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    SubjectRe: [PATCH 03/10] KVM: SVM: Move nested INTR #vmexit into preemtible code
    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 <joerg.roedel@amd.com>
    > > ---
    > > 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




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