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-rw-r--r--main/xen/xsa344-2.patch210
1 files changed, 210 insertions, 0 deletions
diff --git a/main/xen/xsa344-2.patch b/main/xen/xsa344-2.patch
new file mode 100644
index 0000000000..c03344bdd3
--- /dev/null
+++ b/main/xen/xsa344-2.patch
@@ -0,0 +1,210 @@
+From: Jan Beulich <jbeulich@suse.com>
+Subject: evtchn: arrange for preemption in evtchn_reset()
+
+Like for evtchn_destroy() looping over all possible event channels to
+close them can take a significant amount of time. Unlike done there, we
+can't alter domain properties (i.e. d->valid_evtchns) here. Borrow, in a
+lightweight form, the paging domctl continuation concept, redirecting
+the continuations to different sub-ops. Just like there this is to be
+able to allow for predictable overall results of the involved sub-ops:
+Racing requests should either complete or be refused.
+
+Note that a domain can't interfere with an already started (by a remote
+domain) reset, due to being paused. It can prevent a remote reset from
+happening by leaving a reset unfinished, but that's only going to affect
+itself.
+
+This is part of XSA-344.
+
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Acked-by: Julien Grall <jgrall@amazon.com>
+Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
+---
+v9: Undo v7 changes.
+v7: Move extension of loop condition in evtchn_reset() here, to match
+ the earlier patch'es change to evtchn_destroy().
+v6: Also protect the last write of d->next_evtchn. Re-base over changes
+ to earlier patches.
+v4: New.
+
+--- a/xen/common/domain.c
++++ b/xen/common/domain.c
+@@ -1145,7 +1145,7 @@ void domain_unpause_except_self(struct d
+ domain_unpause(d);
+ }
+
+-int domain_soft_reset(struct domain *d)
++int domain_soft_reset(struct domain *d, bool resuming)
+ {
+ struct vcpu *v;
+ int rc;
+@@ -1159,7 +1159,7 @@ int domain_soft_reset(struct domain *d)
+ }
+ spin_unlock(&d->shutdown_lock);
+
+- rc = evtchn_reset(d);
++ rc = evtchn_reset(d, resuming);
+ if ( rc )
+ return rc;
+
+--- a/xen/common/domctl.c
++++ b/xen/common/domctl.c
+@@ -477,12 +477,22 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xe
+ }
+
+ case XEN_DOMCTL_soft_reset:
++ case XEN_DOMCTL_soft_reset_cont:
+ if ( d == current->domain ) /* no domain_pause() */
+ {
+ ret = -EINVAL;
+ break;
+ }
+- ret = domain_soft_reset(d);
++ ret = domain_soft_reset(d, op->cmd == XEN_DOMCTL_soft_reset_cont);
++ if ( ret == -ERESTART )
++ {
++ op->cmd = XEN_DOMCTL_soft_reset_cont;
++ if ( !__copy_field_to_guest(u_domctl, op, cmd) )
++ ret = hypercall_create_continuation(__HYPERVISOR_domctl,
++ "h", u_domctl);
++ else
++ ret = -EFAULT;
++ }
+ break;
+
+ case XEN_DOMCTL_destroydomain:
+--- a/xen/common/event_channel.c
++++ b/xen/common/event_channel.c
+@@ -1057,7 +1057,7 @@ int evtchn_unmask(unsigned int port)
+ return 0;
+ }
+
+-int evtchn_reset(struct domain *d)
++int evtchn_reset(struct domain *d, bool resuming)
+ {
+ unsigned int i;
+ int rc = 0;
+@@ -1065,11 +1065,40 @@ int evtchn_reset(struct domain *d)
+ if ( d != current->domain && !d->controller_pause_count )
+ return -EINVAL;
+
+- for ( i = 0; port_is_valid(d, i); i++ )
++ spin_lock(&d->event_lock);
++
++ /*
++ * If we are resuming, then start where we stopped. Otherwise, check
++ * that a reset operation is not already in progress, and if none is,
++ * record that this is now the case.
++ */
++ i = resuming ? d->next_evtchn : !d->next_evtchn;
++ if ( i > d->next_evtchn )
++ d->next_evtchn = i;
++
++ spin_unlock(&d->event_lock);
++
++ if ( !i )
++ return -EBUSY;
++
++ for ( ; port_is_valid(d, i); i++ )
++ {
+ evtchn_close(d, i, 1);
+
++ /* NB: Choice of frequency is arbitrary. */
++ if ( !(i & 0x3f) && hypercall_preempt_check() )
++ {
++ spin_lock(&d->event_lock);
++ d->next_evtchn = i;
++ spin_unlock(&d->event_lock);
++ return -ERESTART;
++ }
++ }
++
+ spin_lock(&d->event_lock);
+
++ d->next_evtchn = 0;
++
+ if ( d->active_evtchns > d->xen_evtchns )
+ rc = -EAGAIN;
+ else if ( d->evtchn_fifo )
+@@ -1204,7 +1233,8 @@ long do_event_channel_op(int cmd, XEN_GU
+ break;
+ }
+
+- case EVTCHNOP_reset: {
++ case EVTCHNOP_reset:
++ case EVTCHNOP_reset_cont: {
+ struct evtchn_reset reset;
+ struct domain *d;
+
+@@ -1217,9 +1247,13 @@ long do_event_channel_op(int cmd, XEN_GU
+
+ rc = xsm_evtchn_reset(XSM_TARGET, current->domain, d);
+ if ( !rc )
+- rc = evtchn_reset(d);
++ rc = evtchn_reset(d, cmd == EVTCHNOP_reset_cont);
+
+ rcu_unlock_domain(d);
++
++ if ( rc == -ERESTART )
++ rc = hypercall_create_continuation(__HYPERVISOR_event_channel_op,
++ "ih", EVTCHNOP_reset_cont, arg);
+ break;
+ }
+
+--- a/xen/include/public/domctl.h
++++ b/xen/include/public/domctl.h
+@@ -1159,7 +1159,10 @@ struct xen_domctl {
+ #define XEN_DOMCTL_iomem_permission 20
+ #define XEN_DOMCTL_ioport_permission 21
+ #define XEN_DOMCTL_hypercall_init 22
+-#define XEN_DOMCTL_arch_setup 23 /* Obsolete IA64 only */
++#ifdef __XEN__
++/* #define XEN_DOMCTL_arch_setup 23 Obsolete IA64 only */
++#define XEN_DOMCTL_soft_reset_cont 23
++#endif
+ #define XEN_DOMCTL_settimeoffset 24
+ #define XEN_DOMCTL_getvcpuaffinity 25
+ #define XEN_DOMCTL_real_mode_area 26 /* Obsolete PPC only */
+--- a/xen/include/public/event_channel.h
++++ b/xen/include/public/event_channel.h
+@@ -74,6 +74,9 @@
+ #define EVTCHNOP_init_control 11
+ #define EVTCHNOP_expand_array 12
+ #define EVTCHNOP_set_priority 13
++#ifdef __XEN__
++#define EVTCHNOP_reset_cont 14
++#endif
+ /* ` } */
+
+ typedef uint32_t evtchn_port_t;
+--- a/xen/include/xen/event.h
++++ b/xen/include/xen/event.h
+@@ -171,7 +171,7 @@ void evtchn_check_pollers(struct domain
+ void evtchn_2l_init(struct domain *d);
+
+ /* Close all event channels and reset to 2-level ABI. */
+-int evtchn_reset(struct domain *d);
++int evtchn_reset(struct domain *d, bool resuming);
+
+ /*
+ * Low-level event channel port ops.
+--- a/xen/include/xen/sched.h
++++ b/xen/include/xen/sched.h
+@@ -371,6 +371,8 @@ struct domain
+ * EVTCHNOP_reset). Read/write access like for active_evtchns.
+ */
+ unsigned int xen_evtchns;
++ /* Port to resume from in evtchn_reset(), when in a continuation. */
++ unsigned int next_evtchn;
+ spinlock_t event_lock;
+ const struct evtchn_port_ops *evtchn_port_ops;
+ struct evtchn_fifo_domain *evtchn_fifo;
+@@ -663,7 +665,7 @@ int domain_kill(struct domain *d);
+ int domain_shutdown(struct domain *d, u8 reason);
+ void domain_resume(struct domain *d);
+
+-int domain_soft_reset(struct domain *d);
++int domain_soft_reset(struct domain *d, bool resuming);
+
+ int vcpu_start_shutdown_deferral(struct vcpu *v);
+ void vcpu_end_shutdown_deferral(struct vcpu *v);