MSI and MSI-X interrupt management for PCI passthrough devices create a new per-interrupt context every time an interrupt is allocated, freeing it when the interrupt is freed. The per-interrupt context contains the properties of a particular interrupt. Without a property that persists across interrupt allocation and free it is acceptable to always create a new per-interrupt context. INTx interrupt context has a "masked" property that persists across allocation and free and thus preserves its interrupt context across interrupt allocation and free calls. MSI and MSI-X interrupts already remain allocated across interrupt allocation and free requests, additionally maintaining the individual interrupt context is a reflection of this existing behavior and matches INTx behavior so that more code can be shared. An additional benefit is that maintaining interrupt context supports a potential future use case of emulated interrupts, where the "is this interrupt emulated" is a property that needs to persist across allocation and free requests. Persistent interrupt contexts means that existence of per-interrupt context no longer implies a valid trigger, pointers to freed memory should be cleared, and a new per-interrupt context cannot be assumed needing allocation when an interrupt is allocated. Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> --- Note to maintainers: This addition originally formed part of the IMS work below that mostly ignored INTx. This work focuses on INTx, MSI, MSI-X where this addition is relevant. https://lore.kernel.org/lkml/cover.1696609476.git.reinette.chatre@xxxxxxxxx drivers/vfio/pci/vfio_pci_intrs.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 31f73c70fcd2..7ca2b983b66e 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -427,7 +427,7 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, ctx = vfio_irq_ctx_get(vdev, vector); - if (ctx) { + if (ctx && ctx->trigger) { irq_bypass_unregister_producer(&ctx->producer); irq = pci_irq_vector(pdev, vector); cmd = vfio_pci_memory_lock_and_enable(vdev); @@ -435,8 +435,9 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, vfio_pci_memory_unlock_and_restore(vdev, cmd); /* Interrupt stays allocated, will be freed at MSI-X disable. */ kfree(ctx->name); + ctx->name = NULL; eventfd_ctx_put(ctx->trigger); - vfio_irq_ctx_free(vdev, ctx, vector); + ctx->trigger = NULL; } if (fd < 0) @@ -449,16 +450,17 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, return irq; } - ctx = vfio_irq_ctx_alloc(vdev, vector); - if (!ctx) - return -ENOMEM; + /* Per-interrupt context remain allocated. */ + if (!ctx) { + ctx = vfio_irq_ctx_alloc(vdev, vector); + if (!ctx) + return -ENOMEM; + } ctx->name = kasprintf(GFP_KERNEL_ACCOUNT, "vfio-msi%s[%d](%s)", msix ? "x" : "", vector, pci_name(pdev)); - if (!ctx->name) { - ret = -ENOMEM; - goto out_free_ctx; - } + if (!ctx->name) + return -ENOMEM; trigger = eventfd_ctx_fdget(fd); if (IS_ERR(trigger)) { @@ -502,8 +504,7 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, eventfd_ctx_put(trigger); out_free_name: kfree(ctx->name); -out_free_ctx: - vfio_irq_ctx_free(vdev, ctx, vector); + ctx->name = NULL; return ret; } @@ -539,6 +540,7 @@ static void vfio_msi_disable(struct vfio_pci_core_device *vdev, vfio_virqfd_disable(&ctx->unmask); vfio_virqfd_disable(&ctx->mask); vfio_msi_set_vector_signal(vdev, i, -1, index); + vfio_irq_ctx_free(vdev, ctx, i); } cmd = vfio_pci_memory_lock_and_enable(vdev); @@ -694,7 +696,7 @@ static int vfio_pci_set_msi_trigger(struct vfio_pci_core_device *vdev, for (i = start; i < start + count; i++) { ctx = vfio_irq_ctx_get(vdev, i); - if (!ctx) + if (!ctx || !ctx->trigger) continue; if (flags & VFIO_IRQ_SET_DATA_NONE) { eventfd_signal(ctx->trigger); -- 2.34.1
