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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HK_RANDOM_FROM,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 B008AC35671 for ; Mon, 24 Feb 2020 12:01:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7690620828 for ; Mon, 24 Feb 2020 12:01:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727425AbgBXMBa (ORCPT ); Mon, 24 Feb 2020 07:01:30 -0500 Received: from mga12.intel.com ([192.55.52.136]:52215 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727185AbgBXMBa (ORCPT ); Mon, 24 Feb 2020 07:01:30 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Feb 2020 04:01:29 -0800 X-IronPort-AV: E=Sophos;i="5.70,480,1574150400"; d="scan'208";a="230626314" Received: from xiaoyaol-mobl.ccr.corp.intel.com (HELO [10.249.174.151]) ([10.249.174.151]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 24 Feb 2020 04:01:26 -0800 Subject: Re: [PATCH 1/2] kvm: vmx: Use basic exit reason to check if it's the specific VM EXIT To: Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel References: <20200224020751.1469-1-xiaoyao.li@intel.com> <20200224020751.1469-2-xiaoyao.li@intel.com> <87lfosp9xs.fsf@vitty.brq.redhat.com> From: Xiaoyao Li Message-ID: Date: Mon, 24 Feb 2020 20:01:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <87lfosp9xs.fsf@vitty.brq.redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/24/2020 6:16 PM, Vitaly Kuznetsov wrote: > Xiaoyao Li writes: > >> Current kvm uses the 32-bit exit reason to check if it's any specific VM >> EXIT, however only the low 16-bit of VM EXIT REASON acts as the basic >> exit reason. >> >> Introduce Macro basic(exit_reaso) > > "exit_reason" Ah, will correct it in v2. >> to help retrieve the basic exit reason >> from VM EXIT REASON, and use the basic exit reason for checking and >> indexing the exit hanlder. >> >> Signed-off-by: Xiaoyao Li >> --- >> arch/x86/kvm/vmx/vmx.c | 44 ++++++++++++++++++++++-------------------- >> arch/x86/kvm/vmx/vmx.h | 2 ++ >> 2 files changed, 25 insertions(+), 21 deletions(-) >> >> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c >> index 9a6664886f2e..85da72d4dc92 100644 >> --- a/arch/x86/kvm/vmx/vmx.c >> +++ b/arch/x86/kvm/vmx/vmx.c >> @@ -1584,7 +1584,7 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu) >> * i.e. we end up advancing IP with some random value. >> */ >> if (!static_cpu_has(X86_FEATURE_HYPERVISOR) || >> - to_vmx(vcpu)->exit_reason != EXIT_REASON_EPT_MISCONFIG) { >> + basic(to_vmx(vcpu)->exit_reason) != EXIT_REASON_EPT_MISCONFIG) { > > "basic" word is probably 'too basic' to be used for this purpose. Even > if we need a macro for it (I'm not really convinced it improves the > readability), I'd suggest we name it 'basic_exit_reason()' instead. Agreed. >> rip = kvm_rip_read(vcpu); >> rip += vmcs_read32(VM_EXIT_INSTRUCTION_LEN); >> kvm_rip_write(vcpu, rip); >> @@ -5797,6 +5797,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, >> { >> struct vcpu_vmx *vmx = to_vmx(vcpu); >> u32 exit_reason = vmx->exit_reason; >> + u16 basic_exit_reason = basic(exit_reason); > > I don't think renaming local variable is needed, let's just do > > 'u16 exit_reason = basic_exit_reason(vmx->exit_reason)' and keep the > rest of the code as-is. No, we can't do this. It's not just renaming local variable, the full 32-bit exit reason is used elsewhere in this function that needs the upper 16-bit. Here variable basic_exit_reason is added for the cases where only basic exit reason number is needed. >> u32 vectoring_info = vmx->idt_vectoring_info; >> >> trace_kvm_exit(exit_reason, vcpu, KVM_ISA_VMX); >> @@ -5842,17 +5843,17 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, >> * will cause infinite loop. >> */ >> if ((vectoring_info & VECTORING_INFO_VALID_MASK) && >> - (exit_reason != EXIT_REASON_EXCEPTION_NMI && >> - exit_reason != EXIT_REASON_EPT_VIOLATION && >> - exit_reason != EXIT_REASON_PML_FULL && >> - exit_reason != EXIT_REASON_TASK_SWITCH)) { >> + (basic_exit_reason != EXIT_REASON_EXCEPTION_NMI && >> + basic_exit_reason != EXIT_REASON_EPT_VIOLATION && >> + basic_exit_reason != EXIT_REASON_PML_FULL && >> + basic_exit_reason != EXIT_REASON_TASK_SWITCH)) { >> vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; >> vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV; >> vcpu->run->internal.ndata = 3; >> vcpu->run->internal.data[0] = vectoring_info; >> vcpu->run->internal.data[1] = exit_reason; >> vcpu->run->internal.data[2] = vcpu->arch.exit_qualification; >> - if (exit_reason == EXIT_REASON_EPT_MISCONFIG) { >> + if (basic_exit_reason == EXIT_REASON_EPT_MISCONFIG) { >> vcpu->run->internal.ndata++; >> vcpu->run->internal.data[3] = >> vmcs_read64(GUEST_PHYSICAL_ADDRESS); >> @@ -5884,32 +5885,32 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, >> return 1; >> } >> >> - if (exit_reason >= kvm_vmx_max_exit_handlers) >> + if (basic_exit_reason >= kvm_vmx_max_exit_handlers) >> goto unexpected_vmexit; >> #ifdef CONFIG_RETPOLINE >> - if (exit_reason == EXIT_REASON_MSR_WRITE) >> + if (basic_exit_reason == EXIT_REASON_MSR_WRITE) >> return kvm_emulate_wrmsr(vcpu); >> - else if (exit_reason == EXIT_REASON_PREEMPTION_TIMER) >> + else if (basic_exit_reason == EXIT_REASON_PREEMPTION_TIMER) >> return handle_preemption_timer(vcpu); >> - else if (exit_reason == EXIT_REASON_INTERRUPT_WINDOW) >> + else if (basic_exit_reason == EXIT_REASON_INTERRUPT_WINDOW) >> return handle_interrupt_window(vcpu); >> - else if (exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) >> + else if (basic_exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) >> return handle_external_interrupt(vcpu); >> - else if (exit_reason == EXIT_REASON_HLT) >> + else if (basic_exit_reason == EXIT_REASON_HLT) >> return kvm_emulate_halt(vcpu); >> - else if (exit_reason == EXIT_REASON_EPT_MISCONFIG) >> + else if (basic_exit_reason == EXIT_REASON_EPT_MISCONFIG) >> return handle_ept_misconfig(vcpu); >> #endif >> >> - exit_reason = array_index_nospec(exit_reason, >> + basic_exit_reason = array_index_nospec(basic_exit_reason, >> kvm_vmx_max_exit_handlers); >> - if (!kvm_vmx_exit_handlers[exit_reason]) >> + if (!kvm_vmx_exit_handlers[basic_exit_reason]) >> goto unexpected_vmexit; >> >> - return kvm_vmx_exit_handlers[exit_reason](vcpu); >> + return kvm_vmx_exit_handlers[basic_exit_reason](vcpu); >> >> unexpected_vmexit: >> - vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", exit_reason); >> + vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", basic_exit_reason); >> dump_vmcs(); >> vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; >> vcpu->run->internal.suberror = >> @@ -6241,13 +6242,14 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu, >> enum exit_fastpath_completion *exit_fastpath) >> { >> struct vcpu_vmx *vmx = to_vmx(vcpu); >> + u16 basic_exit_reason = basic(vmx->exit_reason); > > Here I'd suggest we also use the same > > 'u16 exit_reason = basic_exit_reason(vmx->exit_reason)' > > as above. > >> >> - if (vmx->exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) >> + if (basic_exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT) >> handle_external_interrupt_irqoff(vcpu); >> - else if (vmx->exit_reason == EXIT_REASON_EXCEPTION_NMI) >> + else if (basic_exit_reason == EXIT_REASON_EXCEPTION_NMI) >> handle_exception_nmi_irqoff(vmx); >> else if (!is_guest_mode(vcpu) && >> - vmx->exit_reason == EXIT_REASON_MSR_WRITE) >> + basic_exit_reason == EXIT_REASON_MSR_WRITE) >> *exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu); >> } >> >> @@ -6621,7 +6623,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) >> vmx->idt_vectoring_info = 0; >> >> vmx->exit_reason = vmx->fail ? 0xdead : vmcs_read32(VM_EXIT_REASON); >> - if ((u16)vmx->exit_reason == EXIT_REASON_MCE_DURING_VMENTRY) >> + if (basic(vmx->exit_reason) == EXIT_REASON_MCE_DURING_VMENTRY) >> kvm_machine_check(); >> >> if (vmx->fail || (vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY)) >> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h >> index 7f42cf3dcd70..c6ba33eedb59 100644 >> --- a/arch/x86/kvm/vmx/vmx.h >> +++ b/arch/x86/kvm/vmx/vmx.h >> @@ -22,6 +22,8 @@ extern u32 get_umwait_control_msr(void); >> >> #define X2APIC_MSR(r) (APIC_BASE_MSR + ((r) >> 4)) >> >> +#define basic(exit_reason) ((u16)(exit_reason)) >> + >> #ifdef CONFIG_X86_64 >> #define NR_SHARED_MSRS 7 >> #else >