lkml.org 
[lkml]   [2018]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 6/8] x86/microcode: Recheck IBRS features on microcode reload
On Fri, Jan 05, 2018 at 06:12:21PM -0800, Tim Chen wrote:
> On new microcode write, check whether IBRS
> is present by rescanning IBRS feature.
>
> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
> ---
> arch/x86/include/asm/spec_ctrl.h | 1 +
> arch/x86/kernel/cpu/microcode/core.c | 4 ++++
> arch/x86/kernel/cpu/spec_ctrl.c | 18 ++++++++++--------
> 3 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/spec_ctrl.h b/arch/x86/include/asm/spec_ctrl.h
> index 62c5dc8..be08ae7 100644
> --- a/arch/x86/include/asm/spec_ctrl.h
> +++ b/arch/x86/include/asm/spec_ctrl.h
> @@ -8,6 +8,7 @@
> #include <asm/microcode.h>
>
> void scan_spec_ctrl_feature(struct cpuinfo_x86 *c);
> +void rescan_spec_ctrl_feature(struct cpuinfo_x86 *c);
> bool ibrs_inuse(void);
>
> extern unsigned int dynamic_ibrs;
> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
> index c4fa4a8..848c3e9 100644
> --- a/arch/x86/kernel/cpu/microcode/core.c
> +++ b/arch/x86/kernel/cpu/microcode/core.c
> @@ -40,6 +40,7 @@
> #include <asm/processor.h>
> #include <asm/cmdline.h>
> #include <asm/setup.h>
> +#include <asm/spec_ctrl.h>
>
> #define DRIVER_VERSION "2.2"
>
> @@ -444,6 +445,9 @@ static ssize_t microcode_write(struct file *file, const char __user *buf,
> if (ret > 0)
> perf_check_microcode();
>
> + /* check spec_ctrl capabilities */
> + rescan_spec_ctrl_feature(&boot_cpu_data);

Needs to be under the if like perf_check_microcode().

> +
> mutex_unlock(&microcode_mutex);
> put_online_cpus();
>
> diff --git a/arch/x86/kernel/cpu/spec_ctrl.c b/arch/x86/kernel/cpu/spec_ctrl.c
> index 1641bec..28107a2 100644
> --- a/arch/x86/kernel/cpu/spec_ctrl.c
> +++ b/arch/x86/kernel/cpu/spec_ctrl.c
> @@ -24,13 +24,18 @@ static bool ibrs_admin_disabled;
> /* mutex to serialize IBRS control changes */
> DEFINE_MUTEX(spec_ctrl_mutex);
>
> +static inline void set_ibrs_feature(void)
> +{
> + if (!ibrs_admin_disabled) {
> + dynamic_ibrs = 1;
> + ibrs_enabled = IBRS_ENABLED;
> + }
> +}
> +
> void scan_spec_ctrl_feature(struct cpuinfo_x86 *c)
> {
> if ((!c->cpu_index) && (boot_cpu_has(X86_FEATURE_SPEC_CTRL))) {
> - if (!ibrs_admin_disabled) {
> - dynamic_ibrs = 1;
> - ibrs_enabled = IBRS_ENABLED;
> - }
> + set_ibrs_feature();
> }
> }
> EXPORT_SYMBOL_GPL(scan_spec_ctrl_feature);
> @@ -43,10 +48,7 @@ void rescan_spec_ctrl_feature(struct cpuinfo_x86 *c)
> {
> mutex_lock(&spec_ctrl_mutex);
> if (boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
> - if (!ibrs_admin_disabled) {
> - dynamic_ibrs = 1;
> - ibrs_enabled = IBRS_ENABLED;
> - }
> + set_ibrs_feature();

As already stated, this does not work. You want to check the CPUID leaf
after the microcode reload and then set X86_FEATURE_SPEC_CTRL on each
CPU.

--
Regards/Gruss,
Boris.

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

\
 
 \ /
  Last update: 2018-01-14 23:18    [W:0.507 / U:2.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site