From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH 1/3] XSA-60 security hole: disable EPT when !cpu_has_vmx_pat Date: Thu, 17 Oct 2013 11:05:30 +0100 Message-ID: <525FB66A.50705@citrix.com> References: <525FD0DB02000078000FBC11@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <525FD0DB02000078000FBC11@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Jinsong Liu , Keir Fraser , Jun Nakajima , Tim Deegan , "zhenzhong.duan@oracle.com" , "xen-devel@lists.xen.org" , Will Auld , "suravee.suthikulpanit@amd.com" , "sherry.hurwitz@amd.com" List-Id: xen-devel@lists.xenproject.org On 17/10/13 10:58, Jan Beulich wrote: >>>> On 16.10.13 at 20:33, "Liu, Jinsong" wrote: >> From 9ec2ca512979e99a229d333038f849a2d5a7fde5 Mon Sep 17 00:00:00 2001 >> From: Liu Jinsong >> Date: Thu, 17 Oct 2013 04:00:49 +0800 >> Subject: [PATCH 1/3] XSA-60 security hole: disable EPT when !cpu_has_vmx_pat >> >> Recently Oracle developers found a Xen security issue as DOS affecting, >> named as XSA-60. Please refer http://xenbits.xen.org/xsa/advisory-60.html >> Basically it involves how to handle guest cr0.cd setting, which under >> some environment it consumes much time resulting in DOS-like behavior. >> >> This is a preparing patch for fixing XSA-60. Later patch will fix XSA-60 >> via PAT under Intel EPT case, which depends on cpu_has_vmx_pat. >> >> Signed-off-by: Liu Jinsong > Reviewed-by: Jan Beulich Reviewed-by: Andrew Cooper > >> --- >> xen/arch/x86/hvm/vmx/vmcs.c | 4 ++-- >> xen/arch/x86/hvm/vmx/vmx.c | 10 +++++++--- >> 2 files changed, 9 insertions(+), 5 deletions(-) >> >> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c >> index 6526504..6916c6d 100644 >> --- a/xen/arch/x86/hvm/vmx/vmcs.c >> +++ b/xen/arch/x86/hvm/vmx/vmcs.c >> @@ -921,7 +921,7 @@ static int construct_vmcs(struct vcpu *v) >> vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_CS, MSR_TYPE_R | >> MSR_TYPE_W); >> vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_ESP, MSR_TYPE_R >> | MSR_TYPE_W); >> vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP, MSR_TYPE_R >> | MSR_TYPE_W); >> - if ( cpu_has_vmx_pat && paging_mode_hap(d) ) >> + if ( paging_mode_hap(d) ) >> vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT, MSR_TYPE_R | >> MSR_TYPE_W); >> } >> >> @@ -1063,7 +1063,7 @@ static int construct_vmcs(struct vcpu *v) >> __vmwrite(EPT_POINTER, ept_get_eptp(ept)); >> } >> >> - if ( cpu_has_vmx_pat && paging_mode_hap(d) ) >> + if ( paging_mode_hap(d) ) >> { >> u64 host_pat, guest_pat; >> >> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c >> index 9ca8632..b59bf59 100644 >> --- a/xen/arch/x86/hvm/vmx/vmx.c >> +++ b/xen/arch/x86/hvm/vmx/vmx.c >> @@ -908,7 +908,7 @@ static unsigned long vmx_get_shadow_gs_base(struct vcpu >> *v) >> >> static int vmx_set_guest_pat(struct vcpu *v, u64 gpat) >> { >> - if ( !cpu_has_vmx_pat || !paging_mode_hap(v->domain) ) >> + if ( !paging_mode_hap(v->domain) ) >> return 0; >> >> vmx_vmcs_enter(v); >> @@ -919,7 +919,7 @@ static int vmx_set_guest_pat(struct vcpu *v, u64 gpat) >> >> static int vmx_get_guest_pat(struct vcpu *v, u64 *gpat) >> { >> - if ( !cpu_has_vmx_pat || !paging_mode_hap(v->domain) ) >> + if ( !paging_mode_hap(v->domain) ) >> return 0; >> >> vmx_vmcs_enter(v); >> @@ -1591,7 +1591,11 @@ const struct hvm_function_table * __init >> start_vmx(void) >> return NULL; >> } >> >> - if ( cpu_has_vmx_ept ) >> + /* >> + * Do not enable EPT when (!cpu_has_vmx_pat), to prevent security hole >> + * which refer to http://xenbits.xen.org/xsa/advisory-60.html >> + */ >> + if ( cpu_has_vmx_ept && cpu_has_vmx_pat ) >> { >> vmx_function_table.hap_supported = 1; >> >> -- >> 1.7.1 > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel