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UPSTREAM: x86/smp: Dont access non-existing CPUID leaf

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commit 9b040453d4440659f33dc6f0aa26af418ebfe70b upstream.

stop_this_cpu() tests CPUID leaf 0x8000001f::EAX unconditionally. Intel
CPUs return the content of the highest supported leaf when a non-existing
leaf is read, while AMD CPUs return all zeros for unsupported leafs.

So the result of the test on Intel CPUs is lottery.

While harmless it's incorrect and causes the conditional wbinvd() to be
issued where not required.

Check whether the leaf is supported before reading it.

[ tglx: Adjusted changelog ]

Fixes: 08f253ec37 ("x86/cpu: Clear SME feature flag when not in use")
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/3817d810-e0f1-8ef8-0bbd-663b919ca49b@cybernetics.com
Link: https://lore.kernel.org/r/20230615193330.322186388@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: Idc8aa8137c9044642f02ec157d18d035359f88ea
(cherry-picked from commit e47037d28b)
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Tony Battersby 2023-06-15 22:33:52 +02:00 committed by Treehugger Robot
parent ba2ccba863
commit 6744547e95
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kernel/process.c
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@ -748,6 +748,7 @@ struct cpumask cpus_stop_mask;
void __noreturn stop_this_cpu(void *dummy)
{
struct cpuinfo_x86 *c = this_cpu_ptr(&cpu_info);
unsigned int cpu = smp_processor_id();
local_irq_disable();
@ -762,7 +763,7 @@ void __noreturn stop_this_cpu(void *dummy)
*/
set_cpu_online(cpu, false);
disable_local_APIC();
mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
mcheck_cpu_clear(c);
/*
* Use wbinvd on processors that support SME. This provides support
@ -776,7 +777,7 @@ void __noreturn stop_this_cpu(void *dummy)
* Test the CPUID bit directly because the machine might've cleared
* X86_FEATURE_SME due to cmdline options.
*/
if (cpuid_eax(0x8000001f) & BIT(0))
if (c->extended_cpuid_level >= 0x8000001f && (cpuid_eax(0x8000001f) & BIT(0)))
native_wbinvd();
/*