| Message ID | 20230911211317.28773-3-philmd@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | target/i386: Restrict system-specific features from user emulation | expand |
On 9/11/23 23:13, Philippe Mathieu-Daudé wrote: > /* > * 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 This can use a variant of x86_cpu_get_supported_cpuid that returns a single register; or it can be rewritten to use x86_cpu_get_supported_cpuid. In general, a lot of checks for accel_uses_host_cpuid() are unnecessary, and the code can be modified to not depend on either KVM or HVF. > } 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 */ These functions should all be used in user-mode emulation as well. > /***** 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; > } This is "!kvm_enabled()" so it should be kept for user-mode emulation. > @@ -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 This need not be limited to KVM, it can likewise use x86_cpu_get_supported_cpuid. Paolo > } > > static void x86_cpu_hyperv_realize(X86CPU *cpu)
On 12/9/23 16:05, Paolo Bonzini wrote: > On 9/11/23 23:13, Philippe Mathieu-Daudé wrote: >> /* >> * 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 > > This can use a variant of x86_cpu_get_supported_cpuid that returns a > single register; or it can be rewritten to use x86_cpu_get_supported_cpuid. Great suggestion, thanks! > In general, a lot of checks for accel_uses_host_cpuid() are unnecessary, > and the code can be modified to not depend on either KVM or HVF. OK.
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)
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@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> --- 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(-)