From: Stefan Hajnoczi <stefanha@redhat.com>
To: Jag Raman <jag.raman@oracle.com>
Cc: "Elena Ufimtseva" <elena.ufimtseva@oracle.com>,
"John Johnson" <john.g.johnson@oracle.com>,
"thuth@redhat.com" <thuth@redhat.com>,
"swapnil.ingle@nutanix.com" <swapnil.ingle@nutanix.com>,
"john.levon@nutanix.com" <john.levon@nutanix.com>,
"philmd@redhat.com" <philmd@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
"Alex Williamson" <alex.williamson@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@gmail.com>,
"thanos.makatos@nutanix.com" <thanos.makatos@nutanix.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"alex.bennee@linaro.org" <alex.bennee@linaro.org>
Subject: Re: [PATCH v3 05/12] vfio-user: find and init PCI device
Date: Mon, 1 Nov 2021 10:38:19 +0000 [thread overview]
Message-ID: <YX/DmwVv19IA5sSe@stefanha-x1.localdomain> (raw)
In-Reply-To: <1D478072-7D63-482A-B32C-6108942BE9F0@oracle.com>
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On Fri, Oct 29, 2021 at 03:58:28PM +0000, Jag Raman wrote:
>
>
> > On Oct 27, 2021, at 12:05 PM, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> >
> > On Mon, Oct 11, 2021 at 01:31:10AM -0400, Jagannathan Raman wrote:
> >> Find the PCI device with specified id. Initialize the device context
> >> with the QEMU PCI device
> >>
> >> 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/remote/vfio-user-obj.c | 32 ++++++++++++++++++++++++++++++++
> >> 1 file changed, 32 insertions(+)
> >>
> >> diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
> >> index d26e5ec9e9..7ce4e5b256 100644
> >> --- a/hw/remote/vfio-user-obj.c
> >> +++ b/hw/remote/vfio-user-obj.c
> >> @@ -44,6 +44,8 @@
> >> #include "qemu/notify.h"
> >> #include "sysemu/sysemu.h"
> >> #include "libvfio-user.h"
> >> +#include "hw/qdev-core.h"
> >> +#include "hw/pci/pci.h"
> >>
> >> #define TYPE_VFU_OBJECT "vfio-user-server"
> >> OBJECT_DECLARE_TYPE(VfuObject, VfuObjectClass, VFU_OBJECT)
> >> @@ -68,6 +70,8 @@ struct VfuObject {
> >> Notifier machine_done;
> >>
> >> vfu_ctx_t *vfu_ctx;
> >> +
> >> + PCIDevice *pci_dev;
> >> };
> >>
> >> static void vfu_object_set_socket(Object *obj, Visitor *v, const char *name,
> >> @@ -112,6 +116,9 @@ static void vfu_object_set_device(Object *obj, const char *str, Error **errp)
> >> static void vfu_object_machine_done(Notifier *notifier, void *data)
> >> {
> >> VfuObject *o = container_of(notifier, VfuObject, machine_done);
> >> + DeviceState *dev = NULL;
> >> + vfu_pci_type_t pci_type = VFU_PCI_TYPE_CONVENTIONAL;
> >> + int ret;
> >>
> >> o->vfu_ctx = vfu_create_ctx(VFU_TRANS_SOCK, o->socket->u.q_unix.path, 0,
> >> o, VFU_DEV_TYPE_PCI);
> >> @@ -120,6 +127,31 @@ static void vfu_object_machine_done(Notifier *notifier, void *data)
> >> strerror(errno));
> >> return;
> >> }
> >> +
> >> + dev = qdev_find_recursive(sysbus_get_default(), o->device);
> >> + if (dev == NULL) {
> >> + error_setg(&error_abort, "vfu: Device %s not found", o->device);
> >> + return;
> >> + }
> >> +
> >> + if (!object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
> >> + error_setg(&error_abort, "vfu: %s not a PCI device", o->device);
> >> + return;
> >> + }
> >> +
> >> + o->pci_dev = PCI_DEVICE(dev);
> >> +
> >> + if (pci_is_express(o->pci_dev)) {
> >> + pci_type = VFU_PCI_TYPE_EXPRESS;
> >> + }
> >> +
> >> + ret = vfu_pci_init(o->vfu_ctx, pci_type, PCI_HEADER_TYPE_NORMAL, 0);
> >> + if (ret < 0) {
> >> + error_setg(&error_abort,
> >> + "vfu: Failed to attach PCI device %s to context - %s",
> >> + o->device, strerror(errno));
> >> + return;
> >> + }
> >
> > It's unclear what happens when one of these error code paths is taken.
> > o->vfu_ctx and o->pci_dev might both be initialized, so how does the
> > code know not to service the vfio-user connection? It would be easy to
> > tell that this is correct if o->pci_dev and o->vfu_ctx were destroyed
> > when an error occurs.
>
> Hey Stefan, if I understand your question correctly, you’re wondering
> if the server would still service the connection if it takes the above
> error path.
>
> I don’t believe that would happen. When the above error path is taken,
> “error_abort” is set. Setting error_abort immediately terminates the
> QEMU process. Additionally, vfu_object_ctx_run() won’t be
> attached to the unix socket as the function exits early - so the
> connection wouldn’t be serviced.
Thanks. I'll revisit this next revision because error_abort cannot be
used for hotplug. It's okay to terminate the process on startup, but for
hotplug the expected behavior is to report an error and continue
running.
Stefan
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next prev parent reply other threads:[~2021-11-01 10:40 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 [this message]
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
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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