From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Baicar, Tyler" Subject: Re: [PATCH V11 10/10] arm/arm64: KVM: add guest SEA support Date: Mon, 6 Mar 2017 07:00:30 -0700 Message-ID: <4b4bea7c-7591-8051-7be0-528581f29d10@codeaurora.org> References: <1487712121-16688-1-git-send-email-tbaicar@codeaurora.org> <1487712121-16688-11-git-send-email-tbaicar@codeaurora.org> <58B00E12.5020602@arm.com> <58BD39B4.9050809@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1EAE840A7F for ; Mon, 6 Mar 2017 08:59:28 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lKYWypr8p8KV for ; Mon, 6 Mar 2017 08:59:22 -0500 (EST) Received: from smtp.codeaurora.org (smtp.codeaurora.org [198.145.29.96]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 2CB8840A7B for ; Mon, 6 Mar 2017 08:59:21 -0500 (EST) In-Reply-To: <58BD39B4.9050809@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: James Morse Cc: linux-efi@vger.kernel.org, kvm@vger.kernel.org, matt@codeblueprint.co.uk, catalin.marinas@arm.com, will.deacon@arm.com, robert.moore@intel.com, paul.gortmaker@windriver.com, lv.zheng@intel.com, kvmarm@lists.cs.columbia.edu, fu.wei@linaro.org, zjzhang@codeaurora.org, linux@armlinux.org.uk, linux-acpi@vger.kernel.org, eun.taik.lee@samsung.com, shijie.huang@arm.com, labbott@redhat.com, lenb@kernel.org, harba@codeaurora.org, john.garry@huawei.com, marc.zyngier@arm.com, punit.agrawal@arm.com, rostedt@goodmis.org, nkaje@codeaurora.org, sandeepa.s.prabhu@gmail.com, linux-arm-kernel@lists.infradead.org, devel@acpica.org, rjw@rjwysocki.net, rruigrok@codeaurora.org, linux-kernel@vger.kernel.org, astone@redhat.com, hanjun.guo@linaro.org, joe@perches.com, pbonzini@redhat.com, akpm@linux-foundation.org, bristot@redhat.com, shiju.jose@huawei.com List-Id: kvmarm@lists.cs.columbia.edu Hello James, On 3/6/2017 3:28 AM, James Morse wrote: > On 28/02/17 19:43, Baicar, Tyler wrote: >> On 2/24/2017 3:42 AM, James Morse wrote: >>> On 21/02/17 21:22, Tyler Baicar wrote: >>>> Currently external aborts are unsupported by the guest abort >>>> handling. Add handling for SEAs so that the host kernel reports >>>> SEAs which occur in the guest kernel. >>>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c >>>> index b2d57fc..403277b 100644 >>>> --- a/arch/arm64/mm/fault.c >>>> +++ b/arch/arm64/mm/fault.c >>>> @@ -602,6 +602,24 @@ static const char *fault_name(unsigned int esr) >>>> } >>>> >>>> /* >>>> + * Handle Synchronous External Aborts that occur in a guest kernel. >>>> + */ >>>> +int handle_guest_sea(unsigned long addr, unsigned int esr) >>>> +{ >>>> + if(IS_ENABLED(HAVE_ACPI_APEI_SEA)) { >>>> + nmi_enter(); >>>> + ghes_notify_sea(); >>>> + nmi_exit(); >>> This nmi stuff was needed for synchronous aborts that may have interrupted >>> APEI's interrupts-masked code. We want to avoid trying to take the same set of >>> locks, hence taking the in_nmi() path through APEI. Here we know we interrupted >>> a guest, so there is no risk that we have interrupted APEI on the host. >>> ghes_notify_sea() can safely take the normal path. >> Makes sense, I can remove the nmi_* calls here. > Just occurs to me: if we do this we need to add the rcu_read_lock() in > ghes_notify_sea() as its not protected by the rcu/nmi weirdness. > True, would you suggest leaving these nmi_* calls or adding the rcu_* calls? And since that's only needed for this KVM case, shouldn't the rcu_* calls just replace the nmi_* calls here (outside of ghes_notify_sea)? Thanks, Tyler -- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.