linux/include/xen
Viresh Kumar f0d7db7b33 xen: privcmd: Add support for ioeventfd
Virtio guests send VIRTIO_MMIO_QUEUE_NOTIFY notification when they need
to notify the backend of an update to the status of the virtqueue. The
backend or another entity, polls the MMIO address for updates to know
when the notification is sent.

It works well if the backend does this polling by itself. But as we move
towards generic backend implementations, we end up implementing this in
a separate user-space program.

Generally, the Virtio backends are implemented to work with the Eventfd
based mechanism. In order to make such backends work with Xen, another
software layer needs to do the polling and send an event via eventfd to
the backend once the notification from guest is received. This results
in an extra context switch.

This is not a new problem in Linux though. It is present with other
hypervisors like KVM, etc. as well. The generic solution implemented in
the kernel for them is to provide an IOCTL call to pass the address to
poll and eventfd, which lets the kernel take care of polling and raise
an event on the eventfd, instead of handling this in user space (which
involves an extra context switch).

This patch adds similar support for xen.

Inspired by existing implementations for KVM, etc..

This also copies ioreq.h header file (only struct ioreq and related
macros) from Xen's source tree (Top commit 5d84f07fe6bf ("xen/pci: drop
remaining uses of bool_t")).

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/b20d83efba6453037d0c099912813c79c81f7714.1697439990.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross <jgross@suse.com>
2023-10-16 15:18:33 +02:00
..
arm arm/xen: remove lazy mode related definitions 2023-09-19 07:04:49 +02:00
interface xen: privcmd: Add support for ioeventfd 2023-10-16 15:18:33 +02:00
acpi.h xen: Remove support for PV ACPI cpu/memory hotplug 2021-04-23 09:31:50 +02:00
balloon.h xen/balloon: Bring alloc(free)_xenballooned_pages helpers back 2022-01-06 09:53:35 +01:00
events.h xen: simplify evtchn_do_upcall() call maze 2023-09-19 07:04:49 +02:00
features.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
grant_table.h xen/grants: support allocating consecutive grants 2022-06-06 08:54:35 +02:00
hvc-console.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hvm.h x86/xen: Add support for HVMOP_set_evtchn_upcall_vector 2022-08-12 11:28:21 +02:00
mem-reservation.h xen/balloon: add runtime control for scrubbing ballooned out pages 2018-09-14 08:51:10 -04:00
page.h swiotlb-xen: remove XEN_PFN_PHYS 2020-08-04 07:50:43 +02:00
pci.h xen-pciback: allow compiling on other archs than x86 2021-11-02 08:03:43 -05:00
platform_pci.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
swiotlb-xen.h swiotlb-xen: fix DMA_ATTR_NO_KERNEL_MAPPING on arm 2022-05-11 19:48:32 +02:00
xen-front-pgdir-shbuf.h xen: Introduce shared buffer helpers for page directory... 2018-12-18 12:15:55 -05:00
xen-ops.h xen/virtio: Optimize the setup of "xen-grant-dma" devices 2022-12-05 12:59:49 +01:00
xen.h xen/pci: add flag for PCI passthrough being possible 2023-07-31 17:54:27 +02:00
xenbus_dev.h xen: xenbus_dev.h: delete incorrect file name 2022-02-03 08:16:32 +01:00
xenbus.h driver core: make struct bus_type.uevent() take a const * 2023-01-27 13:45:52 +01:00