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, 110 insertions, 0 deletions

diff --git a/scripts/package/buildtar b/scripts/package/buildtar
new file mode 100755
index 000000000..cc87a473c
--- /dev/null
+++ b/scripts/package/buildtar
@@ -0,0 +1,110 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+#
+# buildtar 0.0.5
+#
+# (C) 2004-2006 by Jan-Benedict Glaw <jbglaw@lug-owl.de>
+#
+# This script is used to compile a tarball from the currently
+# prepared kernel. Based upon the builddeb script from
+# Wichert Akkerman <wichert@wiggy.net>.
+#
+
+set -eu
+
+#
+# Some variables and settings used throughout the script
+#
+tmpdir=$1
+
+#
+# Clean-up and re-create the temporary directory
+#
+rm -rf -- "${tmpdir}"
+mkdir -p -- "${tmpdir}/boot"
+
+
+#
+# Try to install dtbs
+#
+if grep -q '^CONFIG_OF_EARLY_FLATTREE=y' include/config/auto.conf; then
+	# Only some architectures with OF support have this target
+	if [ -d "${srctree}/arch/${SRCARCH}/boot/dts" ]; then
+		$MAKE ARCH="${ARCH}" -f ${srctree}/Makefile INSTALL_DTBS_PATH="${tmpdir}/boot/dtbs/${KERNELRELEASE}" dtbs_install
+    fi
+fi
+
+
+#
+# Install modules
+#
+make ARCH="${ARCH}" -f ${srctree}/Makefile INSTALL_MOD_PATH="${tmpdir}" modules_install
+
+
+#
+# Install basic kernel files
+#
+cp -v -- "${objtree}/System.map" "${tmpdir}/boot/System.map-${KERNELRELEASE}"
+cp -v -- "${KCONFIG_CONFIG}" "${tmpdir}/boot/config-${KERNELRELEASE}"
+cp -v -- "${objtree}/vmlinux" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+
+
+#
+# Install arch-specific kernel image(s)
+#
+# Note:
+#   mips and arm64 copy the first image found. This may not produce the desired
+#   outcome because it may pick up a stale file remaining in the build tree.
+#
+case "${ARCH}" in
+	alpha)
+		cp -v -- "${objtree}/arch/alpha/boot/vmlinux.gz" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+		;;
+	parisc*)
+		cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		[ -f "${objtree}/lifimage" ] && cp -v -- "${objtree}/lifimage" "${tmpdir}/boot/lifimage-${KERNELRELEASE}"
+		;;
+	mips)
+		# Please note the following code may copy a stale file.
+		if [ -f "${objtree}/arch/mips/boot/compressed/vmlinux.bin" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/compressed/vmlinux.bin" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+		elif [ -f "${objtree}/arch/mips/boot/compressed/vmlinux.ecoff" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/compressed/vmlinux.ecoff" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+		elif [ -f "${objtree}/arch/mips/boot/compressed/vmlinux.srec" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/compressed/vmlinux.srec" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+		elif [ -f "${objtree}/vmlinux.32" ]; then
+			cp -v -- "${objtree}/vmlinux.32" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		elif [ -f "${objtree}/vmlinux.64" ]; then
+			cp -v -- "${objtree}/vmlinux.64" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		elif [ -f "${objtree}/arch/mips/boot/vmlinux.bin" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/vmlinux.bin" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		elif [ -f "${objtree}/arch/mips/boot/vmlinux.ecoff" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/vmlinux.ecoff" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		elif [ -f "${objtree}/arch/mips/boot/vmlinux.srec" ]; then
+			cp -v -- "${objtree}/arch/mips/boot/vmlinux.srec" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		elif [ -f "${objtree}/vmlinux" ]; then
+			cp -v -- "${objtree}/vmlinux" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
+		fi
+		;;
+	arm64)
+		# Please note the following code may copy a stale file.
+		for i in Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo vmlinuz.efi ; do
+			if [ -f "${objtree}/arch/arm64/boot/${i}" ] ; then
+				cp -v -- "${objtree}/arch/arm64/boot/${i}" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+				break
+			fi
+		done
+		;;
+	riscv)
+		case "${KBUILD_IMAGE##*/}" in
+			Image.*|vmlinuz.efi)
+				cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}";;
+			*)
+				cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}";;
+		esac
+		;;
+	*)
+		cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
+		;;
+esac