On Mon, 1 Aug 2016 10:24:52 +0000
chris thompson <[email protected]> wrote:
> Hi,
>
> I'm trying to talk to my PCI-e card (USB3 host controller) from userland, and
> have been successful accessing the PCI Config registers and device memory,
> and able to register eventfd file descriptors for legacy interrupts (IRQx)
> and Error interrupts - including stimulating these via the ioctl calls.
> Unfortunately the MSI and MSI-X interrupts return EINVAL (invalid argument)
> when trying to register them.
>
> Sample from the code:
> printf("\nInterrupts:\n");
> int * irq_fds[VFIO_PCI_NUM_IRQS];
> int num_irqs[VFIO_PCI_NUM_IRQS];
> for (i = 0; i < device_info.num_irqs; i++) {
> struct vfio_irq_info irq = { .argsz = sizeof(irq) };
> irq.index = i;
> ioctl(device, VFIO_DEVICE_GET_IRQ_INFO, &irq);
> printf("argsz 0x%x, flags 0x%x, index 0x%x, count 0x%x,\n", irq.argsz,
> irq.flags, irq.index, irq.count);
> num_irqs[i] = irq.count;
> irq_fds[i]=(int*)malloc(irq.count * sizeof(int));
> int j;
> for(j=0; j<irq.count; j++)
> {
> irq_fds[i][j] = eventfd(0, 0);
> printf("config IRQ %u : %u\n", i, j);
> struct vfio_irq_set *irq_setup;
> unsigned int size = sizeof(struct vfio_irq_set) + sizeof(int);
> irq_setup = malloc(size);
> irq_setup->argsz = size;
> irq_setup->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> VFIO_IRQ_SET_ACTION_TRIGGER ;
> irq_setup->index = i;
> irq_setup->start = j;
> irq_setup->count = 1;
> *(int*)(irq_setup->data)=irq_fds[i][j];
> int ret = ioctl(device, VFIO_DEVICE_SET_IRQS, irq_setup);
> if(ret){ printf("failed to register interrupt %u : %u, error %i %s\n", i,
> j, ret, strerror(errno)); }
> free(irq_setup);
> }
> }
>
> Which gives the output:
>
> Interrupts:
> argsz 0x10, flags 0x7, index 0x0, count 0x1,
> config IRQ 0 : 0
> argsz 0x10, flags 0x9, index 0x1, count 0x40,
> config IRQ 1 : 0
> failed to register interrupt 1 : 0, error -1 Invalid argument
> config IRQ 1 : 1
> failed to register interrupt 1 : 1, error -1 Invalid argument
> config IRQ 1 : 2
> ...
>
> Does anyone know a likely reason that I can't register these? From what I've
> read my IOMMUs all support IRQ remapping:
> [ 0.016443] dmar: IOMMU 0: reg_base_addr fed90000 ver 1:0 cap
> c0000020e60262 ecap f0101a
> [ 0.016450] dmar: IOMMU 1: reg_base_addr fed91000 ver 1:0 cap
> c9008020660262 ecap f0105a
>
> The hardware is an Intel i5 2500 in an HP 8200 Elite small form-factor PC,
> running Ubuntu 14.04 on the 3.13 kernel.
include/uapi/linux/vfio.h:
* The NORESIZE flag indicates that the interrupt lines within the index
* are setup as a set and new subindexes cannot be enabled without first
* disabling the entire index. This is used for interrupts like PCI MSI
* and MSI-X where the driver may only use a subset of the available
* indexes, but VFIO needs to enable a specific number of vectors
* upfront. In the case of MSI-X, where the user can enable MSI-X and
* then add and unmask vectors, it's up to userspace to make the decision
* whether to allocate the maximum supported number of vectors or tear
* down setup and incrementally increase the vectors as each is enabled.
struct vfio_irq_info {
__u32 argsz;
__u32 flags;
#define VFIO_IRQ_INFO_EVENTFD (1 << 0)
#define VFIO_IRQ_INFO_MASKABLE (1 << 1)
#define VFIO_IRQ_INFO_AUTOMASKED (1 << 2)
#define VFIO_IRQ_INFO_NORESIZE (1 << 3) <----
__u32 index; /* IRQ index */
__u32 count; /* Number of IRQs within this index */
};
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