On 09.12.2011, at 19:19, Scott Wood wrote:
> 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?
Ah, thanks for the reminder. Yeah, we probably want to disable interrupts in parallel to checking for signals (basically from one signal check point to world switch). I'm just not 100% sure how to easily sync the C and asm code on the first entry though. Doing local_irq_disable in C and undoing it in asm could become ugly with lazy interrupt disabling.
Alex
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