[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 1/1] evtchn: make EVTCHNOP_reset suitable for kexec
It would be nice to allow guests to close all event channels in ABI-agnostic way in case of kexec/kdump. EVTCHNOP_reset looks suitable for this purpose. However control blocks for vcpus and event array need cleanup when FIFO ABI is being used. With this change a guest can simply do EVTCHNOP_reset before kexec in both 2-level and FIFO cases. It is also important to perform store/console channel remapping after such call. The issue can also be solved by introducing a new EVTCHNOP operation but it seems that EVTCHNOP_reset can be reused. [The idea was suggested by Ian Campbell, Andrew Cooper, and David Vrabel] Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> --- Changes from v2: - use d->event_lock when switching ABI [David Vrabel] - add documentation to xen/include/public/event_channel.h [David Vrabel] - check for 'dom == DOMID_SELF' instead of 'd == current->domain' to allow guests use unaltered behavior [Jan Beulich] Changes from v1: - Change EVTCHNOP_reset behavior when it is being called by the guest with DOMID_SELF only [Andrew Cooper, Jan Beulich]. - Do not skip interdomain store/console channels, let the guest rebind them [David Vrabel]. - Do evtchn_2l_init() after evtchn_fifo_destroy() so the guest can perform e.g. EVTCHNOP_bind_interdomain operations after EVTCHNOP_reset. --- xen/common/event_channel.c | 15 +++++++++++++++ xen/common/event_fifo.c | 1 + xen/include/public/event_channel.h | 4 ++++ 3 files changed, 20 insertions(+) diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c index db952af..a7becae 100644 --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -957,6 +957,21 @@ static long evtchn_reset(evtchn_reset_t *r) for ( i = 0; port_is_valid(d, i); i++ ) (void)__evtchn_close(d, i); + spin_lock(&d->event_lock); + + if ( (dom == DOMID_SELF) && d->evtchn_fifo ) + { + /* + * Guest domain called EVTCHNOP_reset with DOMID_SELF, destroying + * FIFO event array and control blocks, resetting evtchn_port_ops to + * evtchn_port_ops_2l. + */ + evtchn_fifo_destroy(d); + evtchn_2l_init(d); + } + + spin_unlock(&d->event_lock); + rc = 0; out: diff --git a/xen/common/event_fifo.c b/xen/common/event_fifo.c index 1fce3f1..51b4ff6 100644 --- a/xen/common/event_fifo.c +++ b/xen/common/event_fifo.c @@ -451,6 +451,7 @@ static void cleanup_event_array(struct domain *d) for ( i = 0; i < EVTCHN_FIFO_MAX_EVENT_ARRAY_PAGES; i++ ) unmap_guest_page(d->evtchn_fifo->event_array[i]); xfree(d->evtchn_fifo); + d->evtchn_fifo = NULL; } static void setup_ports(struct domain *d) diff --git a/xen/include/public/event_channel.h b/xen/include/public/event_channel.h index 49ac8cc..05e531d 100644 --- a/xen/include/public/event_channel.h +++ b/xen/include/public/event_channel.h @@ -264,6 +264,10 @@ typedef struct evtchn_unmask evtchn_unmask_t; * NOTES: * 1. <dom> may be specified as DOMID_SELF. * 2. Only a sufficiently-privileged domain may specify other than DOMID_SELF. + * 3. Destroys all control blocks and event array, resets event channel + * operations to 2-level ABI if called with <dom> == DOMID_SELF and FIFO + * ABI was used. Guests should not bind events during EVTCHNOP_reset call + * as these events are likely to be lost. */ struct evtchn_reset { /* IN parameters. */ -- 1.9.3 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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