Re: [PATCH 3/3] KVM: Add documents for MSI-X MMIO API

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

On Monday 17 January 2011 20:21:45 Avi Kivity wrote:
> On 01/06/2011 12:19 PM, Sheng Yang wrote:
> > Signed-off-by: Sheng Yang<sheng@linux.intel.com>
> > ---
> > 
> >   Documentation/kvm/api.txt |   41
> >   +++++++++++++++++++++++++++++++++++++++++ 1 files changed, 41
> >   insertions(+), 0 deletions(-)
> > 
> > diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
> > index e1a9297..4978b94 100644
> > --- a/Documentation/kvm/api.txt
> > +++ b/Documentation/kvm/api.txt
> > @@ -1263,6 +1263,47 @@ struct kvm_assigned_msix_entry {
> > 
> >   	__u16 padding[3];
> >   
> >   };
> > 
> > +4.54 KVM_REGISTER_MSIX_MMIO
> > +
> > +Capability: KVM_CAP_MSIX_MMIO
> > +Architectures: x86
> > +Type: vm ioctl
> > +Parameters: struct kvm_msix_mmio_user (in)
> > +Returns: 0 on success, -1 on error
> > +
> > +This API indicates an MSI-X MMIO address of a guest device. Then all
> > MMIO +operation would be handled by kernel. When necessary(e.g. MSI
> > data/address +changed), KVM would exit to userspace using
> > KVM_EXIT_MSIX_ROUTING_UPDATE to +indicate the MMIO modification and
> > require userspace to update IRQ routing +table.
> > +
> > +struct kvm_msix_mmio_user {
> > +	__u32 dev_id;
> > +	__u16 type;		/* Device type and MMIO address type */
> > +	__u16 max_entries_nr;	/* Maximum entries supported */
> > +	__u64 base_addr;	/* Guest physical address of MMIO */
> > +	__u64 base_va;		/* Host virtual address of MMIO mapping */
> > +	__u64 flags;		/* Reserved for now */
> > +	__u64 reserved[4];
> > +};
> > +
> > +Current device type can be:
> > +#define KVM_MSIX_MMIO_TYPE_ASSIGNED_DEV	    (1<<  0)
> > +
> > +Current MMIO type can be:
> > +#define KVM_MSIX_MMIO_TYPE_BASE_TABLE	    (1<<  8)
> > +
> 
> How does userspace know which entry of which table changed?  Need a
> field in struct kvm_run for that.

We already got an guest MMIO address for that in the exit information. I've 
created a chain of handler in qemu to handle it.

--
regards
Yang, Sheng