Juergen Gross 85d9d02a49 xen/events: block rogue events for some time ... commit 5f7f77400a upstream. In order to avoid high dom0 load due to rogue guests sending events at high frequency, block those events in case there was no action needed in dom0 to handle the events. This is done by adding a per-event counter, which set to zero in case an EOI without the XEN_EOI_FLAG_SPURIOUS is received from a backend driver, and incremented when this flag has been set. In case the counter is 2 or higher delay the EOI by 1 << (cnt - 2) jiffies, but not more than 1 second. In order not to waste memory shorten the per-event refcnt to two bytes (it should normally never exceed a value of 2). Add an overflow check to evtchn_get() to make sure the 2 bytes really won't overflow. This is part of XSA-332. Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Wei Liu <wl@xen.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-11-05 11:43:12 +01:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
events_2l.c	xen/events: defer eoi in case of excessive number of events	2020-11-05 11:43:12 +01:00
events_base.c	xen/events: block rogue events for some time	2020-11-05 11:43:12 +01:00
events_fifo.c	xen/events: defer eoi in case of excessive number of events	2020-11-05 11:43:12 +01:00
events_internal.h	xen/events: block rogue events for some time	2020-11-05 11:43:12 +01:00