Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2129 insertions, 0 deletions

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
new file mode 100644
index 0000000000..40edf4d197
--- /dev/null
+++ b/arch/x86/kvm/xen.c
@@ -0,0 +1,2129 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright © 2019 Oracle and/or its affiliates. All rights reserved.
+ * Copyright © 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * KVM Xen emulation
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include "x86.h"
+#include "xen.h"
+#include "hyperv.h"
+#include "lapic.h"
+
+#include <linux/eventfd.h>
+#include <linux/kvm_host.h>
+#include <linux/sched/stat.h>
+
+#include <trace/events/kvm.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/vcpu.h>
+#include <xen/interface/version.h>
+#include <xen/interface/event_channel.h>
+#include <xen/interface/sched.h>
+
+#include <asm/xen/cpuid.h>
+
+#include "cpuid.h"
+#include "trace.h"
+
+static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm);
+static int kvm_xen_setattr_evtchn(struct kvm *kvm, struct kvm_xen_hvm_attr *data);
+static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r);
+
+DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
+
+static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
+{
+	struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;
+	struct pvclock_wall_clock *wc;
+	gpa_t gpa = gfn_to_gpa(gfn);
+	u32 *wc_sec_hi;
+	u32 wc_version;
+	u64 wall_nsec;
+	int ret = 0;
+	int idx = srcu_read_lock(&kvm->srcu);
+
+	if (gfn == KVM_XEN_INVALID_GFN) {
+		kvm_gpc_deactivate(gpc);
+		goto out;
+	}
+
+	do {
+		ret = kvm_gpc_activate(gpc, gpa, PAGE_SIZE);
+		if (ret)
+			goto out;
+
+		/*
+		 * This code mirrors kvm_write_wall_clock() except that it writes
+		 * directly through the pfn cache and doesn't mark the page dirty.
+		 */
+		wall_nsec = ktime_get_real_ns() - get_kvmclock_ns(kvm);
+
+		/* It could be invalid again already, so we need to check */
+		read_lock_irq(&gpc->lock);
+
+		if (gpc->valid)
+			break;
+
+		read_unlock_irq(&gpc->lock);
+	} while (1);
+
+	/* Paranoia checks on the 32-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);
+	BUILD_BUG_ON(offsetof(struct compat_shared_info, arch.wc_sec_hi) != 0x924);
+	BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);
+
+#ifdef CONFIG_X86_64
+	/* Paranoia checks on the 64-bit struct layout */
+	BUILD_BUG_ON(offsetof(struct shared_info, wc) != 0xc00);
+	BUILD_BUG_ON(offsetof(struct shared_info, wc_sec_hi) != 0xc0c);
+
+	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
+		struct shared_info *shinfo = gpc->khva;
+
+		wc_sec_hi = &shinfo->wc_sec_hi;
+		wc = &shinfo->wc;
+	} else
+#endif
+	{
+		struct compat_shared_info *shinfo = gpc->khva;
+
+		wc_sec_hi = &shinfo->arch.wc_sec_hi;
+		wc = &shinfo->wc;
+	}
+
+	/* Increment and ensure an odd value */
+	wc_version = wc->version = (wc->version + 1) | 1;
+	smp_wmb();
+
+	wc->nsec = do_div(wall_nsec,  1000000000);
+	wc->sec = (u32)wall_nsec;
+	*wc_sec_hi = wall_nsec >> 32;
+	smp_wmb();
+
+	wc->version = wc_version + 1;
+	read_unlock_irq(&gpc->lock);
+
+	kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
+
+out:
+	srcu_read_unlock(&kvm->srcu, idx);
+	return ret;
+}
+
+void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu)
+{
+	if (atomic_read(&vcpu->arch.xen.timer_pending) > 0) {
+		struct kvm_xen_evtchn e;
+
+		e.vcpu_id = vcpu->vcpu_id;
+		e.vcpu_idx = vcpu->vcpu_idx;
+		e.port = vcpu->arch.xen.timer_virq;
+		e.priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL;
+
+		kvm_xen_set_evtchn(&e, vcpu->kvm);
+
+		vcpu->arch.xen.timer_expires = 0;
+		atomic_set(&vcpu->arch.xen.timer_pending, 0);
+	}
+}
+
+static enum hrtimer_restart xen_timer_callback(struct hrtimer *timer)
+{
+	struct kvm_vcpu *vcpu = container_of(timer, struct kvm_vcpu,
+					     arch.xen.timer);
+	if (atomic_read(&vcpu->arch.xen.timer_pending))
+		return HRTIMER_NORESTART;
+
+	atomic_inc(&vcpu->arch.xen.timer_pending);
+	kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
+	kvm_vcpu_kick(vcpu);
+
+	return HRTIMER_NORESTART;
+}
+
+static void kvm_xen_start_timer(struct kvm_vcpu *vcpu, u64 guest_abs, s64 delta_ns)
+{
+	atomic_set(&vcpu->arch.xen.timer_pending, 0);
+	vcpu->arch.xen.timer_expires = guest_abs;
+
+	if (delta_ns <= 0) {
+		xen_timer_callback(&vcpu->arch.xen.timer);
+	} else {
+		ktime_t ktime_now = ktime_get();
+		hrtimer_start(&vcpu->arch.xen.timer,
+			      ktime_add_ns(ktime_now, delta_ns),
+			      HRTIMER_MODE_ABS_HARD);
+	}
+}
+
+static void kvm_xen_stop_timer(struct kvm_vcpu *vcpu)
+{
+	hrtimer_cancel(&vcpu->arch.xen.timer);
+	vcpu->arch.xen.timer_expires = 0;
+	atomic_set(&vcpu->arch.xen.timer_pending, 0);
+}
+
+static void kvm_xen_init_timer(struct kvm_vcpu *vcpu)
+{
+	hrtimer_init(&vcpu->arch.xen.timer, CLOCK_MONOTONIC,
+		     HRTIMER_MODE_ABS_HARD);
+	vcpu->arch.xen.timer.function = xen_timer_callback;
+}
+
+static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
+{
+	struct kvm_vcpu_xen *vx = &v->arch.xen;
+	struct gfn_to_pfn_cache *gpc1 = &vx->runstate_cache;
+	struct gfn_to_pfn_cache *gpc2 = &vx->runstate2_cache;
+	size_t user_len, user_len1, user_len2;
+	struct vcpu_runstate_info rs;
+	unsigned long flags;
+	size_t times_ofs;
+	uint8_t *update_bit = NULL;
+	uint64_t entry_time;
+	uint64_t *rs_times;
+	int *rs_state;
+
+	/*
+	 * The only difference between 32-bit and 64-bit versions of the
+	 * runstate struct is the alignment of uint64_t in 32-bit, which
+	 * means that the 64-bit version has an additional 4 bytes of
+	 * padding after the first field 'state'. Let's be really really
+	 * paranoid about that, and matching it with our internal data
+	 * structures that we memcpy into it...
+	 */
+	BUILD_BUG_ON(offsetof(struct vcpu_runstate_info, state) != 0);
+	BUILD_BUG_ON(offsetof(struct compat_vcpu_runstate_info, state) != 0);
+	BUILD_BUG_ON(sizeof(struct compat_vcpu_runstate_info) != 0x2c);
+#ifdef CONFIG_X86_64
+	/*
+	 * The 64-bit structure has 4 bytes of padding before 'state_entry_time'
+	 * so each subsequent field is shifted by 4, and it's 4 bytes longer.
+	 */
+	BUILD_BUG_ON(offsetof(struct vcpu_runstate_info, state_entry_time) !=
+		     offsetof(struct compat_vcpu_runstate_info, state_entry_time) + 4);
+	BUILD_BUG_ON(offsetof(struct vcpu_runstate_info, time) !=
+		     offsetof(struct compat_vcpu_runstate_info, time) + 4);
+	BUILD_BUG_ON(sizeof(struct vcpu_runstate_info) != 0x2c + 4);
+#endif
+	/*
+	 * The state field is in the same place at the start of both structs,
+	 * and is the same size (int) as vx->current_runstate.
+	 */
+	BUILD_BUG_ON(offsetof(struct vcpu_runstate_info, state) !=
+		     offsetof(struct compat_vcpu_runstate_info, state));
+	BUILD_BUG_ON(sizeof_field(struct vcpu_runstate_info, state) !=
+		     sizeof(vx->current_runstate));
+	BUILD_BUG_ON(sizeof_field(struct compat_vcpu_runstate_info, state) !=
+		     sizeof(vx->current_runstate));
+
+	/*
+	 * The state_entry_time field is 64 bits in both versions, and the
+	 * XEN_RUNSTATE_UPDATE flag is in the top bit, which given that x86
+	 * is little-endian means that it's in the last *byte* of the word.
+	 * That detail is important later.
+	 */
+	BUILD_BUG_ON(sizeof_field(struct vcpu_runstate_info, state_entry_time) !=
+		     sizeof(uint64_t));
+	BUILD_BUG_ON(sizeof_field(struct compat_vcpu_runstate_info, state_entry_time) !=
+		     sizeof(uint64_t));
+	BUILD_BUG_ON((XEN_RUNSTATE_UPDATE >> 56) != 0x80);
+
+	/*
+	 * The time array is four 64-bit quantities in both versions, matching
+	 * the vx->runstate_times and immediately following state_entry_time.
+	 */
+	BUILD_BUG_ON(offsetof(struct vcpu_runstate_info, state_entry_time) !=
+		     offsetof(struct vcpu_runstate_info, time) - sizeof(uint64_t));
+	BUILD_BUG_ON(offsetof(struct compat_vcpu_runstate_info, state_entry_time) !=
+		     offsetof(struct compat_vcpu_runstate_info, time) - sizeof(uint64_t));
+	BUILD_BUG_ON(sizeof_field(struct vcpu_runstate_info, time) !=
+		     sizeof_field(struct compat_vcpu_runstate_info, time));
+	BUILD_BUG_ON(sizeof_field(struct vcpu_runstate_info, time) !=
+		     sizeof(vx->runstate_times));
+
+	if (IS_ENABLED(CONFIG_64BIT) && v->kvm->arch.xen.long_mode) {
+		user_len = sizeof(struct vcpu_runstate_info);
+		times_ofs = offsetof(struct vcpu_runstate_info,
+				     state_entry_time);
+	} else {
+		user_len = sizeof(struct compat_vcpu_runstate_info);
+		times_ofs = offsetof(struct compat_vcpu_runstate_info,
+				     state_entry_time);
+	}
+
+	/*
+	 * There are basically no alignment constraints. The guest can set it
+	 * up so it crosses from one page to the next, and at arbitrary byte
+	 * alignment (and the 32-bit ABI doesn't align the 64-bit integers
+	 * anyway, even if the overall struct had been 64-bit aligned).
+	 */
+	if ((gpc1->gpa & ~PAGE_MASK) + user_len >= PAGE_SIZE) {
+		user_len1 = PAGE_SIZE - (gpc1->gpa & ~PAGE_MASK);
+		user_len2 = user_len - user_len1;
+	} else {
+		user_len1 = user_len;
+		user_len2 = 0;
+	}
+	BUG_ON(user_len1 + user_len2 != user_len);
+
+ retry:
+	/*
+	 * Attempt to obtain the GPC lock on *both* (if there are two)
+	 * gfn_to_pfn caches that cover the region.
+	 */
+	if (atomic) {
+		local_irq_save(flags);
+		if (!read_trylock(&gpc1->lock)) {
+			local_irq_restore(flags);
+			return;
+		}
+	} else {
+		read_lock_irqsave(&gpc1->lock, flags);
+	}
+	while (!kvm_gpc_check(gpc1, user_len1)) {
+		read_unlock_irqrestore(&gpc1->lock, flags);
+
+		/* When invoked from kvm_sched_out() we cannot sleep */
+		if (atomic)
+			return;
+
+		if (kvm_gpc_refresh(gpc1, user_len1))
+			return;
+
+		read_lock_irqsave(&gpc1->lock, flags);
+	}
+
+	if (likely(!user_len2)) {
+		/*
+		 * Set up three pointers directly to the runstate_info
+		 * struct in the guest (via the GPC).
+		 *
+		 *  • @rs_state   → state field
+		 *  • @rs_times   → state_entry_time field.
+		 *  • @update_bit → last byte of state_entry_time, which
+		 *                  contains the XEN_RUNSTATE_UPDATE bit.
+		 */
+		rs_state = gpc1->khva;
+		rs_times = gpc1->khva + times_ofs;
+		if (v->kvm->arch.xen.runstate_update_flag)
+			update_bit = ((void *)(&rs_times[1])) - 1;
+	} else {
+		/*
+		 * The guest's runstate_info is split across two pages and we
+		 * need to hold and validate both GPCs simultaneously. We can
+		 * declare a lock ordering GPC1 > GPC2 because nothing else
+		 * takes them more than one at a time. Set a subclass on the
+		 * gpc1 lock to make lockdep shut up about it.
+		 */
+		lock_set_subclass(&gpc1->lock.dep_map, 1, _THIS_IP_);
+		if (atomic) {
+			if (!read_trylock(&gpc2->lock)) {
+				read_unlock_irqrestore(&gpc1->lock, flags);
+				return;
+			}
+		} else {
+			read_lock(&gpc2->lock);
+		}
+
+		if (!kvm_gpc_check(gpc2, user_len2)) {
+			read_unlock(&gpc2->lock);
+			read_unlock_irqrestore(&gpc1->lock, flags);
+
+			/* When invoked from kvm_sched_out() we cannot sleep */
+			if (atomic)
+				return;
+
+			/*
+			 * Use kvm_gpc_activate() here because if the runstate
+			 * area was configured in 32-bit mode and only extends
+			 * to the second page now because the guest changed to
+			 * 64-bit mode, the second GPC won't have been set up.
+			 */
+			if (kvm_gpc_activate(gpc2, gpc1->gpa + user_len1,
+					     user_len2))
+				return;
+
+			/*
+			 * We dropped the lock on GPC1 so we have to go all the
+			 * way back and revalidate that too.
+			 */
+			goto retry;
+		}
+
+		/*
+		 * In this case, the runstate_info struct will be assembled on
+		 * the kernel stack (compat or not as appropriate) and will
+		 * be copied to GPC1/GPC2 with a dual memcpy. Set up the three
+		 * rs pointers accordingly.
+		 */
+		rs_times = &rs.state_entry_time;
+
+		/*
+		 * The rs_state pointer points to the start of what we'll
+		 * copy to the guest, which in the case of a compat guest
+		 * is the 32-bit field that the compiler thinks is padding.
+		 */
+		rs_state = ((void *)rs_times) - times_ofs;
+
+		/*
+		 * The update_bit is still directly in the guest memory,
+		 * via one GPC or the other.
+		 */
+		if (v->kvm->arch.xen.runstate_update_flag) {
+			if (user_len1 >= times_ofs + sizeof(uint64_t))
+				update_bit = gpc1->khva + times_ofs +
+					sizeof(uint64_t) - 1;
+			else
+				update_bit = gpc2->khva + times_ofs +
+					sizeof(uint64_t) - 1 - user_len1;
+		}
+
+#ifdef CONFIG_X86_64
+		/*
+		 * Don't leak kernel memory through the padding in the 64-bit
+		 * version of the struct.
+		 */
+		memset(&rs, 0, offsetof(struct vcpu_runstate_info, state_entry_time));
+#endif
+	}
+
+	/*
+	 * First, set the XEN_RUNSTATE_UPDATE bit in the top bit of the
+	 * state_entry_time field, directly in the guest. We need to set
+	 * that (and write-barrier) before writing to the rest of the
+	 * structure, and clear it last. Just as Xen does, we address the
+	 * single *byte* in which it resides because it might be in a
+	 * different cache line to the rest of the 64-bit word, due to
+	 * the (lack of) alignment constraints.
+	 */
+	entry_time = vx->runstate_entry_time;
+	if (update_bit) {
+		entry_time |= XEN_RUNSTATE_UPDATE;
+		*update_bit = (vx->runstate_entry_time | XEN_RUNSTATE_UPDATE) >> 56;
+		smp_wmb();
+	}
+
+	/*
+	 * Now assemble the actual structure, either on our kernel stack
+	 * or directly in the guest according to how the rs_state and
+	 * rs_times pointers were set up above.
+	 */
+	*rs_state = vx->current_runstate;
+	rs_times[0] = entry_time;
+	memcpy(rs_times + 1, vx->runstate_times, sizeof(vx->runstate_times));
+
+	/* For the split case, we have to then copy it to the guest. */
+	if (user_len2) {
+		memcpy(gpc1->khva, rs_state, user_len1);
+		memcpy(gpc2->khva, ((void *)rs_state) + user_len1, user_len2);
+	}
+	smp_wmb();
+
+	/* Finally, clear the XEN_RUNSTATE_UPDATE bit. */
+	if (update_bit) {
+		entry_time &= ~XEN_RUNSTATE_UPDATE;
+		*update_bit = entry_time >> 56;
+		smp_wmb();
+	}
+
+	if (user_len2)
+		read_unlock(&gpc2->lock);
+
+	read_unlock_irqrestore(&gpc1->lock, flags);
+
+	mark_page_dirty_in_slot(v->kvm, gpc1->memslot, gpc1->gpa >> PAGE_SHIFT);
+	if (user_len2)
+		mark_page_dirty_in_slot(v->kvm, gpc2->memslot, gpc2->gpa >> PAGE_SHIFT);
+}
+
+void kvm_xen_update_runstate(struct kvm_vcpu *v, int state)
+{
+	struct kvm_vcpu_xen *vx = &v->arch.xen;
+	u64 now = get_kvmclock_ns(v->kvm);
+	u64 delta_ns = now - vx->runstate_entry_time;
+	u64 run_delay = current->sched_info.run_delay;
+
+	if (unlikely(!vx->runstate_entry_time))
+		vx->current_runstate = RUNSTATE_offline;
+
+	/*
+	 * Time waiting for the scheduler isn't "stolen" if the
+	 * vCPU wasn't running anyway.
+	 */
+	if (vx->current_runstate == RUNSTATE_running) {
+		u64 steal_ns = run_delay - vx->last_steal;
+
+		delta_ns -= steal_ns;
+
+		vx->runstate_times[RUNSTATE_runnable] += steal_ns;
+	}
+	vx->last_steal = run_delay;
+
+	vx->runstate_times[vx->current_runstate] += delta_ns;
+	vx->current_runstate = state;
+	vx->runstate_entry_time = now;
+
+	if (vx->runstate_cache.active)
+		kvm_xen_update_runstate_guest(v, state == RUNSTATE_runnable);
+}
+
+static void kvm_xen_inject_vcpu_vector(struct kvm_vcpu *v)
+{
+	struct kvm_lapic_irq irq = { };
+	int r;
+
+	irq.dest_id = v->vcpu_id;
+	irq.vector = v->arch.xen.upcall_vector;
+	irq.dest_mode = APIC_DEST_PHYSICAL;
+	irq.shorthand = APIC_DEST_NOSHORT;
+	irq.delivery_mode = APIC_DM_FIXED;
+	irq.level = 1;
+
+	/* The fast version will always work for physical unicast */
+	WARN_ON_ONCE(!kvm_irq_delivery_to_apic_fast(v->kvm, NULL, &irq, &r, NULL));
+}
+
+/*
+ * On event channel delivery, the vcpu_info may not have been accessible.
+ * In that case, there are bits in vcpu->arch.xen.evtchn_pending_sel which
+ * need to be marked into the vcpu_info (and evtchn_upcall_pending set).
+ * Do so now that we can sleep in the context of the vCPU to bring the
+ * page in, and refresh the pfn cache for it.
+ */
+void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
+{
+	unsigned long evtchn_pending_sel = READ_ONCE(v->arch.xen.evtchn_pending_sel);
+	struct gfn_to_pfn_cache *gpc = &v->arch.xen.vcpu_info_cache;
+	unsigned long flags;
+
+	if (!evtchn_pending_sel)
+		return;
+
+	/*
+	 * Yes, this is an open-coded loop. But that's just what put_user()
+	 * does anyway. Page it in and retry the instruction. We're just a
+	 * little more honest about it.
+	 */
+	read_lock_irqsave(&gpc->lock, flags);
+	while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
+		read_unlock_irqrestore(&gpc->lock, flags);
+
+		if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info)))
+			return;
+
+		read_lock_irqsave(&gpc->lock, flags);
+	}
+
+	/* Now gpc->khva is a valid kernel address for the vcpu_info */
+	if (IS_ENABLED(CONFIG_64BIT) && v->kvm->arch.xen.long_mode) {
+		struct vcpu_info *vi = gpc->khva;
+
+		asm volatile(LOCK_PREFIX "orq %0, %1\n"
+			     "notq %0\n"
+			     LOCK_PREFIX "andq %0, %2\n"
+			     : "=r" (evtchn_pending_sel),
+			       "+m" (vi->evtchn_pending_sel),
+			       "+m" (v->arch.xen.evtchn_pending_sel)
+			     : "0" (evtchn_pending_sel));
+		WRITE_ONCE(vi->evtchn_upcall_pending, 1);
+	} else {
+		u32 evtchn_pending_sel32 = evtchn_pending_sel;
+		struct compat_vcpu_info *vi = gpc->khva;
+
+		asm volatile(LOCK_PREFIX "orl %0, %1\n"
+			     "notl %0\n"
+			     LOCK_PREFIX "andl %0, %2\n"
+			     : "=r" (evtchn_pending_sel32),
+			       "+m" (vi->evtchn_pending_sel),
+			       "+m" (v->arch.xen.evtchn_pending_sel)
+			     : "0" (evtchn_pending_sel32));
+		WRITE_ONCE(vi->evtchn_upcall_pending, 1);
+	}
+	read_unlock_irqrestore(&gpc->lock, flags);
+
+	/* For the per-vCPU lapic vector, deliver it as MSI. */
+	if (v->arch.xen.upcall_vector)
+		kvm_xen_inject_vcpu_vector(v);
+
+	mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
+}
+
+int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
+{
+	struct gfn_to_pfn_cache *gpc = &v->arch.xen.vcpu_info_cache;
+	unsigned long flags;
+	u8 rc = 0;
+
+	/*
+	 * If the global upcall vector (HVMIRQ_callback_vector) is set and
+	 * the vCPU's evtchn_upcall_pending flag is set, the IRQ is pending.
+	 */
+
+	/* No need for compat handling here */
+	BUILD_BUG_ON(offsetof(struct vcpu_info, evtchn_upcall_pending) !=
+		     offsetof(struct compat_vcpu_info, evtchn_upcall_pending));
+	BUILD_BUG_ON(sizeof(rc) !=
+		     sizeof_field(struct vcpu_info, evtchn_upcall_pending));
+	BUILD_BUG_ON(sizeof(rc) !=
+		     sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending));
+
+	read_lock_irqsave(&gpc->lock, flags);
+	while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
+		read_unlock_irqrestore(&gpc->lock, flags);
+
+		/*
+		 * This function gets called from kvm_vcpu_block() after setting the
+		 * task to TASK_INTERRUPTIBLE, to see if it needs to wake immediately
+		 * from a HLT. So we really mustn't sleep. If the page ended up absent
+		 * at that point, just return 1 in order to trigger an immediate wake,
+		 * and we'll end up getting called again from a context where we *can*
+		 * fault in the page and wait for it.
+		 */
+		if (in_atomic() || !task_is_running(current))
+			return 1;
+
+		if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info))) {
+			/*
+			 * If this failed, userspace has screwed up the
+			 * vcpu_info mapping. No interrupts for you.
+			 */
+			return 0;
+		}
+		read_lock_irqsave(&gpc->lock, flags);
+	}
+
+	rc = ((struct vcpu_info *)gpc->khva)->evtchn_upcall_pending;
+	read_unlock_irqrestore(&gpc->lock, flags);
+	return rc;
+}
+
+int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
+{
+	int r = -ENOENT;
+
+
+	switch (data->type) {
+	case KVM_XEN_ATTR_TYPE_LONG_MODE:
+		if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
+			r = -EINVAL;
+		} else {
+			mutex_lock(&kvm->arch.xen.xen_lock);
+			kvm->arch.xen.long_mode = !!data->u.long_mode;
+			mutex_unlock(&kvm->arch.xen.xen_lock);
+			r = 0;
+		}
+		break;
+
+	case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+		mutex_lock(&kvm->arch.xen.xen_lock);
+		r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
+		mutex_unlock(&kvm->arch.xen.xen_lock);
+		break;
+
+	case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
+		if (data->u.vector && data->u.vector < 0x10)
+			r = -EINVAL;
+		else {
+			mutex_lock(&kvm->arch.xen.xen_lock);
+			kvm->arch.xen.upcall_vector = data->u.vector;
+			mutex_unlock(&kvm->arch.xen.xen_lock);
+			r = 0;
+		}
+		break;
+
+	case KVM_XEN_ATTR_TYPE_EVTCHN:
+		r = kvm_xen_setattr_evtchn(kvm, data);
+		break;
+
+	case KVM_XEN_ATTR_TYPE_XEN_VERSION:
+		mutex_lock(&kvm->arch.xen.xen_lock);
+		kvm->arch.xen.xen_version = data->u.xen_version;
+		mutex_unlock(&kvm->arch.xen.xen_lock);
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_RUNSTATE_UPDATE_FLAG:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		mutex_lock(&kvm->arch.xen.xen_lock);
+		kvm->arch.xen.runstate_update_flag = !!data->u.runstate_update_flag;
+		mutex_unlock(&kvm->arch.xen.xen_lock);
+		r = 0;
+		break;
+
+	default:
+		break;
+	}
+
+	return r;
+}
+
+int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
+{
+	int r = -ENOENT;
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+
+	switch (data->type) {
+	case KVM_XEN_ATTR_TYPE_LONG_MODE:
+		data->u.long_mode = kvm->arch.xen.long_mode;
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_SHARED_INFO:
+		if (kvm->arch.xen.shinfo_cache.active)
+			data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);
+		else
+			data->u.shared_info.gfn = KVM_XEN_INVALID_GFN;
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
+		data->u.vector = kvm->arch.xen.upcall_vector;
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_XEN_VERSION:
+		data->u.xen_version = kvm->arch.xen.xen_version;
+		r = 0;
+		break;
+
+	case KVM_XEN_ATTR_TYPE_RUNSTATE_UPDATE_FLAG:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		data->u.runstate_update_flag = kvm->arch.xen.runstate_update_flag;
+		r = 0;
+		break;
+
+	default:
+		break;
+	}
+
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+	return r;
+}
+
+int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
+{
+	int idx, r = -ENOENT;
+
+	mutex_lock(&vcpu->kvm->arch.xen.xen_lock);
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	switch (data->type) {
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
+		/* No compat necessary here. */
+		BUILD_BUG_ON(sizeof(struct vcpu_info) !=
+			     sizeof(struct compat_vcpu_info));
+		BUILD_BUG_ON(offsetof(struct vcpu_info, time) !=
+			     offsetof(struct compat_vcpu_info, time));
+
+		if (data->u.gpa == KVM_XEN_INVALID_GPA) {
+			kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_info_cache);
+			r = 0;
+			break;
+		}
+
+		r = kvm_gpc_activate(&vcpu->arch.xen.vcpu_info_cache,
+				     data->u.gpa, sizeof(struct vcpu_info));
+		if (!r)
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
+		if (data->u.gpa == KVM_XEN_INVALID_GPA) {
+			kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_time_info_cache);
+			r = 0;
+			break;
+		}
+
+		r = kvm_gpc_activate(&vcpu->arch.xen.vcpu_time_info_cache,
+				     data->u.gpa,
+				     sizeof(struct pvclock_vcpu_time_info));
+		if (!r)
+			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR: {
+		size_t sz, sz1, sz2;
+
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		if (data->u.gpa == KVM_XEN_INVALID_GPA) {
+			r = 0;
+		deactivate_out:
+			kvm_gpc_deactivate(&vcpu->arch.xen.runstate_cache);
+			kvm_gpc_deactivate(&vcpu->arch.xen.runstate2_cache);
+			break;
+		}
+
+		/*
+		 * If the guest switches to 64-bit mode after setting the runstate
+		 * address, that's actually OK. kvm_xen_update_runstate_guest()
+		 * will cope.
+		 */
+		if (IS_ENABLED(CONFIG_64BIT) && vcpu->kvm->arch.xen.long_mode)
+			sz = sizeof(struct vcpu_runstate_info);
+		else
+			sz = sizeof(struct compat_vcpu_runstate_info);
+
+		/* How much fits in the (first) page? */
+		sz1 = PAGE_SIZE - (data->u.gpa & ~PAGE_MASK);
+		r = kvm_gpc_activate(&vcpu->arch.xen.runstate_cache,
+				     data->u.gpa, sz1);
+		if (r)
+			goto deactivate_out;
+
+		/* Either map the second page, or deactivate the second GPC */
+		if (sz1 >= sz) {
+			kvm_gpc_deactivate(&vcpu->arch.xen.runstate2_cache);
+		} else {
+			sz2 = sz - sz1;
+			BUG_ON((data->u.gpa + sz1) & ~PAGE_MASK);
+			r = kvm_gpc_activate(&vcpu->arch.xen.runstate2_cache,
+					     data->u.gpa + sz1, sz2);
+			if (r)
+				goto deactivate_out;
+		}
+
+		kvm_xen_update_runstate_guest(vcpu, false);
+		break;
+	}
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		if (data->u.runstate.state > RUNSTATE_offline) {
+			r = -EINVAL;
+			break;
+		}
+
+		kvm_xen_update_runstate(vcpu, data->u.runstate.state);
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		if (data->u.runstate.state > RUNSTATE_offline) {
+			r = -EINVAL;
+			break;
+		}
+		if (data->u.runstate.state_entry_time !=
+		    (data->u.runstate.time_running +
+		     data->u.runstate.time_runnable +
+		     data->u.runstate.time_blocked +
+		     data->u.runstate.time_offline)) {
+			r = -EINVAL;
+			break;
+		}
+		if (get_kvmclock_ns(vcpu->kvm) <
+		    data->u.runstate.state_entry_time) {
+			r = -EINVAL;
+			break;
+		}
+
+		vcpu->arch.xen.current_runstate = data->u.runstate.state;
+		vcpu->arch.xen.runstate_entry_time =
+			data->u.runstate.state_entry_time;
+		vcpu->arch.xen.runstate_times[RUNSTATE_running] =
+			data->u.runstate.time_running;
+		vcpu->arch.xen.runstate_times[RUNSTATE_runnable] =
+			data->u.runstate.time_runnable;
+		vcpu->arch.xen.runstate_times[RUNSTATE_blocked] =
+			data->u.runstate.time_blocked;
+		vcpu->arch.xen.runstate_times[RUNSTATE_offline] =
+			data->u.runstate.time_offline;
+		vcpu->arch.xen.last_steal = current->sched_info.run_delay;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		if (data->u.runstate.state > RUNSTATE_offline &&
+		    data->u.runstate.state != (u64)-1) {
+			r = -EINVAL;
+			break;
+		}
+		/* The adjustment must add up */
+		if (data->u.runstate.state_entry_time !=
+		    (data->u.runstate.time_running +
+		     data->u.runstate.time_runnable +
+		     data->u.runstate.time_blocked +
+		     data->u.runstate.time_offline)) {
+			r = -EINVAL;
+			break;
+		}
+
+		if (get_kvmclock_ns(vcpu->kvm) <
+		    (vcpu->arch.xen.runstate_entry_time +
+		     data->u.runstate.state_entry_time)) {
+			r = -EINVAL;
+			break;
+		}
+
+		vcpu->arch.xen.runstate_entry_time +=
+			data->u.runstate.state_entry_time;
+		vcpu->arch.xen.runstate_times[RUNSTATE_running] +=
+			data->u.runstate.time_running;
+		vcpu->arch.xen.runstate_times[RUNSTATE_runnable] +=
+			data->u.runstate.time_runnable;
+		vcpu->arch.xen.runstate_times[RUNSTATE_blocked] +=
+			data->u.runstate.time_blocked;
+		vcpu->arch.xen.runstate_times[RUNSTATE_offline] +=
+			data->u.runstate.time_offline;
+
+		if (data->u.runstate.state <= RUNSTATE_offline)
+			kvm_xen_update_runstate(vcpu, data->u.runstate.state);
+		else if (vcpu->arch.xen.runstate_cache.active)
+			kvm_xen_update_runstate_guest(vcpu, false);
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID:
+		if (data->u.vcpu_id >= KVM_MAX_VCPUS)
+			r = -EINVAL;
+		else {
+			vcpu->arch.xen.vcpu_id = data->u.vcpu_id;
+			r = 0;
+		}
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_TIMER:
+		if (data->u.timer.port &&
+		    data->u.timer.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) {
+			r = -EINVAL;
+			break;
+		}
+
+		if (!vcpu->arch.xen.timer.function)
+			kvm_xen_init_timer(vcpu);
+
+		/* Stop the timer (if it's running) before changing the vector */
+		kvm_xen_stop_timer(vcpu);
+		vcpu->arch.xen.timer_virq = data->u.timer.port;
+
+		/* Start the timer if the new value has a valid vector+expiry. */
+		if (data->u.timer.port && data->u.timer.expires_ns)
+			kvm_xen_start_timer(vcpu, data->u.timer.expires_ns,
+					    data->u.timer.expires_ns -
+					    get_kvmclock_ns(vcpu->kvm));
+
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_UPCALL_VECTOR:
+		if (data->u.vector && data->u.vector < 0x10)
+			r = -EINVAL;
+		else {
+			vcpu->arch.xen.upcall_vector = data->u.vector;
+			r = 0;
+		}
+		break;
+
+	default:
+		break;
+	}
+
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+	mutex_unlock(&vcpu->kvm->arch.xen.xen_lock);
+	return r;
+}
+
+int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data)
+{
+	int r = -ENOENT;
+
+	mutex_lock(&vcpu->kvm->arch.xen.xen_lock);
+
+	switch (data->type) {
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO:
+		if (vcpu->arch.xen.vcpu_info_cache.active)
+			data->u.gpa = vcpu->arch.xen.vcpu_info_cache.gpa;
+		else
+			data->u.gpa = KVM_XEN_INVALID_GPA;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO:
+		if (vcpu->arch.xen.vcpu_time_info_cache.active)
+			data->u.gpa = vcpu->arch.xen.vcpu_time_info_cache.gpa;
+		else
+			data->u.gpa = KVM_XEN_INVALID_GPA;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		if (vcpu->arch.xen.runstate_cache.active) {
+			data->u.gpa = vcpu->arch.xen.runstate_cache.gpa;
+			r = 0;
+		}
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		data->u.runstate.state = vcpu->arch.xen.current_runstate;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA:
+		if (!sched_info_on()) {
+			r = -EOPNOTSUPP;
+			break;
+		}
+		data->u.runstate.state = vcpu->arch.xen.current_runstate;
+		data->u.runstate.state_entry_time =
+			vcpu->arch.xen.runstate_entry_time;
+		data->u.runstate.time_running =
+			vcpu->arch.xen.runstate_times[RUNSTATE_running];
+		data->u.runstate.time_runnable =
+			vcpu->arch.xen.runstate_times[RUNSTATE_runnable];
+		data->u.runstate.time_blocked =
+			vcpu->arch.xen.runstate_times[RUNSTATE_blocked];
+		data->u.runstate.time_offline =
+			vcpu->arch.xen.runstate_times[RUNSTATE_offline];
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST:
+		r = -EINVAL;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID:
+		data->u.vcpu_id = vcpu->arch.xen.vcpu_id;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_TIMER:
+		data->u.timer.port = vcpu->arch.xen.timer_virq;
+		data->u.timer.priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL;
+		data->u.timer.expires_ns = vcpu->arch.xen.timer_expires;
+		r = 0;
+		break;
+
+	case KVM_XEN_VCPU_ATTR_TYPE_UPCALL_VECTOR:
+		data->u.vector = vcpu->arch.xen.upcall_vector;
+		r = 0;
+		break;
+
+	default:
+		break;
+	}
+
+	mutex_unlock(&vcpu->kvm->arch.xen.xen_lock);
+	return r;
+}
+
+int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
+{
+	struct kvm *kvm = vcpu->kvm;
+	u32 page_num = data & ~PAGE_MASK;
+	u64 page_addr = data & PAGE_MASK;
+	bool lm = is_long_mode(vcpu);
+
+	/* Latch long_mode for shared_info pages etc. */
+	vcpu->kvm->arch.xen.long_mode = lm;
+
+	/*
+	 * If Xen hypercall intercept is enabled, fill the hypercall
+	 * page with VMCALL/VMMCALL instructions since that's what
+	 * we catch. Else the VMM has provided the hypercall pages
+	 * with instructions of its own choosing, so use those.
+	 */
+	if (kvm_xen_hypercall_enabled(kvm)) {
+		u8 instructions[32];
+		int i;
+
+		if (page_num)
+			return 1;
+
+		/* mov imm32, %eax */
+		instructions[0] = 0xb8;
+
+		/* vmcall / vmmcall */
+		static_call(kvm_x86_patch_hypercall)(vcpu, instructions + 5);
+
+		/* ret */
+		instructions[8] = 0xc3;
+
+		/* int3 to pad */
+		memset(instructions + 9, 0xcc, sizeof(instructions) - 9);
+
+		for (i = 0; i < PAGE_SIZE / sizeof(instructions); i++) {
+			*(u32 *)&instructions[1] = i;
+			if (kvm_vcpu_write_guest(vcpu,
+						 page_addr + (i * sizeof(instructions)),
+						 instructions, sizeof(instructions)))
+				return 1;
+		}
+	} else {
+		/*
+		 * Note, truncation is a non-issue as 'lm' is guaranteed to be
+		 * false for a 32-bit kernel, i.e. when hva_t is only 4 bytes.
+		 */
+		hva_t blob_addr = lm ? kvm->arch.xen_hvm_config.blob_addr_64
+				     : kvm->arch.xen_hvm_config.blob_addr_32;
+		u8 blob_size = lm ? kvm->arch.xen_hvm_config.blob_size_64
+				  : kvm->arch.xen_hvm_config.blob_size_32;
+		u8 *page;
+		int ret;
+
+		if (page_num >= blob_size)
+			return 1;
+
+		blob_addr += page_num * PAGE_SIZE;
+
+		page = memdup_user((u8 __user *)blob_addr, PAGE_SIZE);
+		if (IS_ERR(page))
+			return PTR_ERR(page);
+
+		ret = kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE);
+		kfree(page);
+		if (ret)
+			return 1;
+	}
+	return 0;
+}
+
+int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
+{
+	/* Only some feature flags need to be *enabled* by userspace */
+	u32 permitted_flags = KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL |
+		KVM_XEN_HVM_CONFIG_EVTCHN_SEND;
+
+	if (xhc->flags & ~permitted_flags)
+		return -EINVAL;
+
+	/*
+	 * With hypercall interception the kernel generates its own
+	 * hypercall page so it must not be provided.
+	 */
+	if ((xhc->flags & KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL) &&
+	    (xhc->blob_addr_32 || xhc->blob_addr_64 ||
+	     xhc->blob_size_32 || xhc->blob_size_64))
+		return -EINVAL;
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+
+	if (xhc->msr && !kvm->arch.xen_hvm_config.msr)
+		static_branch_inc(&kvm_xen_enabled.key);
+	else if (!xhc->msr && kvm->arch.xen_hvm_config.msr)
+		static_branch_slow_dec_deferred(&kvm_xen_enabled);
+
+	memcpy(&kvm->arch.xen_hvm_config, xhc, sizeof(*xhc));
+
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+	return 0;
+}
+
+static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
+{
+	kvm_rax_write(vcpu, result);
+	return kvm_skip_emulated_instruction(vcpu);
+}
+
+static int kvm_xen_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+
+	if (unlikely(!kvm_is_linear_rip(vcpu, vcpu->arch.xen.hypercall_rip)))
+		return 1;
+
+	return kvm_xen_hypercall_set_result(vcpu, run->xen.u.hcall.result);
+}
+
+static inline int max_evtchn_port(struct kvm *kvm)
+{
+	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode)
+		return EVTCHN_2L_NR_CHANNELS;
+	else
+		return COMPAT_EVTCHN_2L_NR_CHANNELS;
+}
+
+static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports,
+			       evtchn_port_t *ports)
+{
+	struct kvm *kvm = vcpu->kvm;
+	struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;
+	unsigned long *pending_bits;
+	unsigned long flags;
+	bool ret = true;
+	int idx, i;
+
+	idx = srcu_read_lock(&kvm->srcu);
+	read_lock_irqsave(&gpc->lock, flags);
+	if (!kvm_gpc_check(gpc, PAGE_SIZE))
+		goto out_rcu;
+
+	ret = false;
+	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
+		struct shared_info *shinfo = gpc->khva;
+		pending_bits = (unsigned long *)&shinfo->evtchn_pending;
+	} else {
+		struct compat_shared_info *shinfo = gpc->khva;
+		pending_bits = (unsigned long *)&shinfo->evtchn_pending;
+	}
+
+	for (i = 0; i < nr_ports; i++) {
+		if (test_bit(ports[i], pending_bits)) {
+			ret = true;
+			break;
+		}
+	}
+
+ out_rcu:
+	read_unlock_irqrestore(&gpc->lock, flags);
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	return ret;
+}
+
+static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
+				 u64 param, u64 *r)
+{
+	struct sched_poll sched_poll;
+	evtchn_port_t port, *ports;
+	struct x86_exception e;
+	int i;
+
+	if (!lapic_in_kernel(vcpu) ||
+	    !(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND))
+		return false;
+
+	if (IS_ENABLED(CONFIG_64BIT) && !longmode) {
+		struct compat_sched_poll sp32;
+
+		/* Sanity check that the compat struct definition is correct */
+		BUILD_BUG_ON(sizeof(sp32) != 16);
+
+		if (kvm_read_guest_virt(vcpu, param, &sp32, sizeof(sp32), &e)) {
+			*r = -EFAULT;
+			return true;
+		}
+
+		/*
+		 * This is a 32-bit pointer to an array of evtchn_port_t which
+		 * are uint32_t, so once it's converted no further compat
+		 * handling is needed.
+		 */
+		sched_poll.ports = (void *)(unsigned long)(sp32.ports);
+		sched_poll.nr_ports = sp32.nr_ports;
+		sched_poll.timeout = sp32.timeout;
+	} else {
+		if (kvm_read_guest_virt(vcpu, param, &sched_poll,
+					sizeof(sched_poll), &e)) {
+			*r = -EFAULT;
+			return true;
+		}
+	}
+
+	if (unlikely(sched_poll.nr_ports > 1)) {
+		/* Xen (unofficially) limits number of pollers to 128 */
+		if (sched_poll.nr_ports > 128) {
+			*r = -EINVAL;
+			return true;
+		}
+
+		ports = kmalloc_array(sched_poll.nr_ports,
+				      sizeof(*ports), GFP_KERNEL);
+		if (!ports) {
+			*r = -ENOMEM;
+			return true;
+		}
+	} else
+		ports = &port;
+
+	if (kvm_read_guest_virt(vcpu, (gva_t)sched_poll.ports, ports,
+				sched_poll.nr_ports * sizeof(*ports), &e)) {
+		*r = -EFAULT;
+		return true;
+	}
+
+	for (i = 0; i < sched_poll.nr_ports; i++) {
+		if (ports[i] >= max_evtchn_port(vcpu->kvm)) {
+			*r = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (sched_poll.nr_ports == 1)
+		vcpu->arch.xen.poll_evtchn = port;
+	else
+		vcpu->arch.xen.poll_evtchn = -1;
+
+	set_bit(vcpu->vcpu_idx, vcpu->kvm->arch.xen.poll_mask);
+
+	if (!wait_pending_event(vcpu, sched_poll.nr_ports, ports)) {
+		vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
+
+		if (sched_poll.timeout)
+			mod_timer(&vcpu->arch.xen.poll_timer,
+				  jiffies + nsecs_to_jiffies(sched_poll.timeout));
+
+		kvm_vcpu_halt(vcpu);
+
+		if (sched_poll.timeout)
+			del_timer(&vcpu->arch.xen.poll_timer);
+
+		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
+	}
+
+	vcpu->arch.xen.poll_evtchn = 0;
+	*r = 0;
+out:
+	/* Really, this is only needed in case of timeout */
+	clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.xen.poll_mask);
+
+	if (unlikely(sched_poll.nr_ports > 1))
+		kfree(ports);
+	return true;
+}
+
+static void cancel_evtchn_poll(struct timer_list *t)
+{
+	struct kvm_vcpu *vcpu = from_timer(vcpu, t, arch.xen.poll_timer);
+
+	kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
+	kvm_vcpu_kick(vcpu);
+}
+
+static bool kvm_xen_hcall_sched_op(struct kvm_vcpu *vcpu, bool longmode,
+				   int cmd, u64 param, u64 *r)
+{
+	switch (cmd) {
+	case SCHEDOP_poll:
+		if (kvm_xen_schedop_poll(vcpu, longmode, param, r))
+			return true;
+		fallthrough;
+	case SCHEDOP_yield:
+		kvm_vcpu_on_spin(vcpu, true);
+		*r = 0;
+		return true;
+	default:
+		break;
+	}
+
+	return false;
+}
+
+struct compat_vcpu_set_singleshot_timer {
+    uint64_t timeout_abs_ns;
+    uint32_t flags;
+} __attribute__((packed));
+
+static bool kvm_xen_hcall_vcpu_op(struct kvm_vcpu *vcpu, bool longmode, int cmd,
+				  int vcpu_id, u64 param, u64 *r)
+{
+	struct vcpu_set_singleshot_timer oneshot;
+	struct x86_exception e;
+	s64 delta;
+
+	if (!kvm_xen_timer_enabled(vcpu))
+		return false;
+
+	switch (cmd) {
+	case VCPUOP_set_singleshot_timer:
+		if (vcpu->arch.xen.vcpu_id != vcpu_id) {
+			*r = -EINVAL;
+			return true;
+		}
+
+		/*
+		 * The only difference for 32-bit compat is the 4 bytes of
+		 * padding after the interesting part of the structure. So
+		 * for a faithful emulation of Xen we have to *try* to copy
+		 * the padding and return -EFAULT if we can't. Otherwise we
+		 * might as well just have copied the 12-byte 32-bit struct.
+		 */
+		BUILD_BUG_ON(offsetof(struct compat_vcpu_set_singleshot_timer, timeout_abs_ns) !=
+			     offsetof(struct vcpu_set_singleshot_timer, timeout_abs_ns));
+		BUILD_BUG_ON(sizeof_field(struct compat_vcpu_set_singleshot_timer, timeout_abs_ns) !=
+			     sizeof_field(struct vcpu_set_singleshot_timer, timeout_abs_ns));
+		BUILD_BUG_ON(offsetof(struct compat_vcpu_set_singleshot_timer, flags) !=
+			     offsetof(struct vcpu_set_singleshot_timer, flags));
+		BUILD_BUG_ON(sizeof_field(struct compat_vcpu_set_singleshot_timer, flags) !=
+			     sizeof_field(struct vcpu_set_singleshot_timer, flags));
+
+		if (kvm_read_guest_virt(vcpu, param, &oneshot, longmode ? sizeof(oneshot) :
+					sizeof(struct compat_vcpu_set_singleshot_timer), &e)) {
+			*r = -EFAULT;
+			return true;
+		}
+
+		delta = oneshot.timeout_abs_ns - get_kvmclock_ns(vcpu->kvm);
+		if ((oneshot.flags & VCPU_SSHOTTMR_future) && delta < 0) {
+			*r = -ETIME;
+			return true;
+		}
+
+		kvm_xen_start_timer(vcpu, oneshot.timeout_abs_ns, delta);
+		*r = 0;
+		return true;
+
+	case VCPUOP_stop_singleshot_timer:
+		if (vcpu->arch.xen.vcpu_id != vcpu_id) {
+			*r = -EINVAL;
+			return true;
+		}
+		kvm_xen_stop_timer(vcpu);
+		*r = 0;
+		return true;
+	}
+
+	return false;
+}
+
+static bool kvm_xen_hcall_set_timer_op(struct kvm_vcpu *vcpu, uint64_t timeout,
+				       u64 *r)
+{
+	if (!kvm_xen_timer_enabled(vcpu))
+		return false;
+
+	if (timeout) {
+		uint64_t guest_now = get_kvmclock_ns(vcpu->kvm);
+		int64_t delta = timeout - guest_now;
+
+		/* Xen has a 'Linux workaround' in do_set_timer_op() which
+		 * checks for negative absolute timeout values (caused by
+		 * integer overflow), and for values about 13 days in the
+		 * future (2^50ns) which would be caused by jiffies
+		 * overflow. For those cases, it sets the timeout 100ms in
+		 * the future (not *too* soon, since if a guest really did
+		 * set a long timeout on purpose we don't want to keep
+		 * churning CPU time by waking it up).
+		 */
+		if (unlikely((int64_t)timeout < 0 ||
+			     (delta > 0 && (uint32_t) (delta >> 50) != 0))) {
+			delta = 100 * NSEC_PER_MSEC;
+			timeout = guest_now + delta;
+		}
+
+		kvm_xen_start_timer(vcpu, timeout, delta);
+	} else {
+		kvm_xen_stop_timer(vcpu);
+	}
+
+	*r = 0;
+	return true;
+}
+
+int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
+{
+	bool longmode;
+	u64 input, params[6], r = -ENOSYS;
+	bool handled = false;
+	u8 cpl;
+
+	input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
+
+	/* Hyper-V hypercalls get bit 31 set in EAX */
+	if ((input & 0x80000000) &&
+	    kvm_hv_hypercall_enabled(vcpu))
+		return kvm_hv_hypercall(vcpu);
+
+	longmode = is_64_bit_hypercall(vcpu);
+	if (!longmode) {
+		params[0] = (u32)kvm_rbx_read(vcpu);
+		params[1] = (u32)kvm_rcx_read(vcpu);
+		params[2] = (u32)kvm_rdx_read(vcpu);
+		params[3] = (u32)kvm_rsi_read(vcpu);
+		params[4] = (u32)kvm_rdi_read(vcpu);
+		params[5] = (u32)kvm_rbp_read(vcpu);
+	}
+#ifdef CONFIG_X86_64
+	else {
+		params[0] = (u64)kvm_rdi_read(vcpu);
+		params[1] = (u64)kvm_rsi_read(vcpu);
+		params[2] = (u64)kvm_rdx_read(vcpu);
+		params[3] = (u64)kvm_r10_read(vcpu);
+		params[4] = (u64)kvm_r8_read(vcpu);
+		params[5] = (u64)kvm_r9_read(vcpu);
+	}
+#endif
+	cpl = static_call(kvm_x86_get_cpl)(vcpu);
+	trace_kvm_xen_hypercall(cpl, input, params[0], params[1], params[2],
+				params[3], params[4], params[5]);
+
+	/*
+	 * Only allow hypercall acceleration for CPL0. The rare hypercalls that
+	 * are permitted in guest userspace can be handled by the VMM.
+	 */
+	if (unlikely(cpl > 0))
+		goto handle_in_userspace;
+
+	switch (input) {
+	case __HYPERVISOR_xen_version:
+		if (params[0] == XENVER_version && vcpu->kvm->arch.xen.xen_version) {
+			r = vcpu->kvm->arch.xen.xen_version;
+			handled = true;
+		}
+		break;
+	case __HYPERVISOR_event_channel_op:
+		if (params[0] == EVTCHNOP_send)
+			handled = kvm_xen_hcall_evtchn_send(vcpu, params[1], &r);
+		break;
+	case __HYPERVISOR_sched_op:
+		handled = kvm_xen_hcall_sched_op(vcpu, longmode, params[0],
+						 params[1], &r);
+		break;
+	case __HYPERVISOR_vcpu_op:
+		handled = kvm_xen_hcall_vcpu_op(vcpu, longmode, params[0], params[1],
+						params[2], &r);
+		break;
+	case __HYPERVISOR_set_timer_op: {
+		u64 timeout = params[0];
+		/* In 32-bit mode, the 64-bit timeout is in two 32-bit params. */
+		if (!longmode)
+			timeout |= params[1] << 32;
+		handled = kvm_xen_hcall_set_timer_op(vcpu, timeout, &r);
+		break;
+	}
+	default:
+		break;
+	}
+
+	if (handled)
+		return kvm_xen_hypercall_set_result(vcpu, r);
+
+handle_in_userspace:
+	vcpu->run->exit_reason = KVM_EXIT_XEN;
+	vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
+	vcpu->run->xen.u.hcall.longmode = longmode;
+	vcpu->run->xen.u.hcall.cpl = cpl;
+	vcpu->run->xen.u.hcall.input = input;
+	vcpu->run->xen.u.hcall.params[0] = params[0];
+	vcpu->run->xen.u.hcall.params[1] = params[1];
+	vcpu->run->xen.u.hcall.params[2] = params[2];
+	vcpu->run->xen.u.hcall.params[3] = params[3];
+	vcpu->run->xen.u.hcall.params[4] = params[4];
+	vcpu->run->xen.u.hcall.params[5] = params[5];
+	vcpu->arch.xen.hypercall_rip = kvm_get_linear_rip(vcpu);
+	vcpu->arch.complete_userspace_io =
+		kvm_xen_hypercall_complete_userspace;
+
+	return 0;
+}
+
+static void kvm_xen_check_poller(struct kvm_vcpu *vcpu, int port)
+{
+	int poll_evtchn = vcpu->arch.xen.poll_evtchn;
+
+	if ((poll_evtchn == port || poll_evtchn == -1) &&
+	    test_and_clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.xen.poll_mask)) {
+		kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+}
+
+/*
+ * The return value from this function is propagated to kvm_set_irq() API,
+ * so it returns:
+ *  < 0   Interrupt was ignored (masked or not delivered for other reasons)
+ *  = 0   Interrupt was coalesced (previous irq is still pending)
+ *  > 0   Number of CPUs interrupt was delivered to
+ *
+ * It is also called directly from kvm_arch_set_irq_inatomic(), where the
+ * only check on its return value is a comparison with -EWOULDBLOCK'.
+ */
+int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
+{
+	struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;
+	struct kvm_vcpu *vcpu;
+	unsigned long *pending_bits, *mask_bits;
+	unsigned long flags;
+	int port_word_bit;
+	bool kick_vcpu = false;
+	int vcpu_idx, idx, rc;
+
+	vcpu_idx = READ_ONCE(xe->vcpu_idx);
+	if (vcpu_idx >= 0)
+		vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+	else {
+		vcpu = kvm_get_vcpu_by_id(kvm, xe->vcpu_id);
+		if (!vcpu)
+			return -EINVAL;
+		WRITE_ONCE(xe->vcpu_idx, vcpu->vcpu_idx);
+	}
+
+	if (!vcpu->arch.xen.vcpu_info_cache.active)
+		return -EINVAL;
+
+	if (xe->port >= max_evtchn_port(kvm))
+		return -EINVAL;
+
+	rc = -EWOULDBLOCK;
+
+	idx = srcu_read_lock(&kvm->srcu);
+
+	read_lock_irqsave(&gpc->lock, flags);
+	if (!kvm_gpc_check(gpc, PAGE_SIZE))
+		goto out_rcu;
+
+	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
+		struct shared_info *shinfo = gpc->khva;
+		pending_bits = (unsigned long *)&shinfo->evtchn_pending;
+		mask_bits = (unsigned long *)&shinfo->evtchn_mask;
+		port_word_bit = xe->port / 64;
+	} else {
+		struct compat_shared_info *shinfo = gpc->khva;
+		pending_bits = (unsigned long *)&shinfo->evtchn_pending;
+		mask_bits = (unsigned long *)&shinfo->evtchn_mask;
+		port_word_bit = xe->port / 32;
+	}
+
+	/*
+	 * If this port wasn't already set, and if it isn't masked, then
+	 * we try to set the corresponding bit in the in-kernel shadow of
+	 * evtchn_pending_sel for the target vCPU. And if *that* wasn't
+	 * already set, then we kick the vCPU in question to write to the
+	 * *real* evtchn_pending_sel in its own guest vcpu_info struct.
+	 */
+	if (test_and_set_bit(xe->port, pending_bits)) {
+		rc = 0; /* It was already raised */
+	} else if (test_bit(xe->port, mask_bits)) {
+		rc = -ENOTCONN; /* Masked */
+		kvm_xen_check_poller(vcpu, xe->port);
+	} else {
+		rc = 1; /* Delivered to the bitmap in shared_info. */
+		/* Now switch to the vCPU's vcpu_info to set the index and pending_sel */
+		read_unlock_irqrestore(&gpc->lock, flags);
+		gpc = &vcpu->arch.xen.vcpu_info_cache;
+
+		read_lock_irqsave(&gpc->lock, flags);
+		if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
+			/*
+			 * Could not access the vcpu_info. Set the bit in-kernel
+			 * and prod the vCPU to deliver it for itself.
+			 */
+			if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel))
+				kick_vcpu = true;
+			goto out_rcu;
+		}
+
+		if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
+			struct vcpu_info *vcpu_info = gpc->khva;
+			if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) {
+				WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
+				kick_vcpu = true;
+			}
+		} else {
+			struct compat_vcpu_info *vcpu_info = gpc->khva;
+			if (!test_and_set_bit(port_word_bit,
+					      (unsigned long *)&vcpu_info->evtchn_pending_sel)) {
+				WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1);
+				kick_vcpu = true;
+			}
+		}
+
+		/* For the per-vCPU lapic vector, deliver it as MSI. */
+		if (kick_vcpu && vcpu->arch.xen.upcall_vector) {
+			kvm_xen_inject_vcpu_vector(vcpu);
+			kick_vcpu = false;
+		}
+	}
+
+ out_rcu:
+	read_unlock_irqrestore(&gpc->lock, flags);
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	if (kick_vcpu) {
+		kvm_make_request(KVM_REQ_UNBLOCK, vcpu);
+		kvm_vcpu_kick(vcpu);
+	}
+
+	return rc;
+}
+
+static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm)
+{
+	bool mm_borrowed = false;
+	int rc;
+
+	rc = kvm_xen_set_evtchn_fast(xe, kvm);
+	if (rc != -EWOULDBLOCK)
+		return rc;
+
+	if (current->mm != kvm->mm) {
+		/*
+		 * If not on a thread which already belongs to this KVM,
+		 * we'd better be in the irqfd workqueue.
+		 */
+		if (WARN_ON_ONCE(current->mm))
+			return -EINVAL;
+
+		kthread_use_mm(kvm->mm);
+		mm_borrowed = true;
+	}
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+
+	/*
+	 * It is theoretically possible for the page to be unmapped
+	 * and the MMU notifier to invalidate the shared_info before
+	 * we even get to use it. In that case, this looks like an
+	 * infinite loop. It was tempting to do it via the userspace
+	 * HVA instead... but that just *hides* the fact that it's
+	 * an infinite loop, because if a fault occurs and it waits
+	 * for the page to come back, it can *still* immediately
+	 * fault and have to wait again, repeatedly.
+	 *
+	 * Conversely, the page could also have been reinstated by
+	 * another thread before we even obtain the mutex above, so
+	 * check again *first* before remapping it.
+	 */
+	do {
+		struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;
+		int idx;
+
+		rc = kvm_xen_set_evtchn_fast(xe, kvm);
+		if (rc != -EWOULDBLOCK)
+			break;
+
+		idx = srcu_read_lock(&kvm->srcu);
+		rc = kvm_gpc_refresh(gpc, PAGE_SIZE);
+		srcu_read_unlock(&kvm->srcu, idx);
+	} while(!rc);
+
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+
+	if (mm_borrowed)
+		kthread_unuse_mm(kvm->mm);
+
+	return rc;
+}
+
+/* This is the version called from kvm_set_irq() as the .set function */
+static int evtchn_set_fn(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,
+			 int irq_source_id, int level, bool line_status)
+{
+	if (!level)
+		return -EINVAL;
+
+	return kvm_xen_set_evtchn(&e->xen_evtchn, kvm);
+}
+
+/*
+ * Set up an event channel interrupt from the KVM IRQ routing table.
+ * Used for e.g. PIRQ from passed through physical devices.
+ */
+int kvm_xen_setup_evtchn(struct kvm *kvm,
+			 struct kvm_kernel_irq_routing_entry *e,
+			 const struct kvm_irq_routing_entry *ue)
+
+{
+	struct kvm_vcpu *vcpu;
+
+	if (ue->u.xen_evtchn.port >= max_evtchn_port(kvm))
+		return -EINVAL;
+
+	/* We only support 2 level event channels for now */
+	if (ue->u.xen_evtchn.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+		return -EINVAL;
+
+	/*
+	 * Xen gives us interesting mappings from vCPU index to APIC ID,
+	 * which means kvm_get_vcpu_by_id() has to iterate over all vCPUs
+	 * to find it. Do that once at setup time, instead of every time.
+	 * But beware that on live update / live migration, the routing
+	 * table might be reinstated before the vCPU threads have finished
+	 * recreating their vCPUs.
+	 */
+	vcpu = kvm_get_vcpu_by_id(kvm, ue->u.xen_evtchn.vcpu);
+	if (vcpu)
+		e->xen_evtchn.vcpu_idx = vcpu->vcpu_idx;
+	else
+		e->xen_evtchn.vcpu_idx = -1;
+
+	e->xen_evtchn.port = ue->u.xen_evtchn.port;
+	e->xen_evtchn.vcpu_id = ue->u.xen_evtchn.vcpu;
+	e->xen_evtchn.priority = ue->u.xen_evtchn.priority;
+	e->set = evtchn_set_fn;
+
+	return 0;
+}
+
+/*
+ * Explicit event sending from userspace with KVM_XEN_HVM_EVTCHN_SEND ioctl.
+ */
+int kvm_xen_hvm_evtchn_send(struct kvm *kvm, struct kvm_irq_routing_xen_evtchn *uxe)
+{
+	struct kvm_xen_evtchn e;
+	int ret;
+
+	if (!uxe->port || uxe->port >= max_evtchn_port(kvm))
+		return -EINVAL;
+
+	/* We only support 2 level event channels for now */
+	if (uxe->priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+		return -EINVAL;
+
+	e.port = uxe->port;
+	e.vcpu_id = uxe->vcpu;
+	e.vcpu_idx = -1;
+	e.priority = uxe->priority;
+
+	ret = kvm_xen_set_evtchn(&e, kvm);
+
+	/*
+	 * None of that 'return 1 if it actually got delivered' nonsense.
+	 * We don't care if it was masked (-ENOTCONN) either.
+	 */
+	if (ret > 0 || ret == -ENOTCONN)
+		ret = 0;
+
+	return ret;
+}
+
+/*
+ * Support for *outbound* event channel events via the EVTCHNOP_send hypercall.
+ */
+struct evtchnfd {
+	u32 send_port;
+	u32 type;
+	union {
+		struct kvm_xen_evtchn port;
+		struct {
+			u32 port; /* zero */
+			struct eventfd_ctx *ctx;
+		} eventfd;
+	} deliver;
+};
+
+/*
+ * Update target vCPU or priority for a registered sending channel.
+ */
+static int kvm_xen_eventfd_update(struct kvm *kvm,
+				  struct kvm_xen_hvm_attr *data)
+{
+	u32 port = data->u.evtchn.send_port;
+	struct evtchnfd *evtchnfd;
+	int ret;
+
+	/* Protect writes to evtchnfd as well as the idr lookup.  */
+	mutex_lock(&kvm->arch.xen.xen_lock);
+	evtchnfd = idr_find(&kvm->arch.xen.evtchn_ports, port);
+
+	ret = -ENOENT;
+	if (!evtchnfd)
+		goto out_unlock;
+
+	/* For an UPDATE, nothing may change except the priority/vcpu */
+	ret = -EINVAL;
+	if (evtchnfd->type != data->u.evtchn.type)
+		goto out_unlock;
+
+	/*
+	 * Port cannot change, and if it's zero that was an eventfd
+	 * which can't be changed either.
+	 */
+	if (!evtchnfd->deliver.port.port ||
+	    evtchnfd->deliver.port.port != data->u.evtchn.deliver.port.port)
+		goto out_unlock;
+
+	/* We only support 2 level event channels for now */
+	if (data->u.evtchn.deliver.port.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+		goto out_unlock;
+
+	evtchnfd->deliver.port.priority = data->u.evtchn.deliver.port.priority;
+	if (evtchnfd->deliver.port.vcpu_id != data->u.evtchn.deliver.port.vcpu) {
+		evtchnfd->deliver.port.vcpu_id = data->u.evtchn.deliver.port.vcpu;
+		evtchnfd->deliver.port.vcpu_idx = -1;
+	}
+	ret = 0;
+out_unlock:
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+	return ret;
+}
+
+/*
+ * Configure the target (eventfd or local port delivery) for sending on
+ * a given event channel.
+ */
+static int kvm_xen_eventfd_assign(struct kvm *kvm,
+				  struct kvm_xen_hvm_attr *data)
+{
+	u32 port = data->u.evtchn.send_port;
+	struct eventfd_ctx *eventfd = NULL;
+	struct evtchnfd *evtchnfd;
+	int ret = -EINVAL;
+
+	evtchnfd = kzalloc(sizeof(struct evtchnfd), GFP_KERNEL);
+	if (!evtchnfd)
+		return -ENOMEM;
+
+	switch(data->u.evtchn.type) {
+	case EVTCHNSTAT_ipi:
+		/* IPI  must map back to the same port# */
+		if (data->u.evtchn.deliver.port.port != data->u.evtchn.send_port)
+			goto out_noeventfd; /* -EINVAL */
+		break;
+
+	case EVTCHNSTAT_interdomain:
+		if (data->u.evtchn.deliver.port.port) {
+			if (data->u.evtchn.deliver.port.port >= max_evtchn_port(kvm))
+				goto out_noeventfd; /* -EINVAL */
+		} else {
+			eventfd = eventfd_ctx_fdget(data->u.evtchn.deliver.eventfd.fd);
+			if (IS_ERR(eventfd)) {
+				ret = PTR_ERR(eventfd);
+				goto out_noeventfd;
+			}
+		}
+		break;
+
+	case EVTCHNSTAT_virq:
+	case EVTCHNSTAT_closed:
+	case EVTCHNSTAT_unbound:
+	case EVTCHNSTAT_pirq:
+	default: /* Unknown event channel type */
+		goto out; /* -EINVAL */
+	}
+
+	evtchnfd->send_port = data->u.evtchn.send_port;
+	evtchnfd->type = data->u.evtchn.type;
+	if (eventfd) {
+		evtchnfd->deliver.eventfd.ctx = eventfd;
+	} else {
+		/* We only support 2 level event channels for now */
+		if (data->u.evtchn.deliver.port.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL)
+			goto out; /* -EINVAL; */
+
+		evtchnfd->deliver.port.port = data->u.evtchn.deliver.port.port;
+		evtchnfd->deliver.port.vcpu_id = data->u.evtchn.deliver.port.vcpu;
+		evtchnfd->deliver.port.vcpu_idx = -1;
+		evtchnfd->deliver.port.priority = data->u.evtchn.deliver.port.priority;
+	}
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+	ret = idr_alloc(&kvm->arch.xen.evtchn_ports, evtchnfd, port, port + 1,
+			GFP_KERNEL);
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+	if (ret >= 0)
+		return 0;
+
+	if (ret == -ENOSPC)
+		ret = -EEXIST;
+out:
+	if (eventfd)
+		eventfd_ctx_put(eventfd);
+out_noeventfd:
+	kfree(evtchnfd);
+	return ret;
+}
+
+static int kvm_xen_eventfd_deassign(struct kvm *kvm, u32 port)
+{
+	struct evtchnfd *evtchnfd;
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+	evtchnfd = idr_remove(&kvm->arch.xen.evtchn_ports, port);
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+
+	if (!evtchnfd)
+		return -ENOENT;
+
+	synchronize_srcu(&kvm->srcu);
+	if (!evtchnfd->deliver.port.port)
+		eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
+	kfree(evtchnfd);
+	return 0;
+}
+
+static int kvm_xen_eventfd_reset(struct kvm *kvm)
+{
+	struct evtchnfd *evtchnfd, **all_evtchnfds;
+	int i;
+	int n = 0;
+
+	mutex_lock(&kvm->arch.xen.xen_lock);
+
+	/*
+	 * Because synchronize_srcu() cannot be called inside the
+	 * critical section, first collect all the evtchnfd objects
+	 * in an array as they are removed from evtchn_ports.
+	 */
+	idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i)
+		n++;
+
+	all_evtchnfds = kmalloc_array(n, sizeof(struct evtchnfd *), GFP_KERNEL);
+	if (!all_evtchnfds) {
+		mutex_unlock(&kvm->arch.xen.xen_lock);
+		return -ENOMEM;
+	}
+
+	n = 0;
+	idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i) {
+		all_evtchnfds[n++] = evtchnfd;
+		idr_remove(&kvm->arch.xen.evtchn_ports, evtchnfd->send_port);
+	}
+	mutex_unlock(&kvm->arch.xen.xen_lock);
+
+	synchronize_srcu(&kvm->srcu);
+
+	while (n--) {
+		evtchnfd = all_evtchnfds[n];
+		if (!evtchnfd->deliver.port.port)
+			eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
+		kfree(evtchnfd);
+	}
+	kfree(all_evtchnfds);
+
+	return 0;
+}
+
+static int kvm_xen_setattr_evtchn(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
+{
+	u32 port = data->u.evtchn.send_port;
+
+	if (data->u.evtchn.flags == KVM_XEN_EVTCHN_RESET)
+		return kvm_xen_eventfd_reset(kvm);
+
+	if (!port || port >= max_evtchn_port(kvm))
+		return -EINVAL;
+
+	if (data->u.evtchn.flags == KVM_XEN_EVTCHN_DEASSIGN)
+		return kvm_xen_eventfd_deassign(kvm, port);
+	if (data->u.evtchn.flags == KVM_XEN_EVTCHN_UPDATE)
+		return kvm_xen_eventfd_update(kvm, data);
+	if (data->u.evtchn.flags)
+		return -EINVAL;
+
+	return kvm_xen_eventfd_assign(kvm, data);
+}
+
+static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r)
+{
+	struct evtchnfd *evtchnfd;
+	struct evtchn_send send;
+	struct x86_exception e;
+
+	/* Sanity check: this structure is the same for 32-bit and 64-bit */
+	BUILD_BUG_ON(sizeof(send) != 4);
+	if (kvm_read_guest_virt(vcpu, param, &send, sizeof(send), &e)) {
+		*r = -EFAULT;
+		return true;
+	}
+
+	/*
+	 * evtchnfd is protected by kvm->srcu; the idr lookup instead
+	 * is protected by RCU.
+	 */
+	rcu_read_lock();
+	evtchnfd = idr_find(&vcpu->kvm->arch.xen.evtchn_ports, send.port);
+	rcu_read_unlock();
+	if (!evtchnfd)
+		return false;
+
+	if (evtchnfd->deliver.port.port) {
+		int ret = kvm_xen_set_evtchn(&evtchnfd->deliver.port, vcpu->kvm);
+		if (ret < 0 && ret != -ENOTCONN)
+			return false;
+	} else {
+		eventfd_signal(evtchnfd->deliver.eventfd.ctx, 1);
+	}
+
+	*r = 0;
+	return true;
+}
+
+void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.xen.vcpu_id = vcpu->vcpu_idx;
+	vcpu->arch.xen.poll_evtchn = 0;
+
+	timer_setup(&vcpu->arch.xen.poll_timer, cancel_evtchn_poll, 0);
+
+	kvm_gpc_init(&vcpu->arch.xen.runstate_cache, vcpu->kvm, NULL,
+		     KVM_HOST_USES_PFN);
+	kvm_gpc_init(&vcpu->arch.xen.runstate2_cache, vcpu->kvm, NULL,
+		     KVM_HOST_USES_PFN);
+	kvm_gpc_init(&vcpu->arch.xen.vcpu_info_cache, vcpu->kvm, NULL,
+		     KVM_HOST_USES_PFN);
+	kvm_gpc_init(&vcpu->arch.xen.vcpu_time_info_cache, vcpu->kvm, NULL,
+		     KVM_HOST_USES_PFN);
+}
+
+void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
+{
+	if (kvm_xen_timer_enabled(vcpu))
+		kvm_xen_stop_timer(vcpu);
+
+	kvm_gpc_deactivate(&vcpu->arch.xen.runstate_cache);
+	kvm_gpc_deactivate(&vcpu->arch.xen.runstate2_cache);
+	kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_info_cache);
+	kvm_gpc_deactivate(&vcpu->arch.xen.vcpu_time_info_cache);
+
+	del_timer_sync(&vcpu->arch.xen.poll_timer);
+}
+
+void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid_entry2 *entry;
+	u32 function;
+
+	if (!vcpu->arch.xen.cpuid.base)
+		return;
+
+	function = vcpu->arch.xen.cpuid.base | XEN_CPUID_LEAF(3);
+	if (function > vcpu->arch.xen.cpuid.limit)
+		return;
+
+	entry = kvm_find_cpuid_entry_index(vcpu, function, 1);
+	if (entry) {
+		entry->ecx = vcpu->arch.hv_clock.tsc_to_system_mul;
+		entry->edx = vcpu->arch.hv_clock.tsc_shift;
+	}
+
+	entry = kvm_find_cpuid_entry_index(vcpu, function, 2);
+	if (entry)
+		entry->eax = vcpu->arch.hw_tsc_khz;
+}
+
+void kvm_xen_init_vm(struct kvm *kvm)
+{
+	mutex_init(&kvm->arch.xen.xen_lock);
+	idr_init(&kvm->arch.xen.evtchn_ports);
+	kvm_gpc_init(&kvm->arch.xen.shinfo_cache, kvm, NULL, KVM_HOST_USES_PFN);
+}
+
+void kvm_xen_destroy_vm(struct kvm *kvm)
+{
+	struct evtchnfd *evtchnfd;
+	int i;
+
+	kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache);
+
+	idr_for_each_entry(&kvm->arch.xen.evtchn_ports, evtchnfd, i) {
+		if (!evtchnfd->deliver.port.port)
+			eventfd_ctx_put(evtchnfd->deliver.eventfd.ctx);
+		kfree(evtchnfd);
+	}
+	idr_destroy(&kvm->arch.xen.evtchn_ports);
+
+	if (kvm->arch.xen_hvm_config.msr)
+		static_branch_slow_dec_deferred(&kvm_xen_enabled);
+}