From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 03/10] KVM: SVM: Move nested INTR #vmexit into preemtible code Date: Thu, 8 Oct 2009 11:12:02 +0200 Message-ID: <20091008091202.GB14073@amd.com> References: <1254925888-13743-1-git-send-email-joerg.roedel@amd.com> <1254925888-13743-4-git-send-email-joerg.roedel@amd.com> <20091007205852.GA7692@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Avi Kivity , kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Marcelo Tosatti Return-path: Content-Disposition: inline In-Reply-To: <20091007205852.GA7692@amt.cnet> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Wed, Oct 07, 2009 at 05:58:52PM -0300, Marcelo Tosatti wrote: > On Wed, Oct 07, 2009 at 04:31:21PM +0200, Joerg Roedel wrote: > > This patch makes use of the KVM_REQ_VMEXIT to move the > > emulation of #vmexit(INTR) out of non-preemptible code. > > > > Signed-off-by: Joerg Roedel > > --- > > arch/x86/kvm/svm.c | 18 ++++++++++++++++-- > > 1 files changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > > index b6ce1a9..7015680 100644 > > --- a/arch/x86/kvm/svm.c > > +++ b/arch/x86/kvm/svm.c > > @@ -1379,8 +1379,14 @@ static inline int nested_svm_intr(struct vcpu_svm *svm) > > > > svm->vmcb->control.exit_code = SVM_EXIT_INTR; > > > > - if (nested_svm_exit_handled(svm)) { > > - nsvm_printk("VMexit -> INTR\n"); > > + if (svm->nested.intercept & 1ULL) { > > + /* > > + * The #vmexit can't be emulated here directly because this > > + * code path runs with irqs and preemtion disabled and a > > + * #vmexit emulation might sleep. Only set the request bit for > > + * the #vmexit here. > > + */ > > + set_bit(KVM_REQ_VMEXIT, &svm->vcpu.requests); > > return 1; > > } > > What if you keep this internal to SVM? Proceed to svm_vcpu_run and > return, do the emulation on the exit handler. > > Then there's no need for the request bit (VMX does that, see > vmx_vcpu_run). Yeah, right. This would be cleaner code. I will change it. Joerg