Re: [Qemu-ppc] [RFC PATCH 09/17] KVM: PPC64: booke: Hard disable interrupts when entering guest

[Alexander Graf]

On 25.06.2012, at 14:26, Mihai Caraman wrote:

> 64-bit host runs with lazy interrupt disabling, so local_irq_disable() does
> not disable interrupts right away and does not protect against preemption
> required by __kvmppc_vcpu_run(). Define a macro for 64-bit to use
> hard_irq_disable().
> 
> Signed-off-by: Mihai Caraman <address@hidden>
> ---
> arch/powerpc/kvm/booke.c |   14 ++++++++++----
> 1 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 93b48e0..db05692 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -45,6 +45,12 @@ unsigned long kvmppc_booke_handlers;
> #define VM_STAT(x) offsetof(struct kvm, stat.x), KVM_STAT_VM
> #define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU
> 
> +#ifdef CONFIG_64BIT
> +#define _hard_irq_disable() hard_irq_disable()
> +#else
> +#define _hard_irq_disable() local_irq_disable()
> +#endif

So you only swap out the disable bit, but not the enable one? Ben, would this 
work out?


Alex

> +
> struct kvm_stats_debugfs_item debugfs_entries[] = {
>       { "mmio",       VCPU_STAT(mmio_exits) },
>       { "dcr",        VCPU_STAT(dcr_exits) },
> @@ -456,7 +462,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
>               local_irq_enable();
>               kvm_vcpu_block(vcpu);
>               clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
> -             local_irq_disable();
> +             _hard_irq_disable();
> 
>               kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS);
>               r = 1;
> @@ -480,7 +486,7 @@ static int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
>               if (need_resched()) {
>                       local_irq_enable();
>                       cond_resched();
> -                     local_irq_disable();
> +                     _hard_irq_disable();
>                       continue;
>               }
> 
> @@ -515,7 +521,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct 
> kvm_vcpu *vcpu)
>               return -EINVAL;
>       }
> 
> -     local_irq_disable();
> +     _hard_irq_disable();
>       if (kvmppc_prepare_to_enter(vcpu)) {
>               kvm_run->exit_reason = KVM_EXIT_INTR;
>               ret = -EINTR;
> @@ -955,7 +961,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
> kvm_vcpu *vcpu,
>        * aren't already exiting to userspace for some other reason.
>        */
>       if (!(r & RESUME_HOST)) {
> -             local_irq_disable();
> +             _hard_irq_disable();
>               if (kvmppc_prepare_to_enter(vcpu)) {
>                       run->exit_reason = KVM_EXIT_INTR;
>                       r = (-EINTR << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
> -- 
> 1.7.4.1
> 
> 
>