From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f182.google.com (mail-qt1-f182.google.com [209.85.160.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AE99D155325 for ; Thu, 3 Oct 2024 11:16:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727954171; cv=none; b=e4Kl4EwuVF+9IJGnxDzzTPsIcb19gEKMOGt0AZhb27gwRqQ5tdX8/w99KUQKlPymR+zRsMuH4HpVZ5mITKX6zJ6BE2pA+14HmXpf8WFz8XNUi8Fvd3NABv0MLjR3brUYPuYl1qINY+Ru7t8iMjP1GoNGXpxYDSzJMHk1+leTKhU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727954171; c=relaxed/simple; bh=8rQYm6rtwxuir+ifBxd1wSN/hSb+QNtacKr43I2KIS4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Wxpi96m/JmJdroHdaDnHyeZOc52cBFHNr36tW8rvxnMSR+LKsI+rYnD1RQHpchwlfBu6AT0Y/04ipBiBph/kq0Fihtt+q/gJOfMlmNea8K6TprSNCZTg54N9rrzuXTv+6/f0bpAQl0Nc5UkO22S/k29wk3Xrjm7vSC/PwEtfUOo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=D4QMyWJx; arc=none smtp.client-ip=209.85.160.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="D4QMyWJx" Received: by mail-qt1-f182.google.com with SMTP id d75a77b69052e-458366791aaso3577391cf.1 for ; Thu, 03 Oct 2024 04:16:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1727954165; x=1728558965; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=lGLXkZTI8lFIxokzB+lI3gIzGTATKncCCeuzE20IZFs=; b=D4QMyWJxZJlNLgKrf7s2dAE7LOJGcq0jMcVk+O0MkDHTIbZD+LlsylJeSoBLKEkdod kIknEqq1W0kTDbPBs2feTZWqr6145o9MAKCpTlYkJ5QV5em98ZfG6w0xcWTwCTqTxThb 0y5ZMasXfIpL9ZQzLZna0WPB+bYa1dWvI5IY6+BSSIlNThmaArQ4jG5VfqasRjwFWx/Q HQ7UQb5J3V40lo642YN9DHmCWPRhGWBD+vVL2gESGY0UUk/f3Fx5gyIQ21aa85/Y2Yxo Js9WzwV1sqJtTm7IApOyfT9A7PzzIF4NGrDmZZgZVY8vaNiAGEoKT1jzsMWbcl/Pnag+ LViw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727954165; x=1728558965; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=lGLXkZTI8lFIxokzB+lI3gIzGTATKncCCeuzE20IZFs=; b=m3NwGNaJBgvb3xUpd7NwGkkjQhrrlljuB1uInuFyO4uS3uSylw+NgqADv7BIJwc19P qtF9HtXNIP4brzAfqRVApFxrMbgMXtkJu5cu6rSQ++9d/HuJjQRQ1uIf5Q6fdd7iKIcI qIPA5iKYj8ZYjL4EzAfXbCJPDERzwCVz12NEej3/lpcuo3NHBnAtetqTwMbCU1e//QnX ZzgOSN9JgcFgdwdV4WvUqZU+nsBHkyVAfnzmiUar7vqzoPoG5MEC2hrJXhiXri58A7oL kQHAmQPUQ1lMAaAyQ/qLEYkMqgIeQ//FHZOA+5OUeq4nzk+DcR3WxalcYlWo4UIjnA5i wTnw== X-Forwarded-Encrypted: i=1; AJvYcCUI4jVzCLY2dz/EnpPUlS4iF7OMSUdh3EKE7mM1RBlWyGJoSr6wVJSmKKBiJ+8wCPVPZg1YizyT2cUs2ls=@vger.kernel.org X-Gm-Message-State: AOJu0YwOAsid758d6gkAb34uwct4XNlRqhCnmInKaQzqmXqw0iFNzRhn GMj57UFDOvJhCXe1s5/xT1IuF1mLASR0inKMpYFVCKbEf5OxnGOpzkFZUFt/VOI= X-Google-Smtp-Source: AGHT+IF1GIYcqrw39Lg9zk5IEgMG8jnEkRhxXjJbsdkvBWAWMDPO2zPjThgyC+sA7a4HTcu9pAF9Lg== X-Received: by 2002:ac8:580e:0:b0:458:3ed8:ecee with SMTP id d75a77b69052e-45d804eb757mr86748451cf.35.1727954165380; Thu, 03 Oct 2024 04:16:05 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-68-128-5.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.128.5]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-45d92e0ed8csm4660151cf.36.2024.10.03.04.16.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Oct 2024 04:16:04 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1swJoR-00AILi-SH; Thu, 03 Oct 2024 08:16:03 -0300 Date: Thu, 3 Oct 2024 08:16:03 -0300 From: Jason Gunthorpe To: Yang Shi Cc: Nicolin Chen , james.morse@arm.com, will@kernel.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH] iommu/arm-smmu-v3: Fix L1 stream table index calculation for 32-bit sid size Message-ID: <20241003111603.GU1369530@ziepe.ca> References: <20241002175514.1165299-1-yang@os.amperecomputing.com> <1c9767e1-4d05-4650-bc14-65a18fc63cc2@os.amperecomputing.com> <20241002194004.GT1369530@ziepe.ca> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Oct 02, 2024 at 01:05:08PM -0700, Yang Shi wrote: > > It would make some sense to have something like: > > > > u64 size = arm_smmu_strtab_max_sid() > > > > /* Would require too much memory */ > > if (size > SZ_512M) > > return -EINVAL; > > Why not just check smmu->sid_bits? > > For example, > > if (smmu->sid_bits > 28) >     return -EINVAL; > > The check can happen before the shift. Sure, but IMHO it reads a bit better to check the size computed from the helper MAX_PAGE_ORDER is often 10, so kmalloc will always fail before we reach 28 bits of sid space. Jason