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Thu, 10 Sep 2020 11:58:03 +0100 MIME-Version: 1.0 Date: Thu, 10 Sep 2020 11:58:03 +0100 From: Marc Zyngier To: Will Deacon Subject: Re: [PATCH v4 17/21] KVM: arm64: Convert user_mem_abort() to generic page-table API In-Reply-To: <20200910105107.GA17887@willie-the-truck> References: <20200907152344.12978-1-will@kernel.org> <20200907152344.12978-18-will@kernel.org> <2ae77a66-9cc4-f4e1-9e98-a50d5891cf20@arm.com> <20200910105107.GA17887@willie-the-truck> User-Agent: Roundcube Webmail/1.4.8 Message-ID: <8302f7defdcc90f74519024c3deea2a6@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: will@kernel.org, alexandru.elisei@arm.com, kvmarm@lists.cs.columbia.edu, qperret@google.com, james.morse@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, gshan@redhat.com, kernel-team@android.com, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200910_065806_677229_4BBCB52B X-CRM114-Status: GOOD ( 18.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, Gavin Shan , Suzuki Poulose , Catalin Marinas , Quentin Perret , James Morse , Alexandru Elisei , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-09-10 11:51, Will Deacon wrote: > On Wed, Sep 09, 2020 at 06:12:29PM +0100, Marc Zyngier wrote: >> On 2020-09-09 15:20, Alexandru Elisei wrote: >> > On 9/7/20 4:23 PM, Will Deacon wrote: >> > > @@ -1610,62 +1605,31 @@ static int user_mem_abort(struct kvm_vcpu >> > > *vcpu, phys_addr_t fault_ipa, >> > > if (vma_pagesize == PAGE_SIZE && !force_pte) >> > > vma_pagesize = transparent_hugepage_adjust(memslot, hva, >> > > &pfn, &fault_ipa); >> > > - if (writable) >> > > + if (writable) { >> > > + prot |= KVM_PGTABLE_PROT_W; >> > > kvm_set_pfn_dirty(pfn); >> > > + mark_page_dirty(kvm, gfn); >> > >> > The previous code called mark_page_dirty() only if the vma_pagesize == >> > PAGE_SIZE >> > (and writable was true, obviously). Is this supposed to fix a bug? >> >> No, this is actually introducing one. mark_page_dirty() checks that >> there is >> an >> associated bitmap, and thus only happens when writing to a single >> page, but >> we >> shouldn't do it for R/O memslots, which the current code avoids. It >> should >> be >> guarded by logging_active. > > gfn_to_pfn_prot() will set "writable" to false for R/O memslots, so I > think > we're good here. Ah, good point. M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel