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Mon, 26 Apr 2021 10:41:14 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B05AF61185; Mon, 26 Apr 2021 10:41:11 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1layft-009SvS-Fz; Mon, 26 Apr 2021 11:41:09 +0100 MIME-Version: 1.0 Date: Mon, 26 Apr 2021 11:41:09 +0100 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: Jean-Philippe Brucker , Suzuki K Poulose , kernel-team@android.com, James Morse , Sumit Gupta , Alexandru Elisei Subject: Re: [PATCH] KVM: arm64: Skip CMOs when updating a PTE pointing to non-memory In-Reply-To: <20210426103605.616908-1-maz@kernel.org> References: <20210426103605.616908-1-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.11 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, jean-philippe@linaro.org, suzuki.poulose@arm.com, kernel-team@android.com, james.morse@arm.com, sumitg@nvidia.com, alexandru.elisei@arm.com 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-20210426_034113_077596_C1A39C23 X-CRM114-Status: GOOD ( 13.31 ) 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: , 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 2021-04-26 11:36, Marc Zyngier wrote: > Sumit Gupta and Krishna Reddy both reported that for MMIO regions > mapped into userspace using VFIO, a PTE update can trigger a MMU > notifier reaching kvm_set_spte_hva(). > > There is an assumption baked in kvm_set_spte_hva() that it only > deals with memory pages, and not MMIO. For this purpose, it > performs a cache cleaning of the potentially newly mapped page. > However, for a MMIO range, this explodes as there is no linear > mapping for this range (and doing cache maintenance on it would > make little sense anyway). > > Check for the validity of the page before performing the CMO > addresses the problem. > > Reported-by: Krishna Reddy > Reported-by: Sumit Gupta , > Tested-by: Sumit Gupta , > Signed-off-by: Marc Zyngier > Link: > https://lore.kernel.org/r/5a8825bc-286e-b316-515f-3bd3c9c70a80@nvidia.com FWIW, I've locally added: Fixes: 694556d54f35 ("KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW") Cc: stable@vger.kernel.org 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