Re: [dpdk-dev] [PATCH v2 4/5] eal: add per rx queue interrupt handling based on VFIO

["Zhou, Danny" <danny.zhou@intel.com>]

> -----Original Message-----
> From: Liang, Cunming
> Sent: Friday, February 13, 2015 11:48 AM
> To: Zhou, Danny; dev@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v2 4/5] eal: add per rx queue interrupt handling based on VFIO
> 
> Hi,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zhou Danny
> > Sent: Tuesday, February 03, 2015 4:19 PM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] [PATCH v2 4/5] eal: add per rx queue interrupt handling
> > based on VFIO
> >
> [...]
> >  #include "eal_private.h"
> >  #include "eal_vfio.h"
> > @@ -127,6 +128,7 @@ static pthread_t intr_thread;
> >  #ifdef VFIO_PRESENT
> >
> >  #define IRQ_SET_BUF_LEN  (sizeof(struct vfio_irq_set) + sizeof(int))
> > +#define MSIX_IRQ_SET_BUF_LEN (sizeof(struct vfio_irq_set) + sizeof(int) *
> > (VFIO_MAX_QUEUE_ID + 1))
> [LCM] Does it better to add comment for '+1' which is the max other interrupts besides rxtx.

Will add.

> >
> >  /* enable legacy (INTx) interrupts */
> >  static int
> > @@ -221,7 +223,7 @@ vfio_disable_intx(struct rte_intr_handle *intr_handle) {
> >  /* enable MSI-X interrupts */
> [LCM] typo on comment. 'enable MSI interrupts' ?

Bug in legacy code and will fix it in V3.

> 
> >
> > @@ -292,8 +284,8 @@ vfio_disable_msi(struct rte_intr_handle *intr_handle) {
> >  /* enable MSI-X interrupts */
> >  static int
> >  vfio_enable_msix(struct rte_intr_handle *intr_handle) {
> > -	int len, ret;
> > -	char irq_set_buf[IRQ_SET_BUF_LEN];
> > +	int len, ret, max_intr;
> > +	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
> >  	struct vfio_irq_set *irq_set;
> >  	int *fd_ptr;
> >
> > @@ -301,12 +293,19 @@ vfio_enable_msix(struct rte_intr_handle *intr_handle)
> > {
> >
> >  	irq_set = (struct vfio_irq_set *) irq_set_buf;
> >  	irq_set->argsz = len;
> > -	irq_set->count = 1;
> > +	if ((!intr_handle->max_intr) ||
> > +		(intr_handle->max_intr > VFIO_MAX_QUEUE_ID))
> > +		max_intr = VFIO_MAX_QUEUE_ID + 1;
> > +	else
> > +		max_intr = intr_handle->max_intr;
> > +
> > +	irq_set->count = max_intr;
> >  	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> > VFIO_IRQ_SET_ACTION_TRIGGER;
> >  	irq_set->index = VFIO_PCI_MSIX_IRQ_INDEX;
> >  	irq_set->start = 0;
> >  	fd_ptr = (int *) &irq_set->data;
> > -	*fd_ptr = intr_handle->fd;
> > +	memcpy(fd_ptr, intr_handle->queue_fd, sizeof(intr_handle-
> > >queue_fd));
> > +	fd_ptr[max_intr - 1] = intr_handle->fd;
> >
> >  	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> >
> > @@ -316,22 +315,6 @@ vfio_enable_msix(struct rte_intr_handle *intr_handle) {
> >  		return -1;
> >  	}
> >
> > -	/* manually trigger interrupt to enable it */
> > -	memset(irq_set, 0, len);
> > -	len = sizeof(struct vfio_irq_set);
> > -	irq_set->argsz = len;
> > -	irq_set->count = 1;
> > -	irq_set->flags = VFIO_IRQ_SET_DATA_NONE |
> > VFIO_IRQ_SET_ACTION_TRIGGER;
> > -	irq_set->index = VFIO_PCI_MSIX_IRQ_INDEX;
> > -	irq_set->start = 0;
> > -
> > -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> > -
> > -	if (ret) {
> > -		RTE_LOG(ERR, EAL, "Error triggering MSI-X interrupts for fd %d\n",
> > -						intr_handle->fd);
> > -		return -1;
> > -	}
> >  	return 0;
> >  }
> >
> > @@ -339,7 +322,7 @@ vfio_enable_msix(struct rte_intr_handle *intr_handle) {
> >  static int
> >  vfio_disable_msix(struct rte_intr_handle *intr_handle) {
> >  	struct vfio_irq_set *irq_set;
> > -	char irq_set_buf[IRQ_SET_BUF_LEN];
> > +	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
> >  	int len, ret;
> >
> >  	len = sizeof(struct vfio_irq_set);
> > @@ -824,3 +807,119 @@ rte_eal_intr_init(void)
> >  	return -ret;
> >  }
> >
> > +static void
> > +eal_intr_process_rx_interrupts(uint8_t port_id, struct epoll_event *events, int
> > nfds)
> > +{
> > +	int n, bytes_read;
> > +	union rte_intr_read_buffer buf;
> > +	struct rte_intr_handle intr_handle = rte_eth_devices[port_id].pci_dev-
> > >intr_handle;
> [LCM] column number large than 80.

Will fix this in V3 patechset

> > +
> > +	for (n = 0; n < nfds; n++) {
> > +		/* set the length to be read for different handle type */
> > +		switch (intr_handle.type) {
> > +		case RTE_INTR_HANDLE_UIO:
> > +			bytes_read = sizeof(buf.uio_intr_count);
> > +			break;
> > +		case RTE_INTR_HANDLE_ALARM:
> > +			bytes_read = sizeof(buf.timerfd_num);
> > +			break;
> > +#ifdef VFIO_PRESENT
> > +		case RTE_INTR_HANDLE_VFIO_MSIX:
> > +		case RTE_INTR_HANDLE_VFIO_MSI:
> > +		case RTE_INTR_HANDLE_VFIO_LEGACY:
> > +			bytes_read = sizeof(buf.vfio_intr_count);
> > +			break;
> > +#endif
> > +		default:
> > +			bytes_read = 1;
> > +			break;
> > +		}
> > +
> > +		/**
> > +		* read out to clear the ready-to-be-read flag
> > +		* for epoll_wait.
> > +		*/
> > +		bytes_read = read(events[n].data.fd, &buf, bytes_read);
> > +		if (bytes_read < 0)
> > +			RTE_LOG(ERR, EAL, "Error reading from file "
> > +				"descriptor %d: %s\n", events[n].data.fd,
> > +							strerror(errno));
> > +		else if (bytes_read == 0)
> > +			RTE_LOG(ERR, EAL, "Read nothing from file "
> > +				"descriptor %d\n", events[n].data.fd);
> > +	}
> > +}
> > +
> > +static void
> > +eal_intr_handle_rx_interrupts(uint8_t port_id, int pfd, unsigned totalfds)
> > +{
> > +	struct epoll_event events[totalfds];
> > +	int nfds = 0;
> > +
> > +	do {
> > +		nfds = epoll_wait(pfd, events, totalfds,
> > +				EAL_INTR_EPOLL_WAIT_FOREVER);
> > +		/* epoll_wait fail */
> > +		if (nfds < 0) {
> > +			RTE_LOG(ERR, EAL,
> > +				"epoll_wait returns with fail\n");
> > +			return;
> > +		}
> > +	} while (nfds == 0);
> > +
> > +	/* epoll_wait has at least one fd ready to read */
> > +	eal_intr_process_rx_interrupts(port_id, events, nfds);
> > +}
> > +
> > +int
> > +rte_eal_wait_rx_intr(uint8_t port_id, uint8_t queue_id)
> > +{
> > +	struct rte_intr_handle intr_handle = rte_eth_devices[port_id].pci_dev-
> > >intr_handle;
> [LCM] exceed margin.
> 

Will fix it in V3 patchset.

> > +	struct epoll_event ev;
> > +	unsigned numfds = 0;
> > +
> > +	/* create epoll fd */
> > +	int pfd = epoll_create(1);
> > +	if (pfd < 0) {
> > +		RTE_LOG(ERR, EAL, "Cannot create epoll instance\n");
> > +		return -1;
> > +	}
> > +
> > +	rte_spinlock_lock(&intr_lock);
> > +
> > +	ev.events = EPOLLIN | EPOLLPRI;
> > +	switch (intr_handle.type) {
> > +	case RTE_INTR_HANDLE_UIO:
> > +		ev.data.fd = intr_handle.fd;
> > +		break;
> > +#ifdef VFIO_PRESENT
> > +	case RTE_INTR_HANDLE_VFIO_MSIX:
> > +	case RTE_INTR_HANDLE_VFIO_MSI:
> > +	case RTE_INTR_HANDLE_VFIO_LEGACY:
> > +		ev.data.fd = intr_handle.queue_fd[queue_id];
> > +		break;
> > +#endif
> > +	default:
> > +		rte_spinlock_unlock(&intr_lock);
> > +		close(pfd);
> > +		return -1;
> > +	}
> > +
> > +	if (epoll_ctl(pfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0) {
> > +		RTE_LOG(ERR, EAL, "Error adding fd %d epoll_ctl, %s\n",
> > +				intr_handle.queue_fd[queue_id],
> > strerror(errno));
> > +	} else
> > +		numfds++;
> > +
> > +	rte_spinlock_unlock(&intr_lock);
> > +	/* serve the interrupt */
> > +	eal_intr_handle_rx_interrupts(port_id, pfd, numfds);
> > +
> > +	/**
> > +	* when we return, we need to rebuild the
> > +	* list of fds to monitor.
> > +	*/
> > +	close(pfd);
> > +
> > +	return 0;
> > +}
> > diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > index 20e0977..63d0ae8 100644
> > --- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > @@ -283,7 +283,6 @@ pci_vfio_setup_interrupts(struct rte_pci_device *dev, int
> > vfio_dev_fd)
> >
> >  		dev->intr_handle.fd = fd;
> >  		dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
> > -
> >  		switch (i) {
> >  		case VFIO_PCI_MSIX_IRQ_INDEX:
> >  			internal_config.vfio_intr_mode = RTE_INTR_MODE_MSIX;
> > @@ -302,6 +301,16 @@ pci_vfio_setup_interrupts(struct rte_pci_device *dev,
> > int vfio_dev_fd)
> >  			return -1;
> >  		}
> >
> > +		for (i = 0; i < VFIO_MAX_QUEUE_ID; i++) {
> [LCM] I think before assigning queue_fd, it shall check VFIO_PCI_MSIX_IRQ_INDEX first.
> Otherwise, no matter MSI or INTX, either one will set queue_fd as well.

Will move this to "case" block.

> 
> > +			fd = eventfd(0, 0);
> > +			if (fd < 0) {
> > +				RTE_LOG(ERR, EAL, "  cannot set up eventfd, "
> > +						"error %i (%s)\n", errno,
> > strerror(errno));
> [LCM] Cleanup the eventfd before return ?

It is not allocated successful if it returns error, so no need to clean it up. 

> 
> 
> -Steve