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

[Nikolay Nikolaev]

On Sat, Nov 29, 2014 at 1:29 PM, Christoffer Dall
<christoffer.dall at 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 at 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
Thanks
Nikolay Nikolaev

>
> -Christoffer