From: Matthew Whitehead <tedheadster@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org,
luto@amacapital.net, bp@alien8.de, hpa@zytor.com,
Matthew Whitehead <tedheadster@gmail.com>
Subject: [PATCH v2 2/2] x86/cpu: Change query logic so cpuid is enabled before testing
Date: Fri, 21 Sep 2018 17:20:41 -0400 [thread overview]
Message-ID: <20180921212041.13096-3-tedheadster@gmail.com> (raw)
In-Reply-To: <20180921212041.13096-1-tedheadster@gmail.com>
Presently we check for cpuid to be enabled first. If it is not already
enabled, then we next call identify_cpu_without_cpuid() and clear
X86_FEATURE_CPUID.
Unfortunately, identify_cpu_without_cpuid() is the function where cpuid
becomes _enabled_ on Cyrix 6x86/6x86L cpus. So we must reverse the
calling sequence so that cpuid is first enabled, and then check a second
time to see if the feature has now been activated.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Matthew Whitehead <tedheadster@gmail.com>
---
arch/x86/kernel/cpu/common.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index eb4cb3efd20e..60c7c5ce7e55 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1040,6 +1040,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
memset(&c->x86_capability, 0, sizeof c->x86_capability);
c->extended_cpuid_level = 0;
+ if (!have_cpuid_p())
+ identify_cpu_without_cpuid(c);
+
/* cyrix could have cpuid enabled via c_identify()*/
if (have_cpuid_p()) {
cpu_detect(c);
@@ -1057,7 +1060,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
if (this_cpu->c_bsp_init)
this_cpu->c_bsp_init(c);
} else {
- identify_cpu_without_cpuid(c);
setup_clear_cpu_cap(X86_FEATURE_CPUID);
}
--
2.16.4
next prev parent reply other threads:[~2018-09-21 21:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 21:20 [PATCH v2 0/2] x86/cpu: Enable cpuid on Cyrix 6x86/6x86L processors Matthew Whitehead
2018-09-21 21:20 ` [PATCH v2 1/2] x86/cpu: Use correct macros for Cyrix calls Matthew Whitehead
2018-09-22 9:57 ` [tip:x86/cpu] x86/CPU: " tip-bot for Matthew Whitehead
2018-09-21 21:20 ` Matthew Whitehead [this message]
2018-09-21 21:54 ` [PATCH v2 2/2] x86/cpu: Change query logic so cpuid is enabled before testing Andy Lutomirski
2018-09-22 9:58 ` [tip:x86/cpu] x86/CPU: Change query logic so CPUID " tip-bot for Matthew Whitehead
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