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/cleanpatch | 260 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 260 insertions(+) create mode 100755 scripts/cleanpatch (limited to 'scripts/cleanpatch') diff --git a/scripts/cleanpatch b/scripts/cleanpatch new file mode 100755 index 000000000..9f1755271 --- /dev/null +++ b/scripts/cleanpatch @@ -0,0 +1,260 @@ +#!/usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0 +# +# Clean a patch file -- or directory of patch files -- of stealth whitespace. +# WARNING: this can be a highly destructive operation. Use with caution. +# + +use warnings; +use bytes; +use File::Basename; + +# Default options +$max_width = 79; + +# Clean up space-tab sequences, either by removing spaces or +# replacing them with tabs. +sub clean_space_tabs($) +{ + no bytes; # Tab alignment depends on characters + + my($li) = @_; + my($lo) = ''; + my $pos = 0; + my $nsp = 0; + my($i, $c); + + for ($i = 0; $i < length($li); $i++) { + $c = substr($li, $i, 1); + if ($c eq "\t") { + my $npos = ($pos+$nsp+8) & ~7; + my $ntab = ($npos >> 3) - ($pos >> 3); + $lo .= "\t" x $ntab; + $pos = $npos; + $nsp = 0; + } elsif ($c eq "\n" || $c eq "\r") { + $lo .= " " x $nsp; + $pos += $nsp; + $nsp = 0; + $lo .= $c; + $pos = 0; + } elsif ($c eq " ") { + $nsp++; + } else { + $lo .= " " x $nsp; + $pos += $nsp; + $nsp = 0; + $lo .= $c; + $pos++; + } + } + $lo .= " " x $nsp; + return $lo; +} + +# Compute the visual width of a string +sub strwidth($) { + no bytes; # Tab alignment depends on characters + + my($li) = @_; + my($c, $i); + my $pos = 0; + my $mlen = 0; + + for ($i = 0; $i < length($li); $i++) { + $c = substr($li,$i,1); + if ($c eq "\t") { + $pos = ($pos+8) & ~7; + } elsif ($c eq "\n") { + $mlen = $pos if ($pos > $mlen); + $pos = 0; + } else { + $pos++; + } + } + + $mlen = $pos if ($pos > $mlen); + return $mlen; +} + +$name = basename($0); + +@files = (); + +while (defined($a = shift(@ARGV))) { + if ($a =~ /^-/) { + if ($a eq '-width' || $a eq '-w') { + $max_width = shift(@ARGV)+0; + } else { + print STDERR "Usage: $name [-width #] files...\n"; + exit 1; + } + } else { + push(@files, $a); + } +} + +foreach $f ( @files ) { + print STDERR "$name: $f\n"; + + if (! -f $f) { + print STDERR "$f: not a file\n"; + next; + } + + if (!open(FILE, '+<', $f)) { + print STDERR "$name: Cannot open file: $f: $!\n"; + next; + } + + binmode FILE; + + # First, verify that it is not a binary file; consider any file + # with a zero byte to be a binary file. Is there any better, or + # additional, heuristic that should be applied? + $is_binary = 0; + + while (read(FILE, $data, 65536) > 0) { + if ($data =~ /\0/) { + $is_binary = 1; + last; + } + } + + if ($is_binary) { + print STDERR "$name: $f: binary file\n"; + next; + } + + seek(FILE, 0, 0); + + $in_bytes = 0; + $out_bytes = 0; + $lineno = 0; + + @lines = (); + + $in_hunk = 0; + $err = 0; + + while ( defined($line = ) ) { + $lineno++; + $in_bytes += length($line); + + if (!$in_hunk) { + if ($line =~ + /^\@\@\s+\-([0-9]+),([0-9]+)\s+\+([0-9]+),([0-9]+)\s\@\@/) { + $minus_lines = $2; + $plus_lines = $4; + if ($minus_lines || $plus_lines) { + $in_hunk = 1; + @hunk_lines = ($line); + } + } else { + push(@lines, $line); + $out_bytes += length($line); + } + } else { + # We're in a hunk + + if ($line =~ /^\+/) { + $plus_lines--; + + $text = substr($line, 1); + $text =~ s/[ \t\r]*$//; # Remove trailing spaces + $text = clean_space_tabs($text); + + $l_width = strwidth($text); + if ($max_width && $l_width > $max_width) { + print STDERR + "$f:$lineno: adds line exceeds $max_width ", + "characters ($l_width)\n"; + } + + push(@hunk_lines, '+'.$text); + } elsif ($line =~ /^\-/) { + $minus_lines--; + push(@hunk_lines, $line); + } elsif ($line =~ /^ /) { + $plus_lines--; + $minus_lines--; + push(@hunk_lines, $line); + } else { + print STDERR "$name: $f: malformed patch\n"; + $err = 1; + last; + } + + if ($plus_lines < 0 || $minus_lines < 0) { + print STDERR "$name: $f: malformed patch\n"; + $err = 1; + last; + } elsif ($plus_lines == 0 && $minus_lines == 0) { + # End of a hunk. Process this hunk. + my $i; + my $l; + my @h = (); + my $adj = 0; + my $done = 0; + + for ($i = scalar(@hunk_lines)-1; $i > 0; $i--) { + $l = $hunk_lines[$i]; + if (!$done && $l eq "+\n") { + $adj++; # Skip this line + } elsif ($l =~ /^[ +]/) { + $done = 1; + unshift(@h, $l); + } else { + unshift(@h, $l); + } + } + + $l = $hunk_lines[0]; # Hunk header + undef @hunk_lines; # Free memory + + if ($adj) { + die unless + ($l =~ /^\@\@\s+\-([0-9]+),([0-9]+)\s+\+([0-9]+),([0-9]+)\s\@\@(.*)$/); + my $mstart = $1; + my $mlin = $2; + my $pstart = $3; + my $plin = $4; + my $tail = $5; # doesn't include the final newline + + $l = sprintf("@@ -%d,%d +%d,%d @@%s\n", + $mstart, $mlin, $pstart, $plin-$adj, + $tail); + } + unshift(@h, $l); + + # Transfer to the output array + foreach $l (@h) { + $out_bytes += length($l); + push(@lines, $l); + } + + $in_hunk = 0; + } + } + } + + if ($in_hunk) { + print STDERR "$name: $f: malformed patch\n"; + $err = 1; + } + + if (!$err) { + if ($in_bytes != $out_bytes) { + # Only write to the file if changed + seek(FILE, 0, 0); + print FILE @lines; + + if ( !defined($where = tell(FILE)) || + !truncate(FILE, $where) ) { + die "$name: Failed to truncate modified file: $f: $!\n"; + } + } + } + + close(FILE); +} -- cgit v1.3.1