From patchwork Wed Mar 21 17:47:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 10299953 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 69C9B600CC for ; Wed, 21 Mar 2018 17:48:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 55455286F4 for ; Wed, 21 Mar 2018 17:48:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4A2D228C57; Wed, 21 Mar 2018 17:48:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C4316286F4 for ; Wed, 21 Mar 2018 17:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=ZYQuayhs4h1rjKg5LVEDdAEbRe2O9+FNn8brS+Tl/PU=; b=cAHGx1eVsk6lyC0i0llqjMdRu8 q9RmKUqrnQlkNMeo8Ul73cXf/mpa6H+WPPuB3Yzn6VWULfx6vhnh0CDCQBTNWyK9YBE177PAh66/p ziBM2UOPAkD2mOkehj70K1lzaEzRj9nmziRk5HgsOAh58Iz8I14UIw/kNJXNty04gWgYOF/rJ88ph QJn+t0QPvffg9yH2IBUeYY8YArYNGmVsrXN4TRiLtxAZYdqr9lN+sUcgGQUk9sWS324k4PaQYb27P /dd9bmG3k15Fx8jXi8+Mmyui6P6oJQy7cgj7flBk5F90HBq/aRvvZcav2kxxDzgownmEaH9+FEuHC x1cBnJcQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1eyhqR-00076d-LR; Wed, 21 Mar 2018 17:48:15 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1eyhq2-0006qJ-TV for linux-arm-kernel@lists.infradead.org; Wed, 21 Mar 2018 17:47:52 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ECDD115B2; Wed, 21 Mar 2018 10:47:40 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DF2CA3F24A; Wed, 21 Mar 2018 10:47:39 -0700 (PDT) From: Dave Martin To: kvmarm@lists.cs.columbia.edu Subject: [RFC PATCH 1/4] KVM: arm/arm64: Introduce kvm_arch_vcpu_run_pid_change Date: Wed, 21 Mar 2018 17:47:30 +0000 Message-Id: <1521654453-3837-2-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1521654453-3837-1-git-send-email-Dave.Martin@arm.com> References: <1521654453-3837-1-git-send-email-Dave.Martin@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180321_104751_065151_641CCE13 X-CRM114-Status: GOOD ( 17.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , Christoffer Dall , Christoffer Dall , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Christoffer Dall KVM/ARM differs from other architectures in having to maintain an additional virtual address space from that of the host and the guest, because we split the execution of KVM across both EL1 and EL2. This results in a need to explicitly map data structures into EL2 (hyp) which are accessed from the hyp code. As we are about to be more clever with our FPSIMD handling, which stores data on the task struct and uses thread_info flags, we have to map the currently executing task struct into the EL2 virtual address space. However, we don't want to do this on every KVM_RUN, because it is a fairly expensive operation to walk the page tables, and the common execution mode is to map a single thread to a VCPU. By introducing a hook that architectures can select with HAVE_KVM_VCPU_RUN_PID_CHANGE, we do not introduce overhead for other architectures, but have a simple way to only map the data we need when required for arm64. Signed-off-by: Christoffer Dall Signed-off-by: Dave Martin --- The use of hyp_current to pass the value of "current" to hyp is backed out compared with Chritoffer's original patch. Instead, I do most of the grubbing around in task_struct to the host side to reduce the amount of stuff that needs to be duplicated in hyp. --- arch/arm64/kvm/Kconfig | 1 + include/linux/kvm_host.h | 9 +++++++++ virt/kvm/Kconfig | 3 +++ virt/kvm/arm/arm.c | 10 ++++++++++ virt/kvm/kvm_main.c | 7 ++++++- 5 files changed, 29 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 2257dfc..5b2c8d8 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -39,6 +39,7 @@ config KVM select HAVE_KVM_IRQ_ROUTING select IRQ_BYPASS_MANAGER select HAVE_KVM_IRQ_BYPASS + select HAVE_KVM_VCPU_RUN_PID_CHANGE ---help--- Support hosting virtualized guest machines. We don't support KVM with 16K page tables yet, due to the multiple diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ac0062b..10a37b1 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1272,4 +1272,13 @@ static inline long kvm_arch_vcpu_async_ioctl(struct file *filp, } #endif /* CONFIG_HAVE_KVM_VCPU_ASYNC_IOCTL */ +#ifdef CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE +int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu); +#else +static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu) +{ + return 0; +} +#endif /* CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE */ + #endif diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index cca7e06..72143cf 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -54,3 +54,6 @@ config HAVE_KVM_IRQ_BYPASS config HAVE_KVM_VCPU_ASYNC_IOCTL bool + +config HAVE_KVM_VCPU_RUN_PID_CHANGE + bool diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 86941f6..02a153a 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -822,6 +822,16 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) return ret; } +#ifdef CONFIG_ARM64 +int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu) +{ + struct task_struct *tsk = current; + + /* Make sure the host task fpsimd state is visible to hyp: */ + return create_hyp_mappings(tsk, tsk + 1, PAGE_HYP); +} +#endif + static int vcpu_interrupt_line(struct kvm_vcpu *vcpu, int number, bool level) { int bit_index; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 4501e65..dbd35ab 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2551,8 +2551,13 @@ static long kvm_vcpu_ioctl(struct file *filp, oldpid = rcu_access_pointer(vcpu->pid); if (unlikely(oldpid != current->pids[PIDTYPE_PID].pid)) { /* The thread running this VCPU changed. */ - struct pid *newpid = get_task_pid(current, PIDTYPE_PID); + struct pid *newpid; + r = kvm_arch_vcpu_run_pid_change(vcpu); + if (r) + break; + + newpid = get_task_pid(current, PIDTYPE_PID); rcu_assign_pointer(vcpu->pid, newpid); if (oldpid) synchronize_rcu();