Re: [PATCH v1 14/24] vfio-user: get and set IRQs

From: "Cédric Le Goater" <clg@redhat.com>
To: John Johnson <john.g.johnson@oracle.com>, qemu-devel@nongnu.org
Subject: Re: [PATCH v1 14/24] vfio-user: get and set IRQs
Date: Tue, 13 Dec 2022 17:39:49 +0100	[thread overview]
Message-ID: <9fb35cf6-53bf-1309-c27e-de3bece7fbe1@redhat.com> (raw)
In-Reply-To: <5532e8b1721cdf68d8932c747dc6b5f42738e139.1667542066.git.john.g.johnson@oracle.com>

On 11/9/22 00:13, John Johnson wrote:
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> ---
>   hw/vfio/pci.c           |   7 ++-
>   hw/vfio/user-protocol.h |  25 +++++++++
>   hw/vfio/user.c          | 135 ++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 166 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 7abe44e..be39a4e 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -713,7 +713,8 @@ retry:
>       ret = vfio_enable_vectors(vdev, false);
>       if (ret) {
>           if (ret < 0) {
> -            error_report("vfio: Error: Failed to setup MSI fds: %m");
> +            error_report("vfio: Error: Failed to setup MSI fds: %s",
> +                         strerror(-ret));

This change belongs to another patch.

>           } else {
>               error_report("vfio: Error: Failed to enable %d "
>                            "MSI vectors, retry with %d", vdev->nr_vectors, ret);
> @@ -2712,6 +2713,7 @@ static void vfio_populate_device(VFIOPCIDevice *vdev, Error **errp)
>       irq_info.index = VFIO_PCI_ERR_IRQ_INDEX;
>   
>       ret = VDEV_GET_IRQ_INFO(vbasedev, &irq_info);
> +
>       if (ret) {
>           /* This can fail for an old kernel or legacy PCI dev */
>           trace_vfio_populate_device_get_irq_info_failure(strerror(errno));
> @@ -3593,6 +3595,9 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
>           goto out_teardown;
>       }
>   
> +    vfio_register_err_notifier(vdev);
> +    vfio_register_req_notifier(vdev);
> +
>       return;
>   
>   out_teardown:
> diff --git a/hw/vfio/user-protocol.h b/hw/vfio/user-protocol.h
> index 124340c..31704cf 100644
> --- a/hw/vfio/user-protocol.h
> +++ b/hw/vfio/user-protocol.h
> @@ -141,6 +141,31 @@ typedef struct {
>   } VFIOUserRegionInfo;
>   
>   /*
> + * VFIO_USER_DEVICE_GET_IRQ_INFO
> + * imported from struct vfio_irq_info
> + */
> +typedef struct {
> +    VFIOUserHdr hdr;
> +    uint32_t argsz;
> +    uint32_t flags;
> +    uint32_t index;
> +    uint32_t count;
> +} VFIOUserIRQInfo;
> +
> +/*
> + * VFIO_USER_DEVICE_SET_IRQS
> + * imported from struct vfio_irq_set
> + */
> +typedef struct {
> +    VFIOUserHdr hdr;
> +    uint32_t argsz;
> +    uint32_t flags;
> +    uint32_t index;
> +    uint32_t start;
> +    uint32_t count;
> +} VFIOUserIRQSet;
> +
> +/*
>    * VFIO_USER_REGION_READ
>    * VFIO_USER_REGION_WRITE
>    */
> diff --git a/hw/vfio/user.c b/hw/vfio/user.c
> index 1453bb5..815385b 100644
> --- a/hw/vfio/user.c
> +++ b/hw/vfio/user.c
> @@ -1164,6 +1164,117 @@ static int vfio_user_get_region_info(VFIOProxy *proxy,
>       return 0;
>   }
>   
> +static int vfio_user_get_irq_info(VFIOProxy *proxy,
> +                                  struct vfio_irq_info *info)
> +{
> +    VFIOUserIRQInfo msg;
> +
> +    memset(&msg, 0, sizeof(msg));
> +    vfio_user_request_msg(&msg.hdr, VFIO_USER_DEVICE_GET_IRQ_INFO,
> +                          sizeof(msg), 0);
> +    msg.argsz = info->argsz;
> +    msg.index = info->index;
> +
> +    vfio_user_send_wait(proxy, &msg.hdr, NULL, 0, false);
> +    if (msg.hdr.flags & VFIO_USER_ERROR) {
> +        return -msg.hdr.error_reply;
> +    }
> +
> +    memcpy(info, &msg.argsz, sizeof(*info));
> +    return 0;
> +}
> +
> +static int irq_howmany(int *fdp, uint32_t cur, uint32_t max)

intriguing routine. See comment below.

> +{
> +    int n = 0;
> +
> +    if (fdp[cur] != -1) {
> +        do {
> +            n++;
> +        } while (n < max && fdp[cur + n] != -1);
> +    } else {
> +        do {
> +            n++;
> +        } while (n < max && fdp[cur + n] == -1);
> +    }
> +
> +    return n;
> +}
> +
> +static int vfio_user_set_irqs(VFIOProxy *proxy, struct vfio_irq_set *irq)
> +{
> +    g_autofree VFIOUserIRQSet *msgp = NULL;
> +    uint32_t size, nfds, send_fds, sent_fds, max;
> +
> +    if (irq->argsz < sizeof(*irq)) {
> +        error_printf("vfio_user_set_irqs argsz too small\n");
> +        return -EINVAL;
> +    }
> +
> +    /*
> +     * Handle simple case
> +     */
> +    if ((irq->flags & VFIO_IRQ_SET_DATA_EVENTFD) == 0) {
> +        size = sizeof(VFIOUserHdr) + irq->argsz;
> +        msgp = g_malloc0(size);
> +
> +        vfio_user_request_msg(&msgp->hdr, VFIO_USER_DEVICE_SET_IRQS, size, 0);
> +        msgp->argsz = irq->argsz;
> +        msgp->flags = irq->flags;
> +        msgp->index = irq->index;
> +        msgp->start = irq->start;
> +        msgp->count = irq->count;
> +
> +        vfio_user_send_wait(proxy, &msgp->hdr, NULL, 0, false);
> +        if (msgp->hdr.flags & VFIO_USER_ERROR) {
> +            return -msgp->hdr.error_reply;
> +        }
> +
> +        return 0;
> +    }
> +
> +    /*
> +     * Calculate the number of FDs to send
> +     * and adjust argsz
> +     */
> +    nfds = (irq->argsz - sizeof(*irq)) / sizeof(int);
> +    irq->argsz = sizeof(*irq);
> +    msgp = g_malloc0(sizeof(*msgp));
> +    /*
> +     * Send in chunks if over max_send_fds
> +     */
> +    for (sent_fds = 0; nfds > sent_fds; sent_fds += send_fds) {
> +        VFIOUserFDs *arg_fds, loop_fds;
> +
> +        /* must send all valid FDs or all invalid FDs in single msg */

why is that ?

> +        max = nfds - sent_fds;
> +        if (max > proxy->max_send_fds) {
> +            max = proxy->max_send_fds;
> +        }
> +        send_fds = irq_howmany((int *)irq->data, sent_fds, max);

sent_fds can never be -1 but irq_howmany() is taking into account this
value. Why ?

> +
> +        vfio_user_request_msg(&msgp->hdr, VFIO_USER_DEVICE_SET_IRQS,
> +                              sizeof(*msgp), 0);
> +        msgp->argsz = irq->argsz;
> +        msgp->flags = irq->flags;
> +        msgp->index = irq->index;
> +        msgp->start = irq->start + sent_fds;
> +        msgp->count = send_fds;
> +
> +        loop_fds.send_fds = send_fds;
> +        loop_fds.recv_fds = 0;
> +        loop_fds.fds = (int *)irq->data + sent_fds;
> +        arg_fds = loop_fds.fds[0] != -1 ? &loop_fds : NULL;
> +
> +        vfio_user_send_wait(proxy, &msgp->hdr, arg_fds, 0, false);
> +        if (msgp->hdr.flags & VFIO_USER_ERROR) {
> +            return -msgp->hdr.error_reply;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>   static int vfio_user_region_read(VFIOProxy *proxy, uint8_t index, off_t offset,
>                                    uint32_t count, void *data)
>   {
> @@ -1277,6 +1388,28 @@ static int vfio_user_io_get_region_info(VFIODevice *vbasedev,
>       return 0;
>   }
>   
> +static int vfio_user_io_get_irq_info(VFIODevice *vbasedev,
> +                                     struct vfio_irq_info *irq)
> +{
> +    int ret;
> +
> +    ret = vfio_user_get_irq_info(vbasedev->proxy, irq);
> +    if (ret) {
> +        return ret;
> +    }
> +
> +    if (irq->index > vbasedev->num_irqs) {
> +        return -EINVAL;
> +    }
> +    return 0;
> +}
> +
> +static int vfio_user_io_set_irqs(VFIODevice *vbasedev,
> +                                 struct vfio_irq_set *irqs)
> +{
> +    return vfio_user_set_irqs(vbasedev->proxy, irqs);
> +}
> +
>   static int vfio_user_io_region_read(VFIODevice *vbasedev, uint8_t index,
>                                       off_t off, uint32_t size, void *data)
>   {
> @@ -1294,6 +1427,8 @@ static int vfio_user_io_region_write(VFIODevice *vbasedev, uint8_t index,
>   VFIODevIO vfio_dev_io_sock = {
>       .get_info = vfio_user_io_get_info,
>       .get_region_info = vfio_user_io_get_region_info,
> +    .get_irq_info = vfio_user_io_get_irq_info,
> +    .set_irqs = vfio_user_io_set_irqs,
>       .region_read = vfio_user_io_region_read,
>       .region_write = vfio_user_io_region_write,
>   };