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/Makefile.compiler | 93 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 scripts/Makefile.compiler (limited to 'scripts/Makefile.compiler') diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler new file mode 100644 index 000000000..06bbe29c8 --- /dev/null +++ b/scripts/Makefile.compiler @@ -0,0 +1,93 @@ +# SPDX-License-Identifier: GPL-2.0-only + +# cc-cross-prefix +# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-) +# Return first where a gcc is found in PATH. +# If no gcc found in PATH with listed prefixes return nothing +# +# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it +# would try to directly execute the shell builtin 'command'. This workaround +# should be kept for a long time since this issue was fixed only after the +# GNU Make 4.2.1 release. +cc-cross-prefix = $(firstword $(foreach c, $(1), \ + $(if $(shell command -v -- $(c)gcc 2>/dev/null), $(c)))) + +# output directory for tests below +TMPOUT = .tmp_$$$$ + +# try-run +# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise) +# Exit code chooses option. "$$TMP" serves as a temporary file and is +# automatically cleaned up. +try-run = $(shell set -e; \ + TMP=$(TMPOUT)/tmp; \ + trap "rm -rf $(TMPOUT)" EXIT; \ + mkdir -p $(TMPOUT); \ + if ($(1)) >/dev/null 2>&1; \ + then echo "$(2)"; \ + else echo "$(3)"; \ + fi) + +# as-option +# Usage: aflags-y += $(call as-option,-Wa$(comma)-isa=foo,) + +as-option = $(call try-run,\ + $(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(1) -c -x assembler-with-cpp /dev/null -o "$$TMP",$(1),$(2)) + +# as-instr +# Usage: aflags-y += $(call as-instr,instr,option1,option2) + +as-instr = $(call try-run,\ + printf "%b\n" "$(1)" | $(CC) -Werror $(CLANG_FLAGS) $(KBUILD_AFLAGS) -Wa$(comma)--fatal-warnings -c -x assembler-with-cpp -o "$$TMP" -,$(2),$(3)) + +# __cc-option +# Usage: MY_CFLAGS += $(call __cc-option,$(CC),$(MY_CFLAGS),-march=winchip-c6,-march=i586) +__cc-option = $(call try-run,\ + $(1) -Werror $(2) $(3:-Wno-%=-W%) -c -x c /dev/null -o "$$TMP",$(3),$(4)) + +# cc-option +# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586) + +cc-option = $(call __cc-option, $(CC),\ + $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS),$(1),$(2)) + +# cc-option-yn +# Usage: flag := $(call cc-option-yn,-march=winchip-c6) +cc-option-yn = $(if $(call cc-option,$1),y,n) + +# cc-disable-warning +# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable) +cc-disable-warning = $(call cc-option,-Wno-$(strip $1)) + +# gcc-min-version +# Usage: cflags-$(call gcc-min-version, 110100) += -foo +gcc-min-version = $(call test-ge, $(CONFIG_GCC_VERSION), $1) + +# clang-min-version +# Usage: cflags-$(call clang-min-version, 110000) += -foo +clang-min-version = $(call test-ge, $(CONFIG_CLANG_VERSION), $1) + +# rustc-min-version +# Usage: rustc-$(call rustc-min-version, 108500) += -Cfoo +rustc-min-version = $(call test-ge, $(CONFIG_RUSTC_VERSION), $1) + +# ld-option +# Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y) +ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3)) + +# __rustc-option +# Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage) +# TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4 +__rustc-option = $(call try-run,\ + echo '$(pound)![allow(missing_docs)]$(pound)![feature(no_core)]$(pound)![no_core]' | RUSTC_BOOTSTRAP=1\ + $(1) --sysroot=/dev/null $(KBUILD_RUSTFLAGS_OPTION_CHKS) $(filter-out --sysroot=/dev/null --target=%target.json,$(2)) $(3)\ + --crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4)) + +# rustc-option +# Usage: rustflags-y += $(call rustc-option,-Cinstrument-coverage,-Zinstrument-coverage) +rustc-option = $(call __rustc-option, $(RUSTC),\ + $(KBUILD_RUSTFLAGS),$(1),$(2)) + +# rustc-option-yn +# Usage: flag := $(call rustc-option-yn,-Cinstrument-coverage) +rustc-option-yn = $(if $(call rustc-option,$1),y,n) -- cgit v1.3.1