Hi David,
On 2020-06-18 13:25, David Brazdil wrote:
Add new folder arch/arm64/kvm/hyp/nvhe and a Makefile for building code
that
runs in EL2 under nVHE KVM.
Compile each source file into a `.hyp.tmp.o` object first, then prefix
all
its symbols with "__kvm_nvhe_" using `objcopy` and produce a `.hyp.o`.
Suffixes were chosen so that it would be possible for VHE and nVHE to
share
some source files, but compiled with different CFLAGS. nVHE build rules
add
-D__KVM_NVHE_HYPERVISOR__.
The nVHE ELF symbol prefix is added to kallsyms.c as ignored. EL2-only
symbols
will never appear in EL1 stack traces.
Signed-off-by: David Brazdil <dbrazdil@xxxxxxxxxx>
---
arch/arm64/kernel/image-vars.h | 12 +++++++++++
arch/arm64/kvm/hyp/Makefile | 2 +-
arch/arm64/kvm/hyp/nvhe/Makefile | 35 ++++++++++++++++++++++++++++++++
scripts/kallsyms.c | 1 +
4 files changed, 49 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kvm/hyp/nvhe/Makefile
diff --git a/arch/arm64/kernel/image-vars.h
b/arch/arm64/kernel/image-vars.h
index be0a63ffed23..f32b406e90c0 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -51,4 +51,16 @@ __efistub__ctype = _ctype;
#endif
+#ifdef CONFIG_KVM
+
+/*
+ * KVM nVHE code has its own symbol namespace prefixed by __kvm_nvhe_,
to
+ * isolate it from the kernel proper. The following symbols are
legally
+ * accessed by it, therefore provide aliases to make them linkable.
+ * Do not include symbols which may not be safely accessed under
hypervisor
+ * memory mappings.
+ */
+
+#endif /* CONFIG_KVM */
+
#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 5d8357ddc234..5f4f217532e0 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile
@@ -6,7 +6,7 @@
ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \
$(DISABLE_STACKLEAK_PLUGIN)
-obj-$(CONFIG_KVM) += hyp.o
+obj-$(CONFIG_KVM) += hyp.o nvhe/
obj-$(CONFIG_KVM_INDIRECT_VECTORS) += smccc_wa.o
hyp-y := vgic-v3-sr.o timer-sr.o aarch32.o vgic-v2-cpuif-proxy.o
sysreg-sr.o \
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile
b/arch/arm64/kvm/hyp/nvhe/Makefile
new file mode 100644
index 000000000000..7d64235dba62
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for Kernel-based Virtual Machine module, HYP/nVHE part
+#
+
+asflags-y := -D__KVM_NVHE_HYPERVISOR__
+ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -fno-stack-protector \
+ -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN)
+
+obj-y :=
+
+obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
+extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
+
+$(obj)/%.hyp.tmp.o: $(src)/%.c FORCE
+ $(call if_changed_rule,cc_o_c)
+$(obj)/%.hyp.tmp.o: $(src)/%.S FORCE
+ $(call if_changed_rule,as_o_S)
+$(obj)/%.hyp.o: $(obj)/%.hyp.tmp.o FORCE
+ $(call if_changed,hypcopy)
+
+quiet_cmd_hypcopy = HYPCOPY $@
+ cmd_hypcopy = $(OBJCOPY) --prefix-symbols=__kvm_nvhe_ $< $@
+
+# KVM nVHE code is run at a different exception code with a different
map, so
+# compiler instrumentation that inserts callbacks or checks into the
code may
+# cause crashes. Just disable it.
+GCOV_PROFILE := n
+KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
+KCOV_INSTRUMENT := n
+
+# Skip objtool checking for this directory because nVHE code is
compiled with
+# non-standard build rules.
+OBJECT_FILES_NON_STANDARD := y
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 6dc3078649fa..0096cd965332 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -109,6 +109,7 @@ static bool is_ignored_symbol(const char *name,
char type)
".LASANPC", /* s390 kasan local symbols */
"__crc_", /* modversions */
"__efistub_", /* arm64 EFI stub namespace */
+ "__kvm_nvhe_", /* arm64 non-VHE KVM namespace */
NULL
};
I guess that one of the first use of this __KVM_NVHE_HYPERVISOR__
flag could be the has_vhe() predicate: if you're running the nVHE
code, you are *guaranteed* not to use VHE at all.
Something like:
diff --git a/arch/arm64/include/asm/virt.h
b/arch/arm64/include/asm/virt.h
index 5051b388c654..b2cb8fce43dd 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -85,10 +85,8 @@ static inline bool is_kernel_in_hyp_mode(void)
static __always_inline bool has_vhe(void)
{
- if (cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN))
- return true;
-
- return false;
+ return (__is_defined(__KVM_NVHE_HYPERVISOR__) &&
+ cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN));
}
#endif /* __ASSEMBLY__ */
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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