[RFC PATCH 3/5] KVM: ARM VGIC add kvm_io_bus_ frontend

[n.nikolaev@virtualopensystems.com (Nikolay Nikolaev)]

On Sat, Nov 29, 2014 at 3:54 PM, Nikolay Nikolaev
<n.nikolaev@virtualopensystems.com> wrote:
> On Sat, Nov 29, 2014 at 1:29 PM, Christoffer Dall
> <christoffer.dall@linaro.org> wrote:
>> On Mon, Nov 24, 2014 at 11:26:58PM +0200, Nikolay Nikolaev wrote:
>>> In io_mem_abort remove the call to vgic_handle_mmio. The target is to have
>>> a single MMIO handling path - that is through the kvm_io_bus_ API.
>>>
>>> Register a kvm_io_device in kvm_vgic_init on the whole vGIC MMIO region.
>>> Both read and write calls are redirected to vgic_io_dev_access where
>>> kvm_exit_mmio is composed to pass it to vm_ops.handle_mmio.
>>>
>>>
>>> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
>>> ---
>>>  arch/arm/kvm/mmio.c    |    3 --
>>>  include/kvm/arm_vgic.h |    3 +-
>>>  virt/kvm/arm/vgic.c    |   88 ++++++++++++++++++++++++++++++++++++++++--------
>>>  3 files changed, 74 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
>>> index 81230da..1c44a2b 100644
>>> --- a/arch/arm/kvm/mmio.c
>>> +++ b/arch/arm/kvm/mmio.c
>>> @@ -227,9 +227,6 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>>       if (mmio.is_write)
>>>               mmio_write_buf(mmio.data, mmio.len, data);
>>>
>>> -     if (vgic_handle_mmio(vcpu, run, &mmio))
>>> -             return 1;
>>> -
>>>       if (handle_kernel_mmio(vcpu, run, &mmio))
>>>               return 1;
>>>
>>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>>> index e452ef7..d9b7d2a 100644
>>> --- a/include/kvm/arm_vgic.h
>>> +++ b/include/kvm/arm_vgic.h
>>> @@ -233,6 +233,7 @@ struct vgic_dist {
>>>       unsigned long           *irq_pending_on_cpu;
>>>
>>>       struct vgic_vm_ops      vm_ops;
>>> +     struct kvm_io_device    *io_dev;
>>>  #endif
>>>  };
>>>
>>> @@ -307,8 +308,6 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
>>>                       bool level);
>>>  void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);
>>>  int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
>>> -bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>> -                   struct kvm_exit_mmio *mmio);
>>>
>>>  #define irqchip_in_kernel(k) (!!((k)->arch.vgic.in_kernel))
>>>  #define vgic_initialized(k)  ((k)->arch.vgic.ready)
>>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>>> index 1213da5..3da1115 100644
>>> --- a/virt/kvm/arm/vgic.c
>>> +++ b/virt/kvm/arm/vgic.c
>>> @@ -31,6 +31,9 @@
>>>  #include <asm/kvm_emulate.h>
>>>  #include <asm/kvm_arm.h>
>>>  #include <asm/kvm_mmu.h>
>>> +#include <asm/kvm.h>
>>> +
>>> +#include "iodev.h"
>>>
>>>  /*
>>>   * How the whole thing works (courtesy of Christoffer Dall):
>>> @@ -775,28 +778,81 @@ bool vgic_handle_mmio_range(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>>       return true;
>>>  }
>>>
>>> -/**
>>> - * vgic_handle_mmio - handle an in-kernel MMIO access for the GIC emulation
>>> - * @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.
>>> - * Calls the actual handling routine for the selected VGIC model.
>>> - */
>>> -bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>>> -                   struct kvm_exit_mmio *mmio)
>>> +static int vgic_io_dev_access(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
>>> +                         gpa_t addr, int len, void *val, bool is_write)
>>>  {
>>> -     if (!irqchip_in_kernel(vcpu->kvm))
>>> -             return false;
>>> +     struct kvm_exit_mmio mmio;
>>> +     bool ret;
>>> +
>>> +     mmio = (struct kvm_exit_mmio) {
>>> +             .phys_addr = addr,
>>> +             .len = len,
>>> +             .is_write = is_write,
>>> +     };
>>> +
>>> +     if (is_write)
>>> +             memcpy(mmio.data, val, len);
>>>
>>>       /*
>>>        * This will currently call either vgic_v2_handle_mmio() or
>>>        * vgic_v3_handle_mmio(), which in turn will call
>>>        * vgic_handle_mmio_range() defined above.
>>>        */
>>> -     return vcpu->kvm->arch.vgic.vm_ops.handle_mmio(vcpu, run, mmio);
>>> +     ret = vcpu->kvm->arch.vgic.vm_ops.handle_mmio(vcpu, vcpu->run, &mmio);
>>> +
>>> +     if (!is_write)
>>> +             memcpy(val, mmio.data, len);
>>> +
>>> +     return ret ? 0 : 1;
>>> +}
>>> +
>>> +static int vgic_io_dev_read(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
>>> +                       gpa_t addr, int len, void *val)
>>> +{
>>> +     return vgic_io_dev_access(vcpu, this, addr, len, val, false);
>>> +}
>>> +
>>> +static int vgic_io_dev_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
>>> +                        gpa_t addr, int len, const void *val)
>>> +{
>>> +     return vgic_io_dev_access(vcpu, this, addr, len, (void *)val, true);
>>> +}
>>> +
>>> +static const struct kvm_io_device_ops vgic_io_dev_ops = {
>>> +     .read       = vgic_io_dev_read,
>>> +     .write      = vgic_io_dev_write,
>>> +};
>>> +
>>> +static int vgic_register_kvm_io_dev(struct kvm *kvm)
>>> +{
>>> +     struct kvm_io_device *dev;
>>> +     int ret;
>>> +
>>> +     struct vgic_dist *dist = &kvm->arch.vgic;
>>> +     unsigned long base = dist->vgic_dist_base;
>>> +
>>> +     dev = kzalloc(sizeof(struct kvm_io_device), GFP_KERNEL);
>>> +     if (!dev)
>>> +             return -ENOMEM;
>>> +
>> Do you even need a dynamic allocation here or can you just have it
>> statically allocated as part of the kvm/vgic struct?
> Right - static allocation should be just fine - will do

Actually static allocation requires inclusion of virt/kvm/iodev.h in
include/kvm/arm_vgic.h
This creates more compilation problems than it's worth. So I am adding
a proper device/unregister kfree upon vgic destroy.

regardsm
Nikolay Nikolaev

> Thanks
> Nikolay Nikolaev
>
>>
>> -Christoffer