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AJvYcCU1hUf+TsqDiGG4TtLwDPvhDrwGewUmoHKjagCs3GXuWa/mq9eHCUF52/3+KB8Pz2f7tM3AB0NC1g==@kvack.org X-Gm-Message-State: AOJu0YzqSK+AlX/lMKE3LbHZwAIsdgtQJOTqoYaH4gsFSUiGOyR8oMTG JNuVrlSarJ3GzF7PnZoP4PQjFmVht/P6Q4JGKVevo4DeMTvZTwJ1mLlJSXnn0kfQG0jkEGoJvDg 9LA== X-Google-Smtp-Source: AGHT+IFTc+rIqSRjWJcaRw8kndrZyrrco4sjKuLnct+lf6dsqkIx8K6CIKBvF3FvIoSW3fNH38TrodlWkBQ= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:9d:3983:ac13:c240]) (user=seanjc job=sendgmr) by 2002:a63:2306:0:b0:7e6:c505:689e with SMTP id 41be03b00d2f7-7ea3f903460mr21417a12.4.1728941830059; Mon, 14 Oct 2024 14:37:10 -0700 (PDT) Date: Mon, 14 Oct 2024 14:37:08 -0700 In-Reply-To: <20241014105912.3207374-17-ryan.roberts@arm.com> Mime-Version: 1.0 References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> <20241014105912.3207374-17-ryan.roberts@arm.com> Message-ID: Subject: Re: [RFC PATCH v1 17/57] kvm: Remove PAGE_SIZE compile-time constant assumption From: Sean Christopherson To: Ryan Roberts Cc: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Will Deacon , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="us-ascii" X-Rspam-User: X-Stat-Signature: ws9wdht3qy7f9w4dfn71adkz5x5iyfmk X-Rspamd-Queue-Id: 42269120011 X-Rspamd-Server: rspam11 X-HE-Tag: 1728941823-311750 X-HE-Meta: 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 qqZRM0Hm 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Nit, "KVM:" for the scope. On Mon, Oct 14, 2024, Ryan Roberts wrote: > To prepare for supporting boot-time page size selection, refactor code > to remove assumptions about PAGE_SIZE being compile-time constant. Code > intended to be equivalent when compile-time page size is active. > > Modify BUILD_BUG_ON() to compare with page size limit. > > Signed-off-by: Ryan Roberts > --- > > ***NOTE*** > Any confused maintainers may want to read the cover note here for context: > https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ The patch should still stand on its own. Most people can probably suss out what PAGE_SIZE_MIN is, but at the same time, it's quite easy to provide a more verbose changelog that's tailored to the actual patch. E.g. To prepare for supporting boot-time page size selection, refactor KVM's check on the size of the kvm_run structure to assert that the size is less than the smallest possible page size, i.e. that kvm_run won't overflow its page regardless of what page size is chosen at boot time. With something like the above, Reviewed-by: Sean Christopherson