Re: [Devel] [PATCH vz8 v2 2/2] x86: don't enable cpuid faults if /proc/vz/cpuid_override unused

2020-11-03 Thread Kirill Tkhai 
On 02.11.2020 20:13, Andrey Ryabinin wrote:
> We don't need to enable cpuid faults if /proc/vz/cpuid_override
> was never used. If task was attached to ve before a write to
> 'cpuid_override' it will not get cpuid faults now. It shouldn't
> be a problem since the proper use of 'cpuid_override' requires
> stopping all containers.
> 
> https://jira.sw.ru/browse/PSBM-121823
> Signed-off-by: Andrey Ryabinin 

Reviewed-by: Kirill Tkhai 

> ---
> 
> Changes since v1:
>  - git add include/linux/cpuid_override.h 
>  
>  arch/x86/kernel/cpuid_fault.c  | 21 ++---
>  include/linux/cpuid_override.h | 30 ++
>  kernel/ve/ve.c |  5 -
>  3 files changed, 36 insertions(+), 20 deletions(-)
>  create mode 100644 include/linux/cpuid_override.h
> 
> diff --git a/arch/x86/kernel/cpuid_fault.c b/arch/x86/kernel/cpuid_fault.c
> index 1e8ffacc4412..cb6c2216fa8a 100644
> --- a/arch/x86/kernel/cpuid_fault.c
> +++ b/arch/x86/kernel/cpuid_fault.c
> @@ -1,3 +1,4 @@
> +#include 
>  #include 
>  #include 
>  #include 
> @@ -9,25 +10,7 @@
>  #include 
>  #include 
>  
> -struct cpuid_override_entry {
> - unsigned int op;
> - unsigned int count;
> - bool has_count;
> - unsigned int eax;
> - unsigned int ebx;
> - unsigned int ecx;
> - unsigned int edx;
> -};
> -
> -#define MAX_CPUID_OVERRIDE_ENTRIES   16
> -
> -struct cpuid_override_table {
> - struct rcu_head rcu_head;
> - int size;
> - struct cpuid_override_entry entries[MAX_CPUID_OVERRIDE_ENTRIES];
> -};
> -
> -static struct cpuid_override_table __rcu *cpuid_override __read_mostly;
> +struct cpuid_override_table __rcu *cpuid_override __read_mostly;
>  static DEFINE_SPINLOCK(cpuid_override_lock);
>  
>  static void cpuid_override_update(struct cpuid_override_table *new_table)
> diff --git a/include/linux/cpuid_override.h b/include/linux/cpuid_override.h
> new file mode 100644
> index ..ea0fa7af3d3c
> --- /dev/null
> +++ b/include/linux/cpuid_override.h
> @@ -0,0 +1,30 @@
> +#ifndef __CPUID_OVERRIDE_H
> +#define __CPUID_OVERRIDE_H
> +
> +#include 
> +
> +struct cpuid_override_entry {
> + unsigned int op;
> + unsigned int count;
> + bool has_count;
> + unsigned int eax;
> + unsigned int ebx;
> + unsigned int ecx;
> + unsigned int edx;
> +};
> +
> +#define MAX_CPUID_OVERRIDE_ENTRIES   16
> +
> +struct cpuid_override_table {
> + struct rcu_head rcu_head;
> + int size;
> + struct cpuid_override_entry entries[MAX_CPUID_OVERRIDE_ENTRIES];
> +};
> +
> +extern struct cpuid_override_table __rcu *cpuid_override;
> +
> +static inline bool cpuid_override_on(void)
> +{
> + return rcu_access_pointer(cpuid_override);
> +}
> +#endif
> diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
> index aad8ce69ca1f..0d4d0ab70369 100644
> --- a/kernel/ve/ve.c
> +++ b/kernel/ve/ve.c
> @@ -9,6 +9,7 @@
>   * 've.c' helper file performing VE sub-system initialization
>   */
>  
> +#include 
>  #include 
>  #include 
>  #include 
> @@ -801,6 +802,7 @@ static void ve_attach(struct cgroup_taskset *tset)
>  {
>   struct cgroup_subsys_state *css;
>   struct task_struct *task;
> + extern struct cpuid_override_table __rcu *cpuid_override;
>  
>   cgroup_taskset_for_each(task, css, tset) {
>   struct ve_struct *ve = css_to_ve(css);
> @@ -816,7 +818,8 @@ static void ve_attach(struct cgroup_taskset *tset)
>   /* Leave parent exec domain */
>   task->parent_exec_id--;
>  
> - set_tsk_thread_flag(task, TIF_CPUID_OVERRIDE);
> + if (cpuid_override_on())
> + set_tsk_thread_flag(task, TIF_CPUID_OVERRIDE);
>   task->task_ve = ve;
>   }
>  }
> 

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[Devel] [PATCH vz8 v2 2/2] x86: don't enable cpuid faults if /proc/vz/cpuid_override unused

2020-11-02 Thread Andrey Ryabinin 
We don't need to enable cpuid faults if /proc/vz/cpuid_override
was never used. If task was attached to ve before a write to
'cpuid_override' it will not get cpuid faults now. It shouldn't
be a problem since the proper use of 'cpuid_override' requires
stopping all containers.

https://jira.sw.ru/browse/PSBM-121823
Signed-off-by: Andrey Ryabinin 
---

Changes since v1:
 - git add include/linux/cpuid_override.h 
 
 arch/x86/kernel/cpuid_fault.c  | 21 ++---
 include/linux/cpuid_override.h | 30 ++
 kernel/ve/ve.c |  5 -
 3 files changed, 36 insertions(+), 20 deletions(-)
 create mode 100644 include/linux/cpuid_override.h

diff --git a/arch/x86/kernel/cpuid_fault.c b/arch/x86/kernel/cpuid_fault.c
index 1e8ffacc4412..cb6c2216fa8a 100644
--- a/arch/x86/kernel/cpuid_fault.c
+++ b/arch/x86/kernel/cpuid_fault.c
@@ -1,3 +1,4 @@
+#include 
 #include 
 #include 
 #include 
@@ -9,25 +10,7 @@
 #include 
 #include 
 
-struct cpuid_override_entry {
-   unsigned int op;
-   unsigned int count;
-   bool has_count;
-   unsigned int eax;
-   unsigned int ebx;
-   unsigned int ecx;
-   unsigned int edx;
-};
-
-#define MAX_CPUID_OVERRIDE_ENTRIES 16
-
-struct cpuid_override_table {
-   struct rcu_head rcu_head;
-   int size;
-   struct cpuid_override_entry entries[MAX_CPUID_OVERRIDE_ENTRIES];
-};
-
-static struct cpuid_override_table __rcu *cpuid_override __read_mostly;
+struct cpuid_override_table __rcu *cpuid_override __read_mostly;
 static DEFINE_SPINLOCK(cpuid_override_lock);
 
 static void cpuid_override_update(struct cpuid_override_table *new_table)
diff --git a/include/linux/cpuid_override.h b/include/linux/cpuid_override.h
new file mode 100644
index ..ea0fa7af3d3c
--- /dev/null
+++ b/include/linux/cpuid_override.h
@@ -0,0 +1,30 @@
+#ifndef __CPUID_OVERRIDE_H
+#define __CPUID_OVERRIDE_H
+
+#include 
+
+struct cpuid_override_entry {
+   unsigned int op;
+   unsigned int count;
+   bool has_count;
+   unsigned int eax;
+   unsigned int ebx;
+   unsigned int ecx;
+   unsigned int edx;
+};
+
+#define MAX_CPUID_OVERRIDE_ENTRIES 16
+
+struct cpuid_override_table {
+   struct rcu_head rcu_head;
+   int size;
+   struct cpuid_override_entry entries[MAX_CPUID_OVERRIDE_ENTRIES];
+};
+
+extern struct cpuid_override_table __rcu *cpuid_override;
+
+static inline bool cpuid_override_on(void)
+{
+   return rcu_access_pointer(cpuid_override);
+}
+#endif
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index aad8ce69ca1f..0d4d0ab70369 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -9,6 +9,7 @@
  * 've.c' helper file performing VE sub-system initialization
  */
 
+#include 
 #include 
 #include 
 #include 
@@ -801,6 +802,7 @@ static void ve_attach(struct cgroup_taskset *tset)
 {
struct cgroup_subsys_state *css;
struct task_struct *task;
+   extern struct cpuid_override_table __rcu *cpuid_override;
 
cgroup_taskset_for_each(task, css, tset) {
struct ve_struct *ve = css_to_ve(css);
@@ -816,7 +818,8 @@ static void ve_attach(struct cgroup_taskset *tset)
/* Leave parent exec domain */
task->parent_exec_id--;
 
-   set_tsk_thread_flag(task, TIF_CPUID_OVERRIDE);
+   if (cpuid_override_on())
+   set_tsk_thread_flag(task, TIF_CPUID_OVERRIDE);
task->task_ve = ve;
}
 }
-- 
2.26.2

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