From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cmx-mtlrgo001.bell.net (mta-mtl-008.bell.net [209.71.208.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E43BD17A2E1; Fri, 3 Oct 2025 20:29:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.71.208.31 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759523367; cv=none; b=NP0mLiN6pWMCvjtrfaML9OSCYsDqx5umCVh0XDXeg4Lx5hBRhPpqVL6pk3BxFRegonRM2eyKo63CpBePX6jJ/6KVInkJRiEOIC1XRj5kWXaNXGlCX3AeuA7hpSLcWQYAHtPY9b/C58/bWFj1pLHD18qUx1J2vBzSdI1/zDDKNPw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759523367; c=relaxed/simple; bh=ElPDQiuadoR9C0rLZs+feEn9fL50HvihNVM98MScwDA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Tfq4qLmAGqNrEF/vyMhK5h71gAukacrg5DxMh3dOS08QKwo/db/JoQczgX5dCs6alVXqMpUbySL2SQExfSWHP4TIM4DgdOLkafSrGE/V3BZkSDQevrWd4A0AkYACUWpZpaakJKjtmHg5yqg/ognncyRJgueTwrdLWVSYCJu89rw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bell.net; spf=pass smtp.mailfrom=bell.net; dkim=pass (2048-bit key) header.d=bell.net header.i=@bell.net header.b=eun5H8An; arc=none smtp.client-ip=209.71.208.31 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bell.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bell.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bell.net header.i=@bell.net header.b="eun5H8An" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bell.net; s=selector1; t=1759523366; bh=ZSiozYL9av6/yqYZ1ojB886S7qQBNu1kIdF3OOFiSt4=; h=Message-ID:Date:MIME-Version:Subject:To:References:From:In-Reply-To:Content-Type; b=eun5H8AnrjvOmqjNaukCXTqNTml2LNruUFRZxvk3CoiWLaf+Swcd6WDi6ewqnHE6gpZeicHFL5m9AxfBVl15NyzBy7r/cSeq1xTJpmbKhKXsmYqEbVOR9t5XvaLLgqh78EqQED8S7ob1SJ1Xh2SgZRpeqLqH/mA/7KUaPRkwEmLUSsaVhEA7e8H01WLJ9jPkksPDN0Gm1whavFIrWgZQrBjgML/pew0uM06GAEr9f0Jmrb0Ptg+MzsLA2YhKRENSwv5+NgQN92MPA+wjmEUau4Qfjwit2p4P3tzq1oe/2h8C/c1UgKV7wPn+Ru9xhIP/xJyUJZK9bwD0BRobrxkHxw== X-RG-SOPHOS: Clean X-RG-VADE-SC: 0 X-RG-VADE: Clean X-RG-Env-Sender: dave.anglin@bell.net X-RG-Rigid: 68C1701503F87783 X-RazorGate-Vade: 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 X-RazorGate-Vade-Verdict: clean 0 X-RazorGate-Vade-Classification: clean Received: from [192.168.2.49] (142.126.189.246) by cmx-mtlrgo001.bell.net (authenticated as dave.anglin@bell.net) id 68C1701503F87783; Fri, 3 Oct 2025 16:28:45 -0400 Message-ID: <45e1dff3-aff1-4a41-ab24-6eddf6171e3a@bell.net> Date: Fri, 3 Oct 2025 16:28:45 -0400 Precedence: bulk X-Mailing-List: linux-alpha@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 3/9] parisc: Convert DMA map_page to map_phys interface To: Jason Gunthorpe Cc: Leon Romanovsky , Marek Szyprowski , Leon Romanovsky , Andreas Larsson , Borislav Petkov , Dave Hansen , "David S. Miller" , Geoff Levand , Helge Deller , Ingo Molnar , iommu@lists.linux.dev, "James E.J. Bottomley" , Jason Wang , Juergen Gross , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Madhavan Srinivasan , Matt Turner , Michael Ellerman , "Michael S. Tsirkin" , Richard Henderson , sparclinux@vger.kernel.org, Stefano Stabellini , Thomas Bogendoerfer , Thomas Gleixner , virtualization@lists.linux.dev, x86@kernel.org, xen-devel@lists.xenproject.org, Magnus Lindholm References: <333ec4dabec16d3d913a93780bc6e7ddb5240fcf.1759071169.git.leon@kernel.org> <20251003150144.GC3360665@nvidia.com> <610b10bc-1aa2-4fad-a40b-be5fcfa04430@bell.net> <20251003172618.GJ3360665@nvidia.com> From: John David Anglin Content-Language: en-US Autocrypt: addr=dave.anglin@bell.net; keydata= xsFNBFJfN1MBEACxBrfJ+5RdCO+UQOUARQLSsnVewkvmNlJRgykqJkkI5BjO2hhScE+MHoTK MoAeKwoLfBwltwoohH5RKxDSAIWajTY5BtkJBT23y0hm37fN2JXHGS4PwwgHTSz63cu5N1MK n8DZ3xbXFmqKtyaWRwdA40dy11UfI4xzX/qWR3llW5lp6ERdsDDGHm5u/xwXdjrAilPDk/av d9WmA4s7TvM/DY3/GCJyNp0aJPcLShU2+1JgBxC6NO6oImVwW07Ico89ETcyaQtlXuGeXYTK UoKdEHQsRf669vwcV5XbmQ6qhur7QYTlOOIdDT+8zmBSlqBLLe09soATDciJnyyXDO1Nf/hZ gcI3lFX86i8Fm7lQvp2oM5tLsODZUTWVT1qAFkHCOJknVwqRZ8MfOvaTE7L9hzQ9QKgIKrSE FRgf+gs1t1vQMRHkIxVWb730C0TGiMGNn2oRUV5O5QEdb/tnH0Te1l+hX540adKZ8/CWzzW9 vcx+qD9IWLRyZMsM9JnmAIvYv06+YIcdpbRYOngWPd2BqvktzIs9mC4n9oU6WmUhBIaGOGnt t/49bTRtJznqm/lgqxtE2NliJN79dbZJuJWe5HkjVa7mP4xtsG59Rh2hat9ByUfROOfoZ0dS sVHF/N6NLWcf44trK9HZdT/wUeftEWtMV9WqxIwsA4cgSHFR2QARAQABzTdKb2huIERhdmlk IEFuZ2xpbiAoRGViaWFuIFBvcnRzKSA8ZGF2ZS5hbmdsaW5AYmVsbC5uZXQ+wsF3BBMBCAAh BQJSXzdTAhsDBQsJCAcDBRUKCQgLBRYCAwEAAh4BAheAAAoJEF2/za5fGU3xs/4P/15sNizR ukZLNYoeGAd6keRtNcEcVGEpRgzc/WYlXCRTEjRknMvmCu9z13z8qB9Y9N4JrPdp+NQj5HEs ODPI+1w1Mjj9R2VZ1v7suFwhjxMTUQUjCsgna1H+zW/UFsrL5ERX2G3aUKlVdYmSWapeGeFL xSMPzawPEDsbWzBzYLSHUOZexMAxoJYWnpN9JceEcGvK1SU2AaGkhomFoPfEf7Ql1u3Pgzie ClWEr2QHl+Ku1xW0qx5OLKHxntaQiu30wKHBcsF0Zx2uVGYoINJl/syazfZyKTdbmJnEYyNa Bdbn7B8jIkVCShLOWJ8AQGX/XiOoL/oE9pSZ60+MBO9qd18TGYByj0X2PvH+OyQGul5zYM7Q 7lT97PEzh8xnib49zJVVrKDdJds/rxFwkcHdeppRkxJH0+4T0GnU2IZsEkvpRQNJAEDmEE8n uRfssr7RudZQQwaBugUGaoouVyFxzCxdpSYL6zWHA51VojvJYEBQDuFNlUCqet9LtNlLKx2z CAKmUPTaDwPcS3uOywOW7WZrAGva1kz9lzxZ+GAwgh38HAFqQT8DQvW8jnBBG4m4q7lbaum3 znERv7kcfKWoWS7fzxLNTIitrbpYA3E7Zl9D2pDV3v55ZQcO/M35K9teRo6glrtFDU/HXM+r ABbh8u9UnADbPmJr9nb7J0tZUSS/zsFNBFJfN1MBEADBzhVn4XyGkPAaFbLPcMUfwcIgvvPF UsLi9Q53H/F00cf7BkMY40gLEXvsvdUjAFyfas6z89gzVoTUx3HXkJTIDTiPuUc1TOdUpGYP hlftgU+UqW5O8MMvKM8gx5qn64DU0UFcS+7/CQrKOJmzktr/72g98nVznf5VGysa44cgYeoA v1HuEoqGO9taA3Io1KcGrzr9cAZtlpwj/tcUJlc6H5mqPHn2EdWYmJeGvNnFtxd0qJDmxp5e YVe4HFNjUwsb3oJekIUopDksAP41RRV0FM/2XaPatkNlTZR2krIVq2YNr0dMU8MbMPxGHnI9 b0GUI+T/EZYeFsbx3eRqjv1rnNg2A6kPRQpn8dN3BKhTR5CA7E/cs+4kTmV76aHpW8m/NmTc t7KNrkMKfi+luhU2P/sKh7Xqfbcs7txOWB2V4/sbco00PPxWr20JCA5hYidaKGyQxuXdPUlQ Qja4WJFnAtBhh3Oajgwhbvd6S79tz1acjNXZ89b8IN7yDm9sQ+4LhWoUQhB5EEUUUVQTrzYS yTGN1YTTO5IUU5UJHb5WGMnSPLLArASctOE01/FYnnOGeU+GFIeQp91p+Jhd07hUr6KWYeJY OgEmu+K8SyjfggCWdo8aGy0H3Yr0YzaHeK2HrfC3eZcUuo+yDW3tnrNwM1rd1i3F3+zJK18q GnBxEQARAQABwsFfBBgBCAAJBQJSXzdTAhsMAAoJEF2/za5fGU3xNDQP/ikzh1NK/UBrWtpN yXLbype4k5/zyQd9FIBxAOYEOogfKdkp+Yc66qNf36gO6vsokxsDXU9me1n8tFoB/DCdzKbQ /RjKQRMNNR4fT2Q9XV6GZYSL/P2A1wzDW06tEI+u+1dV40ciQULQ3ZH4idBW3LdN+nloQf/C qoYkOf4WoLyhSzW7xdNPZqiJCAdcz9djN79FOz8US+waBCJrL6q5dFSvvsYj6PoPJkCgXhiJ hI91/ERMuK9oA1oaBxCvuObBPiFlBDNXZCwmUk6qzLDjfZ3wdiZCxc5g7d2e2taBZw/MsKFc k+m6bN5+Hi1lkmZEP0L4MD6zcPuOjHmYYzX4XfQ61lQ8c4ztXp5cKkrvaMuN/bD57HJ6Y73Q Y+wVxs9x7srl4iRnbulCeiSOAqHmwBAoWaolthqe7EYL4d2+CjPCcfIuK7ezsEm8c3o3EqC4 /UpL1nTi0rknRTGc0VmPef+IqQUj33GGj5JRzVJZPnYyCx8sCb35Lhs6X8ggpsafUkuKrH76 XV2KRzaE359RgbM3pNEViXp3NclPYmeu+XI8Ls/y6tSq5e/o/egktdyJj+xvAj9ZS18b10Jp e67qK8wZC/+N7LGON05VcLrdZ+FXuEEojJWbabF6rJGN5X/UlH5OowVFEMhD9s31tciAvBwy T70V9SSrl2hiw38vRzsl In-Reply-To: <20251003172618.GJ3360665@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2025-10-03 1:26 p.m., Jason Gunthorpe wrote: > On Fri, Oct 03, 2025 at 01:18:32PM -0400, John David Anglin wrote: >> On 2025-10-03 11:01 a.m., Jason Gunthorpe wrote: >>> This doesn't actually use the virt at all: >>> >>> offset = ((unsigned long) addr) & ~IOVP_MASK; >>> if((size % L1_CACHE_BYTES) || ((unsigned long)addr % L1_CACHE_BYTES)) >>> ccio_io_pdir_entry(pdir_start, KERNEL_SPACE, (unsigned long)addr, hint); >>> >>> And ccio_io_pdir_entry(): >>> pa = lpa(vba); >>> >>> Is a special instruction that uses virt but AI tells me that special >>> LPA instruction is returning phys. Not sure if that is a different >>> value than virt_to_phys().. >> >> ccio_io_pdir_entry currently only supports KERNEL_SPACE. For KERNEL_SPACE, lpa() and >> virt_to_phys() are equivalent if page is mapped. lpa() returns 0 if a non-access data >> TLB fault occurs (i.e., page isn't mapped). Not sure if that >> matters. > > After unfolding everything the expression is > > lpa(phys_to_virt(pa)) > > So if that is always equal to pa then lets just drop it. If lpa() was replaced by virt_to_phys(), the result would always be equal to pa. So, I think it can be dropped. Dave -- John David Anglin dave.anglin@bell.net