Re: [PATCH 2/4] KVM: Add kvm_io_ext_data to IO handler

[Sheng Yang <sheng@linux.intel.com>]

On Friday 25 February 2011 16:12:30 Michael S. Tsirkin wrote:
> On Fri, Feb 25, 2011 at 11:23:30AM +0800, Sheng Yang wrote:
> > On Thursday 24 February 2011 18:22:19 Michael S. Tsirkin wrote:
> > > On Thu, Feb 24, 2011 at 05:51:03PM +0800, Sheng Yang wrote:
> > > > Add a new parameter to IO writing handler, so that we can transfer
> > > > information from IO handler to caller.
> > > > 
> > > > Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> > > > ---
> > > > 
> > > >  arch/x86/kvm/i8254.c      |    6 ++++--
> > > >  arch/x86/kvm/i8259.c      |    3 ++-
> > > >  arch/x86/kvm/lapic.c      |    3 ++-
> > > >  arch/x86/kvm/x86.c        |   13 ++++++++-----
> > > >  include/linux/kvm_host.h  |   12 ++++++++++--
> > > >  virt/kvm/coalesced_mmio.c |    3 ++-
> > > >  virt/kvm/eventfd.c        |    2 +-
> > > >  virt/kvm/ioapic.c         |    2 +-
> > > >  virt/kvm/iodev.h          |    6 ++++--
> > > >  virt/kvm/kvm_main.c       |    4 ++--
> > > >  10 files changed, 36 insertions(+), 18 deletions(-)
> > > > 
> > > > diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
> > > > index efad723..bd8f0c5 100644
> > > > --- a/arch/x86/kvm/i8254.c
> > > > +++ b/arch/x86/kvm/i8254.c
> > > > @@ -439,7 +439,8 @@ static inline int pit_in_range(gpa_t addr)
> > > > 
> > > >  }
> > > >  
> > > >  static int pit_ioport_write(struct kvm_io_device *this,
> > > > 
> > > > -			    gpa_t addr, int len, const void *data)
> > > > +			    gpa_t addr, int len, const void *data,
> > > > +			    struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_pit *pit = dev_to_pit(this);
> > > >  	struct kvm_kpit_state *pit_state = &pit->pit_state;
> > > > 
> > > > @@ -585,7 +586,8 @@ static int pit_ioport_read(struct kvm_io_device
> > > > *this,
> > > > 
> > > >  }
> > > >  
> > > >  static int speaker_ioport_write(struct kvm_io_device *this,
> > > > 
> > > > -				gpa_t addr, int len, const void *data)
> > > > +				gpa_t addr, int len, const void *data,
> > > > +				struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_pit *pit = speaker_to_pit(this);
> > > >  	struct kvm_kpit_state *pit_state = &pit->pit_state;
> > > > 
> > > > diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> > > > index 3cece05..96b1070 100644
> > > > --- a/arch/x86/kvm/i8259.c
> > > > +++ b/arch/x86/kvm/i8259.c
> > > > @@ -480,7 +480,8 @@ static inline struct kvm_pic *to_pic(struct
> > > > kvm_io_device *dev)
> > > > 
> > > >  }
> > > >  
> > > >  static int picdev_write(struct kvm_io_device *this,
> > > > 
> > > > -			 gpa_t addr, int len, const void *val)
> > > > +			 gpa_t addr, int len, const void *val,
> > > > +			 struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_pic *s = to_pic(this);
> > > >  	unsigned char data = *(unsigned char *)val;
> > > > 
> > > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > > > index 93cf9d0..f413e9c 100644
> > > > --- a/arch/x86/kvm/lapic.c
> > > > +++ b/arch/x86/kvm/lapic.c
> > > > @@ -836,7 +836,8 @@ static int apic_reg_write(struct kvm_lapic *apic,
> > > > u32 reg, u32 val)
> > > > 
> > > >  }
> > > >  
> > > >  static int apic_mmio_write(struct kvm_io_device *this,
> > > > 
> > > > -			    gpa_t address, int len, const void *data)
> > > > +			    gpa_t address, int len, const void *data,
> > > > +			    struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_lapic *apic = to_lapic(this);
> > > >  	unsigned int offset = address - apic->base_address;
> > > > 
> > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > > index fa708c9..21b84e2 100644
> > > > --- a/arch/x86/kvm/x86.c
> > > > +++ b/arch/x86/kvm/x86.c
> > > > @@ -3571,13 +3571,14 @@ static void kvm_init_msr_list(void)
> > > > 
> > > >  }
> > > >  
> > > >  static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int
> > > >  len,
> > > > 
> > > > -			   const void *v)
> > > > +			   const void *v, struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	if (vcpu->arch.apic &&
> > > > 
> > > > -	    !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v))
> > > > +	    !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v,
> > > > ext_data))
> > > > 
> > > >  		return 0;
> > > > 
> > > > -	return kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
> > > > +	return kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS,
> > > > +				addr, len, v, ext_data);
> > > > 
> > > >  }
> > > >  
> > > >  static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int
> > > >  len, void *v)
> > > > 
> > > > @@ -3807,6 +3808,7 @@ static int
> > > > emulator_write_emulated_onepage(unsigned long addr,
> > > > 
> > > >  					   struct kvm_vcpu *vcpu)
> > > >  
> > > >  {
> > > >  
> > > >  	gpa_t                 gpa;
> > > > 
> > > > +	struct kvm_io_ext_data ext_data;
> > > > 
> > > >  	gpa = kvm_mmu_gva_to_gpa_write(vcpu, addr, exception);
> > > > 
> > > > @@ -3825,7 +3827,7 @@ mmio:
> > > >  	/*
> > > >  	
> > > >  	 * Is this MMIO handled locally?
> > > >  	 */
> > > > 
> > > > -	if (!vcpu_mmio_write(vcpu, gpa, bytes, val))
> > > > +	if (!vcpu_mmio_write(vcpu, gpa, bytes, val, &ext_data))
> > > > 
> > > >  		return X86EMUL_CONTINUE;
> > > >  	
> > > >  	vcpu->mmio_needed = 1;
> > > > 
> > > > @@ -3940,6 +3942,7 @@ static int kernel_pio(struct kvm_vcpu *vcpu,
> > > > void *pd)
> > > > 
> > > >  {
> > > >  
> > > >  	/* TODO: String I/O for in kernel device */
> > > >  	int r;
> > > > 
> > > > +	struct kvm_io_ext_data ext_data;
> > > > 
> > > >  	if (vcpu->arch.pio.in)
> > > >  	
> > > >  		r = kvm_io_bus_read(vcpu->kvm, KVM_PIO_BUS, vcpu-
>arch.pio.port,
> > > > 
> > > > @@ -3947,7 +3950,7 @@ static int kernel_pio(struct kvm_vcpu *vcpu,
> > > > void *pd)
> > > > 
> > > >  	else
> > > >  	
> > > >  		r = kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS,
> > > >  		
> > > >  				     vcpu->arch.pio.port, vcpu->arch.pio.size,
> > > > 
> > > > -				     pd);
> > > > +				     pd, &ext_data);
> > > > 
> > > >  	return r;
> > > >  
> > > >  }
> > > > 
> > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > > > index 7d313e0..6bb211d 100644
> > > > --- a/include/linux/kvm_host.h
> > > > +++ b/include/linux/kvm_host.h
> > > > @@ -68,8 +68,15 @@ enum kvm_bus {
> > > > 
> > > >  	KVM_NR_BUSES
> > > >  
> > > >  };
> > > > 
> > > > +struct kvm_io_ext_data {
> > > > +	int type;
> > > 
> > > What values does this get? Please add documentation in comments.
> > 
> > See the next patch.
> > 
> > > > +	union {
> > > > +		char padding[256];
> > > > +	};
> > > 
> > > So the structure size is 260 bytes?
> > > What's the point of the padding?
> > 
> > Reserved spaces. Also used in the next patch.
> 
> I was unable to find anything related to padding in the next patch.
> This is an internal API, isn't it? So why reserve space? Further,
> 256 bytes is quite a lot to reserve. Also,
> making the total size a power of 2 would seem to make more sense if we
> do need to reserve any space.

Yes you're right. Use union alone should be fine. Would update it.

--
regards
Yang, Sheng

> 
> > --
> > regards
> > Yang, Sheng
> > 
> > > > +};
> > > > +
> > > > 
> > > >  int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t
> > > >  addr,
> > > > 
> > > > -		     int len, const void *val);
> > > > +		     int len, const void *val, struct kvm_io_ext_data *data);
> > > > 
> > > >  int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t
> > > >  addr, int len,
> > > >  
> > > >  		    void *val);
> > > >  
> > > >  int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx,
> > > > 
> > > > @@ -113,7 +120,8 @@ struct kvm_io_device_ops {
> > > > 
> > > >  	int (*write)(struct kvm_io_device *this,
> > > >  	
> > > >  		     gpa_t addr,
> > > >  		     int len,
> > > > 
> > > > -		     const void *val);
> > > > +		     const void *val,
> > > > +		     struct kvm_io_ext_data *data);
> > > > 
> > > >  	void (*destructor)(struct kvm_io_device *this);
> > > >  
> > > >  };
> > > > 
> > > > diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
> > > > index fc84875..37b254c 100644
> > > > --- a/virt/kvm/coalesced_mmio.c
> > > > +++ b/virt/kvm/coalesced_mmio.c
> > > > @@ -59,7 +59,8 @@ static int coalesced_mmio_in_range(struct
> > > > kvm_coalesced_mmio_dev *dev,
> > > > 
> > > >  }
> > > >  
> > > >  static int coalesced_mmio_write(struct kvm_io_device *this,
> > > > 
> > > > -				gpa_t addr, int len, const void *val)
> > > > +				gpa_t addr, int len, const void *val,
> > > > +				struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
> > > >  	struct kvm_coalesced_mmio_ring *ring =
> > > >  	dev->kvm->coalesced_mmio_ring;
> > > > 
> > > > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> > > > index 2ca4535..8edd757 100644
> > > > --- a/virt/kvm/eventfd.c
> > > > +++ b/virt/kvm/eventfd.c
> > > > @@ -483,7 +483,7 @@ ioeventfd_in_range(struct _ioeventfd *p, gpa_t
> > > > addr, int len, const void *val)
> > > > 
> > > >  /* MMIO/PIO writes trigger an event if the addr/val match */
> > > >  static int
> > > >  ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
> > > > 
> > > > -		const void *val)
> > > > +		const void *val, struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct _ioeventfd *p = to_ioeventfd(this);
> > > > 
> > > > diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
> > > > index 0b9df83..6a027ef 100644
> > > > --- a/virt/kvm/ioapic.c
> > > > +++ b/virt/kvm/ioapic.c
> > > > @@ -321,7 +321,7 @@ static int ioapic_mmio_read(struct kvm_io_device
> > > > *this, gpa_t addr, int len,
> > > > 
> > > >  }
> > > >  
> > > >  static int ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr,
> > > >  int len,
> > > > 
> > > > -			     const void *val)
> > > > +			     const void *val, struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	struct kvm_ioapic *ioapic = to_ioapic(this);
> > > >  	u32 data;
> > > > 
> > > > diff --git a/virt/kvm/iodev.h b/virt/kvm/iodev.h
> > > > index d1f5651..340ab79 100644
> > > > --- a/virt/kvm/iodev.h
> > > > +++ b/virt/kvm/iodev.h
> > > > @@ -33,9 +33,11 @@ static inline int kvm_iodevice_read(struct
> > > > kvm_io_device *dev,
> > > > 
> > > >  }
> > > >  
> > > >  static inline int kvm_iodevice_write(struct kvm_io_device *dev,
> > > > 
> > > > -				     gpa_t addr, int l, const void *v)
> > > > +				     gpa_t addr, int l, const void *v,
> > > > +				     struct kvm_io_ext_data *data)
> > > > 
> > > >  {
> > > > 
> > > > -	return dev->ops->write ? dev->ops->write(dev, addr, l, v) :
> > > > -EOPNOTSUPP; +	return dev->ops->write ?
> > > > +		dev->ops->write(dev, addr, l, v, data) : -EOPNOTSUPP;
> > > > 
> > > >  }
> > > >  
> > > >  static inline void kvm_iodevice_destructor(struct kvm_io_device
> > > >  *dev)
> > > > 
> > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > > > index b1b6cbb..a61f90e 100644
> > > > --- a/virt/kvm/kvm_main.c
> > > > +++ b/virt/kvm/kvm_main.c
> > > > @@ -2221,14 +2221,14 @@ static void kvm_io_bus_destroy(struct
> > > > kvm_io_bus *bus)
> > > > 
> > > >  /* kvm_io_bus_write - called under kvm->slots_lock */
> > > >  int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t
> > > >  addr,
> > > > 
> > > > -		     int len, const void *val)
> > > > +		     int len, const void *val, struct kvm_io_ext_data *ext_data)
> > > > 
> > > >  {
> > > >  
> > > >  	int i;
> > > >  	struct kvm_io_bus *bus;
> > > >  	
> > > >  	bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
> > > >  	for (i = 0; i < bus->dev_count; i++)
> > > > 
> > > > -		if (!kvm_iodevice_write(bus->devs[i], addr, len, val))
> > > > +		if (!kvm_iodevice_write(bus->devs[i], addr, len, val, ext_data))
> > > > 
> > > >  			return 0;
> > > >  	
> > > >  	return -EOPNOTSUPP;
> > > >  
> > > >  }