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Tsirkin" , Peter Xu , Avihai Horon , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= Subject: [RFC PATCH 08/11] igb: Fix post-migration RX ring deadlock Date: Mon, 27 Jul 2026 07:39:32 +0200 Message-ID: <20260727053935.1392269-9-clg@redhat.com> In-Reply-To: <20260727053935.1392269-1-clg@redhat.com> References: <20260727053935.1392269-1-clg@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -2 X-Spam_score: -0.3 X-Spam_bar: / X-Spam_report: (-0.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.58, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org After migration, the VF unquiesce path calls igb_start_recv() to kick RX processing. This does not trigger an interrupt, so NAPI stays idle and the RX ring is never replenished. Replace igb_start_recv() with igb_core_vf_rearm_irqs(): re-apply the VF's PVT shadow register into the PF aggregates, then raise interrupt causes via igb_set_eics(). This follows the normal EICR -> EIMS -> MSI-X routing. NAPI wakes, replenishes the ring via igbvf_alloc_rx_buffers(), and writes RDT - breaking the deadlock. The PVT re-application is needed because the L1 PF driver's normal interrupt handling may have cleared EIMS between state load and unquiesce. Assisted-by: Claude Signed-off-by: Cédric Le Goater --- hw/net/igb_core.h | 1 + hw/net/igb_core.c | 12 ++++++++++++ hw/net/igb_migration.c | 2 +- 3 files changed, 14 insertions(+), 1 deletion(-) diff --git a/hw/net/igb_core.h b/hw/net/igb_core.h index 50cee2c7683c..3db520048732 100644 --- a/hw/net/igb_core.h +++ b/hw/net/igb_core.h @@ -147,5 +147,6 @@ igb_start_recv(IGBCore *core); IGBCore *igb_pf_get_core(void *pf); void igb_core_vf_propagate_irqs(IGBCore *core, uint16_t vfn); +void igb_core_vf_rearm_irqs(IGBCore *core, uint16_t vfn); void igb_core_vf_propagate_ivar(IGBCore *core, uint16_t vfn); #endif diff --git a/hw/net/igb_core.c b/hw/net/igb_core.c index 03c349575c0a..1621ee6602d5 100644 --- a/hw/net/igb_core.c +++ b/hw/net/igb_core.c @@ -4589,6 +4589,18 @@ void igb_core_vf_propagate_irqs(IGBCore *core, uint16_t vfn) core->mac[EICR] &= ~(0x7 << shift); } +/* + * Re-apply VF interrupt enables to PF aggregates and raise interrupt + * causes to wake NAPI so it replenishes the ring after migration. + */ +void igb_core_vf_rearm_irqs(IGBCore *core, uint16_t vfn) +{ + uint32_t shift = 22 - vfn * IGBVF_MSIX_VEC_NUM; + + igb_core_vf_propagate_irqs(core, vfn); + igb_set_eics(core, EICS, 0x7 << shift); +} + /* * Re-apply VTIVAR -> IVAR0 interrupt routing. The L1 PF driver * may have overwritten the shared IVAR0 entries with its own diff --git a/hw/net/igb_migration.c b/hw/net/igb_migration.c index 187077c14c48..a0b4a52c865f 100644 --- a/hw/net/igb_migration.c +++ b/hw/net/igb_migration.c @@ -630,7 +630,7 @@ static void igb_core_vf_unquiesce(IgbVfState *s) trace_igbvf_mig_unquiesce(s->vfn, core->mac[VFRE], core->mac[VFTE]); if (re) { - igb_start_recv(core); + igb_core_vf_rearm_irqs(core, s->vfn); } } -- 2.55.0