On Wed, Apr 30, 2008 at 10:45:12AM +0200, Jan Kiszka wrote:
> Joerg Roedel wrote:
> > The current KVM x86 exception code handles double and triple faults only for
> > page fault exceptions. This patch extends this detection for every exception
> > that gets queued for the guest.
> >
> > Signed-off-by: Joerg Roedel <[EMAIL PROTECTED]>
> > Cc: Jan Kiszka <[EMAIL PROTECTED]>
> > ---
> > arch/x86/kvm/x86.c | 31 +++++++++++++++++--------------
> > 1 files changed, 17 insertions(+), 14 deletions(-)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 578a0c1..c05aa32 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -144,9 +144,21 @@ void kvm_set_apic_base(struct kvm_vcpu *vcpu, u64 data)
> > }
> > EXPORT_SYMBOL_GPL(kvm_set_apic_base);
> >
> > +static void handle_multiple_faults(struct kvm_vcpu *vcpu)
> > +{
> > + if (vcpu->arch.exception.nr != DF_VECTOR) {
> > + vcpu->arch.exception.nr = DF_VECTOR;
> > + vcpu->arch.exception.error_code = 0;
> > + } else
> > + set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
> > +}
> > +
> > void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
> > {
> > - WARN_ON(vcpu->arch.exception.pending);
> > + if (vcpu->arch.exception.pending) {
> > + handle_multiple_faults(vcpu);
> > + return;
> > + }
> > vcpu->arch.exception.pending = true;
> > vcpu->arch.exception.has_error_code = false;
> > vcpu->arch.exception.nr = nr;
> > @@ -157,25 +169,16 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu,
> > unsigned long addr,
> > u32 error_code)
> > {
> > ++vcpu->stat.pf_guest;
> > - if (vcpu->arch.exception.pending) {
> > - if (vcpu->arch.exception.nr == PF_VECTOR) {
> > - printk(KERN_DEBUG "kvm: inject_page_fault:"
> > - " double fault 0x%lx\n", addr);
> > - vcpu->arch.exception.nr = DF_VECTOR;
> > - vcpu->arch.exception.error_code = 0;
> > - } else if (vcpu->arch.exception.nr == DF_VECTOR) {
> > - /* triple fault -> shutdown */
> > - set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
> > - }
> > - return;
> > - }
> > vcpu->arch.cr2 = addr;
> > kvm_queue_exception_e(vcpu, PF_VECTOR, error_code);
> > }
> >
> > void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32
> > error_code)
> > {
> > - WARN_ON(vcpu->arch.exception.pending);
> > + if (vcpu->arch.exception.pending) {
> > + handle_multiple_faults(vcpu);
> > + return;
> > + }
> > vcpu->arch.exception.pending = true;
> > vcpu->arch.exception.has_error_code = true;
> > vcpu->arch.exception.nr = nr;
>
> And here is an add-on patch to fix reset-on-triple-fault:
>
>
> Clear the pending original exception when raising a triple fault. This
> allows to re-use the vcpu instance, e.g. after a reset which is
> typically issued as reaction on the triple fault.
>
> Signed-off-by: Jan Kiszka <[EMAIL PROTECTED]>
>
> ---
> arch/x86/kvm/x86.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> Index: b/arch/x86/kvm/x86.c
> ===================================================================
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -149,8 +149,10 @@ static void handle_multiple_faults(struc
> if (vcpu->arch.exception.nr != DF_VECTOR) {
> vcpu->arch.exception.nr = DF_VECTOR;
> vcpu->arch.exception.error_code = 0;
> - } else
> + } else {
> set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
> + vcpu->arch.exception.pending = false;
> + }
> }
>
> void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr)
Ah, indeed. Thanks.
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