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/headerdep.pl | 193 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 193 insertions(+) create mode 100755 scripts/headerdep.pl (limited to 'scripts/headerdep.pl') diff --git a/scripts/headerdep.pl b/scripts/headerdep.pl new file mode 100755 index 000000000..ebfcbef43 --- /dev/null +++ b/scripts/headerdep.pl @@ -0,0 +1,193 @@ +#! /usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0 +# +# Detect cycles in the header file dependency graph +# Vegard Nossum +# + +use strict; +use warnings; + +use Getopt::Long; + +my $opt_all; +my @opt_include; +my $opt_graph; + +&Getopt::Long::Configure(qw(bundling pass_through)); +&GetOptions( + help => \&help, + version => \&version, + + all => \$opt_all, + "I=s" => \@opt_include, + graph => \$opt_graph, +); + +push @opt_include, 'include'; +my %deps = (); +my %linenos = (); + +my @headers = grep { strip($_) } @ARGV; + +parse_all(@headers); + +if($opt_graph) { + graph(); +} else { + detect_cycles(@headers); +} + + +sub help { + print "Usage: $0 [options] file...\n"; + print "\n"; + print "Options:\n"; + print " --all\n"; + print " --graph\n"; + print "\n"; + print " -I includedir\n"; + print "\n"; + print "To make nice graphs, try:\n"; + print " $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n"; + exit; +} + +sub version { + print "headerdep version 2\n"; + exit; +} + +# Get a file name that is relative to our include paths +sub strip { + my $filename = shift; + + for my $i (@opt_include) { + my $stripped = $filename; + $stripped =~ s/^$i\///; + + return $stripped if $stripped ne $filename; + } + + return $filename; +} + +# Search for the file name in the list of include paths +sub search { + my $filename = shift; + return $filename if -f $filename; + + for my $i (@opt_include) { + my $path = "$i/$filename"; + return $path if -f $path; + } + return; +} + +sub parse_all { + # Parse all the headers. + my @queue = @_; + while(@queue) { + my $header = pop @queue; + next if exists $deps{$header}; + + $deps{$header} = [] unless exists $deps{$header}; + + my $path = search($header); + next unless $path; + + open(my $file, '<', $path) or die($!); + chomp(my @lines = <$file>); + close($file); + + for my $i (0 .. $#lines) { + my $line = $lines[$i]; + if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) { + push @queue, $dep; + push @{$deps{$header}}, [$i + 1, $dep]; + } + } + } +} + +sub print_cycle { + # $cycle[n] includes $cycle[n + 1]; + # $cycle[-1] will be the culprit + my $cycle = shift; + + # Adjust the line numbers + for my $i (0 .. $#$cycle - 1) { + $cycle->[$i]->[0] = $cycle->[$i + 1]->[0]; + } + $cycle->[-1]->[0] = 0; + + my $first = shift @$cycle; + my $last = pop @$cycle; + + my $msg = "In file included"; + printf "%s from %s,\n", $msg, $last->[1] if defined $last; + + for my $header (reverse @$cycle) { + printf "%s from %s:%d%s\n", + " " x length $msg, + $header->[1], $header->[0], + $header->[1] eq $last->[1] ? ' <-- here' : ''; + } + + printf "%s:%d: warning: recursive header inclusion\n", + $first->[1], $first->[0]; +} + +# Find and print the smallest cycle starting in the specified node. +sub detect_cycles { + my @queue = map { [[0, $_]] } @_; + while(@queue) { + my $top = pop @queue; + my $name = $top->[-1]->[1]; + + for my $dep (@{$deps{$name}}) { + my $chain = [@$top, [$dep->[0], $dep->[1]]]; + + # If the dep already exists in the chain, we have a + # cycle... + if(grep { $_->[1] eq $dep->[1] } @$top) { + print_cycle($chain); + next if $opt_all; + return; + } + + push @queue, $chain; + } + } +} + +sub mangle { + $_ = shift; + s/\//__/g; + s/\./_/g; + s/-/_/g; + $_; +} + +# Output dependency graph in GraphViz language. +sub graph { + print "digraph {\n"; + + print "\t/* vertices */\n"; + for my $header (keys %deps) { + printf "\t%s [label=\"%s\"];\n", + mangle($header), $header; + } + + print "\n"; + + print "\t/* edges */\n"; + for my $header (keys %deps) { + for my $dep (@{$deps{$header}}) { + printf "\t%s -> %s;\n", + mangle($header), mangle($dep->[1]); + } + } + + print "}\n"; +} -- cgit v1.3.1