On Fri, 2011-09-30 at 18:46 +1000, David Gibson wrote:
> On Mon, Sep 26, 2011 at 12:34:52PM -0600, Alex Williamson wrote:
> > On Mon, 2011-09-26 at 12:04 +0200, Alexander Graf wrote:
> > > Am 26.09.2011 um 09:51 schrieb David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>:
> [snip]
> > > Also, if you can come up with an interface that does not have variable
> > > length descriptors but is still able to export all the required
> > > generic information, please send a proposal to the list :)
> > >
> >
> > Hi,
> >
> > The other obvious possibility is a pure ioctl interface. To match what
> > this proposal is trying to describe, plus the runtime interfaces, we'd
> > need something like:
>
> Right, this also seems a reasonable possibility to me, depending on
> the details.
>
> > /* :0 - PCI devices, :1 - Devices path device, 63:2 - reserved */
> > #define VFIO_DEVICE_GET_FLAGS _IOR(, , u64)
> >
> >
> > /* Return number of mmio/iop/config regions.
> > * For PCI this is always 8 (BAR0-5 + ROM + Config) */
> > #define VFIO_DEVICE_GET_NUM_REGIONS _IOR(, , int)
> >
> > /* Return length for region index (may be zero) */
> > #define VFIO_DEVICE_GET_REGION_LEN _IOWR(, , u64)
> >
> > /* Return flags for region index
> > * :0 - mmap'able, :1 - read-only, 63:2 - reserved */
> > #define VFIO_DEVICE_GET_REGION_FLAGS _IOR(, , u64)
> >
> > /* Return file offset for region index */
> > #define VFIO_DEVICE_GET_REGION_OFFSET _IOWR(, , u64)
>
> The above 3 can be be folded into one "getregioninfo" call.
Yep, and the phys addr one below. We can use a flags bit to indicate
whether it's valid.
> > /* Return physical address for region index - not implemented for PCI */
> > #define VFIO_DEVICE_GET_REGION_PHYS_ADDR _IOWR(, , u64)
> >
> >
> >
> > /* Return number of IRQs (Not including MSI/MSI-X for PCI) */
> > #define VFIO_DEVICE_GET_NUM_IRQ _IOR(, , int)
> >
> > /* Set IRQ eventfd for IRQ index, arg[0] = index, arg[1] = fd */
> > #define VFIO_DEVICE_SET_IRQ_EVENTFD _IOW(, , int)
> >
> > /* Unmask IRQ index */
> > #define VFIO_DEVICE_UNMASK_IRQ _IOW(, , int)
> >
> > /* Set unmask eventfd for index, arg[0] = index, arg[1] = fd */
> > #define VFIO_DEVICE_SET_UNMASK_IRQ_EVENTFD _IOW(, , int)
> >
> >
> > /* Return the device tree path for type/index into the user
> > * allocated buffer */
> > struct dtpath {
> > u32 type; (0 = region, 1 = IRQ)
> > u32 index;
> > u32 buf_len;
> > char *buf;
> > };
> > #define VFIO_DEVICE_GET_DTPATH _IOWR(, , struct dtpath)
> >
> > /* Return the device tree index for type/index */
> > struct dtindex {
> > u32 type; (0 = region, 1 = IRQ)
> > u32 index;
> > u32 prop_type;
> > u32 prop_index;
> > };
> > #define VFIO_DEVICE_GET_DTINDEX _IOWR(, , struct dtindex)
>
> I think those need some work, but that doesn't impinge on the core
> semantics.
>
> > /* Reset the device */
> > #define VFIO_DEVICE_RESET _IO(, ,)
> >
> >
> > /* PCI MSI setup, arg[0] = #, arg[1-n] = eventfds */
> > #define VFIO_DEVICE_PCI_SET_MSI_EVENTFDS _IOW(, , int)
> > #define VFIO_DEVICE_PCI_SET_MSIX_EVENTFDS _IOW(, , int)
>
> Why does this need seperate controls, rather than just treating MSIs
> as interrupts beyond the first for PCI devices?
Well, we could say that PCI will always report 3 for
VFIO_DEVICE_GET_NUM_IRQ where 0 = legacy, 1 = MSI, 2 = MSI-X. ioctls on
unimplemented IRQs will fail, UNMASK* ioctls on non-level triggered
interrupts will fail, and the parameter to SET_IRQ_EVENTFD becomes
arg[0] = index, arg[1] = count, arg[2-n] = fd. Maybe we'd then have a
GET_IRQ_INFO that takes something like:
struct vfio_irq_info {
int index;
unsigned int count;
u64 flags;
#define VFIO_IRQ_INFO_FLAGS_LEVEL (1 << 0)
};
count would be 0 on PCI if the type of interrupt isn't supported.
Better? Thanks,
Alex
> > Hope that covers it. Something I prefer about this interface is that
> > everything can easily be generated on the fly, whereas reading out a
> > table from the device means we really need to have that table somewhere
> > in kernel memory to easily support reading random offsets.
> > Thoughts?
>
> I certainly prefer it to the previous proposal.
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