Since commits 3adce820cf ("target/i386: Remove unused KVM
stubs") and ef1cf6890f ("target/i386: Allow elision of
kvm_hv_vpindex_settable()"), when building on a x86 host
configured as:
$ ./configure --cc=clang \
--target-list=x86_64-linux-user,x86_64-softmmu \
--enable-debug
we get:
[71/71] Linking target qemu-x86_64
FAILED: qemu-x86_64
/usr/bin/ld: libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o: in function `cpu_x86_cpuid':
cpu.c:(.text+0x1374): undefined reference to `kvm_arch_get_supported_cpuid'
/usr/bin/ld: libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o: in function `x86_cpu_filter_features':
cpu.c:(.text+0x81c2): undefined reference to `kvm_arch_get_supported_cpuid'
/usr/bin/ld: cpu.c:(.text+0x81da): undefined reference to `kvm_arch_get_supported_cpuid'
/usr/bin/ld: cpu.c:(.text+0x81f2): undefined reference to `kvm_arch_get_supported_cpuid'
/usr/bin/ld: cpu.c:(.text+0x820a): undefined reference to `kvm_arch_get_supported_cpuid'
/usr/bin/ld: libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o:cpu.c:(.text+0x8225): more undefined references to `kvm_arch_get_supported_cpuid' follow
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
libqemu-x86_64-linux-user.fa is user emulation specific, so
having system emulation code called there is dubious.
'--enable-debug' disables optimizations (CFLAGS=-O0).
While at this (un)optimization level GCC eliminate the
following dead code (CPP output of mentioned build):
static void x86_cpu_get_supported_cpuid(uint32_t func, uint32_t index,
uint32_t *eax, uint32_t *ebx,
uint32_t *ecx, uint32_t *edx)
{
if ((0)) {
*eax = kvm_arch_get_supported_cpuid(kvm_state, func, index, R_EAX);
*ebx = kvm_arch_get_supported_cpuid(kvm_state, func, index, R_EBX);
*ecx = kvm_arch_get_supported_cpuid(kvm_state, func, index, R_ECX);
*edx = kvm_arch_get_supported_cpuid(kvm_state, func, index, R_EDX);
} else if (0) {
*eax = 0;
*ebx = 0;
*ecx = 0;
*edx = 0;
} else {
*eax = 0;
*ebx = 0;
*ecx = 0;
*edx = 0;
}
}
Clang does not.
Instead of trying to deal with compiler specific checks around
__OPTIMIZE__ (see commit 2140cfa51d "i386: Fix build by providing
stub kvm_arch_get_supported_cpuid()"), simply restrict code
belonging to system emulation, easing user emulation linking.
Reported-by: Kevin Wolf <kwolf@xxxxxxxxxx>
Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
---
RFC: I might have been overzealous in x86_cpu_expand_features(),
please double check.
---
target/i386/cpu.c | 47 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 760428d4dc..8b57708604 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -1664,6 +1664,7 @@ static inline uint64_t x86_cpu_xsave_xss_components(X86CPU *cpu)
cpu->env.features[FEAT_XSAVE_XSS_LO];
}
+#ifndef CONFIG_USER_ONLY
/*
* Returns the set of feature flags that are supported and migratable by
* QEMU, for a given FeatureWord.
@@ -1686,6 +1687,7 @@ static uint64_t x86_cpu_get_migratable_flags(FeatureWord w)
}
return r;
}
+#endif /* !CONFIG_USER_ONLY */
void host_cpuid(uint32_t function, uint32_t count,
uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
@@ -5677,8 +5679,6 @@ CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
return cpu_list;
}
-#endif /* !CONFIG_USER_ONLY */
-
uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
bool migratable_only)
{
@@ -5781,6 +5781,38 @@ static void x86_cpu_get_cache_cpuid(uint32_t func, uint32_t index,
}
}
+#else /* CONFIG_USER_ONLY */
+
+uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
+ bool migratable_only)
+{
+ FeatureWordInfo *wi = &feature_word_info[w];
+
+ return wi->tcg_features;
+}
+
+static void x86_cpu_get_supported_cpuid(uint32_t func, uint32_t index,
+ uint32_t *eax, uint32_t *ebx,
+ uint32_t *ecx, uint32_t *edx)
+{
+ *eax = 0;
+ *ebx = 0;
+ *ecx = 0;
+ *edx = 0;
+}
+
+static void x86_cpu_get_cache_cpuid(uint32_t func, uint32_t index,
+ uint32_t *eax, uint32_t *ebx,
+ uint32_t *ecx, uint32_t *edx)
+{
+ *eax = 0;
+ *ebx = 0;
+ *ecx = 0;
+ *edx = 0;
+}
+
+#endif /* !CONFIG_USER_ONLY */
+
/*
* Only for builtin_x86_defs models initialized with x86_register_cpudef_types.
*/
@@ -6163,6 +6195,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
}
*edx = env->features[FEAT_7_0_EDX]; /* Feature flags */
+#ifndef CONFIG_USER_ONLY
/*
* SGX cannot be emulated in software. If hardware does not
* support enabling SGX and/or SGX flexible launch control,
@@ -6181,6 +6214,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
CPUID_7_0_ECX_SGX_LC))) {
*ecx &= ~CPUID_7_0_ECX_SGX_LC;
}
+#endif
} else if (count == 1) {
*eax = env->features[FEAT_7_1_EAX];
*edx = env->features[FEAT_7_1_EDX];
@@ -6876,6 +6910,8 @@ static void mce_init(X86CPU *cpu)
}
}
+#ifndef CONFIG_USER_ONLY
+
static void x86_cpu_adjust_level(X86CPU *cpu, uint32_t *min, uint32_t value)
{
if (*min < value) {
@@ -6948,6 +6984,8 @@ static void x86_cpu_enable_xsave_components(X86CPU *cpu)
env->features[FEAT_XSAVE_XSS_HI] = mask >> 32;
}
+#endif /* !CONFIG_USER_ONLY */
+
/***** Steps involved on loading and filtering CPUID data
*
* When initializing and realizing a CPU object, the steps
@@ -7040,6 +7078,7 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
}
}
+#ifndef CONFIG_USER_ONLY
if (!kvm_enabled() || !cpu->expose_kvm) {
env->features[FEAT_KVM] = 0;
}
@@ -7111,6 +7150,8 @@ void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
return;
}
+#endif /* !CONFIG_USER_ONLY */
+
/* Set cpuid_*level* based on cpuid_min_*level, if not explicitly set */
if (env->cpuid_level_func7 == UINT32_MAX) {
env->cpuid_level_func7 = env->cpuid_min_level_func7;
@@ -7152,6 +7193,7 @@ static void x86_cpu_filter_features(X86CPU *cpu, bool verbose)
mark_unavailable_features(cpu, w, unavailable_features, prefix);
}
+#ifndef CONFIG_USER_ONLY
if ((env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_INTEL_PT) &&
kvm_enabled()) {
KVMState *s = CPU(cpu)->kvm_state;
@@ -7179,6 +7221,7 @@ static void x86_cpu_filter_features(X86CPU *cpu, bool verbose)
mark_unavailable_features(cpu, FEAT_7_0_EBX, CPUID_7_0_EBX_INTEL_PT, prefix);
}
}
+#endif
}
static void x86_cpu_hyperv_realize(X86CPU *cpu)
--
2.41.0
