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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::32c; envelope-from=daan.j.demeyer@gmail.com; helo=mail-wm1-x32c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Sat, 21 Oct 2023 09:48:48 -0400 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1697896191906100005 Content-Type: text/plain; charset="utf-8" This allows passing the KVM device node to use as a file descriptor via /dev/fdset/XX. Passing the device node to use as a file descriptor allows running qemu unprivileged even when the user running qemu is not in the kvm group on distributions where access to /dev/kvm is gated behind membership of the kvm group (as long as the process invoking qemu is able to open /dev/kvm and passes the file descriptor to qemu). Signed-off-by: Daan De Meyer Reviewed-by: Daniel P. Berrang=C3=A9 --- accel/kvm/kvm-all.c | 25 ++++++++++++++++++++++++- include/sysemu/kvm_int.h | 1 + qemu-options.hx | 8 +++++++- 3 files changed, 32 insertions(+), 2 deletions(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index 72e1d1141c..3e0b2d00e9 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -2478,7 +2478,7 @@ static int kvm_init(MachineState *ms) QTAILQ_INIT(&s->kvm_sw_breakpoints); #endif QLIST_INIT(&s->kvm_parked_vcpus); - s->fd =3D qemu_open_old("/dev/kvm", O_RDWR); + s->fd =3D qemu_open_old(s->device ?: "/dev/kvm", O_RDWR); if (s->fd =3D=3D -1) { fprintf(stderr, "Could not access KVM kernel module: %m\n"); ret =3D -errno; @@ -3775,6 +3775,24 @@ static void kvm_set_dirty_ring_size(Object *obj, Vis= itor *v, s->kvm_dirty_ring_size =3D value; } =20 +static char *kvm_get_device(Object *obj, + Error **errp G_GNUC_UNUSED) +{ + KVMState *s =3D KVM_STATE(obj); + + return g_strdup(s->device); +} + +static void kvm_set_device(Object *obj, + const char *value, + Error **errp G_GNUC_UNUSED) +{ + KVMState *s =3D KVM_STATE(obj); + + g_free(s->device); + s->device =3D g_strdup(value); +} + static void kvm_accel_instance_init(Object *obj) { KVMState *s =3D KVM_STATE(obj); @@ -3793,6 +3811,7 @@ static void kvm_accel_instance_init(Object *obj) s->xen_version =3D 0; s->xen_gnttab_max_frames =3D 64; s->xen_evtchn_max_pirq =3D 256; + s->device =3D NULL; } =20 /** @@ -3833,6 +3852,10 @@ static void kvm_accel_class_init(ObjectClass *oc, vo= id *data) object_class_property_set_description(oc, "dirty-ring-size", "Size of KVM dirty page ring buffer (default: 0, i.e. use bitmap)"= ); =20 + object_class_property_add_str(oc, "device", kvm_get_device, kvm_set_de= vice); + object_class_property_set_description(oc, "device", + "Path to the device node to use (default: /dev/kvm)"); + kvm_arch_accel_class_init(oc); } =20 diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h index a5b9122cb8..19a5364a4b 100644 --- a/include/sysemu/kvm_int.h +++ b/include/sysemu/kvm_int.h @@ -124,6 +124,7 @@ struct KVMState uint32_t xen_caps; uint16_t xen_gnttab_max_frames; uint16_t xen_evtchn_max_pirq; + char *device; }; =20 void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml, diff --git a/qemu-options.hx b/qemu-options.hx index 54a7e94970..40ad15a9da 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -188,7 +188,8 @@ DEF("accel", HAS_ARG, QEMU_OPTION_accel, " dirty-ring-size=3Dn (KVM dirty ring GFN count, defaul= t 0)\n" " eager-split-size=3Dn (KVM Eager Page Split chunk size= , default 0, disabled. ARM only)\n" " notify-vmexit=3Drun|internal-error|disable,notify-win= dow=3Dn (enable notify VM exit and set notify window, x86 only)\n" - " thread=3Dsingle|multi (enable multi-threaded TCG)\n",= QEMU_ARCH_ALL) + " thread=3Dsingle|multi (enable multi-threaded TCG)\n" + " device=3Dpath (KVM device path, default /dev/kvm)\n",= QEMU_ARCH_ALL) SRST ``-accel name[,prop=3Dvalue[,...]]`` This is used to enable an accelerator. Depending on the target @@ -269,6 +270,11 @@ SRST open up for a specified of time (i.e. notify-window). Default: notify-vmexit=3Drun,notify-window=3D0. =20 + ``device=3Dpath`` + Sets the path to the KVM device node. Defaults to ``/dev/kvm``. Th= is + option can be used to pass the KVM device to use via a file descri= ptor + by setting the value to ``/dev/fdset/NN``. + ERST =20 DEF("smp", HAS_ARG, QEMU_OPTION_smp, --=20 2.41.0