[PATCH v2 3/4] kvm/ppc: Call trace_hardirqs_on before entry

[Bhushan Bharat-R65777]

> -----Original Message-----
> From: kvm-owner at vger.kernel.org [mailto:kvm-owner at vger.kernel.org] On Behalf Of
> Scott Wood
> Sent: Friday, May 10, 2013 8:40 AM
> To: Alexander Graf; Benjamin Herrenschmidt
> Cc: kvm-ppc at vger.kernel.org; kvm at vger.kernel.org; linuxppc-dev at lists.ozlabs.org;
> Wood Scott-B07421
> Subject: [PATCH v2 3/4] kvm/ppc: Call trace_hardirqs_on before entry
> 
> Currently this is only being done on 64-bit.  Rather than just move it
> out of the 64-bit ifdef, move it to kvm_lazy_ee_enable() so that it is
> consistent with lazy ee state, and so that we don't track more host
> code as interrupts-enabled than necessary.
> 
> Rename kvm_lazy_ee_enable() to kvm_fix_ee_before_entry() to reflect
> that this function now has a role on 32-bit as well.
> 
> Signed-off-by: Scott Wood <scottwood at freescale.com>
> ---
>  arch/powerpc/include/asm/kvm_ppc.h |   11 ++++++++---
>  arch/powerpc/kvm/book3s_pr.c       |    4 ++--
>  arch/powerpc/kvm/booke.c           |    4 ++--
>  arch/powerpc/kvm/powerpc.c         |    2 --
>  4 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h
> b/arch/powerpc/include/asm/kvm_ppc.h
> index a5287fe..6885846 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -394,10 +394,15 @@ static inline void kvmppc_mmu_flush_icache(pfn_t pfn)
>  	}
>  }
> 
> -/* Please call after prepare_to_enter. This function puts the lazy ee state
> -   back to normal mode, without actually enabling interrupts. */
> -static inline void kvmppc_lazy_ee_enable(void)
> +/*
> + * Please call after prepare_to_enter. This function puts the lazy ee and irq
> + * disabled tracking state back to normal mode, without actually enabling
> + * interrupts.
> + */
> +static inline void kvmppc_fix_ee_before_entry(void)
>  {
> +	trace_hardirqs_on();
> +
>  #ifdef CONFIG_PPC64
>  	/* Only need to enable IRQs by hard enabling them after this */
>  	local_paca->irq_happened = 0;
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index bdc40b8..0b97ce4 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -890,7 +890,7 @@ program_interrupt:
>  			local_irq_enable();
>  			r = s;
>  		} else {
> -			kvmppc_lazy_ee_enable();
> +			kvmppc_fix_ee_before_entry();
>  		}
>  	}
> 
> @@ -1161,7 +1161,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct
> kvm_vcpu *vcpu)
>  	if (vcpu->arch.shared->msr & MSR_FP)
>  		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
> 
> -	kvmppc_lazy_ee_enable();
> +	kvmppc_fix_ee_before_entry();
> 
>  	ret = __kvmppc_vcpu_run(kvm_run, vcpu);
> 
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 705fc5c..eb89b83 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -673,7 +673,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu
> *vcpu)
>  		ret = s;
>  		goto out;
>  	}
> -	kvmppc_lazy_ee_enable();
> +	kvmppc_fix_ee_before_entry();

local_irq_disable() is called before kvmppc_prepare_to_enter().
Now we put the irq_happend and soft_enabled back to previous state without checking for any interrupt happened in between. If any interrupt happens in between, will not that be lost?

-Bharat

> 
>  	kvm_guest_enter();
> 
> @@ -1154,7 +1154,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct
> kvm_vcpu *vcpu,
>  			local_irq_enable();
>  			r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
>  		} else {
> -			kvmppc_lazy_ee_enable();
> +			kvmppc_fix_ee_before_entry();
>  		}
>  	}
> 
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 6316ee3..4e05f8c 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -117,8 +117,6 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu)
>  			kvm_guest_exit();
>  			continue;
>  		}
> -
> -		trace_hardirqs_on();
>  #endif
> 
>  		kvm_guest_enter();
> --
> 1.7.10.4
> 
> 
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