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, 176 insertions, 0 deletions

diff --git a/arch/mips/boot/Makefile b/arch/mips/boot/Makefile
new file mode 100644
index 000000000..8473c4671
--- /dev/null
+++ b/arch/mips/boot/Makefile
@@ -0,0 +1,176 @@
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+# Copyright (C) 1995, 1998, 2001, 2002 by Ralf Baechle
+# Copyright (C) 2004  Maciej W. Rozycki
+#
+
+#
+# Some DECstations need all possible sections of an ECOFF executable
+#
+ifdef CONFIG_MACH_DECSTATION
+  e2eflag := -a
+endif
+
+#
+# Drop some uninteresting sections in the kernel.
+# This is only relevant for ELF kernels but doesn't hurt a.out
+#
+drop-sections := .reginfo .mdebug .comment .note .pdr .options .MIPS.options
+strip-flags   := $(addprefix --remove-section=,$(drop-sections))
+
+hostprogs := elf2ecoff
+
+suffix-y			:= bin
+suffix-$(CONFIG_KERNEL_BZIP2)	:= bz2
+suffix-$(CONFIG_KERNEL_GZIP)	:= gz
+suffix-$(CONFIG_KERNEL_LZMA)	:= lzma
+suffix-$(CONFIG_KERNEL_LZO)	:= lzo
+
+targets := vmlinux.ecoff
+quiet_cmd_ecoff = ECOFF	  $@
+      cmd_ecoff = $(obj)/elf2ecoff $(VMLINUX) $@ $(e2eflag)
+$(obj)/vmlinux.ecoff: $(obj)/elf2ecoff $(VMLINUX) FORCE
+	$(call if_changed,ecoff)
+
+targets += vmlinux.bin
+quiet_cmd_bin = OBJCOPY $@
+      cmd_bin = $(OBJCOPY) -O binary $(strip-flags) $(VMLINUX) $@
+$(obj)/vmlinux.bin: $(VMLINUX) FORCE
+	$(call if_changed,bin)
+
+targets += vmlinux.srec
+quiet_cmd_srec = OBJCOPY $@
+      cmd_srec = $(OBJCOPY) -S -O srec $(strip-flags) $(VMLINUX) $@
+$(obj)/vmlinux.srec: $(VMLINUX) FORCE
+	$(call if_changed,srec)
+
+UIMAGE_LOADADDR  = $(VMLINUX_LOAD_ADDRESS)
+UIMAGE_ENTRYADDR = $(VMLINUX_ENTRY_ADDRESS)
+
+#
+# Compressed vmlinux images
+#
+
+targets += vmlinux.bin.bz2
+targets += vmlinux.bin.gz
+targets += vmlinux.bin.lzma
+targets += vmlinux.bin.lzo
+
+$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,bzip2)
+
+$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,gzip)
+
+$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,lzma)
+
+$(obj)/vmlinux.bin.lzo: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,lzo)
+
+#
+# Compressed u-boot images
+#
+
+targets += uImage
+targets += uImage.bin
+targets += uImage.bz2
+targets += uImage.gz
+targets += uImage.lzma
+targets += uImage.lzo
+
+$(obj)/uImage.bin: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,uimage,none)
+
+$(obj)/uImage.bz2: $(obj)/vmlinux.bin.bz2 FORCE
+	$(call if_changed,uimage,bzip2)
+
+$(obj)/uImage.gz: $(obj)/vmlinux.bin.gz FORCE
+	$(call if_changed,uimage,gzip)
+
+$(obj)/uImage.lzma: $(obj)/vmlinux.bin.lzma FORCE
+	$(call if_changed,uimage,lzma)
+
+$(obj)/uImage.lzo: $(obj)/vmlinux.bin.lzo FORCE
+	$(call if_changed,uimage,lzo)
+
+$(obj)/uImage: $(obj)/uImage.$(suffix-y)
+	@ln -sf $(notdir $<) $@
+	@echo '  Image $@ is ready'
+
+#
+# Flattened Image Tree (.itb) images
+#
+
+ifeq ($(ADDR_BITS),32)
+itb_addr_cells = 1
+endif
+ifeq ($(ADDR_BITS),64)
+itb_addr_cells = 2
+endif
+
+targets += vmlinux.its.S
+
+quiet_cmd_its_cat = CAT     $@
+      cmd_its_cat = cat $(real-prereqs) >$@
+
+$(obj)/vmlinux.its.S: $(addprefix $(srctree)/arch/mips/$(PLATFORM)/,$(ITS_INPUTS)) FORCE
+	$(call if_changed,its_cat)
+
+targets += vmlinux.its
+targets += vmlinux.gz.its
+targets += vmlinux.bz2.its
+targets += vmlinux.lzma.its
+targets += vmlinux.lzo.its
+
+quiet_cmd_cpp_its_S = ITS     $@
+      cmd_cpp_its_S = $(CPP) -P -C -o $@ $< \
+		        -DKERNEL_NAME="\"Linux $(KERNELRELEASE)\"" \
+			-DVMLINUX_BINARY="\"$(3)\"" \
+			-DVMLINUX_COMPRESSION="\"$(2)\"" \
+			-DVMLINUX_LOAD_ADDRESS=$(VMLINUX_LOAD_ADDRESS) \
+			-DVMLINUX_ENTRY_ADDRESS=$(VMLINUX_ENTRY_ADDRESS) \
+			-DADDR_BITS=$(ADDR_BITS) \
+			-DADDR_CELLS=$(itb_addr_cells)
+
+$(obj)/vmlinux.its: $(obj)/vmlinux.its.S $(VMLINUX) FORCE
+	$(call if_changed,cpp_its_S,none,vmlinux.bin)
+
+$(obj)/vmlinux.gz.its: $(obj)/vmlinux.its.S $(VMLINUX) FORCE
+	$(call if_changed,cpp_its_S,gzip,vmlinux.bin.gz)
+
+$(obj)/vmlinux.bz2.its: $(obj)/vmlinux.its.S $(VMLINUX)  FORCE
+	$(call if_changed,cpp_its_S,bzip2,vmlinux.bin.bz2)
+
+$(obj)/vmlinux.lzma.its: $(obj)/vmlinux.its.S $(VMLINUX) FORCE
+	$(call if_changed,cpp_its_S,lzma,vmlinux.bin.lzma)
+
+$(obj)/vmlinux.lzo.its: $(obj)/vmlinux.its.S $(VMLINUX) FORCE
+	$(call if_changed,cpp_its_S,lzo,vmlinux.bin.lzo)
+
+targets += vmlinux.itb
+targets += vmlinux.gz.itb
+targets += vmlinux.bz2.itb
+targets += vmlinux.lzma.itb
+targets += vmlinux.lzo.itb
+
+quiet_cmd_itb-image = ITB     $@
+      cmd_itb-image = \
+		env PATH="$(objtree)/scripts/dtc:$(PATH)" \
+		$(BASH) $(MKIMAGE) \
+		-D "-I dts -O dtb -p 500 \
+			--include $(objtree)/arch/mips \
+			--warning no-unit_address_vs_reg" \
+		-f $(2) $@
+
+$(obj)/vmlinux.itb: $(obj)/vmlinux.its $(obj)/vmlinux.bin FORCE
+	$(call if_changed,itb-image,$<)
+
+$(obj)/vmlinux.%.itb: $(obj)/vmlinux.%.its $(obj)/vmlinux.bin.% FORCE
+	$(call if_changed,itb-image,$<)
+
+# for cleaning
+subdir- += compressed tools