2018-03-28 03:24:21

by Eric Dumazet

[permalink] [raw]
Subject: [PATCH] x86, msr: fix rdmsrl_safe_on_cpu()

When changing rdmsr_safe_on_cpu() to schedule, I missed that
__rdmsr_safe_on_cpu() was also used by rdmsrl_safe_on_cpu()

Lets make rdmsrl_safe_on_cpu() a wrapper instead of copy/pasting
the code I added for the completion handling.

Fixes: 07cde313b2d2 ("x86/msr: Allow rdmsr_safe_on_cpu() to schedule")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: kbuild test robot <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
---
arch/x86/lib/msr-smp.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c
index 761ba062afdaf7f7d0603ed94ed6cc3e46b37f76..fee8b9c0520c9954e3cf9093332e1a9b53009b8b 100644
--- a/arch/x86/lib/msr-smp.c
+++ b/arch/x86/lib/msr-smp.c
@@ -225,16 +225,13 @@ EXPORT_SYMBOL(wrmsrl_safe_on_cpu);

int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
{
+ u32 low, high;
int err;
- struct msr_info rv;

- memset(&rv, 0, sizeof(rv));
+ err = rdmsr_safe_on_cpu(cpu, msr_no, &low, &high);
+ *q = (u64)high << 32 | low;

- rv.msr_no = msr_no;
- err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);
- *q = rv.reg.q;
-
- return err ? err : rv.err;
+ return err;
}
EXPORT_SYMBOL(rdmsrl_safe_on_cpu);

--
2.17.0.rc1.321.gba9d0f2565-goog



Subject: [tip:x86/cleanups] x86/msr: Make rdmsrl_safe_on_cpu() scheduling safe as well

Commit-ID: 9b9a51354cae933f5640b5bb73bbcd32f989122f
Gitweb: https://git.kernel.org/tip/9b9a51354cae933f5640b5bb73bbcd32f989122f
Author: Eric Dumazet <[email protected]>
AuthorDate: Tue, 27 Mar 2018 20:22:33 -0700
Committer: Thomas Gleixner <[email protected]>
CommitDate: Wed, 28 Mar 2018 10:34:13 +0200

x86/msr: Make rdmsrl_safe_on_cpu() scheduling safe as well

When changing rdmsr_safe_on_cpu() to schedule, it was missed that
__rdmsr_safe_on_cpu() was also used by rdmsrl_safe_on_cpu()

Make rdmsrl_safe_on_cpu() a wrapper instead of copy/pasting the code which
was added for the completion handling.

Fixes: 07cde313b2d2 ("x86/msr: Allow rdmsr_safe_on_cpu() to schedule")
Reported-by: kbuild test robot <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

---
arch/x86/lib/msr-smp.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c
index 761ba062afda..fee8b9c0520c 100644
--- a/arch/x86/lib/msr-smp.c
+++ b/arch/x86/lib/msr-smp.c
@@ -225,16 +225,13 @@ EXPORT_SYMBOL(wrmsrl_safe_on_cpu);

int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
{
+ u32 low, high;
int err;
- struct msr_info rv;

- memset(&rv, 0, sizeof(rv));
+ err = rdmsr_safe_on_cpu(cpu, msr_no, &low, &high);
+ *q = (u64)high << 32 | low;

- rv.msr_no = msr_no;
- err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);
- *q = rv.reg.q;
-
- return err ? err : rv.err;
+ return err;
}
EXPORT_SYMBOL(rdmsrl_safe_on_cpu);


2018-03-28 10:10:42

by Borislav Petkov

[permalink] [raw]
Subject: Re: [PATCH] x86, msr: fix rdmsrl_safe_on_cpu()

On Tue, Mar 27, 2018 at 08:22:33PM -0700, Eric Dumazet wrote:
> When changing rdmsr_safe_on_cpu() to schedule, I missed that
> __rdmsr_safe_on_cpu() was also used by rdmsrl_safe_on_cpu()
>
> Lets make rdmsrl_safe_on_cpu() a wrapper instead of copy/pasting
> the code I added for the completion handling.
>
> Fixes: 07cde313b2d2 ("x86/msr: Allow rdmsr_safe_on_cpu() to schedule")
> Signed-off-by: Eric Dumazet <[email protected]>
> Reported-by: kbuild test robot <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> ---
> arch/x86/lib/msr-smp.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c
> index 761ba062afdaf7f7d0603ed94ed6cc3e46b37f76..fee8b9c0520c9954e3cf9093332e1a9b53009b8b 100644
> --- a/arch/x86/lib/msr-smp.c
> +++ b/arch/x86/lib/msr-smp.c
> @@ -225,16 +225,13 @@ EXPORT_SYMBOL(wrmsrl_safe_on_cpu);
>
> int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
> {
> + u32 low, high;
> int err;
> - struct msr_info rv;
>
> - memset(&rv, 0, sizeof(rv));
> + err = rdmsr_safe_on_cpu(cpu, msr_no, &low, &high);
> + *q = (u64)high << 32 | low;
>
> - rv.msr_no = msr_no;
> - err = smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 1);
> - *q = rv.reg.q;
> -
> - return err ? err : rv.err;
> + return err;
> }
> EXPORT_SYMBOL(rdmsrl_safe_on_cpu);
>
> --

I guess now that the rdmsr* side does this, you probably should convert
the wrmsr* side as well.

Thx.

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

2018-03-28 16:34:43

by Eric Dumazet

[permalink] [raw]
Subject: Re: [PATCH] x86, msr: fix rdmsrl_safe_on_cpu()



On 03/28/2018 03:08 AM, Borislav Petkov wrote:

> I guess now that the rdmsr* side does this, you probably should convert
> the wrmsr* side as well.

Yes indeed, thanks for the reminder.