[PATCH] KVM: arm64: Mark set_sysreg_masks() as inline to avoid build failure

[PATCH] KVM: arm64: Mark set_sysreg_masks() as inline to avoid build failure

[Marc Zyngier]

When compiling with CONFIG_CC_OPTIMIZE_FOR_SIZE=y, set_sysreg_masks()
fails to compile thanks to:

	BUILD_BUG_ON(!__builtin_constant_p(sr));

as the compiler doesn't identify sr as a constant, despite all the
callers passing constants.

Fix the issue by always inlining this function, which allows GCC to
do the right thing.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411201857.ZNudtGJl-lkp@intel.com/
Fixes: a0162020095e2 ("KVM: arm64: Extend masking facility to arbitrary registers")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/nested.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index aeaa6017ffd89..9b36218b48def 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -951,7 +951,7 @@ u64 kvm_vcpu_apply_reg_masks(const struct kvm_vcpu *vcpu,
 	return v;
 }
 
-static void set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1)
+static __always_inline void set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1)
 {
 	int i = sr - __SANITISED_REG_START__;
 
-- 
2.39.2

Re: [PATCH] KVM: arm64: Mark set_sysreg_masks() as inline to avoid build failure

[Joey Gouly]

On Wed, Nov 20, 2024 at 11:15:16AM +0000, Marc Zyngier wrote:
> When compiling with CONFIG_CC_OPTIMIZE_FOR_SIZE=y, set_sysreg_masks()
> fails to compile thanks to:
> 
> 	BUILD_BUG_ON(!__builtin_constant_p(sr));
> 
> as the compiler doesn't identify sr as a constant, despite all the
> callers passing constants.
> 
> Fix the issue by always inlining this function, which allows GCC to
> do the right thing.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202411201857.ZNudtGJl-lkp@intel.com/
> Fixes: a0162020095e2 ("KVM: arm64: Extend masking facility to arbitrary registers")
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/arm64/kvm/nested.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
> index aeaa6017ffd89..9b36218b48def 100644
> --- a/arch/arm64/kvm/nested.c
> +++ b/arch/arm64/kvm/nested.c
> @@ -951,7 +951,7 @@ u64 kvm_vcpu_apply_reg_masks(const struct kvm_vcpu *vcpu,
>  	return v;
>  }
>  
> -static void set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1)
> +static __always_inline void set_sysreg_masks(struct kvm *kvm, int sr, u64 res0, u64 res1)
>  {
>  	int i = sr - __SANITISED_REG_START__;
>  


Reviewed-by: Joey Gouly <joey.gouly@arm.com>

Re: [PATCH] KVM: arm64: Mark set_sysreg_masks() as inline to avoid build failure

[Oliver Upton]

On Wed, 20 Nov 2024 11:15:16 +0000, Marc Zyngier wrote:
> When compiling with CONFIG_CC_OPTIMIZE_FOR_SIZE=y, set_sysreg_masks()
> fails to compile thanks to:
> 
> 	BUILD_BUG_ON(!__builtin_constant_p(sr));
> 
> as the compiler doesn't identify sr as a constant, despite all the
> callers passing constants.
> 
> [...]

Applied to fixes, thanks!

[1/1] KVM: arm64: Mark set_sysreg_masks() as inline to avoid build failure
      https://git.kernel.org/kvmarm/kvmarm/c/0f3a0f23f562

--
Best,
Oliver