Recently introduced pci_msix_alloc_irq_at() and pci_msix_free_irq() enables an individual MSI-X interrupt to be allocated and freed after MSI-X enabling. Use dynamic MSI-X (if supported by the device) to allocate an interrupt after MSI-X is enabled. An MSI-X interrupt is dynamically allocated at the time a valid eventfd is assigned. This is different behavior from a range provided during MSI-X enabling where interrupts are allocated for the entire range whether a valid eventfd is provided for each interrupt or not. Do not dynamically free interrupts, leave that to when MSI-X is disabled. Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> Link: https://lore.kernel.org/lkml/20230403211841.0e206b67.alex.williamson@xxxxxxxxxx/ --- The get_cached_msi_msg()/pci_write_msi_msg() behavior is kept similar to the scenario when MSI-X is enabled with triggers provided for new interrupts. get_cached_msi_msg()/pci_write_msi_msg() follows for interrupts recently allocated with pci_msix_alloc_irq_at() just like get_cached_msi_msg()/pci_write_msi_msg() is done for interrupts recently allocated with pci_alloc_irq_vectors(). Changes since V2: - Move vfio_irq_ctx_free() to earlier in series to support earlier usage. (Alex) - Use consistent terms in changelog: MSI-x changed to MSI-X. - Make dynamic interrupt context creation generic across all MSI/MSI-X interrupts. This resulted in code moving to earlier in series as part of xarray introduction patch. (Alex) - Remove the local allow_dyn_alloc and direct calling of pci_msix_can_alloc_dyn(), use the new vdev->has_dyn_msix introduced earlier instead. (Alex) - Stop tracking new allocations (remove "new_ctx"). (Alex) - Introduce new wrapper that returns Linux interrupt number or dynamically allocate a new interrupt. Wrapper can be used for all interrupt cases. (Alex) - Only free dynamic MSI-X interrupts on MSI-X teardown. (Alex) Changes since RFC V1: - Add pointer to interrupt context as function parameter to vfio_irq_ctx_free(). (Alex) - Initialize new_ctx to false. (Dan Carpenter) - Only support dynamic allocation if device supports it. (Alex) drivers/vfio/pci/vfio_pci_intrs.c | 73 +++++++++++++++++++++++++++---- 1 file changed, 65 insertions(+), 8 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index bdda7f46c2be..c1a3e224c867 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -372,27 +372,74 @@ static int vfio_msi_enable(struct vfio_pci_core_device *vdev, int nvec, bool msi return 0; } +/* + * Return Linux IRQ number of an MSI or MSI-X device interrupt vector. + * If a Linux IRQ number is not available then a new interrupt will be + * allocated if dynamic MSI-X is supported. + */ +static int vfio_msi_alloc_irq(struct vfio_pci_core_device *vdev, + unsigned int vector, bool msix) +{ + struct pci_dev *pdev = vdev->pdev; + struct msi_map map; + int irq; + u16 cmd; + + irq = pci_irq_vector(pdev, vector); + if (irq > 0 || !msix || !vdev->has_dyn_msix) + return irq; + + cmd = vfio_pci_memory_lock_and_enable(vdev); + map = pci_msix_alloc_irq_at(pdev, vector, NULL); + vfio_pci_memory_unlock_and_restore(vdev, cmd); + + return map.index < 0 ? map.index : map.virq; +} + +/* + * Free interrupt if it can be re-allocated dynamically (while MSI-X + * is enabled). + */ +static void vfio_msi_free_irq(struct vfio_pci_core_device *vdev, + unsigned int vector, bool msix) +{ + struct pci_dev *pdev = vdev->pdev; + struct msi_map map; + int irq; + u16 cmd; + + if (!msix || !vdev->has_dyn_msix) + return; + + irq = pci_irq_vector(pdev, vector); + map = (struct msi_map) { .index = vector, .virq = irq }; + + if (WARN_ON(irq < 0)) + return; + + cmd = vfio_pci_memory_lock_and_enable(vdev); + pci_msix_free_irq(pdev, map); + vfio_pci_memory_unlock_and_restore(vdev, cmd); +} + static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, unsigned int vector, int fd, bool msix) { struct pci_dev *pdev = vdev->pdev; struct vfio_pci_irq_ctx *ctx; struct eventfd_ctx *trigger; - int irq, ret; + int irq = -EINVAL, ret; u16 cmd; - irq = pci_irq_vector(pdev, vector); - if (irq < 0) - return -EINVAL; - ctx = vfio_irq_ctx_get(vdev, vector); if (ctx) { irq_bypass_unregister_producer(&ctx->producer); - + irq = pci_irq_vector(pdev, vector); cmd = vfio_pci_memory_lock_and_enable(vdev); free_irq(irq, ctx->trigger); vfio_pci_memory_unlock_and_restore(vdev, cmd); + /* Interrupt stays allocated, will be freed at MSI-X disable. */ kfree(ctx->name); eventfd_ctx_put(ctx->trigger); vfio_irq_ctx_free(vdev, ctx, vector); @@ -401,9 +448,17 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, if (fd < 0) return 0; + if (irq == -EINVAL) { + irq = vfio_msi_alloc_irq(vdev, vector, msix); + if (irq < 0) + return irq; + } + ctx = vfio_irq_ctx_alloc(vdev, vector); - if (!ctx) - return -ENOMEM; + if (!ctx) { + ret = -ENOMEM; + goto out_free_irq; + } ctx->name = kasprintf(GFP_KERNEL_ACCOUNT, "vfio-msi%s[%d](%s)", msix ? "x" : "", vector, pci_name(pdev)); @@ -456,6 +511,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev, kfree(ctx->name); out_free_ctx: vfio_irq_ctx_free(vdev, ctx, vector); +out_free_irq: + vfio_msi_free_irq(vdev, vector, msix); return ret; } -- 2.34.1
