Oleksandr Andrushchenko c77edcd242 xen/gntdev: fix unmap notification order ... commit ce2f46f353 upstream. While working with Xen's libxenvchan library I have faced an issue with unmap notifications sent in wrong order if both UNMAP_NOTIFY_SEND_EVENT and UNMAP_NOTIFY_CLEAR_BYTE were requested: first we send an event channel notification and then clear the notification byte which renders in the below inconsistency (cli_live is the byte which was requested to be cleared on unmap): [ 444.514243] gntdev_put_map UNMAP_NOTIFY_SEND_EVENT map->notify.event 6 libxenvchan_is_open cli_live 1 [ 444.515239] __unmap_grant_pages UNMAP_NOTIFY_CLEAR_BYTE at 14 Thus it is not possible to reliably implement the checks like - wait for the notification (UNMAP_NOTIFY_SEND_EVENT) - check the variable (UNMAP_NOTIFY_CLEAR_BYTE) because it is possible that the variable gets checked before it is cleared by the kernel. To fix that we need to re-order the notifications, so the variable is first gets cleared and then the event channel notification is sent. With this fix I can see the correct order of execution: [ 54.522611] __unmap_grant_pages UNMAP_NOTIFY_CLEAR_BYTE at 14 [ 54.537966] gntdev_put_map UNMAP_NOTIFY_SEND_EVENT map->notify.event 6 libxenvchan_is_open cli_live 0 Cc: stable@vger.kernel.org Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20211210092817.580718-1-andr2000@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-01-27 11:05:08 +01:00
..
events	xen/console: harden hvc_xen against event channel storms	2021-12-22 09:32:52 +01:00
xen-pciback	xen-pciback: Fix return in pm_ctrl_init()	2021-11-18 19:17:05 +01:00
xenbus	xen: detect uninitialized xenbus in xenbus_init	2021-12-01 09:04:42 +01:00
xenfs
acpi.c
arm-device.c
balloon.c	xen/balloon: add late_initcall_sync() for initial ballooning done	2021-11-18 19:16:04 +01:00
biomerge.c
cpu_hotplug.c
dbgp.c
efi.c
evtchn.c
features.c	xen: check required Xen features	2021-08-30 11:57:45 +02:00
gntalloc.c
gntdev-common.h
gntdev-dmabuf.c
gntdev-dmabuf.h
gntdev.c	xen/gntdev: fix unmap notification order	2022-01-27 11:05:08 +01:00
grant-table.c
Kconfig	xen/x86: allow PVH Dom0 without XEN_PV=y	2021-10-05 08:35:56 +02:00
Makefile
manage.c
mcelog.c
mem-reservation.c
pci.c
pcpu.c	xen: Use DEVICE_ATTR_*() macro	2021-07-05 09:23:31 +02:00
platform-pci.c
privcmd-buf.c
privcmd.c	xen/privcmd: drop "pages" parameter from xen_remap_pfn()	2021-10-05 08:20:27 +02:00
privcmd.h
pvcalls-back.c
pvcalls-front.c
pvcalls-front.h
swiotlb-xen.c	xen: branch for v5.15-rc3	2021-09-25 15:37:31 -07:00
sys-hypervisor.c
time.c
unpopulated-alloc.c	xen/unpopulated-alloc: fix error return code in fill_list()	2021-05-10 09:42:25 +02:00
xen-acpi-pad.c
xen-acpi-processor.c
xen-balloon.c	xen: Use DEVICE_ATTR_*() macro	2021-07-05 09:23:31 +02:00
xen-front-pgdir-shbuf.c
xen-scsiback.c	isystem: trim/fixup stdarg.h and other headers	2021-08-19 09:02:55 +09:00
xlate_mmu.c