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SubjectRe: [RFC PATCH 1/4] ARM: KVM: on unhandled IO mem abort, route the call to the KVM MMIO bus
On Thu, Mar 13, 2014 at 04:57:26PM +0100, Antonios Motakis wrote:
> On an unhandled IO memory abort, use the kvm_io_bus_* API in order to
> handle the MMIO access through any registered read/write callbacks. This
> is a dependency for eventfd support (ioeventfd and irqfd).
>
> However, accesses to the VGIC are still left implemented independently,
> since the kvm_io_bus_* API doesn't pass the VCPU pointer doing the access.
>
> Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> ---
> arch/arm/kvm/mmio.c | 32 ++++++++++++++++++++++++++++++++
> virt/kvm/arm/vgic.c | 5 ++++-
> 2 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
> index 4cb5a93..1d17831 100644
> --- a/arch/arm/kvm/mmio.c
> +++ b/arch/arm/kvm/mmio.c
> @@ -162,6 +162,35 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> return 0;
> }
>
> +/**
> + * kvm_handle_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, KVM_MMIO_BUS, mmio->phys_addr,
> + mmio->len, &mmio->data);
> +
> + } else {
> + ret = kvm_io_bus_read(vcpu->kvm, 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;
> +}
> +
> int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
> phys_addr_t fault_ipa)
> {
> @@ -200,6 +229,9 @@ 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;
> +

this special-casing of the vgic is now really terrible. Is there
anything holding you back from doing the necessary restructure of the
kvm_bus_io_*() API instead? That would allow us to get rid of the ugly
Fix it! in the vgic driver as well.

-Christoffer

> kvm_prepare_mmio(run, &mmio);
> return 0;
> }
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 8ca405c..afdecc3 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -849,13 +849,16 @@ struct mmio_range *find_matching_range(const struct mmio_range *ranges,
> }
>
> /**
> - * vgic_handle_mmio - handle an in-kernel MMIO access
> + * vgic_handle_mmio - handle an in-kernel vgic 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.
> + *
> + * This is handled outside of kvm_handle_mmio because the kvm_io_bus only
> + * passes the VM pointer, while we need the VCPU performing the access.
> */
> bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
> struct kvm_exit_mmio *mmio)
> --
> 1.8.3.2
>


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