[coreboot-gerrit] Change in coreboot[master]: cpu/x86/mpinit: Serialize microcode updates for HT threads

[Paul Menzel (Code Review)]

Paul Menzel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/44904 )

Change subject: cpu/x86/mpinit: Serialize microcode updates for HT threads
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Patch Set 5:

Trying to test, if QEMU x86 still works (though it doesn’t use microcode updates, right), it fails to build.

```
    CC         ramstage/arch/x86/cpu.o
In file included from src/arch/x86/cpu.c:15:
src/include/smp/spinlock.h:8: error: "DECLARE_SPIN_LOCK" redefined [-Werror]
 #define DECLARE_SPIN_LOCK(x)

In file included from src/include/cpu/x86/mp.h:6,
                 from src/arch/x86/cpu.c:9:
src/arch/x86/include/arch/smp/spinlock.h:20: note: this is the location of the previous definition
 #define DECLARE_SPIN_LOCK(x) \

In file included from src/arch/x86/cpu.c:15:
src/include/smp/spinlock.h:9: error: "spin_is_locked" redefined [-Werror]
 #define spin_is_locked(lock) 0

In file included from src/include/cpu/x86/mp.h:6,
                 from src/arch/x86/cpu.c:9:
src/arch/x86/include/arch/smp/spinlock.h:30: note: this is the location of the previous definition
 #define spin_is_locked(x) (*(volatile char *)(&(x)->lock) <= 0)

In file included from src/arch/x86/cpu.c:15:
src/include/smp/spinlock.h:10: error: "spin_unlock_wait" redefined [-Werror]
 #define spin_unlock_wait(lock) do {} while (0)

In file included from src/include/cpu/x86/mp.h:6,
                 from src/arch/x86/cpu.c:9:
src/arch/x86/include/arch/smp/spinlock.h:31: note: this is the location of the previous definition
 #define spin_unlock_wait(x) do { barrier(); } while (spin_is_locked(x))
```