From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] x86: handle double and triple faults for every exception Date: Wed, 30 Apr 2008 10:45:12 +0200 Message-ID: <48183198.1050508@siemens.com> References: <1209481325-14892-1-git-send-email-joerg.roedel@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Avi Kivity To: Joerg Roedel Return-path: In-Reply-To: <1209481325-14892-1-git-send-email-joerg.roedel@amd.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org 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 > Cc: Jan Kiszka > --- > 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 --- 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) ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone