From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45174) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZvkEf-0003CU-Gb for qemu-devel@nongnu.org; Mon, 09 Nov 2015 06:03:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZvkEe-0002pk-JC for qemu-devel@nongnu.org; Mon, 09 Nov 2015 06:03:41 -0500 References: <1446747358-18214-1-git-send-email-peter.maydell@linaro.org> <1446747358-18214-10-git-send-email-peter.maydell@linaro.org> <56407AC8.9020100@redhat.com> From: Paolo Bonzini Message-ID: <56407D82.4090005@redhat.com> Date: Mon, 9 Nov 2015 12:03:30 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 09/16] target-arm: Support multiple address spaces in page table walks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Patch Tracking , QEMU Developers , qemu-arm@nongnu.org, "Edgar E. Iglesias" , =?UTF-8?Q?Alex_Benn=c3=a9e?= , =?UTF-8?Q?Andreas_F=c3=a4rber?= On 09/11/2015 11:58, Peter Maydell wrote: > On 9 November 2015 at 10:51, Paolo Bonzini wrote: >> >> >> On 05/11/2015 19:15, Peter Maydell wrote: >>> If we have a secure address space, use it in page table walks: >>> * when doing the physical accesses to read descriptors, >>> make them through the correct address space >>> * when the final result indicates a secure access, pass the >>> correct address space index to tlb_set_page_with_attrs() >>> >>> (The descriptor reads are the only direct physical accesses >>> made in target-arm/ for CPUs which might have TrustZone.) >> >> What is the case where you have no secure address space and you have >> TrustZone? KVM doesn't have TrustZone, so it should never be in a >> secure regime, should it? > > You mean "what is the case where is_secure but cpu->num_ases == 1" ? > That happens if you have a TrustZone CPU but the board has only > connected up one address space, because there is no difference > in the view from Secure and NonSecure. (vexpress is like this > in hardware, and most of our board models for TZ CPUS are like > that now even if the real h/w makes a distinction.) > > I could have handled that by making the CPU init code always > register two ASes (using the same one twice if the board code > only passes one or using system_address_space twice if the > board code doesn't pass one at all), but that seemed a bit wasteful. I think it's simpler though. Complicating the init code is better than handling the condition throughout all the helpers... Paolo