From patchwork Sun May 11 23:19:40 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 347841 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 6015E14009F for ; Mon, 12 May 2014 09:19:46 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753484AbaEKXTo (ORCPT ); Sun, 11 May 2014 19:19:44 -0400 Received: from cantor2.suse.de ([195.135.220.15]:46841 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751954AbaEKXTn (ORCPT ); Sun, 11 May 2014 19:19:43 -0400 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 1CC82AD0C; Sun, 11 May 2014 23:19:41 +0000 (UTC) From: Alexander Graf To: kvm-ppc@vger.kernel.org Cc: kvm@vger.kernel.org Subject: [PATCH 1/2] KVM: PPC: Disable NX for old magic page using guests Date: Mon, 12 May 2014 01:19:40 +0200 Message-Id: <1399850380-23274-1-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.7.12.4 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Old guests try to use the magic page, but map their trampoline code inside of an NX region. Since we can't fix those old kernels, try to detect whether the guest is sane or not. If not, just disable NX functionality in KVM so that old guests at least work at all. For newer guests, add a bit that we can set to keep NX functionality available. Signed-off-by: Alexander Graf --- Documentation/virtual/kvm/ppc-pv.txt | 14 ++++++++++++++ arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/include/uapi/asm/kvm_para.h | 6 ++++++ arch/powerpc/kvm/book3s_64_mmu.c | 3 +++ arch/powerpc/kvm/powerpc.c | 14 ++++++++++++-- 5 files changed, 36 insertions(+), 2 deletions(-) diff --git a/Documentation/virtual/kvm/ppc-pv.txt b/Documentation/virtual/kvm/ppc-pv.txt index 4643cde..3195606 100644 --- a/Documentation/virtual/kvm/ppc-pv.txt +++ b/Documentation/virtual/kvm/ppc-pv.txt @@ -94,10 +94,24 @@ a bitmap of available features inside the magic page. The following enhancements to the magic page are currently available: KVM_MAGIC_FEAT_SR Maps SR registers r/w in the magic page + KVM_MAGIC_FEAT_MAS0_TO_SPRG7 Maps MASn, ESR, PIR and high SPRGs For enhanced features in the magic page, please check for the existence of the feature before using them! +Magic page flags +================ + +In addition to features that indicate whether a host is capable of a particular +feature we also have a channel for a guest to tell the guest whether it's capable +of something. This is what we call "flags". + +Flags are passed to the host in the low 12 bits of the Effective Address. + +The following flags are currently available for a guest to expose: + + MAGIC_PAGE_FLAG_NOT_MAPPED_NX Guest handles NX bits correclty wrt magic page + MSR bits ======== diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 29fbb55..bb66d8b 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -631,6 +631,7 @@ struct kvm_vcpu_arch { #endif unsigned long magic_page_pa; /* phys addr to map the magic page to */ unsigned long magic_page_ea; /* effect. addr to map the magic page to */ + bool disable_kernel_nx; int irq_type; /* one of KVM_IRQ_* */ int irq_cpu_id; diff --git a/arch/powerpc/include/uapi/asm/kvm_para.h b/arch/powerpc/include/uapi/asm/kvm_para.h index e3af328..91e42f0 100644 --- a/arch/powerpc/include/uapi/asm/kvm_para.h +++ b/arch/powerpc/include/uapi/asm/kvm_para.h @@ -82,10 +82,16 @@ struct kvm_vcpu_arch_shared { #define KVM_FEATURE_MAGIC_PAGE 1 +/* Magic page flags from host to guest */ + #define KVM_MAGIC_FEAT_SR (1 << 0) /* MASn, ESR, PIR, and high SPRGs */ #define KVM_MAGIC_FEAT_MAS0_TO_SPRG7 (1 << 1) +/* Magic page flags from guest to host */ + +#define MAGIC_PAGE_FLAG_NOT_MAPPED_NX (1 << 0) + #endif /* _UAPI__POWERPC_KVM_PARA_H__ */ diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c index 278729f..774a253 100644 --- a/arch/powerpc/kvm/book3s_64_mmu.c +++ b/arch/powerpc/kvm/book3s_64_mmu.c @@ -313,6 +313,9 @@ do_second: gpte->raddr = (r & HPTE_R_RPN & ~eaddr_mask) | (eaddr & eaddr_mask); gpte->page_size = pgsize; gpte->may_execute = ((r & HPTE_R_N) ? false : true); + if (unlikely(vcpu->arch.disable_kernel_nx) && + !(kvmppc_get_msr(vcpu) & MSR_PR)) + gpte->may_execute = true; gpte->may_read = false; gpte->may_write = false; diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index b4e15bf..154f352 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -177,8 +177,18 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu) vcpu->arch.shared_big_endian = shared_big_endian; #endif - vcpu->arch.magic_page_pa = param1; - vcpu->arch.magic_page_ea = param2; + if (!(param2 & MAGIC_PAGE_FLAG_NOT_MAPPED_NX)) { + /* + * Older versions of the Linux magic page code had + * a bug where they would map their trampoline code + * NX. If that's the case, remove !PR NX capability. + */ + vcpu->arch.disable_kernel_nx = true; + kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); + } + + vcpu->arch.magic_page_pa = param1 & ~0xfffULL; + vcpu->arch.magic_page_ea = param2 & ~0xfffULL; r2 = KVM_MAGIC_FEAT_SR | KVM_MAGIC_FEAT_MAS0_TO_SPRG7;