[PATCH] KVM: fix kvm_mmu_memory_cache allocation warning

[PATCH] KVM: fix kvm_mmu_memory_cache allocation warning

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

gcc-14 notices that the arguments to kvmalloc_array() are mixed up:

arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_mmu_topup_memory_cache':
arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: error: 'kvmalloc_array' sizes specified with 'sizeof' in the earlier argument and not in the later argument [-Werror=calloc-transposed-args]
  424 |                 mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
      |                                                     ^~~~
arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: note: earlier argument should specify number of elements, later size of each element

The code still works correctly, but the incorrect order prevents the compiler
from properly tracking the object sizes.

Fixes: 837f66c71207 ("KVM: Allow for different capacities in kvm_mmu_memory_cache structs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8f03b56dafbd..4c48f61cae35 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -421,7 +421,7 @@ int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity,
 		if (WARN_ON_ONCE(!capacity))
 			return -EIO;
 
-		mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
+		mc->objects = kvmalloc_array(capacity, sizeof(void *), gfp);
 		if (!mc->objects)
 			return -ENOMEM;
 
-- 
2.39.2

Re: [PATCH] KVM: fix kvm_mmu_memory_cache allocation warning

[Marc Zyngier]

On Mon, 12 Feb 2024 11:24:10 +0000,
Arnd Bergmann <arnd@kernel.org> wrote:
> 
> From: Arnd Bergmann <arnd@arndb.de>
> 
> gcc-14 notices that the arguments to kvmalloc_array() are mixed up:
> 
> arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_mmu_topup_memory_cache':
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: error: 'kvmalloc_array' sizes specified with 'sizeof' in the earlier argument and not in the later argument [-Werror=calloc-transposed-args]
>   424 |                 mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
>       |                                                     ^~~~
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: note: earlier argument should specify number of elements, later size of each element
> 
> The code still works correctly, but the incorrect order prevents the compiler
> from properly tracking the object sizes.
> 
> Fixes: 837f66c71207 ("KVM: Allow for different capacities in kvm_mmu_memory_cache structs")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  virt/kvm/kvm_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 8f03b56dafbd..4c48f61cae35 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -421,7 +421,7 @@ int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity,
>  		if (WARN_ON_ONCE(!capacity))
>  			return -EIO;
>  
> -		mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
> +		mc->objects = kvmalloc_array(capacity, sizeof(void *), gfp);
>  		if (!mc->objects)
>  			return -ENOMEM;
>  

Huh, well spotted GCC. And thanks Arnd for the fix.

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH] KVM: fix kvm_mmu_memory_cache allocation warning

[Sean Christopherson]

On Mon, 12 Feb 2024 12:24:10 +0100, Arnd Bergmann wrote:
> gcc-14 notices that the arguments to kvmalloc_array() are mixed up:
> 
> arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function '__kvm_mmu_topup_memory_cache':
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: error: 'kvmalloc_array' sizes specified with 'sizeof' in the earlier argument and not in the later argument [-Werror=calloc-transposed-args]
>   424 |                 mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
>       |                                                     ^~~~
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:424:53: note: earlier argument should specify number of elements, later size of each element
> 
> [...]

Applied to kvm-x86 generic, so that this doesn't languish with everyone looking
at each other.

[1/1] KVM: fix kvm_mmu_memory_cache allocation warning
      https://github.com/kvm-x86/linux/commit/ea3689d9df50

--
https://github.com/kvm-x86/linux/tree/next