| Date | Tue, 5 Apr 2022 17:32:39 +0200 | Subject | Re: [RFC PATCH v5 074/104] KVM: x86: Add a switch_db_regs flag to handle TDX's auto-switched behavior | From | Paolo Bonzini <> |
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On 3/4/22 20:49, isaku.yamahata@intel.com wrote: > vcpu->arch.efer = EFER_SCE | EFER_LME | EFER_LMA | EFER_NX; > > + vcpu->arch.switch_db_regs = KVM_DEBUGREG_AUTO_SWITCH; > vcpu->arch.cr0_guest_owned_bits = -1ul; > vcpu->arch.cr4_guest_owned_bits = -1ul; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 45e8a02e99bf..89d04cd64cd0 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10084,7 +10084,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > if (vcpu->arch.guest_fpu.xfd_err) > wrmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err); > > - if (unlikely(vcpu->arch.switch_db_regs)) { > + if (unlikely(vcpu->arch.switch_db_regs & ~KVM_DEBUGREG_AUTO_SWITCH)) { > set_debugreg(0, 7); > set_debugreg(vcpu->arch.eff_db[0], 0); > set_debugreg(vcpu->arch.eff_db[1], 1);
I'm confused. I'm probably missing something obvious, but where does KVM_DEBUGREG_AUTO_SWITCH affect the behavior of KVM? vcpu_enter_guest would still write %db0-%db3 if KVM_DEBUGREG_BP_ENABLED is set, for example.
Do you mean:
if (unlikely(vcpu->arch.switch_db_regs) && !unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH)) {
?
Paolo > @@ -10126,6 +10126,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) > */ > if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) { > WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP); > + WARN_ON(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH); > static_call(kvm_x86_sync_dirty_debug_regs)(vcpu); > kvm_update_dr0123(vcpu); > kvm_update_dr7(vcpu);
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