[v2,04/19] powerpc/kvm: Prefer fault_in_pages_readable function

Message ID 20180328195811.27758-1-malat@debian.org
State Accepted
Headers show
Series
  • Untitled series #36371
Related show

Commit Message

Mathieu Malaterre March 28, 2018, 7:58 p.m.
Directly use fault_in_pages_readable instead of manual __get_user code. Fix
warning treated as error with W=1:

  arch/powerpc/kernel/kvm.c:675:6: error: variable ‘tmp’ set but not used [-Werror=unused-but-set-variable]

Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
v2: use fault_in_pages_readable instead
 arch/powerpc/kernel/kvm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Christophe LEROY March 29, 2018, 4:18 p.m. | #1
Mathieu Malaterre <malat@debian.org> a écrit :

> Directly use fault_in_pages_readable instead of manual __get_user code. Fix
> warning treated as error with W=1:
>
>   arch/powerpc/kernel/kvm.c:675:6: error: variable ‘tmp’ set but not  
> used [-Werror=unused-but-set-variable]
>
> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Signed-off-by: Mathieu Malaterre <malat@debian.org>

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

> ---
> v2: use fault_in_pages_readable instead
>  arch/powerpc/kernel/kvm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
> index 9ad37f827a97..124c51030b75 100644
> --- a/arch/powerpc/kernel/kvm.c
> +++ b/arch/powerpc/kernel/kvm.c
> @@ -25,6 +25,7 @@
>  #include <linux/kvm_para.h>
>  #include <linux/slab.h>
>  #include <linux/of.h>
> +#include <linux/pagemap.h>
>
>  #include <asm/reg.h>
>  #include <asm/sections.h>
> @@ -672,14 +673,13 @@ static void kvm_use_magic_page(void)
>  {
>  	u32 *p;
>  	u32 *start, *end;
> -	u32 tmp;
>  	u32 features;
>
>  	/* Tell the host to map the magic page to -4096 on all CPUs */
>  	on_each_cpu(kvm_map_magic_page, &features, 1);
>
>  	/* Quick self-test to see if the mapping works */
> -	if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
> +	if (!fault_in_pages_readable((const char *)KVM_MAGIC_PAGE, sizeof(u32))) {
>  		kvm_patching_worked = false;
>  		return;
>  	}
> --
> 2.11.0


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Michael Ellerman May 25, 2018, 1:59 a.m. | #2
On Wed, 2018-03-28 at 19:58:11 UTC, Mathieu Malaterre wrote:
> Directly use fault_in_pages_readable instead of manual __get_user code. Fix
> warning treated as error with W=1:
> 
>   arch/powerpc/kernel/kvm.c:675:6: error: variable ‘tmp’ set but not used [-Werror=unused-but-set-variable]
> 
> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Signed-off-by: Mathieu Malaterre <malat@debian.org>
> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

Applied to powerpc topic/ppc-kvm, thanks.

https://git.kernel.org/powerpc/c/9f9eae5ce717f497812dfc1bda5219

cheers
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Patch

diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 9ad37f827a97..124c51030b75 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -25,6 +25,7 @@ 
 #include <linux/kvm_para.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/pagemap.h>
 
 #include <asm/reg.h>
 #include <asm/sections.h>
@@ -672,14 +673,13 @@  static void kvm_use_magic_page(void)
 {
 	u32 *p;
 	u32 *start, *end;
-	u32 tmp;
 	u32 features;
 
 	/* Tell the host to map the magic page to -4096 on all CPUs */
 	on_each_cpu(kvm_map_magic_page, &features, 1);
 
 	/* Quick self-test to see if the mapping works */
-	if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
+	if (!fault_in_pages_readable((const char *)KVM_MAGIC_PAGE, sizeof(u32))) {
 		kvm_patching_worked = false;
 		return;
 	}