Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754295AbaKLB0K (ORCPT ); Tue, 11 Nov 2014 20:26:10 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:58882 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754264AbaKLB0I (ORCPT ); Tue, 11 Nov 2014 20:26:08 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrew Honig , Paolo Bonzini Subject: [PATCH 3.17 129/319] KVM: x86: Prevent host from panicking on shared MSR writes. Date: Wed, 12 Nov 2014 10:14:27 +0900 Message-Id: <20141112011013.946755620@linuxfoundation.org> X-Mailer: git-send-email 2.1.3 In-Reply-To: <20141112010952.553519040@linuxfoundation.org> References: <20141112010952.553519040@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Honig commit 8b3c3104c3f4f706e99365c3e0d2aa61b95f969f upstream. The previous patch blocked invalid writes directly when the MSR is written. As a precaution, prevent future similar mistakes by gracefulling handle GPs caused by writes to shared MSRs. Signed-off-by: Andrew Honig [Remove parts obsoleted by Nadav's patch. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/vmx.c | 7 +++++-- arch/x86/kvm/x86.c | 11 ++++++++--- 3 files changed, 14 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1049,7 +1049,7 @@ int kvm_cpu_get_interrupt(struct kvm_vcp void kvm_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_define_shared_msr(unsigned index, u32 msr); -void kvm_set_shared_msr(unsigned index, u64 val, u64 mask); +int kvm_set_shared_msr(unsigned index, u64 val, u64 mask); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip); --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2632,12 +2632,15 @@ static int vmx_set_msr(struct kvm_vcpu * default: msr = find_msr_entry(vmx, msr_index); if (msr) { + u64 old_msr_data = msr->data; msr->data = data; if (msr - vmx->guest_msrs < vmx->save_nmsrs) { preempt_disable(); - kvm_set_shared_msr(msr->index, msr->data, - msr->mask); + ret = kvm_set_shared_msr(msr->index, msr->data, + msr->mask); preempt_enable(); + if (ret) + msr->data = old_msr_data; } break; } --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -229,20 +229,25 @@ static void kvm_shared_msr_cpu_online(vo shared_msr_update(i, shared_msrs_global.msrs[i]); } -void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) +int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) { unsigned int cpu = smp_processor_id(); struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); + int err; if (((value ^ smsr->values[slot].curr) & mask) == 0) - return; + return 0; smsr->values[slot].curr = value; - wrmsrl(shared_msrs_global.msrs[slot], value); + err = wrmsrl_safe(shared_msrs_global.msrs[slot], value); + if (err) + return 1; + if (!smsr->registered) { smsr->urn.on_user_return = kvm_on_user_return; user_return_notifier_register(&smsr->urn); smsr->registered = true; } + return 0; } EXPORT_SYMBOL_GPL(kvm_set_shared_msr); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/