Messages in this thread | | | Subject | Re: [PATCH v5 2/3] KVM: nVMX: Validate the IA32_BNDCFGS on nested VM-entry | From | Krish Sadhukhan <> | Date | Fri, 3 Nov 2017 10:13:08 -0700 |
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On 11/02/2017 11:40 PM, Wanpeng Li wrote: > 2017-11-03 14:31 GMT+08:00 Krish Sadhukhan <krish.sadhukhan@oracle.com>: >> >> On 11/02/2017 05:50 PM, Wanpeng Li wrote: >>> From: Wanpeng Li <wanpeng.li@hotmail.com> >>> >>> According to the SDM, if the "load IA32_BNDCFGS" VM-entry controls is 1, >>> the >>> following checks are performed on the field for the IA32_BNDCFGS MSR: >>> - Bits reserved in the IA32_BNDCFGS MSR must be 0. >>> - The linear address in bits 63:12 must be canonical. >>> >>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> Cc: Paolo Bonzini <pbonzini@redhat.com> >>> Cc: Radim Krčmář <rkrcmar@redhat.com> >>> Cc: Jim Mattson <jmattson@google.com> >>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> >>> --- >>> v3 -> v4: >>> * simply condition >>> * use && instead of nested "if"s >>> >>> arch/x86/kvm/vmx.c | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index e6c8ffa..6cf3972 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -10805,6 +10805,11 @@ static int check_vmentry_postreqs(struct kvm_vcpu >>> *vcpu, struct vmcs12 *vmcs12, >>> return 1; >>> } >>> + if (kvm_mpx_supported() && >>> + (is_noncanonical_address(vmcs12->guest_bndcfgs & >>> PAGE_MASK, vcpu) || >>> + (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD))) >>> + return 1; >>> + >>> return 0; >>> } >>> >> Hi Wanpeng, >> The SDM check is performed only when "load IA32_BNDCFGS" VM-entry control >> is 1. But vmx_mpx_supported() returns true when both "load IA32_BNDCFGS" and >> "store IA32_BNDCFGS" VM-entry controls are 1. Therefore your check is >> performed when both controls are 1. Did I miss something here ? > https://lkml.org/lkml/2017/11/2/748 Paolo hopes the simplification. > > Regards, > Wanpeng Li I got that simplification and your changes look good to me.
However, I am still curious know the reason why vmx_mpx_supported() returns true only when both controls are true whereas the SDM states the following:
"IA32_BNDCFGS (64 bits). This field is supported only on processors that support either the 1-setting of the “load IA32_BNDCFGS” VM-entry control or that of the “clear IA32_BNDCFGS” VM-exit control."
Thanks, Krish
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