On 28/04/2015 12:32, Christian Borntraeger wrote:
> Some architectures already have irq disabled when calling
> kvm_guest_exit. Push down the disabling into the architectures
> to avoid double disabling. This also allows to replace
> irq_save with irq_disable which might be cheaper.
> arm and mips already have interrupts disabled. s390/power/x86
> need adoptions.
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_hv.c | 2 ++
> arch/powerpc/kvm/book3s_pr.c | 2 ++
> arch/powerpc/kvm/booke.c | 4 ++--
> arch/s390/kvm/kvm-s390.c | 2 ++
> arch/x86/kvm/x86.c | 2 ++
> include/linux/kvm_host.h | 4 ----
> 6 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index a5f392d..63b35b1 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1811,7 +1811,9 @@ static void kvmppc_run_core(struct kvmppc_vcore *vc)
>
> /* make sure updates to secondary vcpu structs are visible now */
> smp_mb();
> + local_irq_disable();
> kvm_guest_exit();
> + local_irq_enable();
>
> preempt_enable();
> cond_resched();
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index f573839..eafcb8c 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -891,7 +891,9 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
>
> /* We get here with MSR.EE=1 */
>
> + local_irq_disable();
> trace_kvm_exit(exit_nr, vcpu);
> + local_irq_enable();
> kvm_guest_exit();
This looks wrong.
>
> switch (exit_nr) {
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 6c1316a..f1d6af3 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -1004,11 +1004,11 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
> break;
> }
>
> - local_irq_enable();
> -
> trace_kvm_exit(exit_nr, vcpu);
> kvm_guest_exit();
>
> + local_irq_enable();
> +
> run->exit_reason = KVM_EXIT_UNKNOWN;
> run->ready_for_interrupt_injection = 1;
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 9f4c954..0aa2534 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2015,7 +2015,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
> local_irq_enable();
> exit_reason = sie64a(vcpu->arch.sie_block,
> vcpu->run->s.regs.gprs);
> + local_irq_disable();
> kvm_guest_exit();
> + local_irq_enable();
> vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
>
> rc = vcpu_post_run(vcpu, exit_reason);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 32bf19e..a5fbd45 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6351,7 +6351,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> */
> barrier();
>
> + local_irq_disable();
> kvm_guest_exit();
> + local_irq_enable();
>
> preempt_enable();
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index a34bf6ed..fe699fb 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -773,11 +773,7 @@ static inline void kvm_guest_enter(void)
>
> static inline void kvm_guest_exit(void)
> {
> - unsigned long flags;
> -
> - local_irq_save(flags);
Why no WARN_ON here?
I think the patches are sensible, especially since you can add warnings.
This kind of code definitely knows if it has interrupts disabled or enabled
Alternatively, the irq-disabled versions could be called
__kvm_guest_{enter,exit}. Then you can use those directly when it makes
sense.
Paolo
> guest_exit();
> - local_irq_restore(flags);
> }
>
> /*
>
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