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path: root/drivers/virt/acrn/ioreq.c
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2023-05-08virt: acrn: Use alloc_ordered_workqueue() to create ordered workqueuesTejun Heo
BACKGROUND ========== When multiple work items are queued to a workqueue, their execution order doesn't match the queueing order. They may get executed in any order and simultaneously. When fully serialized execution - one by one in the queueing order - is needed, an ordered workqueue should be used which can be created with alloc_ordered_workqueue(). However, alloc_ordered_workqueue() was a later addition. Before it, an ordered workqueue could be obtained by creating an UNBOUND workqueue with @max_active==1. This originally was an implementation side-effect which was broken by 4c16bd327c74 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered"). Because there were users that depended on the ordered execution, 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered") made workqueue allocation path to implicitly promote UNBOUND workqueues w/ @max_active==1 to ordered workqueues. While this has worked okay, overloading the UNBOUND allocation interface this way creates other issues. It's difficult to tell whether a given workqueue actually needs to be ordered and users that legitimately want a min concurrency level wq unexpectedly gets an ordered one instead. With planned UNBOUND workqueue updates to improve execution locality and more prevalence of chiplet designs which can benefit from such improvements, this isn't a state we wanna be in forever. This patch series audits all callsites that create an UNBOUND workqueue w/ @max_active==1 and converts them to alloc_ordered_workqueue() as necessary. WHAT TO LOOK FOR ================ The conversions are from alloc_workqueue(WQ_UNBOUND | flags, 1, args..) to alloc_ordered_workqueue(flags, args...) which don't cause any functional changes. If you know that fully ordered execution is not ncessary, please let me know. I'll drop the conversion and instead add a comment noting the fact to reduce confusion while conversion is in progress. If you aren't fully sure, it's completely fine to let the conversion through. The behavior will stay exactly the same and we can always reconsider later. As there are follow-up workqueue core changes, I'd really appreciate if the patch can be routed through the workqueue tree w/ your acks. Thanks. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Fei Li <fei1.li@intel.com>
2022-07-08virt: acrn: using for_each_set_bit to simplify the codeYang Yingliang
It's more cleanly to use for_each_set_bit() instead of opencoding it. Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Fei Li <fei1.li@intel.com> Link: https://lore.kernel.org/r/20220704125044.2192381-1-yangyingliang@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-15all: replace find_next{,_zero}_bit with find_first{,_zero}_bit where appropriateYury Norov
find_first{,_zero}_bit is a more effective analogue of 'next' version if start == 0. This patch replaces 'next' with 'first' where things look trivial. Signed-off-by: Yury Norov <yury.norov@gmail.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
2021-02-09virt: acrn: Introduce I/O ranges operation interfacesShuo Liu
An I/O request of a User VM, which is constructed by hypervisor, is distributed by the ACRN Hypervisor Service Module to an I/O client corresponding to the address range of the I/O request. I/O client maintains a list of address ranges. Introduce acrn_ioreq_range_{add,del}() to manage these address ranges. Cc: Zhi Wang <zhi.a.wang@intel.com> Cc: Zhenyu Wang <zhenyuw@linux.intel.com> Cc: Yu Wang <yu1.wang@intel.com> Cc: Reinette Chatre <reinette.chatre@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Shuo Liu <shuo.a.liu@intel.com> Link: https://lore.kernel.org/r/20210207031040.49576-15-shuo.a.liu@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-09virt: acrn: Introduce PCI configuration space PIO accesses combinerShuo Liu
A User VM can access its virtual PCI configuration spaces via port IO approach, which has two following steps: 1) writes address into port 0xCF8 2) put/get data in/from port 0xCFC To distribute a complete PCI configuration space access one time, HSM need to combine such two accesses together. Combine two paired PIO I/O requests into one PCI I/O request and continue the I/O request distribution. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Shuo Liu <shuo.a.liu@intel.com> Link: https://lore.kernel.org/r/20210207031040.49576-11-shuo.a.liu@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-09virt: acrn: Introduce I/O request managementShuo Liu
An I/O request of a User VM, which is constructed by the hypervisor, is distributed by the ACRN Hypervisor Service Module to an I/O client corresponding to the address range of the I/O request. For each User VM, there is a shared 4-KByte memory region used for I/O requests communication between the hypervisor and Service VM. An I/O request is a 256-byte structure buffer, which is 'struct acrn_io_request', that is filled by an I/O handler of the hypervisor when a trapped I/O access happens in a User VM. ACRN userspace in the Service VM first allocates a 4-KByte page and passes the GPA (Guest Physical Address) of the buffer to the hypervisor. The buffer is used as an array of 16 I/O request slots with each I/O request slot being 256 bytes. This array is indexed by vCPU ID. An I/O client, which is 'struct acrn_ioreq_client', is responsible for handling User VM I/O requests whose accessed GPA falls in a certain range. Multiple I/O clients can be associated with each User VM. There is a special client associated with each User VM, called the default client, that handles all I/O requests that do not fit into the range of any other I/O clients. The ACRN userspace acts as the default client for each User VM. The state transitions of a ACRN I/O request are as follows. FREE -> PENDING -> PROCESSING -> COMPLETE -> FREE -> ... FREE: this I/O request slot is empty PENDING: a valid I/O request is pending in this slot PROCESSING: the I/O request is being processed COMPLETE: the I/O request has been processed An I/O request in COMPLETE or FREE state is owned by the hypervisor. HSM and ACRN userspace are in charge of processing the others. The processing flow of I/O requests are listed as following: a) The I/O handler of the hypervisor will fill an I/O request with PENDING state when a trapped I/O access happens in a User VM. b) The hypervisor makes an upcall, which is a notification interrupt, to the Service VM. c) The upcall handler schedules a worker to dispatch I/O requests. d) The worker looks for the PENDING I/O requests, assigns them to different registered clients based on the address of the I/O accesses, updates their state to PROCESSING, and notifies the corresponding client to handle. e) The notified client handles the assigned I/O requests. f) The HSM updates I/O requests states to COMPLETE and notifies the hypervisor of the completion via hypercalls. Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Zhi Wang <zhi.a.wang@intel.com> Cc: Zhenyu Wang <zhenyuw@linux.intel.com> Cc: Yu Wang <yu1.wang@intel.com> Cc: Reinette Chatre <reinette.chatre@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Zhi Wang <zhi.a.wang@intel.com> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Shuo Liu <shuo.a.liu@intel.com> Link: https://lore.kernel.org/r/20210207031040.49576-10-shuo.a.liu@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>