On Mon, Mar 18, 2019 at 11:03:48PM +0800, Yang Weijiang wrote: > "Load Guest CET state" bit controls whether guest CET states > will be loaded at Guest entry. Before doing that, KVM needs > to check if CPU CET feature is available.
Use the changelog to describe *why* the patch does what it does, for something this simple it's obvious *what* the patch adds. Specifically, there was a decent amount of discussion regarding the virtualization hole that gets introduced when SHSTK!=IBT, and that need to be captured in the changelog. > > Signed-off-by: Zhang Yi Z <[email protected]> > Signed-off-by: Yang Weijiang <[email protected]> > --- > arch/x86/kvm/vmx.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 28b8ac027bd7..246467c12930 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -55,6 +55,7 @@ > #include <asm/mmu_context.h> > #include <asm/spec-ctrl.h> > #include <asm/mshyperv.h> > +#include <asm/cet.h> > > #include "trace.h" > #include "pmu.h" > @@ -5414,6 +5415,23 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned > long cr4) > return 1; > } > > + /* > + * To enable Guest CET, check whether CPU CET feature is > + * available, if it's there, set Guest CET state loading bit > + * per CR4.CET status, otherwise, return a fault to Guest. > + */ No need for the comment, the code is straightforward. > + if (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > + guest_cpuid_has(vcpu, X86_FEATURE_IBT)) { > + if (cr4 & X86_CR4_CET) > + vmcs_set_bits(VM_ENTRY_CONTROLS, > + VM_ENTRY_LOAD_GUEST_CET_STATE); > + else > + vmcs_clear_bits(VM_ENTRY_CONTROLS, > + VM_ENTRY_LOAD_GUEST_CET_STATE); > + } else if (cr4 & X86_CR4_CET) { > + return 1; > + } > + > if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4)) > return 1; > > -- > 2.17.1 >
