From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [RFC][PATCH] KVM: SVM: Defer NMI injection after IRET via interrupt Date: Sun, 14 Feb 2010 18:51:15 +0100 Message-ID: <4B783813.8000400@web.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigEAEC8EB18C3C50D33A54514B" Cc: kvm To: Gleb Natapov Return-path: Received: from fmmailgate02.web.de ([217.72.192.227]:46392 "EHLO fmmailgate02.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752372Ab0BNRvZ (ORCPT ); Sun, 14 Feb 2010 12:51:25 -0500 Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigEAEC8EB18C3C50D33A54514B Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable From: Jan Kiszka Stolen from Xen: Instead if stepping over IRET, use the interrupt shadow to inject the NMI on IRET while still deferring its delivery after the instruction. This has the same limitation as the existing approach: Exceptions raised by the IRET will trigger an early NMI injection. The advantages are that we avoid one VM exit and we no longer have to fiddle with TF which can conflict with other users. Signed-off-by: Jan Kiszka --- Note: untested! arch/x86/kvm/svm.c | 40 +++++++++++++--------------------------- 1 files changed, 13 insertions(+), 27 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 52f78dd..f355dc6 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -107,8 +107,6 @@ struct vcpu_svm { u32 *msrpm; =20 struct nested_state nested; - - bool nmi_singlestep; }; =20 /* enable NPT for AMD64 and X86 with PAE */ @@ -1075,9 +1073,6 @@ static void update_db_intercept(struct kvm_vcpu *vc= pu) svm->vmcb->control.intercept_exceptions &=3D ~((1 << DB_VECTOR) | (1 << BP_VECTOR)); =20 - if (svm->nmi_singlestep) - svm->vmcb->control.intercept_exceptions |=3D (1 << DB_VECTOR); - if (vcpu->guest_debug & KVM_GUESTDBG_ENABLE) { if (vcpu->guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) @@ -1213,20 +1208,11 @@ static int db_interception(struct vcpu_svm *svm) struct kvm_run *kvm_run =3D svm->vcpu.run; =20 if (!(svm->vcpu.guest_debug & - (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) && - !svm->nmi_singlestep) { + (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))) { kvm_queue_exception(&svm->vcpu, DB_VECTOR); return 1; } =20 - if (svm->nmi_singlestep) { - svm->nmi_singlestep =3D false; - if (!(svm->vcpu.guest_debug & KVM_GUESTDBG_SINGLESTEP)) - svm->vmcb->save.rflags &=3D - ~(X86_EFLAGS_TF | X86_EFLAGS_RF); - update_db_intercept(&svm->vcpu); - } - if (svm->vcpu.guest_debug & (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)){ kvm_run->exit_reason =3D KVM_EXIT_DEBUG; @@ -2471,6 +2457,17 @@ static void svm_inject_nmi(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm =3D to_svm(vcpu); =20 + if (svm->vcpu.arch.hflags & HF_IRET_MASK) { + /* + * Inject the NMI before IRET completed, but defer delivery + * by one instruction with the help of the interrupt shadow. + * Works at least as long as the IRET does not trigger an + * exception. + */ + svm->vcpu.arch.hflags &=3D ~HF_IRET_MASK; + svm->vmcb->control.int_state |=3D SVM_INTERRUPT_SHADOW_MASK; + } + svm->vmcb->control.event_inj =3D SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_NMI= ; vcpu->arch.hflags |=3D HF_NMI_MASK; svm->vmcb->control.intercept |=3D (1UL << INTERCEPT_IRET); @@ -2576,18 +2573,7 @@ static void enable_irq_window(struct kvm_vcpu *vcp= u) =20 static void enable_nmi_window(struct kvm_vcpu *vcpu) { - struct vcpu_svm *svm =3D to_svm(vcpu); - - if ((svm->vcpu.arch.hflags & (HF_NMI_MASK | HF_IRET_MASK)) - =3D=3D HF_NMI_MASK) - return; /* IRET will cause a vm exit */ - - /* Something prevents NMI from been injected. Single step over - possible problem (IRET or exception injection or interrupt - shadow) */ - svm->nmi_singlestep =3D true; - svm->vmcb->save.rflags |=3D (X86_EFLAGS_TF | X86_EFLAGS_RF); - update_db_intercept(vcpu); + /* VM exit on IRET was already armed on injection */ } =20 static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr) --------------enigEAEC8EB18C3C50D33A54514B Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkt4OBMACgkQitSsb3rl5xRLVQCg3M3YJibJKVss1dUztXDsAMvE 0wEAoOKR9uPBF2diKjLSYZGlrrngnlTa =L/gr -----END PGP SIGNATURE----- --------------enigEAEC8EB18C3C50D33A54514B--