Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbaKEBnK (ORCPT ); Tue, 4 Nov 2014 20:43:10 -0500 Received: from mga03.intel.com ([134.134.136.65]:46125 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751435AbaKEBnI (ORCPT ); Tue, 4 Nov 2014 20:43:08 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,316,1413270000"; d="scan'208";a="602419697" Message-ID: <545980A9.8030405@intel.com> Date: Wed, 05 Nov 2014 09:43:05 +0800 From: "Chen, Tiejun" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] kvm: x86: vmx: avoid returning bool to distinguish success from error References: <1415122394-31986-1-git-send-email-pbonzini@redhat.com> In-Reply-To: <1415122394-31986-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/11/5 1:33, Paolo Bonzini wrote: > Return a negative error code instead, and WARN() when we should be covering > the entire 2-bit space of vmcs_field_type's return value. For increased > robustness, add a BUILD_BUG_ON checking the range of vmcs_field_to_offset. > > Suggested-by: Tiejun Chen > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/vmx.c | 51 +++++++++++++++++++++++++++++++-------------------- > 1 file changed, 31 insertions(+), 20 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 12f6f9a8dd8d..0ee148f1687f 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -720,12 +720,15 @@ static const unsigned short vmcs_field_to_offset_table[] = { > FIELD(HOST_RSP, host_rsp), > FIELD(HOST_RIP, host_rip), > }; > -static const int max_vmcs_field = ARRAY_SIZE(vmcs_field_to_offset_table); > > static inline short vmcs_field_to_offset(unsigned long field) > { > - if (field >= max_vmcs_field || vmcs_field_to_offset_table[field] == 0) > - return -1; > + BUILD_BUG_ON(ARRAY_SIZE(vmcs_field_to_offset_table) > SHRT_MAX); > + > + if (field >= ARRAY_SIZE(vmcs_field_to_offset_table) || > + vmcs_field_to_offset_table[field] == 0) > + return -ENOENT; > + > return vmcs_field_to_offset_table[field]; > } > > @@ -6492,58 +6495,60 @@ static inline int vmcs_field_readonly(unsigned long field) > * some of the bits we return here (e.g., on 32-bit guests, only 32 bits of > * 64-bit fields are to be returned). > */ > -static inline bool vmcs12_read_any(struct kvm_vcpu *vcpu, > - unsigned long field, u64 *ret) > +static inline int vmcs12_read_any(struct kvm_vcpu *vcpu, > + unsigned long field, u64 *ret) > { > short offset = vmcs_field_to_offset(field); > char *p; > > if (offset < 0) > - return 0; > + return offset; > > p = ((char *)(get_vmcs12(vcpu))) + offset; > > switch (vmcs_field_type(field)) { > case VMCS_FIELD_TYPE_NATURAL_WIDTH: > *ret = *((natural_width *)p); > - return 1; > + return 0; > case VMCS_FIELD_TYPE_U16: > *ret = *((u16 *)p); > - return 1; > + return 0; > case VMCS_FIELD_TYPE_U32: > *ret = *((u32 *)p); > - return 1; > + return 0; > case VMCS_FIELD_TYPE_U64: > *ret = *((u64 *)p); > - return 1; > + return 0; > default: > - return 0; /* can never happen. */ > + WARN_ON(1); > + return -ENOENT; > } > } > > > -static inline bool vmcs12_write_any(struct kvm_vcpu *vcpu, > - unsigned long field, u64 field_value){ > +static inline int vmcs12_write_any(struct kvm_vcpu *vcpu, > + unsigned long field, u64 field_value){ > short offset = vmcs_field_to_offset(field); > char *p = ((char *) get_vmcs12(vcpu)) + offset; > if (offset < 0) > - return false; > + return offset; > > switch (vmcs_field_type(field)) { > case VMCS_FIELD_TYPE_U16: > *(u16 *)p = field_value; > - return true; > + return 0; > case VMCS_FIELD_TYPE_U32: > *(u32 *)p = field_value; > - return true; > + return 0; > case VMCS_FIELD_TYPE_U64: > *(u64 *)p = field_value; > - return true; > + return 0; > case VMCS_FIELD_TYPE_NATURAL_WIDTH: > *(natural_width *)p = field_value; > - return true; > + return 0; > default: > - return false; /* can never happen. */ > + WARN_ON(1); > + return -ENOENT; > } > > } > @@ -6576,6 +6581,9 @@ static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx) > case VMCS_FIELD_TYPE_NATURAL_WIDTH: > field_value = vmcs_readl(field); > break; > + default: > + WARN_ON(1); > + continue; 'continue' versus 'break'? Thanks Tiejun > } > vmcs12_write_any(&vmx->vcpu, field, field_value); > } > @@ -6621,6 +6629,9 @@ static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx) > case VMCS_FIELD_TYPE_NATURAL_WIDTH: > vmcs_writel(field, (long)field_value); > break; > + default: > + WARN_ON(1); > + break; > } > } > } > @@ -6659,7 +6670,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) > /* Decode instruction info and find the field to read */ > field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28) & 0xf)); > /* Read the field, zero-extended to a u64 field_value */ > - if (!vmcs12_read_any(vcpu, field, &field_value)) { > + if (vmcs12_read_any(vcpu, field, &field_value) < 0) { > nested_vmx_failValid(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT); > skip_emulated_instruction(vcpu); > return 1; > -- 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/