From patchwork Fri Jun 16 06:42:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 9790613 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 BDE7460231 for ; Fri, 16 Jun 2017 06:43:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B578C2853A for ; Fri, 16 Jun 2017 06:43:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AA6A828543; Fri, 16 Jun 2017 06:43:22 +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 3A6B82853A for ; Fri, 16 Jun 2017 06:43:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752427AbdFPGnV (ORCPT ); Fri, 16 Jun 2017 02:43:21 -0400 Received: from ozlabs.org ([103.22.144.67]:43423 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752369AbdFPGnN (ORCPT ); Fri, 16 Jun 2017 02:43:13 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 3wprRM4xzvz9sDF; Fri, 16 Jun 2017 16:43:11 +1000 (AEST) From: Paul Mackerras To: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Cc: Michael Neuling Subject: [PATCH 2/4] KVM: PPC: Book3S HV: Restore critical SPRs to host values on guest exit Date: Fri, 16 Jun 2017 16:42:51 +1000 Message-Id: <1497595373-3451-3-git-send-email-paulus@ozlabs.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1497595373-3451-1-git-send-email-paulus@ozlabs.org> References: <1497595373-3451-1-git-send-email-paulus@ozlabs.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This restores several special-purpose registers (SPRs) to sane values on guest exit that were missed before. TAR and VRSAVE are readable and writable by userspace, and we need to save and restore them to prevent the guest from potentially affecting userspace execution (not that TAR or VRSAVE are used by any known program that run uses the KVM_RUN ioctl). We save/restore these in kvmppc_vcpu_run_hv() rather than on every guest entry/exit. FSCR affects userspace execution in that it can prohibit access to certain facilities by userspace. We restore it to the normal value for the task on exit from the KVM_RUN ioctl. IAMR is normally 0, and is restored to 0 on guest exit. However, with a radix host on POWER9, it is set to a value that prevents the kernel from executing user-accessible memory. On POWER9, we save IAMR on guest entry and restore it on guest exit to the saved value rather than 0. On POWER8 we continue to set it to 0 on guest exit. PSPB is normally 0. We restore it to 0 on guest exit to prevent userspace taking advantage of the guest having set it non-zero (which would allow userspace to set its SMT priority to high). UAMOR is normally 0. We restore it to 0 on guest exit to prevent the AMR from being used as a covert channel between userspace processes, since the AMR is not context-switched at present. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 11 +++++++++-- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 9 ++++++++- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 400a599..a963762 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2908,6 +2908,8 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) int r; int srcu_idx; unsigned long ebb_regs[3] = {}; /* shut up GCC */ + unsigned long user_tar = 0; + unsigned int user_vrsave; if (!vcpu->arch.sane) { run->exit_reason = KVM_EXIT_INTERNAL_ERROR; @@ -2935,12 +2937,14 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) flush_all_to_thread(current); - /* Save userspace EBB register values */ + /* Save userspace EBB and other register values */ if (cpu_has_feature(CPU_FTR_ARCH_207S)) { ebb_regs[0] = mfspr(SPRN_EBBHR); ebb_regs[1] = mfspr(SPRN_EBBRR); ebb_regs[2] = mfspr(SPRN_BESCR); + user_tar = mfspr(SPRN_TAR); } + user_vrsave = mfspr(SPRN_VRSAVE); vcpu->arch.wqp = &vcpu->arch.vcore->wq; vcpu->arch.pgdir = current->mm->pgd; @@ -2968,12 +2972,15 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) } } while (is_kvmppc_resume_guest(r)); - /* Restore userspace EBB register values */ + /* Restore userspace EBB and other register values */ if (cpu_has_feature(CPU_FTR_ARCH_207S)) { mtspr(SPRN_EBBHR, ebb_regs[0]); mtspr(SPRN_EBBRR, ebb_regs[1]); mtspr(SPRN_BESCR, ebb_regs[2]); + mtspr(SPRN_TAR, user_tar); + mtspr(SPRN_FSCR, current->thread.fscr); } + mtspr(SPRN_VRSAVE, user_vrsave); out: vcpu->arch.state = KVMPPC_VCPU_NOTREADY; diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index e390b38..4e43905 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -558,6 +558,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) #define STACK_SLOT_TID (112-16) #define STACK_SLOT_PSSCR (112-24) #define STACK_SLOT_PID (112-32) +#define STACK_SLOT_IAMR (112-40) .global kvmppc_hv_entry kvmppc_hv_entry: @@ -758,9 +759,11 @@ BEGIN_FTR_SECTION mfspr r5, SPRN_TIDR mfspr r6, SPRN_PSSCR mfspr r7, SPRN_PID + mfspr r8, SPRN_IAMR std r5, STACK_SLOT_TID(r1) std r6, STACK_SLOT_PSSCR(r1) std r7, STACK_SLOT_PID(r1) + std r8, STACK_SLOT_IAMR(r1) END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) BEGIN_FTR_SECTION @@ -1515,11 +1518,12 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) * set by the guest could disrupt the host. */ li r0, 0 - mtspr SPRN_IAMR, r0 mtspr SPRN_CIABR, r0 mtspr SPRN_DAWRX, r0 + mtspr SPRN_PSPB, r0 mtspr SPRN_WORT, r0 BEGIN_FTR_SECTION + mtspr SPRN_IAMR, r0 mtspr SPRN_TCSCR, r0 /* Set MMCRS to 1<<31 to freeze and disable the SPMC counters */ li r0, 1 @@ -1535,6 +1539,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) std r6,VCPU_UAMOR(r9) li r6,0 mtspr SPRN_AMR,r6 + mtspr SPRN_UAMOR, r6 /* Switch DSCR back to host value */ mfspr r8, SPRN_DSCR @@ -1683,9 +1688,11 @@ BEGIN_FTR_SECTION ld r5, STACK_SLOT_TID(r1) ld r6, STACK_SLOT_PSSCR(r1) ld r7, STACK_SLOT_PID(r1) + ld r8, STACK_SLOT_IAMR(r1) mtspr SPRN_TIDR, r5 mtspr SPRN_PSSCR, r6 mtspr SPRN_PID, r7 + mtspr SPRN_IAMR, r8 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) BEGIN_FTR_SECTION PPC_INVALIDATE_ERAT