From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 150E6C282DD for ; Sat, 20 Apr 2019 05:35:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC1A721479 for ; Sat, 20 Apr 2019 05:35:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727452AbfDTFfR (ORCPT ); Sat, 20 Apr 2019 01:35:17 -0400 Received: from mga05.intel.com ([192.55.52.43]:43741 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725884AbfDTFfR (ORCPT ); Sat, 20 Apr 2019 01:35:17 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Apr 2019 22:35:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,372,1549958400"; d="scan'208";a="144225083" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.181]) by orsmga003.jf.intel.com with ESMTP; 19 Apr 2019 22:35:16 -0700 Date: Fri, 19 Apr 2019 22:35:16 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: nVMX: allow tests to use bad virtual-APIC page address Message-ID: <20190420053516.GA15539@linux.intel.com> References: <1555335333-23636-2-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1555335333-23636-2-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 15, 2019 at 03:35:33PM +0200, Paolo Bonzini wrote: > As mentioned in the comment, there are some special cases where we can simply > clear the TPR shadow bit from the CPU-based execution controls in the vmcs02. > Handle them so that we can remove some XFAILs from vmx.flat. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/vmx/nested.c | 25 ++++++++++++++++--------- > arch/x86/kvm/vmx/vmx.c | 2 +- > arch/x86/kvm/vmx/vmx.h | 2 ++ > 3 files changed, 19 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 7ec9bb1dd723..a22af5a85540 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2873,20 +2873,27 @@ static void nested_get_vmcs12_pages(struct kvm_vcpu *vcpu) > /* > * If translation failed, VM entry will fail because > * prepare_vmcs02 set VIRTUAL_APIC_PAGE_ADDR to -1ull. > - * Failing the vm entry is _not_ what the processor > - * does but it's basically the only possibility we > - * have. We could still enter the guest if CR8 load > - * exits are enabled, CR8 store exits are enabled, and > - * virtualize APIC access is disabled; in this case > - * the processor would never use the TPR shadow and we > - * could simply clear the bit from the execution > - * control. But such a configuration is useless, so > - * let's keep the code simple. > */ > if (!is_error_page(page)) { > vmx->nested.virtual_apic_page = page; > hpa = page_to_phys(vmx->nested.virtual_apic_page); > vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, hpa); > + } else if (nested_cpu_has(vmcs12, CPU_BASED_CR8_LOAD_EXITING) && > + nested_cpu_has(vmcs12, CPU_BASED_CR8_STORE_EXITING) && > + !nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) { > + /* > + * The processor will never use the TPR shadow, simply > + * clear the bit from the execution control. Such a > + * configuration is useless, but it happens in tests. > + * For any other configuration, failing the vm entry is > + * _not_ what the processor does but it's basically the > + * only possibility we have. > + */ > + vmcs_clear_bits(CPU_BASED_VM_EXEC_CONTROL, > + CPU_BASED_TPR_SHADOW); > + } else { > + printk("bad virtual-APIC page address\n"); > + dump_vmcs(); I don't think we should dump the VMCS here, or have any form of print at all. dump_vmcs() is especially bad as it allows userspace to spam the kernel log at the error level. I haven't actually checked, but I assume the nested consistency check tracing patch would be a better way to debug something of this nature in production. > } > } > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index f8054dc1de65..14cacfd7ffd0 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -5603,7 +5603,7 @@ static void vmx_dump_dtsel(char *name, uint32_t limit) > vmcs_readl(limit + GUEST_GDTR_BASE - GUEST_GDTR_LIMIT)); > } > > -static void dump_vmcs(void) > +void dump_vmcs(void) > { > u32 vmentry_ctl = vmcs_read32(VM_ENTRY_CONTROLS); > u32 vmexit_ctl = vmcs_read32(VM_EXIT_CONTROLS); > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index a1e00d0a2482..f879529906b4 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -517,4 +517,6 @@ static inline void decache_tsc_multiplier(struct vcpu_vmx *vmx) > vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio); > } > > +void dump_vmcs(void); > + > #endif /* __KVM_X86_VMX_H */ > -- > 1.8.3.1 >