From patchwork Tue Oct 25 15:08:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: James Hogan X-Patchwork-Id: 9394741 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 81C876077F for ; Tue, 25 Oct 2016 15:08:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7520929636 for ; Tue, 25 Oct 2016 15:08:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 69EAC29637; Tue, 25 Oct 2016 15:08:47 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BDD4C2963B for ; Tue, 25 Oct 2016 15:08:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941884AbcJYPIg (ORCPT ); Tue, 25 Oct 2016 11:08:36 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:27462 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941882AbcJYPId (ORCPT ); Tue, 25 Oct 2016 11:08:33 -0400 Received: from HHMAIL01.hh.imgtec.org (unknown [10.100.10.19]) by Forcepoint Email with ESMTPS id DD55134BC3CD1; Tue, 25 Oct 2016 16:08:27 +0100 (IST) Received: from jhogan-linux.le.imgtec.org (192.168.154.110) by HHMAIL01.hh.imgtec.org (10.100.10.21) with Microsoft SMTP Server (TLS) id 14.3.294.0; Tue, 25 Oct 2016 16:08:31 +0100 From: James Hogan To: CC: James Hogan , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Ralf Baechle , Subject: [PATCH 1/3] KVM: MIPS: Fix lazy user ASID regenerate for SMP Date: Tue, 25 Oct 2016 16:08:19 +0100 Message-ID: <26798303b5e56962d2afcdbf878fc7a85f99ba98.1477320903.git-series.james.hogan@imgtec.com> X-Mailer: git-send-email 2.10.1 MIME-Version: 1.0 In-Reply-To: References: X-Originating-IP: [192.168.154.110] Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP kvm_mips_check_asids() runs before entering the guest and performs lazy regeneration of host ASID for guest usermode, using last_user_gasid to track the last guest ASID in the VCPU that was used by guest usermode on any host CPU. last_user_gasid is reset after performing the lazy ASID regeneration on the current CPU, and by kvm_arch_vcpu_load() if the host ASID for guest usermode is regenerated due to staleness (to cancel outstanding lazy ASID regenerations). Unfortunately neither case handles SMP hosts correctly: - When the lazy ASID regeneration is performed it should apply to all CPUs (as last_user_gasid does), so reset the ASID on other CPUs to zero to trigger regeneration when the VCPU is next loaded on those CPUs. - When the ASID is found to be stale on the current CPU, we should not cancel lazy ASID regenerations globally, so drop the reset of last_user_gasid altogether here. Both cases would require a guest ASID change and two host CPU migrations (and in the latter case one of the CPUs to start a new ASID cycle) before guest usermode could potentially access stale user pages from a previously running ASID in the same VCPU. Fixes: 25b08c7fb0e4 ("KVM: MIPS: Invalidate TLB by regenerating ASIDs") Signed-off-by: James Hogan Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/kvm/mips.c | 5 ++++- arch/mips/kvm/mmu.c | 4 ---- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index 622037d851a3..06a60b19acfb 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -426,7 +426,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, static void kvm_mips_check_asids(struct kvm_vcpu *vcpu) { struct mips_coproc *cop0 = vcpu->arch.cop0; - int cpu = smp_processor_id(); + int i, cpu = smp_processor_id(); unsigned int gasid; /* @@ -442,6 +442,9 @@ static void kvm_mips_check_asids(struct kvm_vcpu *vcpu) vcpu); vcpu->arch.guest_user_asid[cpu] = vcpu->arch.guest_user_mm.context.asid[cpu]; + for_each_possible_cpu(i) + if (i != cpu) + vcpu->arch.guest_user_asid[cpu] = 0; vcpu->arch.last_user_gasid = gasid; } } diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c index 03883ba806e2..3b677c851be0 100644 --- a/arch/mips/kvm/mmu.c +++ b/arch/mips/kvm/mmu.c @@ -260,13 +260,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) if ((vcpu->arch.guest_user_asid[cpu] ^ asid_cache(cpu)) & asid_version_mask(cpu)) { - u32 gasid = kvm_read_c0_guest_entryhi(vcpu->arch.cop0) & - KVM_ENTRYHI_ASID; - kvm_get_new_mmu_context(&vcpu->arch.guest_user_mm, cpu, vcpu); vcpu->arch.guest_user_asid[cpu] = vcpu->arch.guest_user_mm.context.asid[cpu]; - vcpu->arch.last_user_gasid = gasid; newasid++; kvm_debug("[%d]: cpu_context: %#lx\n", cpu,