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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id a10sm1235482edn.77.2020.11.20.07.33.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Nov 2020 07:33:45 -0800 (PST) Subject: Re: [PATCH v6 16/17] RFC: kvm: pass kvm argument to follow_pfn callsites To: Daniel Vetter , DRI Development , LKML Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, Daniel Vetter , Christoph Hellwig , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara References: <20201119144146.1045202-1-daniel.vetter@ffwll.ch> <20201119144146.1045202-17-daniel.vetter@ffwll.ch> From: Paolo Bonzini Message-ID: Date: Fri, 20 Nov 2020 16:33:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201119144146.1045202-17-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 19/11/20 15:41, Daniel Vetter wrote: > Both Christoph Hellwig and Jason Gunthorpe suggested that usage of > follow_pfn by modules should be locked down more. To do so callers > need to be able to pass the mmu_notifier subscription corresponding > to the mm_struct to follow_pfn(). > > This patch does the rote work of doing that in the kvm subsystem. In > most places this is solved by passing struct kvm * down the call > stacks as an additional parameter, since that contains the > mmu_notifier. > > Compile tested on all affected arch. It's a bit of a pity, it's making an API more complex (the point of gfn_to_pfn_memslot vs gfn_to_pfn is exactly that you don't need a "struct kvm*" and it's clear that you've already done the lookup into that struct kvm. But it's not a big deal, and the rationale at least makes sense. So, Acked-by: Paolo Bonzini Paolo