlUnf67JUi+LIckE8F0XyjwS03kQ4Kihs7OUJ+kl js/IK1Y3uMfM/OsWcLAcLuhzxKcwTU4KO+QGl3AL1IHuWwSJWqfegqczM/FfUT1Jl75R79o9fEK49 WQui7tpx/4KGELkxZ6/CLdN7TAHJtgSX/rxXakm7xeUX7xsFCsSOK6kAWjSh0x77VuhP3IiuM/3Bd RzgDvLUw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMolm-0000000HATn-13zQ; Tue, 12 May 2026 15:11:38 +0000 Received: from mail-qk1-x732.google.com ([2607:f8b0:4864:20::732]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wMolk-0000000HAT3-1le6 for linux-arm-kernel@lists.infradead.org; Tue, 12 May 2026 15:11:37 +0000 Received: by mail-qk1-x732.google.com with SMTP id af79cd13be357-900fa9f178dso612412385a.1 for ; Tue, 12 May 2026 08:11:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1778598695; x=1779203495; darn=lists.infradead.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=vWXMLSbqiyEkH0k1UKJeayzUqXsbhd23PKmYFrT067Y=; b=C37sB+VeIB3VyPPEiNvOq8h5ILLgh5chV0B2SosggNF1t2U8XcpzbzIW74ZFscixmN t03kPxD4UjrHZ6iuHYddQ21nMolDQcbTrcSvWBLH7LYhGvFuK0XBCmsEbp8rjfC5BFkn atQI+L8kRHvH4wBepz/Nii39mpMzLEyYSctNsBJYrft05V5RscE9jEbVEiUgVoO5/SwK aYpfFQLTTGkHDpDJB/ni2aHWltSkQieEhq/ozQqfZf0eKx64SaqyZRCxkMxtxR2smZAE a5LCpwH4SKLsdv10EUSmSQesBcKv0OsOR8jIoWsmlqppNsZHiYuKGlps57BFQT6ivQI8 EiaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778598695; x=1779203495; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vWXMLSbqiyEkH0k1UKJeayzUqXsbhd23PKmYFrT067Y=; b=DEjoyIEbS98Xfr8L49BNLtRTXKp0um77dpvJoqA7WjeriOupZrV6OC4Iwyqmn3RivR BVuJt1taylNZ9Sw/H6qHfI53l+MIcc08YpEWZPYiF+G9wQQLLBmTgWXs/0RjfWpSWwuW /UOiRzzavB6UbBPinsW/pBPj4O1U/lDM66rA1rCauKyW67yH4fdc27dOrfFUY5WmTsT/ x0D7eh/tHXDNu+wzgweN9y5ZbAyxmzOR7g2X/mjjCq6IigcU/6XdXOSf786By2yWYoz2 E/TxWblvy26ujS+XLO3t9AlFB6yKNZU9EgKv8aVd1Cl4jth5ld3u5kuukZhsBFK1SdOD v9+Q== X-Forwarded-Encrypted: i=1; AFNElJ9Vu/80Py/9XPFSf53keMkXYBxM3j0d3FJXp7iWYetrKLVeCJr/Yf71P+T770tc75bJWWiQ7HIMDgTPJdam+n/B@lists.infradead.org X-Gm-Message-State: AOJu0Yxycn2Z1RpyGZu1ESvkZLaoV4rEgoQ/V+J0SHR8iryhG3zLRfed Q7I909Mw7v0mo23blCf8liEQwj8Y55wI7+/6FhRnzSCPG2AoQeoh/xXVbWJLXQWuoSs= X-Gm-Gg: Acq92OG8HHg5xHuQvGphBjLmQpDKsAORkxFdaMGdI6lUINnG/ny5WxZdVOZQYIEul0g ORgAYLnCseCZNWpRLK6CPJt+xteC9UW7ALhzPCsLImntRqR3B9UM+c1ppBowMwy/jiLOluWwoJH NtAqQ4gY5epjo1SQBKewkeTb1LTSyNi0EFANk8eYbSev9QFpB6dRuqVV8wPHx5rM8HDBCDeGbFP t+VrPjmy9PdR5WOZH0l10edjBfJY3ZaB0R1f1k8dLLqZXx3GfugNv0e3Q85+cVcIEvehzp5+yg5 QzUjhRPL0Zmc9viyj2bj5M1DLf9N85lF/y6XEGl4XebluXMUEG4QrEf78C8rS+jpjQOKZeY0RAA 4dXtkA64PZp4KdMfpoUFhs04mkwi+55sADaZ8+PdHQ7X3bIjYopgJ65ah3lnQcMhWx7ClSR9cUg xb4bawDdE7RfimO3aDsuyXjzNj1LRBMXxUa2I/KVH6j8BNYSFP4KTR6FVhCbHobNaLiR/VDRFcM QUS3tMiFI6WHYjT X-Received: by 2002:a05:620a:c45:b0:8d6:39c0:e6a0 with SMTP id af79cd13be357-90910ffe81cmr2184465385a.54.1778598694733; Tue, 12 May 2026 08:11:34 -0700 (PDT) Received: from ziepe.ca (crbknf0213w-47-54-130-67.pppoe-dynamic.high-speed.nl.bellaliant.net. [47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-907b918cffesm1444739385a.14.2026.05.12.08.11.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2026 08:11:34 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wMolh-00000000ATo-2WZI; Tue, 12 May 2026 12:11:33 -0300 Date: Tue, 12 May 2026 12:11:33 -0300 From: Jason Gunthorpe To: Joonwon Kang Cc: robin.murphy@arm.com, Alexander.Grest@microsoft.com, amhetre@nvidia.com, baolu.lu@linux.intel.com, easwar.hariharan@linux.microsoft.com, iommu@lists.linux.dev, jacob.jun.pan@linux.intel.com, joro@8bytes.org, jpb@kernel.org, kees@kernel.org, kevin.tian@intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, nicolinc@nvidia.com, praan@google.com, smostafa@google.com, will@kernel.org Subject: Re: [PATCH RFC] iommu: Enable per-device SSID space for SVA Message-ID: <20260512151133.GD7702@ziepe.ca> References: <20260512145138.3414002-1-joonwonkang@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260512145138.3414002-1-joonwonkang@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260512_081136_461953_0B3E171D X-CRM114-Status: GOOD ( 10.94 ) 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 On Tue, May 12, 2026 at 02:51:38PM +0000, Joonwon Kang wrote: > Appreciate all your clarifications here. So, my understanding is that if > our system does not support ST64BV and ST64BV0 or if our device does not > distinguish between the posted write and the non-posted write regarding > PASID, then we can lift the use of the global PASID space. Can I say this? You should do what Robin said - just have your driver use a per-device PASID that it allocates and never use the global pasid allocator. To do this lightly re-organize the SVA code so the driver can supply its own PASID, and in this mode we wouldn't activate the ENQCMD features in the mm. Jason