None of these barriers serve any purpose, as they are not synchronising with
any anything on remote CPUs.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Stefano Stabellini <sstabell...@kernel.org>
CC: Julien Grall <julien.gr...@arm.com>
Restricting to just the $ARCH maintainers, as this is a project-wide sweep.
Julien/Stefano: I think the ARM smpboot inhereted the erronious barrier usage
from x86, but I don't know whether further development has gained a dependence
on them.
---
xen/arch/x86/acpi/cpu_idle.c | 2 --
xen/arch/x86/cpu/mcheck/mce.c | 1 -
xen/arch/x86/crash.c | 3 ---
xen/arch/x86/smpboot.c | 2 --
4 files changed, 8 deletions(-)
diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index f36b184..09c8848 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -1331,8 +1331,6 @@ void cpuidle_disable_deep_cstate(void)
max_cstate = 1;
}
- mb();
-
hpet_disable_legacy_broadcast();
}
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 2695b0c..460e336 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -86,7 +86,6 @@ static x86_mce_vector_t _machine_check_vector =
unexpected_machine_check;
void x86_mce_vector_register(x86_mce_vector_t hdlr)
{
_machine_check_vector = hdlr;
- wmb();
}
/* Call the installed machine check handler for this CPU setup. */
diff --git a/xen/arch/x86/crash.c b/xen/arch/x86/crash.c
index f28f527..4cadb5e 100644
--- a/xen/arch/x86/crash.c
+++ b/xen/arch/x86/crash.c
@@ -146,9 +146,6 @@ static void nmi_shootdown_cpus(void)
write_atomic((unsigned long *)__va(__pa(&exception_table[TRAP_nmi])),
(unsigned long)&do_nmi_crash);
- /* Ensure the new callback function is set before sending out the NMI. */
- wmb();
-
smp_send_nmi_allbutself();
msecs = 1000; /* Wait at most a second for the other cpus to stop */
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 3a9dd3e..0aa377a 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -346,7 +346,6 @@ void start_secondary(void *unused)
spin_debug_enable();
set_cpu_sibling_map(cpu);
notify_cpu_starting(cpu);
- wmb();
/*
* We need to hold vector_lock so there the set of online cpus
@@ -364,7 +363,6 @@ void start_secondary(void *unused)
microcode_resume_cpu(cpu);
- wmb();
startup_cpu_idle_loop();
}
--
2.1.4
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