From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v8 01/26] arm64: Fix HCR.TGE status for NMI contexts Date: Mon, 14 Jan 2019 15:56:35 +0000 Message-ID: <20190114155634.GB84430@arrakis.emea.arm.com> References: <1546956464-48825-1-git-send-email-julien.thierry@arm.com> <1546956464-48825-2-git-send-email-julien.thierry@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1546956464-48825-2-git-send-email-julien.thierry@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Julien Thierry Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, linux-arch@vger.kernel.org, daniel.thompson@linaro.org, Arnd Bergmann , marc.zyngier@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, christoffer.dall@arm.com, james.morse@arm.com, joel@joelfernandes.org List-Id: linux-arch.vger.kernel.org On Tue, Jan 08, 2019 at 02:07:19PM +0000, Julien Thierry wrote: > When using VHE, the host needs to clear HCR_EL2.TGE bit in order > to interract with guest TLBs, switching from EL2&0 translation regime > to EL1&0. > > However, some non-maskable asynchronous event could happen while TGE is > cleared like SDEI. Because of this address translation operations > relying on EL2&0 translation regime could fail (tlb invalidation, > userspace access, ...). Why would an NMI context need to access user space? (just curious what breaks exactly without this patch; otherwise it looks fine) -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.101.70]:36198 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726646AbfANP4k (ORCPT ); Mon, 14 Jan 2019 10:56:40 -0500 Date: Mon, 14 Jan 2019 15:56:35 +0000 From: Catalin Marinas Subject: Re: [PATCH v8 01/26] arm64: Fix HCR.TGE status for NMI contexts Message-ID: <20190114155634.GB84430@arrakis.emea.arm.com> References: <1546956464-48825-1-git-send-email-julien.thierry@arm.com> <1546956464-48825-2-git-send-email-julien.thierry@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1546956464-48825-2-git-send-email-julien.thierry@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Julien Thierry Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, linux-arch@vger.kernel.org, daniel.thompson@linaro.org, Arnd Bergmann , marc.zyngier@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, christoffer.dall@arm.com, james.morse@arm.com, joel@joelfernandes.org Message-ID: <20190114155635.xSelWuXQYYZ7eBqDnNPmLUYu9Kvn3vnPYQk6kTjymbs@z> On Tue, Jan 08, 2019 at 02:07:19PM +0000, Julien Thierry wrote: > When using VHE, the host needs to clear HCR_EL2.TGE bit in order > to interract with guest TLBs, switching from EL2&0 translation regime > to EL1&0. > > However, some non-maskable asynchronous event could happen while TGE is > cleared like SDEI. Because of this address translation operations > relying on EL2&0 translation regime could fail (tlb invalidation, > userspace access, ...). Why would an NMI context need to access user space? (just curious what breaks exactly without this patch; otherwise it looks fine) -- Catalin