From patchwork Fri Nov 29 02:55:00 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 295071 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 22BBE2C00AD for ; Fri, 29 Nov 2013 13:55:37 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753498Ab3K2Czf (ORCPT ); Thu, 28 Nov 2013 21:55:35 -0500 Received: from cantor2.suse.de ([195.135.220.15]:50976 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752834Ab3K2CzG (ORCPT ); Thu, 28 Nov 2013 21:55:06 -0500 Received: from relay1.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id BE853A7D76; Fri, 29 Nov 2013 03:55:05 +0100 (CET) From: Alexander Graf To: "\"" , " "@suse.de Cc: "kvm@vger.kernel.org mailing list" Subject: [PATCH 3/4] KVM: PPC: Book3S: PR: Make svcpu -> vcpu store preempt savvy Date: Fri, 29 Nov 2013 03:55:00 +0100 Message-Id: <1385693701-27632-4-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.7.12.4 In-Reply-To: <1385693701-27632-1-git-send-email-agraf@suse.de> References: <1385693701-27632-1-git-send-email-agraf@suse.de> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org As soon as we get back to our "highmem" handler in virtual address space we may get preempted. Today the reason we can get preempted is that we replay interrupts and all the lazy logic thinks we have interrupts enabled. However, it's not hard to make the code interruptible and that way we can enable and handle interrupts even earlier. This fixes random guest crashes that happened with CONFIG_PREEMPT=y for me. Signed-off-by: Alexander Graf --- arch/powerpc/include/asm/kvm_book3s_asm.h | 1 + arch/powerpc/kvm/book3s_pr.c | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h index 0bd9348..412b2f3 100644 --- a/arch/powerpc/include/asm/kvm_book3s_asm.h +++ b/arch/powerpc/include/asm/kvm_book3s_asm.h @@ -106,6 +106,7 @@ struct kvmppc_host_state { }; struct kvmppc_book3s_shadow_vcpu { + bool in_use; ulong gpr[14]; u32 cr; u32 xer; diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index fe14ca3..5b9e906 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -66,6 +66,7 @@ static void kvmppc_core_vcpu_load_pr(struct kvm_vcpu *vcpu, int cpu) struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); memcpy(svcpu->slb, to_book3s(vcpu)->slb_shadow, sizeof(svcpu->slb)); svcpu->slb_max = to_book3s(vcpu)->slb_shadow_max; + svcpu->in_use = 0; svcpu_put(svcpu); #endif vcpu->cpu = smp_processor_id(); @@ -78,6 +79,9 @@ static void kvmppc_core_vcpu_put_pr(struct kvm_vcpu *vcpu) { #ifdef CONFIG_PPC_BOOK3S_64 struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); + if (svcpu->in_use) { + kvmppc_copy_from_svcpu(vcpu, svcpu); + } memcpy(to_book3s(vcpu)->slb_shadow, svcpu->slb, sizeof(svcpu->slb)); to_book3s(vcpu)->slb_shadow_max = svcpu->slb_max; svcpu_put(svcpu); @@ -110,12 +114,26 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu, svcpu->ctr = vcpu->arch.ctr; svcpu->lr = vcpu->arch.lr; svcpu->pc = vcpu->arch.pc; + svcpu->in_use = true; } /* Copy data touched by real-mode code from shadow vcpu back to vcpu */ void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, struct kvmppc_book3s_shadow_vcpu *svcpu) { + /* + * vcpu_put would just call us again because in_use hasn't + * been updated yet. + */ + preempt_disable(); + + /* + * Maybe we were already preempted and synced the svcpu from + * our preempt notifiers. Don't bother touching this svcpu then. + */ + if (!svcpu->in_use) + goto out; + vcpu->arch.gpr[0] = svcpu->gpr[0]; vcpu->arch.gpr[1] = svcpu->gpr[1]; vcpu->arch.gpr[2] = svcpu->gpr[2]; @@ -139,6 +157,10 @@ void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, vcpu->arch.fault_dar = svcpu->fault_dar; vcpu->arch.fault_dsisr = svcpu->fault_dsisr; vcpu->arch.last_inst = svcpu->last_inst; + svcpu->in_use = false; + +out: + preempt_enable(); } static int kvmppc_core_check_requests_pr(struct kvm_vcpu *vcpu)