From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Auger <eric.auger@linaro.org>
Subject: Re: [PATCH v2 2/5] KVM: ARM: on IO mem abort - route the call to
 KVM MMIO bus
Date: Mon, 12 Jan 2015 18:09:13 +0100
Message-ID: <54B3FFB9.3050406@linaro.org>
References: <20141207093641.17563.84226.stgit@i3820> <20141207093749.17563.12497.stgit@i3820>
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Cc: tech@virtualopensystems.com, linux-arm-kernel@lists.infradead.org
To: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>,
	kvm@vger.kernel.org, marc.zyngier@arm.com, andre.przywara@arm.com,
	kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org
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Hi Nikolay,
On 12/07/2014 10:37 AM, Nikolay Nikolaev wrote:
> On IO memory abort, try to handle the MMIO access thorugh the KVM
> registered read/write callbacks. This is done by invoking the relevant
> kvm_io_bus_* API.
> 
> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> ---
>  arch/arm/kvm/mmio.c |   33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
> index 4cb5a93..e42469f 100644
> --- a/arch/arm/kvm/mmio.c
> +++ b/arch/arm/kvm/mmio.c
> @@ -162,6 +162,36 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  	return 0;
>  }
>  
> +/**
> + * handle_kernel_mmio - handle an in-kernel MMIO access
> + * @vcpu:	pointer to the vcpu performing the access
> + * @run:	pointer to the kvm_run structure
> + * @mmio:	pointer to the data describing the access
> + *
> + * returns true if the MMIO access has been performed in kernel space,
> + * and false if it needs to be emulated in user space.
> + */
> +static bool handle_kernel_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
> +		struct kvm_exit_mmio *mmio)
> +{
> +	int ret;
> +
> +	if (mmio->is_write) {
> +		ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, mmio->phys_addr,
> +				mmio->len, &mmio->data);
> +
> +	} else {
> +		ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, mmio->phys_addr,
> +				mmio->len, &mmio->data);
> +	}
> +	if (!ret) {
> +		kvm_prepare_mmio(run, mmio);
> +		kvm_handle_mmio_return(vcpu, run);
> +	}
> +
> +	return !ret;
in case ret < 0 (-EOPNOTSUPP = -95) aren't we returning true too? return
(ret==0)?

> +}
> +
>  int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>  		 phys_addr_t fault_ipa)
>  {
> @@ -200,6 +230,9 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>  	if (vgic_handle_mmio(vcpu, run, &mmio))
>  		return 1;
>  
> +	if (handle_kernel_mmio(vcpu, run, &mmio))
> +		return 1;
> +
>  	kvm_prepare_mmio(run, &mmio);
>  	return 0;
currently the io_mem_abort returned value is not used by mmu.c code. I
think this should be handed in kvm_handle_guest_abort. What do you think?

Best Regards

Eric
>  }
>