From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.auger@linaro.org (Eric Auger) Date: Thu, 19 Mar 2015 15:55:42 +0100 Subject: [RFC v5 04/13] KVM: kvm-vfio: User API for IRQ forwarding In-Reply-To: <1426776951-24901-1-git-send-email-eric.auger@linaro.org> References: <1426776951-24901-1-git-send-email-eric.auger@linaro.org> Message-ID: <1426776951-24901-5-git-send-email-eric.auger@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org This patch adds and documents a new KVM_DEV_VFIO_DEVICE group and 2 device attributes: KVM_DEV_VFIO_DEVICE_FORWARD_IRQ, KVM_DEV_VFIO_DEVICE_UNFORWARD_IRQ. The purpose is to be able to set a VFIO device IRQ as forwarded or not forwarded. the command takes as argument a handle to a new struct named kvm_vfio_dev_irq. Signed-off-by: Eric Auger --- v3 -> v4: - rename kvm_arch_forwarded_irq into kvm_vfio_dev_irq - some rewording in commit message - document forwarding restrictions and remove unforwarding ones v2 -> v3: - rework vfio kvm device documentation - reword commit message and title - add subindex in kvm_arch_forwarded_irq to be closer to VFIO API - forwarding state can only be changed with VFIO IRQ signaling is off v1 -> v2: - struct kvm_arch_forwarded_irq moved from arch/arm/include/uapi/asm/kvm.h to include/uapi/linux/kvm.h also irq_index renamed into index and guest_irq renamed into gsi - ASSIGN/DEASSIGN renamed into FORWARD/UNFORWARD --- Documentation/virtual/kvm/devices/vfio.txt | 34 ++++++++++++++++++++++++------ include/uapi/linux/kvm.h | 12 +++++++++++ 2 files changed, 40 insertions(+), 6 deletions(-) diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt index ef51740..6186e6d 100644 --- a/Documentation/virtual/kvm/devices/vfio.txt +++ b/Documentation/virtual/kvm/devices/vfio.txt @@ -4,15 +4,20 @@ VFIO virtual device Device types supported: KVM_DEV_TYPE_VFIO -Only one VFIO instance may be created per VM. The created device -tracks VFIO groups in use by the VM and features of those groups -important to the correctness and acceleration of the VM. As groups -are enabled and disabled for use by the VM, KVM should be updated -about their presence. When registered with KVM, a reference to the -VFIO-group is held by KVM. +Only one VFIO instance may be created per VM. + +The created device tracks VFIO groups in use by the VM and features +of those groups important to the correctness and acceleration of +the VM. As groups are enabled and disabled for use by the VM, KVM +should be updated about their presence. When registered with KVM, +a reference to the VFIO-group is held by KVM. + +The device also enables to control some IRQ settings of VFIO devices: +forwarding/posting. Groups: KVM_DEV_VFIO_GROUP + KVM_DEV_VFIO_DEVICE KVM_DEV_VFIO_GROUP attributes: KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking @@ -20,3 +25,20 @@ KVM_DEV_VFIO_GROUP attributes: For each, kvm_device_attr.addr points to an int32_t file descriptor for the VFIO group. + +KVM_DEV_VFIO_DEVICE attributes: + KVM_DEV_VFIO_DEVICE_FORWARD_IRQ: set a VFIO device IRQ as forwarded + KVM_DEV_VFIO_DEVICE_UNFORWARD_IRQ: set a VFIO device IRQ as not forwarded + +For each, kvm_device_attr.addr points to a kvm_vfio_dev_irq struct. + +When forwarded, a physical IRQ is completed by the guest and not by the +host. This requires HW support in the interrupt controller. + +Forwarding can only be set when the corresponding VFIO IRQ is not masked +(would it be through VFIO_DEVICE_SET_IRQS command or as a consequence of this +IRQ being currently handled) or active at interrupt controller level. +In such a situation, -EAGAIN is returned. It is advised to to set the +forwarding before the VFIO signaling is set up, this avoids trial and errors. + +Unforwarding can happen at any time. diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 8055706..1b78dd3 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -945,6 +945,9 @@ struct kvm_device_attr { #define KVM_DEV_VFIO_GROUP 1 #define KVM_DEV_VFIO_GROUP_ADD 1 #define KVM_DEV_VFIO_GROUP_DEL 2 +#define KVM_DEV_VFIO_DEVICE 2 +#define KVM_DEV_VFIO_DEVICE_FORWARD_IRQ 1 +#define KVM_DEV_VFIO_DEVICE_UNFORWARD_IRQ 2 enum kvm_device_type { KVM_DEV_TYPE_FSL_MPIC_20 = 1, @@ -964,6 +967,15 @@ enum kvm_device_type { KVM_DEV_TYPE_MAX, }; +struct kvm_vfio_dev_irq { + __u32 argsz; /* structure length */ + __u32 fd; /* file descriptor of the VFIO device */ + __u32 index; /* VFIO device IRQ index */ + __u32 start; /* start of subindex range */ + __u32 count; /* size of subindex range */ + __u32 gsi[]; /* gsi, ie. virtual IRQ number */ +}; + /* * ioctls for VM fds */ -- 1.9.1