KVM: x86: Suppress code #DBs on Intel if MOV/POP SS blocking is active
Suppress code breakpoints if MOV/POP SS blocking is active and the guest CPU is Intel, i.e. if the guest thinks it's running on an Intel CPU. Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active, whereas AMD (and its descendents) do not. Signed-off-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20220830231614.3580124-6-seanjc@google.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -8554,6 +8554,23 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
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}
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EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
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static bool kvm_is_code_breakpoint_inhibited(struct kvm_vcpu *vcpu)
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{
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u32 shadow;
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if (kvm_get_rflags(vcpu) & X86_EFLAGS_RF)
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return true;
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/*
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* Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active,
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* but AMD CPUs do not. MOV/POP SS blocking is rare, check that first
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* to avoid the relatively expensive CPUID lookup.
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*/
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shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
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return (shadow & KVM_X86_SHADOW_INT_MOV_SS) &&
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guest_cpuid_is_intel(vcpu);
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}
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static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
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int emulation_type, int *r)
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{
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@ -8596,7 +8613,7 @@ static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
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}
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if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK) &&
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!(kvm_get_rflags(vcpu) & X86_EFLAGS_RF)) {
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!kvm_is_code_breakpoint_inhibited(vcpu)) {
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unsigned long eip = kvm_get_linear_rip(vcpu);
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u32 dr6 = kvm_vcpu_check_hw_bp(eip, 0,
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vcpu->arch.dr7,
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