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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-441ef3d88a1sm74750201cf.18.2024.06.20.06.31.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Jun 2024 06:31:45 -0700 (PDT) Date: Thu, 20 Jun 2024 09:31:43 -0400 From: Peter Xu To: Ryan Roberts Cc: Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v1] arm64: mm: Permit PTE SW bits to change in live mappings Message-ID: References: <20240619121859.4153966-1-ryan.roberts@arm.com> <3a42e195-9392-442f-aba7-fdd2c186b98f@arm.com> <807640e2-3a79-4b65-a7f9-4b47f2a39f23@arm.com> MIME-Version: 1.0 In-Reply-To: <807640e2-3a79-4b65-a7f9-4b47f2a39f23@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240620_063151_361858_B72941FE X-CRM114-Status: GOOD ( 11.67 ) 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 Thu, Jun 20, 2024 at 11:26:07AM +0100, Ryan Roberts wrote: > Yes, I think this works as expected. huge_pte_mkuffd_wp() is just modifying the > bits in a pte passed on the stack and returns the modified pte. The pgtable is > not touched at this point. The magic happens in set_huge_pte_at() (called by > huge_ptep_modify_prot_commit() in your case), which knows how the abstract "huge > pte" maps to real PMDs or PTEs in the pgtable and applies the passed in pte > value appropriately to all real pmds/ptes (adjusting the pfn as required in the > process). Ah indeed! That's good enough. :) Thanks, -- Peter Xu