2018-09-21 21:21:41

by tedheadster

Subject: [PATCH v2 0/2] x86/cpu: Enable cpuid on Cyrix 6x86/6x86L processors

On power up, the cpuid instruction is disabled on Cyrix 6x86 and 6x86L
processors and needs to be enabled. This patchset enables it.

Matthew Whitehead (2):
x86/cpu: Use correct macros for Cyrix calls
x86/cpu: Change query logic so cpuid is enabled before testing

arch/x86/kernel/cpu/common.c | 4 +++-
arch/x86/kernel/cpu/cyrix.c | 2 +-
2 files changed, 4 insertions(+), 2 deletions(-)

--
2.16.4

2018-09-21 21:21:41

by tedheadster

Subject: [PATCH v2 2/2] x86/cpu: Change query logic so cpuid is enabled before testing

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 <[email protected]>
Signed-off-by: Matthew Whitehead <[email protected]>
---
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

2018-09-21 21:23:08

by tedheadster

Subject: [PATCH v2 1/2] x86/cpu: Use correct macros for Cyrix calls

There are comments in processor-cyrix.h advising you to _not_ make calls
using the deprecated macros in this style:

setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);

This is because it expands the macro into a non-functioning calling
sequence. The calling order must be:

outb(CX86_CCR2, 0x22);
inb(0x23);

From the comments:

* When using the old macros a line like
* setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
* gets expanded to:
* do {
* outb((CX86_CCR2), 0x22);
* outb((({
* outb((CX86_CCR2), 0x22);
* inb(0x23);
* }) | 0x88), 0x23);
* } while (0);

The new macros fix this problem, so we use them instead.

Reviewed-by: Andy Lutomirski <[email protected]>
Signed-off-by: Matthew Whitehead <[email protected]>
---
arch/x86/kernel/cpu/cyrix.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index 8949b7ae6d92..d12226f60168 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -437,7 +437,7 @@ static void cyrix_identify(struct cpuinfo_x86 *c)
/* enable MAPEN */
setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
/* enable cpuid */
- setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);
+ setCx86(CX86_CCR4, getCx86(CX86_CCR4) | 0x80);
/* disable MAPEN */
setCx86(CX86_CCR3, ccr3);
local_irq_restore(flags);
--
2.16.4

2018-09-21 21:55:30

by Andy Lutomirski

Subject: Re: [PATCH v2 2/2] x86/cpu: Change query logic so cpuid is enabled before testing

On Fri, Sep 21, 2018 at 2:21 PM Matthew Whitehead <[email protected]> wrote:
>
> 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 <[email protected]>

How about Suggested-and-reviewed-by: Andy Lutomirski <[email protected]> instead?

(No need to resubmit for just that. Ingo or Thomas, if you like
these, can you just make that substitution?)

> Signed-off-by: Matthew Whitehead <[email protected]>
> ---
> 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
>


--
Andy Lutomirski
AMA Capital Management, LLC

2018-09-22 09:59:41

by tip-bot for Vasyl Gomonovych

Subject: [tip:x86/cpu] x86/CPU: Change query logic so CPUID is enabled before testing

Commit-ID: 2893cc8ff892fa74972d8dc0e1d0dc65116daaa3
Gitweb: https://git.kernel.org/tip/2893cc8ff892fa74972d8dc0e1d0dc65116daaa3
Author: Matthew Whitehead <[email protected]>
AuthorDate: Fri, 21 Sep 2018 17:20:41 -0400
Committer: Borislav Petkov <[email protected]>
CommitDate: Sat, 22 Sep 2018 11:47:39 +0200

x86/CPU: Change query logic so CPUID is enabled before testing

Presently we check first if CPUID is enabled. 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.

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.

[ bp: Massage commit message and remove trailing whitespace. ]

Suggested-by: Andy Lutomirski <[email protected]>
Signed-off-by: Matthew Whitehead <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Andy Lutomirski <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
---
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 44c4ef3d989b..658c85d16a9b 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1076,6 +1076,9 @@ 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);
@@ -1093,7 +1096,6 @@ 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);
}

2018-09-22 10:00:20

by tip-bot for Vasyl Gomonovych

Subject: [tip:x86/cpu] x86/CPU: Use correct macros for Cyrix calls

Commit-ID: 03b099bdcdf7125d4a63dc9ddeefdd454e05123d
Gitweb: https://git.kernel.org/tip/03b099bdcdf7125d4a63dc9ddeefdd454e05123d
Author: Matthew Whitehead <[email protected]>
AuthorDate: Fri, 21 Sep 2018 17:20:40 -0400
Committer: Borislav Petkov <[email protected]>
CommitDate: Sat, 22 Sep 2018 11:46:56 +0200

x86/CPU: Use correct macros for Cyrix calls

There are comments in processor-cyrix.h advising you to _not_ make calls
using the deprecated macros in this style:

setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);

This is because it expands the macro into a non-functioning calling
sequence. The calling order must be:

outb(CX86_CCR2, 0x22);
inb(0x23);

From the comments:

* When using the old macros a line like
* setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
* gets expanded to:
* do {
* outb((CX86_CCR2), 0x22);
* outb((({
* outb((CX86_CCR2), 0x22);
* inb(0x23);
* }) | 0x88), 0x23);
* } while (0);

The new macros fix this problem, so use them instead.

Signed-off-by: Matthew Whitehead <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Andy Lutomirski <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jia Zhang <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
---
arch/x86/kernel/cpu/cyrix.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index 8949b7ae6d92..d12226f60168 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -437,7 +437,7 @@ static void cyrix_identify(struct cpuinfo_x86 *c)
/* enable MAPEN */
setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
/* enable cpuid */
- setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);
+ setCx86(CX86_CCR4, getCx86(CX86_CCR4) | 0x80);
/* disable MAPEN */
setCx86(CX86_CCR3, ccr3);
local_irq_restore(flags);