[dpdk-dev] [EXT] [RFC PATCH] vfio: move eventfd/interrupt pairing at setup time

[Shahed Shaikh]

> -----Original Message-----
> From: dev <dev-bounces at dpdk.org> On Behalf Of David Marchand
> Sent: Tuesday, July 2, 2019 6:18 PM
> To: dev at dpdk.org
> Cc: anatoly.burakov at intel.com; alex.williamson at redhat.com;
> maxime.coquelin at redhat.com; thomas at monjalon.net;
> stephen at networkplumber.org
> Subject: [EXT] [dpdk-dev] [RFC PATCH] vfio: move eventfd/interrupt pairing at
> setup time
> 
> 
> ----------------------------------------------------------------------
> Populating the eventfd in rte_intr_enable in each request to vfio triggers a
> reconfiguration of the interrupt handler on the kernel side.
> The problem is that rte_intr_enable is often used to re-enable masked interrupts
> from drivers interrupt handlers.
> 
> This reconfiguration leaves a window during which a device could send an
> interrupt and then the kernel logs this unsolicited interrupt:
> [158764.159833] do_IRQ: 9.34 No irq handler for vector
> 
> VFIO api makes it possible to set the fd at setup time.
> Make use of this and then we only need to ask for masking/unmasking legacy
> interrupts and we have nothing to do for MSI/MSIX.
> 
> "rxtx" interrupts are left untouched but are most likely subject to the same issue.
> 
> Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=1654824
> Signed-off-by: David Marchand <david.marchand at redhat.com>

Thanks David for this patch.
I have tested this patch with FastLinq adapters on which original issue is reported.
Tested this with MSI-x and legacy interrupt mode.

Tested-by: Shahed Shaikh <shshaikh at marvell.com>

> ---
> Sending as a RFC patch since it is not trivial and can eat your babies.
> Could people that know well this parts have a look at this?
> Thanks!
> 
> ---
>  drivers/bus/pci/linux/pci_vfio.c          |  78 ++++++------
>  lib/librte_eal/linux/eal/eal_interrupts.c | 197 +++++++-----------------------
>  2 files changed, 86 insertions(+), 189 deletions(-)
> 
> diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
> index ebf6ccd..e4c32c4 100644
> --- a/drivers/bus/pci/linux/pci_vfio.c
> +++ b/drivers/bus/pci/linux/pci_vfio.c
> @@ -186,8 +186,11 @@
>  static int
>  pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)  {
> -	int i, ret, intr_idx;
> +	char irq_set_buf[sizeof(struct vfio_irq_set) + sizeof(int)];
> +	struct vfio_irq_set *irq_set;
>  	enum rte_intr_mode intr_mode;
> +	int i, ret, intr_idx;
> +	int fd;
> 
>  	/* default to invalid index */
>  	intr_idx = VFIO_PCI_NUM_IRQS;
> @@ -219,7 +222,6 @@
>  	/* start from MSI-X interrupt type */
>  	for (i = VFIO_PCI_MSIX_IRQ_INDEX; i >= 0; i--) {
>  		struct vfio_irq_info irq = { .argsz = sizeof(irq) };
> -		int fd = -1;
> 
>  		/* skip interrupt modes we don't want */
>  		if (intr_mode != RTE_INTR_MODE_NONE && @@ -235,51
> +237,51 @@
>  			return -1;
>  		}
> 
> +		/* found a usable interrupt mode */
> +		if ((irq.flags & VFIO_IRQ_INFO_EVENTFD) != 0)
> +			break;
> +
>  		/* if this vector cannot be used with eventfd, fail if we explicitly
>  		 * specified interrupt type, otherwise continue */
> -		if ((irq.flags & VFIO_IRQ_INFO_EVENTFD) == 0) {
> -			if (intr_mode != RTE_INTR_MODE_NONE) {
> -				RTE_LOG(ERR, EAL,
> -						"  interrupt vector does not
> support eventfd!\n");
> -				return -1;
> -			} else
> -				continue;
> -		}
> -
> -		/* set up an eventfd for interrupts */
> -		fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
> -		if (fd < 0) {
> -			RTE_LOG(ERR, EAL, "  cannot set up eventfd, "
> -					"error %i (%s)\n", errno,
> strerror(errno));
> +		if (intr_mode != RTE_INTR_MODE_NONE) {
> +			RTE_LOG(ERR, EAL, "  interrupt vector does not support
> eventfd!\n");
>  			return -1;
>  		}
> +	}
> 
> -		dev->intr_handle.fd = fd;
> -		dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
> +	if (i < 0)
> +		return -1;
> 
> -		switch (i) {
> -		case VFIO_PCI_MSIX_IRQ_INDEX:
> -			intr_mode = RTE_INTR_MODE_MSIX;
> -			dev->intr_handle.type =
> RTE_INTR_HANDLE_VFIO_MSIX;
> -			break;
> -		case VFIO_PCI_MSI_IRQ_INDEX:
> -			intr_mode = RTE_INTR_MODE_MSI;
> -			dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSI;
> -			break;
> -		case VFIO_PCI_INTX_IRQ_INDEX:
> -			intr_mode = RTE_INTR_MODE_LEGACY;
> -			dev->intr_handle.type =
> RTE_INTR_HANDLE_VFIO_LEGACY;
> -			break;
> -		default:
> -			RTE_LOG(ERR, EAL, "  unknown interrupt type!\n");
> -			return -1;
> -		}
> +	fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
> +	if (fd < 0) {
> +		RTE_LOG(ERR, EAL, "  cannot set up eventfd, error %i (%s)\n",
> +			errno, strerror(errno));
> +		return -1;
> +	}
> 
> -		return 0;
> +	irq_set = (struct vfio_irq_set *)irq_set_buf;
> +	irq_set->argsz = sizeof(irq_set_buf);
> +	irq_set->flags =
> VFIO_IRQ_SET_DATA_EVENTFD|VFIO_IRQ_SET_ACTION_TRIGGER;
> +	irq_set->index = i;
> +	irq_set->start = 0;
> +	irq_set->count = 1;
> +	memcpy(&irq_set->data, &fd, sizeof(int));
> +	if (ioctl(vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set) < 0) {
> +		RTE_LOG(ERR, EAL, "  error configuring interrupt\n");
> +		close(fd);
> +		return -1;
>  	}
> 
> -	/* if we're here, we haven't found a suitable interrupt vector */
> -	return -1;
> +	dev->intr_handle.fd = fd;
> +	dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
> +	if (i == VFIO_PCI_MSIX_IRQ_INDEX)
> +		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSIX;
> +	else if (i == VFIO_PCI_MSI_IRQ_INDEX)
> +		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSI;
> +	else if (i == VFIO_PCI_INTX_IRQ_INDEX)
> +		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_LEGACY;
> +
> +	return 0;
>  }
> 
>  #ifdef HAVE_VFIO_DEV_REQ_INTERFACE
> diff --git a/lib/librte_eal/linux/eal/eal_interrupts.c
> b/lib/librte_eal/linux/eal/eal_interrupts.c
> index 79ad5e8..27976b3 100644
> --- a/lib/librte_eal/linux/eal/eal_interrupts.c
> +++ b/lib/librte_eal/linux/eal/eal_interrupts.c
> @@ -109,42 +109,19 @@ struct rte_intr_source {
> 
>  /* enable legacy (INTx) interrupts */
>  static int
> -vfio_enable_intx(const struct rte_intr_handle *intr_handle) {
> -	struct vfio_irq_set *irq_set;
> -	char irq_set_buf[IRQ_SET_BUF_LEN];
> -	int len, ret;
> -	int *fd_ptr;
> -
> -	len = sizeof(irq_set_buf);
> -
> -	/* enable INTx */
> -	irq_set = (struct vfio_irq_set *) irq_set_buf;
> -	irq_set->argsz = len;
> -	irq_set->count = 1;
> -	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> VFIO_IRQ_SET_ACTION_TRIGGER;
> -	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
> -	irq_set->start = 0;
> -	fd_ptr = (int *) &irq_set->data;
> -	*fd_ptr = intr_handle->fd;
> -
> -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> -
> -	if (ret) {
> -		RTE_LOG(ERR, EAL, "Error enabling INTx interrupts for fd
> %d\n",
> -						intr_handle->fd);
> -		return -1;
> -	}
> +vfio_enable_intx(const struct rte_intr_handle *intr_handle) {
> +	struct vfio_irq_set irq_set;
> +	int ret;
> 
> -	/* unmask INTx after enabling */
> -	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_UNMASK;
> -	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
> -	irq_set->start = 0;
> +	/* unmask INTx */
> +	irq_set.argsz = sizeof(irq_set);
> +	irq_set.flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_UNMASK;
> +	irq_set.index = VFIO_PCI_INTX_IRQ_INDEX;
> +	irq_set.start = 0;
> +	irq_set.count = 1;
> 
> -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> +	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
> 
>  	if (ret) {
>  		RTE_LOG(ERR, EAL, "Error unmasking INTx interrupts for fd
> %d\n", @@ -156,128 +133,51 @@ struct rte_intr_source {
> 
>  /* disable legacy (INTx) interrupts */
>  static int
> -vfio_disable_intx(const struct rte_intr_handle *intr_handle) {
> -	struct vfio_irq_set *irq_set;
> -	char irq_set_buf[IRQ_SET_BUF_LEN];
> -	int len, ret;
> -
> -	len = sizeof(struct vfio_irq_set);
> +vfio_disable_intx(const struct rte_intr_handle *intr_handle) {
> +	struct vfio_irq_set irq_set;
> +	int ret;
> 
> -	/* mask interrupts before disabling */
> -	irq_set = (struct vfio_irq_set *) irq_set_buf;
> -	irq_set->argsz = len;
> -	irq_set->count = 1;
> -	irq_set->flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_MASK;
> -	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
> -	irq_set->start = 0;
> +	/* mask interrupts */
> +	irq_set.argsz = sizeof(irq_set);
> +	irq_set.flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_MASK;
> +	irq_set.index = VFIO_PCI_INTX_IRQ_INDEX;
> +	irq_set.start = 0;
> +	irq_set.count = 1;
> 
> -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> +	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
> 
>  	if (ret) {
>  		RTE_LOG(ERR, EAL, "Error masking INTx interrupts for fd %d\n",
>  						intr_handle->fd);
>  		return -1;
>  	}
> -
> -	/* disable INTx*/
> -	memset(irq_set, 0, len);
> -	irq_set->argsz = len;
> -	irq_set->count = 0;
> -	irq_set->flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_TRIGGER;
> -	irq_set->index = VFIO_PCI_INTX_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 disabling INTx interrupts for fd %d\n",
> intr_handle->fd);
> -		return -1;
> -	}
> -	return 0;
> -}
> -
> -/* enable MSI interrupts */
> -static int
> -vfio_enable_msi(const struct rte_intr_handle *intr_handle) {
> -	int len, ret;
> -	char irq_set_buf[IRQ_SET_BUF_LEN];
> -	struct vfio_irq_set *irq_set;
> -	int *fd_ptr;
> -
> -	len = sizeof(irq_set_buf);
> -
> -	irq_set = (struct vfio_irq_set *) irq_set_buf;
> -	irq_set->argsz = len;
> -	irq_set->count = 1;
> -	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> VFIO_IRQ_SET_ACTION_TRIGGER;
> -	irq_set->index = VFIO_PCI_MSI_IRQ_INDEX;
> -	irq_set->start = 0;
> -	fd_ptr = (int *) &irq_set->data;
> -	*fd_ptr = intr_handle->fd;
> -
> -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> -
> -	if (ret) {
> -		RTE_LOG(ERR, EAL, "Error enabling MSI interrupts for fd %d\n",
> -						intr_handle->fd);
> -		return -1;
> -	}
>  	return 0;
>  }
> 
> -/* disable MSI interrupts */
> -static int
> -vfio_disable_msi(const struct rte_intr_handle *intr_handle) {
> -	struct vfio_irq_set *irq_set;
> -	char irq_set_buf[IRQ_SET_BUF_LEN];
> -	int len, ret;
> -
> -	len = sizeof(struct vfio_irq_set);
> -
> -	irq_set = (struct vfio_irq_set *) irq_set_buf;
> -	irq_set->argsz = len;
> -	irq_set->count = 0;
> -	irq_set->flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_TRIGGER;
> -	irq_set->index = VFIO_PCI_MSI_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 disabling MSI interrupts for fd %d\n",
> intr_handle->fd);
> -
> -	return ret;
> -}
> -
>  /* enable MSI-X interrupts */
>  static int
> -vfio_enable_msix(const struct rte_intr_handle *intr_handle) {
> -	int len, ret;
> +vfio_enable_msix(const struct rte_intr_handle *intr_handle) {
>  	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
>  	struct vfio_irq_set *irq_set;
> -	int *fd_ptr;
> +	int len, ret;
> +
> +	if (intr_handle->nb_efd == 0)
> +		return 0;
> 
>  	len = sizeof(irq_set_buf);
> 
>  	irq_set = (struct vfio_irq_set *) irq_set_buf;
>  	irq_set->argsz = len;
> -	/* 0 < irq_set->count < RTE_MAX_RXTX_INTR_VEC_ID + 1 */
> -	irq_set->count = intr_handle->max_intr ?
> -		(intr_handle->max_intr > RTE_MAX_RXTX_INTR_VEC_ID + 1 ?
> -		RTE_MAX_RXTX_INTR_VEC_ID + 1 : intr_handle->max_intr) : 1;
>  	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;
> -	/* INTR vector offset 0 reserve for non-efds mapping */
> -	fd_ptr[RTE_INTR_VEC_ZERO_OFFSET] = intr_handle->fd;
> -	memcpy(&fd_ptr[RTE_INTR_VEC_RXTX_OFFSET], intr_handle->efds,
> -		sizeof(*intr_handle->efds) * intr_handle->nb_efd);
> +	irq_set->start = RTE_INTR_VEC_RXTX_OFFSET;
> +	irq_set->count = intr_handle->nb_efd;
> +	memcpy(&irq_set->data, intr_handle->efds,
> +	       sizeof(*intr_handle->efds) * intr_handle->nb_efd);
> 
>  	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> -
>  	if (ret) {
>  		RTE_LOG(ERR, EAL, "Error enabling MSI-X interrupts for fd
> %d\n",
>  						intr_handle->fd);
> @@ -289,22 +189,21 @@ struct rte_intr_source {
> 
>  /* disable MSI-X interrupts */
>  static int
> -vfio_disable_msix(const struct rte_intr_handle *intr_handle) {
> -	struct vfio_irq_set *irq_set;
> -	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
> -	int len, ret;
> -
> -	len = sizeof(struct vfio_irq_set);
> +vfio_disable_msix(const struct rte_intr_handle *intr_handle) {
> +	struct vfio_irq_set irq_set;
> +	int ret;
> 
> -	irq_set = (struct vfio_irq_set *) irq_set_buf;
> -	irq_set->argsz = len;
> -	irq_set->count = 0;
> -	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;
> +	if (intr_handle->nb_efd == 0)
> +		return 0;
> 
> -	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
> +	irq_set.argsz = sizeof(irq_set);
> +	irq_set.flags = VFIO_IRQ_SET_DATA_NONE |
> VFIO_IRQ_SET_ACTION_TRIGGER;
> +	irq_set.index = VFIO_PCI_MSIX_IRQ_INDEX;
> +	irq_set.start = RTE_INTR_VEC_RXTX_OFFSET;
> +	irq_set.count = intr_handle->nb_efd;
> 
> +	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
>  	if (ret)
>  		RTE_LOG(ERR, EAL,
>  			"Error disabling MSI-X interrupts for fd %d\n",
> intr_handle->fd); @@ -665,9 +564,7 @@ struct rte_intr_source {
>  			return -1;
>  		break;
>  	case RTE_INTR_HANDLE_VFIO_MSI:
> -		if (vfio_enable_msi(intr_handle))
> -			return -1;
> -		break;
> +		return 0;
>  	case RTE_INTR_HANDLE_VFIO_LEGACY:
>  		if (vfio_enable_intx(intr_handle))
>  			return -1;
> @@ -721,9 +618,7 @@ struct rte_intr_source {
>  			return -1;
>  		break;
>  	case RTE_INTR_HANDLE_VFIO_MSI:
> -		if (vfio_disable_msi(intr_handle))
> -			return -1;
> -		break;
> +		return 0;
>  	case RTE_INTR_HANDLE_VFIO_LEGACY:
>  		if (vfio_disable_intx(intr_handle))
>  			return -1;
> --
> 1.8.3.1