From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- scripts/timer_migration_tree.py | 122 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100755 scripts/timer_migration_tree.py (limited to 'scripts/timer_migration_tree.py') diff --git a/scripts/timer_migration_tree.py b/scripts/timer_migration_tree.py new file mode 100755 index 000000000..faac9de85 --- /dev/null +++ b/scripts/timer_migration_tree.py @@ -0,0 +1,122 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 + +""" +Draw the timer migration tree. + +1) Boot with trace_event==tmigr_connect_cpu_parent,tmigr_connect_child_parent +2) ./timer_migration_tree.py < /sys/kernel/tracing/trace +""" + +import re, sys +from ete3 import Tree + +class Node: + def __init__(self, group): + self.group = group + self.children = [] + self.parent = None + self.num_children = 0 + self.groupmask = 0 + self.lvl = -1 + + def set_groupmask(self, groupmask): + self.groupmask = groupmask + + def set_parent(self, parent): + self.parent = parent + + def add_child(self, child): + self.children.append(child) + + def set_lvl(self, lvl): + self.lvl = lvl + + def set_numa(self, numa): + self.numa = numa + + def set_num_children(self, num_children): + self.num_children = num_children + + def __repr__(self): + if self.parent: + parent_grp = self.parent.group + else: + parent_grp = "-" + return "Group: %s mask: %s parent: %s lvl: %d numa: %d num_children: %d" % (self.group, self.groupmask, parent_grp, self.lvl, self.numa, self.num_children) + +hierarchies = { } + +def get_hierarchy(capacity): + if capacity not in hierarchies: + hierarchies[capacity] = {} + return hierarchies[capacity] + +def get_node(capacity, group): + hier = get_hierarchy(capacity) + if group in hier: + return hier[group] + else: + n = Node(group) + hier[group] = n + return n + +def tmigr_connect_cpu_parent(ts, line): + s = re.search("tmigr_connect_cpu_parent: cpu=([0-9]+) groupmask=([0-9a-zA-Z]+) parent=([0-9a-zA-Z]+) lvl=([0-9]+) numa=([-]?[0-9]+) capacity=([-]?[0-9]+) num_children=([0-9]+)", line) + if s is None: + return False + (cpu, groupmask, parent, lvl, numa, capacity, num_children) = (int(s.group(1)), s.group(2), s.group(3), int(s.group(4)), int(s.group(5)), int(s.group(6)), int(s.group(7))) + n = get_node(capacity, cpu) + p = get_node(capacity, parent) + n.set_parent(p) + n.set_groupmask(groupmask) + n.set_lvl(-1) + p.set_lvl(lvl) + p.set_numa(numa) + n.set_numa(numa) + p.set_num_children(num_children) + p.add_child(n) + +def tmigr_connect_child_parent(ts, line): + s = re.search("tmigr_connect_child_parent: group=([0-9a-zA-Z]+) groupmask=([0-9a-zA-Z]+) parent=([0-9a-zA-Z]+) lvl=([0-9]+) numa=([-]?[0-9]+) capacity=([-]?[0-9]+) num_children=([0-9]+)", line) + if s is None: + return False + (group, groupmask, parent, lvl, numa, capacity, num_children) = (s.group(1), s.group(2), s.group(3), int(s.group(4)), int(s.group(5)), int(s.group(6)), int(s.group(7))) + n = get_node(capacity, group) + p = get_node(capacity, parent) + n.set_parent(p) + n.set_groupmask(groupmask) + p.set_lvl(lvl) + p.set_numa(numa) + p.set_num_children(num_children) + p.add_child(n) + +def populate(enode, node): + enode = enode.add_child(name = node.group) + enode.add_feature("groupmask", "m:%s" % node.groupmask) + enode.add_feature("lvl", "lvl:%d" % node.lvl) + enode.add_feature("numa", "node %d" % node.numa) + enode.add_feature("num_children", "c=%d" % node.num_children) + for child in node.children: + populate(enode, child) + +if __name__ == "__main__": + for line in sys.stdin: + s = re.search("([0-9]+[.][0-9]{6}): (.+?)$", line, re.S) + if s is not None: + if tmigr_connect_cpu_parent(float(s.group(1)), s.group(2)): + continue + if tmigr_connect_child_parent(float(s.group(1)), s.group(2)): + continue + + for cap in hierarchies: + h = hierarchies[cap] + print("Tree for capacity %d" % cap) + for k in h: + n = h[k] + while n.parent != None: + n = n.parent + root = Tree() + populate(root, n) + print(root.get_ascii(show_internal=True, attributes=["name", "numa", "lvl"])) + break -- cgit v1.3.1