On 12/09/2011 09:26 AM, Alexander Graf wrote:
> When entering the guest, we want to make sure we're not getting preempted
> away, so let's disable preemption on entry, but enable it again while handling
> guest exits.
>
> Reported-by: Jörg Sommer <joerg@xxxxxxxxxxxx>
> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
> ---
> arch/powerpc/kvm/book3s_pr.c | 7 +++++++
> 1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index 726512b..8e4f800 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -519,6 +519,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
> run->ready_for_interrupt_injection = 1;
>
> trace_kvm_book3s_exit(exit_nr, vcpu);
> + preempt_enable();
> kvm_resched(vcpu);
> switch (exit_nr) {
> case BOOK3S_INTERRUPT_INST_STORAGE:
> @@ -763,6 +764,8 @@ program_interrupt:
> run->exit_reason = KVM_EXIT_INTR;
> r = -EINTR;
> } else {
> + preempt_disable();
> +
> /* In case an interrupt came in that was triggered
> * from userspace (like DEC), we need to check what
> * to inject now! */
Shouldn't you really have interrupts disabled here, as booke does?
Otherwise an interrupt (including an IPI kick) could send you a signal
or guest exception after you check.
Likewise for other guest entry points.
-Scott
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