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, 212 insertions, 0 deletions

diff --git a/scripts/setlocalversion b/scripts/setlocalversion
new file mode 100755
index 000000000..28169d7e1
--- /dev/null
+++ b/scripts/setlocalversion
@@ -0,0 +1,212 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# This scripts adds local version information from the version
+# control system git.
+#
+# If something goes wrong, send a mail the kernel build mailinglist
+# (see MAINTAINERS) and CC Nico Schottelius
+# <nico-linuxsetlocalversion -at- schottelius.org>.
+#
+#
+
+set -e
+
+usage() {
+	echo "Usage: $0 [--no-local] [srctree]" >&2
+	exit 1
+}
+
+no_local=false
+if test "$1" = "--no-local"; then
+	no_local=true
+	shift
+fi
+
+srctree=.
+if test $# -gt 0; then
+	srctree=$1
+	shift
+fi
+if test $# -gt 0 -o ! -d "$srctree"; then
+	usage
+fi
+
+try_tag() {
+	tag="$1"
+
+	# Is $tag an annotated tag?
+	if [ "$(git cat-file -t "$tag" 2> /dev/null)" != tag ]; then
+		 return
+	fi
+
+	# Is it an ancestor of HEAD, and if so, how many commits are in $tag..HEAD?
+	# shellcheck disable=SC2046 # word splitting is the point here
+	set -- $(git rev-list --count --left-right "$tag"...HEAD 2> /dev/null)
+
+	# $1 is 0 if and only if $tag is an ancestor of HEAD. Use
+	# string comparison, because $1 is empty if the 'git rev-list'
+	# command somehow failed.
+	if [ "$1" != 0 ]; then
+		return
+	fi
+
+	# $2 is the number of commits in the range $tag..HEAD, possibly 0.
+	count="$2"
+}
+
+scm_version()
+{
+	local short=false
+	local no_dirty=false
+	local tag
+
+	while [ $# -gt 0 ];
+	do
+		case "$1" in
+		--short)
+			short=true;;
+		--no-dirty)
+			no_dirty=true;;
+		esac
+		shift
+	done
+
+	cd "$srctree"
+
+	if test -n "$(git rev-parse --show-cdup 2>/dev/null)"; then
+		return
+	fi
+
+	if ! head=$(git rev-parse --verify HEAD 2>/dev/null); then
+		return
+	fi
+
+	# mainline kernel:  6.2.0-rc5  ->  v6.2-rc5
+	# stable kernel:    6.1.7      ->  v6.1.7
+	version_tag=v$(echo "${KERNELVERSION}" | sed -E 's/^([0-9]+\.[0-9]+)\.0(.*)$/\1\2/')
+
+	# try_tag initializes count if the tag is usable.
+	count=
+
+	# If a localversion* file exists, and the corresponding
+	# annotated tag exists and is an ancestor of HEAD, use
+	# it. This is the case in linux-next.
+	if [ -n "${file_localversion#-}" ] ; then
+		try_tag "${file_localversion#-}"
+	fi
+
+	# Otherwise, if a localversion* file exists, and the tag
+	# obtained by appending it to the tag derived from
+	# KERNELVERSION exists and is an ancestor of HEAD, use
+	# it. This is e.g. the case in linux-rt.
+	if [ -z "${count}" ] && [ -n "${file_localversion}" ]; then
+		try_tag "${version_tag}${file_localversion}"
+	fi
+
+	# Otherwise, default to the annotated tag derived from KERNELVERSION.
+	if [ -z "${count}" ]; then
+		try_tag "${version_tag}"
+	fi
+
+	# If we are at the tagged commit, we ignore it because the
+	# version is well-defined. If none of the attempted tags exist
+	# or were usable, $count is still empty.
+	if [ -z "${count}" ] || [ "${count}" -gt 0 ]; then
+
+		# If only the short version is requested, don't bother
+		# running further git commands
+		if $short; then
+			echo "+"
+			return
+		fi
+
+		# If we are past the tagged commit, we pretty print it.
+		# (like 6.1.0-14595-g292a089d78d3)
+		if [ -n "${count}" ]; then
+			printf "%s%05d" "-" "${count}"
+		fi
+
+		# Add -g and exactly 12 hex chars.
+		printf '%s%.12s' -g "$head"
+	fi
+
+	if ${no_dirty}; then
+		return
+	fi
+
+	# Check for uncommitted changes.
+	# This script must avoid any write attempt to the source tree, which
+	# might be read-only.
+	# You cannot use 'git describe --dirty' because it tries to create
+	# .git/index.lock .
+	# First, with git-status, but --no-optional-locks is only supported in
+	# git >= 2.14, so fall back to git-diff-index if it fails. Note that
+	# git-diff-index does not refresh the index, so it may give misleading
+	# results.
+	# See git-update-index(1), git-diff-index(1), and git-status(1).
+	if {
+		git --no-optional-locks status -uno --porcelain 2>/dev/null ||
+		git diff-index --name-only HEAD
+	} | read dummy; then
+		printf '%s' -dirty
+	fi
+}
+
+collect_files()
+{
+	local file res=
+
+	for file; do
+		case "$file" in
+		*\~*)
+			continue
+			;;
+		esac
+		if test -e "$file"; then
+			res="$res$(cat "$file")"
+		fi
+	done
+	echo "$res"
+}
+
+if [ -z "${KERNELVERSION}" ]; then
+	echo "KERNELVERSION is not set" >&2
+	exit 1
+fi
+
+# localversion* files in the build and source directory
+file_localversion="$(collect_files localversion*)"
+if test ! "$srctree" -ef .; then
+	file_localversion="${file_localversion}$(collect_files "$srctree"/localversion*)"
+fi
+
+if ${no_local}; then
+	echo "${KERNELVERSION}$(scm_version --no-dirty)"
+	exit 0
+fi
+
+if ! test -e include/config/auto.conf; then
+	echo "Error: kernelrelease not valid - run 'make prepare' to update it" >&2
+	exit 1
+fi
+
+# version string from CONFIG_LOCALVERSION
+config_localversion=$(sed -n 's/^CONFIG_LOCALVERSION=\(.*\)$/\1/p' include/config/auto.conf)
+
+# scm version string if not at the kernel version tag or at the file_localversion
+if grep -q "^CONFIG_LOCALVERSION_AUTO=y$" include/config/auto.conf; then
+	# full scm version string
+	scm_version="$(scm_version)"
+elif [ "${LOCALVERSION+set}" != "set" ]; then
+	# If the variable LOCALVERSION is not set, append a plus
+	# sign if the repository is not in a clean annotated or
+	# signed tagged state (as git describe only looks at signed
+	# or annotated tags - git tag -a/-s).
+	#
+	# If the variable LOCALVERSION is set (including being set
+	# to an empty string), we don't want to append a plus sign.
+	scm_version="$(scm_version --short)"
+fi
+
+echo "${KERNELVERSION}${file_localversion}${config_localversion}${LOCALVERSION}${scm_version}"