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X-CSE-ConnectionGUID: qiFJ48dRRP2EWFGA1GY92w== X-CSE-MsgGUID: iciG1WSiTS2fLbx4rZdQNA== X-IronPort-AV: E=McAfee;i="6800,10657,11536"; a="58838089" X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="58838089" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2025 12:31:44 -0700 X-CSE-ConnectionGUID: tCXifuv/Tz2do340lMhRCw== X-CSE-MsgGUID: f93abq4MR6qN1FaRujuQaA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="169717524" Received: from kcaccard-desk.amr.corp.intel.com (HELO [10.125.109.98]) ([10.125.109.98]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2025 12:31:41 -0700 Message-ID: Date: Thu, 28 Aug 2025 12:31:40 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] iommu/sva: Invalidate KVA range on kernel TLB flush To: Jason Gunthorpe Cc: "Tian, Kevin" , Baolu Lu , Joerg Roedel , Will Deacon , Robin Murphy , Jann Horn , Vasant Hegde , Alistair Popple , Peter Zijlstra , Uladzislau Rezki , Jean-Philippe Brucker , Andy Lutomirski , "Lai, Yi1" , "iommu@lists.linux.dev" , "security@kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "vishal.moola@gmail.com" , Matthew Wilcox References: <9a649ff4-55fe-478a-bfd7-f3287534499a@intel.com> <400cf9ab-de3f-4e8a-ab0a-4ac68c534bb8@intel.com> <20250828191057.GG7333@nvidia.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/28/25 12:10, Jason Gunthorpe wrote: >> The biggest single chunk of code is defining ptdesc_*_kernel(). The rest >> of it is painfully simple. > Seems not great to be casting ptdesc to folio just to use > folio_set_referenced(), I'm pretty sure that is no the direction > things are going in.. Ideally, the ptdesc->__page_flags fields would have their own set of macros just like folios do, right? Alas, I was too lazy to go to the trouble of conjuring those up for this single bit. > I'd set the flag yourself or perhaps use the memory of __page_mapping > to store a flag (but zero it before freeing). That was my first inclination as well (actually I was going to use __page_type since the lower 24 bits are evidently open, but same idea). Willy pointed me in the direction of PG_referenced on IRC, so I took that path. But I'm open to doing whatever. It's just three lines of code that probably end up boiling down to bts 0x1, 0x8(%rax) versus bts 0x2, 0x16(%rax) ;)