From: John Levon <john.levon@nutanix.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: "elena.ufimtseva@oracle.com" <elena.ufimtseva@oracle.com>,
"john.g.johnson@oracle.com" <john.g.johnson@oracle.com>,
"thuth@redhat.com" <thuth@redhat.com>,
Jagannathan Raman <jag.raman@oracle.com>,
Swapnil Ingle <swapnil.ingle@nutanix.com>,
"alex.bennee@linaro.org" <alex.bennee@linaro.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"marcandre.lureau@gmail.com" <marcandre.lureau@gmail.com>,
Thanos Makatos <thanos.makatos@nutanix.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"philmd@redhat.com" <philmd@redhat.com>
Subject: Re: [PATCH v3 06/12] vfio-user: run vfio-user context
Date: Thu, 28 Oct 2021 21:55:37 +0000 [thread overview]
Message-ID: <YXscWS/qmwEDKOTO@movementarian.org> (raw)
In-Reply-To: <YXl8ilTXICU+0EHk@stefanha-x1.localdomain>
On Wed, Oct 27, 2021 at 05:21:30PM +0100, Stefan Hajnoczi wrote:
> > +static void vfu_object_ctx_run(void *opaque)
> > +{
> > + VfuObject *o = opaque;
> > + int ret = -1;
> > +
> > + while (ret != 0) {
> > + ret = vfu_run_ctx(o->vfu_ctx);
> > + if (ret < 0) {
> > + if (errno == EINTR) {
> > + continue;
> > + } else if (errno == ENOTCONN) {
> > + qemu_set_fd_handler(o->vfu_poll_fd, NULL, NULL, NULL);
> > + o->vfu_poll_fd = -1;
> > + object_unparent(OBJECT(o));
> > + break;
> > + } else {
> > + error_setg(&error_abort, "vfu: Failed to run device %s - %s",
> > + o->device, strerror(errno));
> > + break;
> > + }
>
> The libvfio-user.h doc comments say this function can return -1 (EAGAIN)
> when LIBVFIO_USER_FLAG_ATTACH_NB was used. Is the doc comment wrong
> since this patch seems to rely on vfu_run_ctx() returning 0 when there
> are no more commands to process?
* @returns the number of requests processed (0 or more); or -1 on error,
* with errno set as follows:
So in fact it does return 0. The EAGAIN line needs removing; I'll fix it
shortly.
> > +static void vfu_object_attach_ctx(void *opaque)
> > +{
> > + VfuObject *o = opaque;
> > + int ret;
> > +
> > + qemu_set_fd_handler(o->vfu_poll_fd, NULL, NULL, NULL);
> > + o->vfu_poll_fd = -1;
> > +
> > +retry_attach:
> > + ret = vfu_attach_ctx(o->vfu_ctx);
> > + if (ret < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
> > + goto retry_attach;
>
> Can we wait for the poll fd to become readable instead of spinning? I
> don't know the libvfio-user APIs so I'm not sure, but it would be nice
> to avoid a busy loop.
At this point, ->vfu_poll_fd is a listening socket, no reason why qemu couldn't
epoll on it.
regards
john
next prev parent reply other threads:[~2021-10-28 21:57 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 5:31 [PATCH v3 00/12] vfio-user server in QEMU Jagannathan Raman
2021-10-11 5:31 ` [PATCH v3 01/12] configure, meson: override C compiler for cmake Jagannathan Raman
2021-10-12 10:44 ` Paolo Bonzini
2021-10-11 5:31 ` [PATCH v3 02/12] vfio-user: build library Jagannathan Raman
2021-10-27 15:17 ` Stefan Hajnoczi
2021-10-29 14:17 ` Jag Raman
2021-11-01 9:56 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 03/12] vfio-user: define vfio-user-server object Jagannathan Raman
2021-10-27 15:40 ` Stefan Hajnoczi
2021-10-29 14:42 ` Jag Raman
2021-11-01 10:34 ` Stefan Hajnoczi
2021-11-04 12:13 ` Markus Armbruster
2021-11-04 14:39 ` Kevin Wolf
2021-11-05 10:08 ` Markus Armbruster
2021-11-05 13:19 ` Kevin Wolf
2021-11-05 13:54 ` Peter Krempa
2021-11-06 6:34 ` Markus Armbruster
2021-11-08 12:05 ` Kevin Wolf
2021-11-08 12:54 ` Peter Krempa
2021-11-04 16:48 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 04/12] vfio-user: instantiate vfio-user context Jagannathan Raman
2021-10-27 15:59 ` Stefan Hajnoczi
2021-10-29 14:59 ` Jag Raman
2021-11-01 10:35 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 05/12] vfio-user: find and init PCI device Jagannathan Raman
2021-10-27 16:05 ` Stefan Hajnoczi
2021-10-29 15:58 ` Jag Raman
2021-11-01 10:38 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 06/12] vfio-user: run vfio-user context Jagannathan Raman
2021-10-27 16:21 ` Stefan Hajnoczi
2021-10-28 21:55 ` John Levon [this message]
2021-10-11 5:31 ` [PATCH v3 07/12] vfio-user: handle PCI config space accesses Jagannathan Raman
2021-10-27 16:35 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 08/12] vfio-user: handle DMA mappings Jagannathan Raman
2021-10-11 5:31 ` [PATCH v3 09/12] vfio-user: handle PCI BAR accesses Jagannathan Raman
2021-10-27 16:38 ` Stefan Hajnoczi
2021-10-11 5:31 ` [PATCH v3 10/12] vfio-user: handle device interrupts Jagannathan Raman
2021-10-11 5:31 ` [PATCH v3 11/12] vfio-user: register handlers to facilitate migration Jagannathan Raman
2021-10-27 18:30 ` Stefan Hajnoczi
2021-12-15 15:49 ` Jag Raman
2021-10-11 5:31 ` [PATCH v3 12/12] vfio-user: acceptance test Jagannathan Raman
2021-10-11 22:26 ` Philippe Mathieu-Daudé
2021-10-27 16:42 ` Stefan Hajnoczi
2021-10-27 18:33 ` [PATCH v3 00/12] vfio-user server in QEMU Stefan Hajnoczi
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