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)
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