KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 224 insertions, 0 deletions

diff --git a/scripts/bootgraph.pl b/scripts/bootgraph.pl
new file mode 100755
index 000000000..79c903292
--- /dev/null
+++ b/scripts/bootgraph.pl
@@ -0,0 +1,224 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0-only
+
+# Copyright 2008, Intel Corporation
+#
+# This file is part of the Linux kernel
+#
+# Authors:
+# 	Arjan van de Ven <arjan@linux.intel.com>
+
+
+#
+# This script turns a dmesg output into a SVG graphic that shows which
+# functions take how much time. You can view SVG graphics with various
+# programs, including Inkscape, The Gimp and Firefox.
+#
+#
+# For this script to work, the kernel needs to be compiled with the
+# CONFIG_PRINTK_TIME configuration option enabled, and with
+# "initcall_debug" passed on the kernel command line.
+#
+# usage:
+# 	dmesg | perl scripts/bootgraph.pl > output.svg
+#
+
+use strict;
+use Getopt::Long;
+my $header = 0;
+
+sub help {
+	my $text = << "EOM";
+Usage:
+1) dmesg | perl scripts/bootgraph.pl [OPTION] > output.svg
+2) perl scripts/bootgraph.pl -h
+
+Options:
+	-header	Insert kernel version and date
+EOM
+	my $std=shift;
+	if ($std == 1) {
+		print STDERR $text;
+	} else {
+		print $text;
+	}
+	exit;
+}
+
+GetOptions(
+	'h|help'	=>\&help,
+	'header'	=>\$header
+);
+
+my %start;
+my %end;
+my %type;
+my $done = 0;
+my $maxtime = 0;
+my $firsttime = 99999;
+my $count = 0;
+my %pids;
+my %pidctr;
+
+my $headerstep = 20;
+my $xheader = 15;
+my $yheader = 25;
+my $cyheader = 0;
+
+while (<>) {
+	my $line = $_;
+	if ($line =~ /([0-9\.]+)\] calling  ([a-zA-Z0-9\_\.]+)\+/) {
+		my $func = $2;
+		if ($done == 0) {
+			$start{$func} = $1;
+			$type{$func} = 0;
+			if ($1 < $firsttime) {
+				$firsttime = $1;
+			}
+		}
+		if ($line =~ /\@ ([0-9]+)/) {
+			$pids{$func} = $1;
+		}
+		$count = $count + 1;
+	}
+
+	if ($line =~ /([0-9\.]+)\] async_waiting @ ([0-9]+)/) {
+		my $pid = $2;
+		my $func;
+		if (!defined($pidctr{$pid})) {
+			$func = "wait_" . $pid . "_1";
+			$pidctr{$pid} = 1;
+		} else {
+			$pidctr{$pid} = $pidctr{$pid} + 1;
+			$func = "wait_" . $pid . "_" . $pidctr{$pid};
+		}
+		if ($done == 0) {
+			$start{$func} = $1;
+			$type{$func} = 1;
+			if ($1 < $firsttime) {
+				$firsttime = $1;
+			}
+		}
+		$pids{$func} = $pid;
+		$count = $count + 1;
+	}
+
+	if ($line =~ /([0-9\.]+)\] initcall ([a-zA-Z0-9\_\.]+)\+.*returned/) {
+		if ($done == 0) {
+			$end{$2} = $1;
+			$maxtime = $1;
+		}
+	}
+
+	if ($line =~ /([0-9\.]+)\] async_continuing @ ([0-9]+)/) {
+		my $pid = $2;
+		my $func =  "wait_" . $pid . "_" . $pidctr{$pid};
+		$end{$func} = $1;
+		$maxtime = $1;
+	}
+	if ($line =~ /Write protecting the/) {
+		$done = 1;
+	}
+	if ($line =~ /Freeing unused kernel memory/) {
+		$done = 1;
+	}
+}
+
+if ($count == 0) {
+    print STDERR <<END;
+No data found in the dmesg. Make sure that 'printk.time=1' and
+'initcall_debug' are passed on the kernel command line.
+END
+	help(1);
+    exit 1;
+}
+
+print "<?xml version=\"1.0\" standalone=\"no\"?> \n";
+print "<svg width=\"2000\" height=\"100%\" version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">\n";
+
+
+if ($header) {
+	my $version = `uname -a`;
+	my $date = `date`;
+	print "<text transform=\"translate($xheader,$yheader)\">Kernel version: $version</text>\n";
+	$cyheader = $yheader+$headerstep;
+	print "<text transform=\"translate($xheader,$cyheader)\">Date: $date</text>\n";
+}
+
+my @styles;
+
+$styles[0] = "fill:rgb(0,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[1] = "fill:rgb(0,255,0);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[2] = "fill:rgb(255,0,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[3] = "fill:rgb(255,255,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[4] = "fill:rgb(255,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[5] = "fill:rgb(0,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[6] = "fill:rgb(0,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[7] = "fill:rgb(0,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[8] = "fill:rgb(255,0,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[9] = "fill:rgb(255,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[10] = "fill:rgb(255,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+$styles[11] = "fill:rgb(128,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)";
+
+my $style_wait = "fill:rgb(128,128,128);fill-opacity:0.5;stroke-width:0;stroke:rgb(0,0,0)";
+
+my $mult = 1950.0 / ($maxtime - $firsttime);
+my $threshold2 = ($maxtime - $firsttime) / 120.0;
+my $threshold = $threshold2/10;
+my $stylecounter = 0;
+my %rows;
+my $rowscount = 1;
+my @initcalls = sort { $start{$a} <=> $start{$b} } keys(%start);
+
+foreach my $key (@initcalls) {
+	my $duration = $end{$key} - $start{$key};
+
+	if ($duration >= $threshold) {
+		my ($s, $s2, $s3, $e, $w, $y, $y2, $style);
+		my $pid = $pids{$key};
+
+		if (!defined($rows{$pid})) {
+			$rows{$pid} = $rowscount;
+			$rowscount = $rowscount + 1;
+		}
+		$s = ($start{$key} - $firsttime) * $mult;
+		$s2 = $s + 6;
+		$s3 = $s + 1;
+		$e = ($end{$key} - $firsttime) * $mult;
+		$w = $e - $s;
+
+		$y = $rows{$pid} * 150;
+		$y2 = $y + 4;
+
+		$style = $styles[$stylecounter];
+		$stylecounter = $stylecounter + 1;
+		if ($stylecounter > 11) {
+			$stylecounter = 0;
+		};
+
+		if ($type{$key} == 1) {
+			$y = $y + 15;
+			print "<rect x=\"$s\" width=\"$w\" y=\"$y\" height=\"115\" style=\"$style_wait\"/>\n";
+		} else {
+			print "<rect x=\"$s\" width=\"$w\" y=\"$y\" height=\"145\" style=\"$style\"/>\n";
+			if ($duration >= $threshold2) {
+				print "<text transform=\"translate($s2,$y2) rotate(90)\">$key</text>\n";
+			} else {
+				print "<text transform=\"translate($s3,$y2) rotate(90)\" font-size=\"3pt\">$key</text>\n";
+			}
+		}
+	}
+}
+
+
+# print the time line on top
+my $time = $firsttime;
+my $step = ($maxtime - $firsttime) / 15;
+while ($time < $maxtime) {
+	my $s3 = ($time - $firsttime) * $mult;
+	my $tm = int($time * 100) / 100.0;
+	print "<text transform=\"translate($s3,89) rotate(90)\">$tm</text>\n";
+	$time = $time + $step;
+}
+
+print "</svg>\n";