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target/i386: Call accel-agnostic x86_cpu_get_supported_cpuid()
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x86_cpu_get_supported_cpuid() is generic and handles the different
accelerators. Use it instead of kvm_arch_get_supported_cpuid().

That fixes a link failure introduced by commit 3adce82
("target/i386: Remove unused KVM stubs") when QEMU is configured
as:

  $ ./configure --cc=clang \
    --target-list=x86_64-linux-user,x86_64-softmmu \
    --enable-debug

We were getting:

  [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.

For the record, this is because '--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 (see commit 2140cfa "i386: Fix build by
providing stub kvm_arch_get_supported_cpuid()").

Cc: qemu-stable@nongnu.org
Fixes: 3adce82 ("target/i386: Remove unused KVM stubs")
Reported-by: Kevin Wolf <kwolf@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230913093009.83520-4-philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@philmd @bonzini
philmd authored and bonzini committed Sep 13, 2023
1 parent da472f9 commit d047402
Showing 1 changed file with 16 additions and 16 deletions.
32 changes: 16 additions & 16 deletions target/i386/cpu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6154,6 +6154,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
case 7:
/* Structured Extended Feature Flags Enumeration Leaf */
if (count == 0) {
uint32_t eax_0_unused, ebx_0, ecx_0, edx_0_unused;

/* Maximum ECX value for sub-leaves */
*eax = env->cpuid_level_func7;
*ebx = env->features[FEAT_7_0_EBX]; /* Feature flags */
Expand All @@ -6168,17 +6170,15 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
* support enabling SGX and/or SGX flexible launch control,
* then we need to update the VM's CPUID values accordingly.
*/
if ((*ebx & CPUID_7_0_EBX_SGX) &&
(!kvm_enabled() ||
!(kvm_arch_get_supported_cpuid(cs->kvm_state, 0x7, 0, R_EBX) &
CPUID_7_0_EBX_SGX))) {
x86_cpu_get_supported_cpuid(0x7, 0,
&eax_0_unused, &ebx_0,
&ecx_0, &edx_0_unused);
if ((*ebx & CPUID_7_0_EBX_SGX) && !(ebx_0 & CPUID_7_0_EBX_SGX)) {
*ebx &= ~CPUID_7_0_EBX_SGX;
}

if ((*ecx & CPUID_7_0_ECX_SGX_LC) &&
(!(*ebx & CPUID_7_0_EBX_SGX) || !kvm_enabled() ||
!(kvm_arch_get_supported_cpuid(cs->kvm_state, 0x7, 0, R_ECX) &
CPUID_7_0_ECX_SGX_LC))) {
if ((*ecx & CPUID_7_0_ECX_SGX_LC)
&& (!(*ebx & CPUID_7_0_EBX_SGX) || !(ecx_0 & CPUID_7_0_ECX_SGX_LC))) {
*ecx &= ~CPUID_7_0_ECX_SGX_LC;
}
} else if (count == 1) {
Expand Down Expand Up @@ -7150,14 +7150,14 @@ static void x86_cpu_filter_features(X86CPU *cpu, bool verbose)
mark_unavailable_features(cpu, w, unavailable_features, prefix);
}

if ((env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_INTEL_PT) &&
kvm_enabled()) {
KVMState *s = CPU(cpu)->kvm_state;
uint32_t eax_0 = kvm_arch_get_supported_cpuid(s, 0x14, 0, R_EAX);
uint32_t ebx_0 = kvm_arch_get_supported_cpuid(s, 0x14, 0, R_EBX);
uint32_t ecx_0 = kvm_arch_get_supported_cpuid(s, 0x14, 0, R_ECX);
uint32_t eax_1 = kvm_arch_get_supported_cpuid(s, 0x14, 1, R_EAX);
uint32_t ebx_1 = kvm_arch_get_supported_cpuid(s, 0x14, 1, R_EBX);
if (env->features[FEAT_7_0_EBX] & CPUID_7_0_EBX_INTEL_PT) {
uint32_t eax_0, ebx_0, ecx_0, edx_0_unused;
uint32_t eax_1, ebx_1, ecx_1_unused, edx_1_unused;

x86_cpu_get_supported_cpuid(0x14, 0,
&eax_0, &ebx_0, &ecx_0, &edx_0_unused);
x86_cpu_get_supported_cpuid(0x14, 1,
&eax_1, &ebx_1, &ecx_1_unused, &edx_1_unused);

if (!eax_0 ||
((ebx_0 & INTEL_PT_MINIMAL_EBX) != INTEL_PT_MINIMAL_EBX) ||
Expand Down

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