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[PATCH] KVM: arm64, x86: make kvm_arch_has_irq_bypass() inline

Paolo Bonzini posted 1 patch 7 months, 4 weeks ago
There is a newer version of this series
arch/arm64/include/asm/kvm_host.h   | 5 +++++
arch/arm64/kvm/arm.c                | 5 -----
arch/powerpc/include/asm/kvm_host.h | 2 ++
arch/x86/include/asm/kvm_host.h     | 6 ++++++
arch/x86/kvm/x86.c                  | 5 -----
include/linux/kvm_host.h            | 1 -
6 files changed, 13 insertions(+), 11 deletions(-)
[PATCH] KVM: arm64, x86: make kvm_arch_has_irq_bypass() inline
Posted by Paolo Bonzini 7 months, 4 weeks ago 
kvm_arch_has_irq_bypass() is a small function and even though it does
not appear in any *really* hot paths, it's also not entirely rare.
Make it inline---it also works out nicely in preparation for using it in
kvm-intel.ko and kvm-amd.ko, since the function is not currently exported.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h   | 5 +++++
 arch/arm64/kvm/arm.c                | 5 -----
 arch/powerpc/include/asm/kvm_host.h | 2 ++
 arch/x86/include/asm/kvm_host.h     | 6 ++++++
 arch/x86/kvm/x86.c                  | 5 -----
 include/linux/kvm_host.h            | 1 -
 6 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e98cfe7855a6..08ba91e6fb03 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1588,4 +1588,9 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val);
 #define kvm_has_s1poe(k)				\
 	(kvm_has_feat((k), ID_AA64MMFR3_EL1, S1POE, IMP))
 
+static inline bool kvm_arch_has_irq_bypass(void)
+{
+	return true;
+}
+
 #endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 68fec8c95fee..19ca57def629 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2743,11 +2743,6 @@ bool kvm_arch_irqchip_in_kernel(struct kvm *kvm)
 	return irqchip_in_kernel(kvm);
 }
 
-bool kvm_arch_has_irq_bypass(void)
-{
-	return true;
-}
-
 int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
 				      struct irq_bypass_producer *prod)
 {
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 2d139c807577..6f761b77b813 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -907,4 +907,6 @@ static inline void kvm_arch_flush_shadow_all(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
 
+bool kvm_arch_has_irq_bypass(void);
+
 #endif /* __POWERPC_KVM_HOST_H__ */
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3bdae454a959..7bc174a1f1cb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -35,6 +35,7 @@
 #include <asm/mtrr.h>
 #include <asm/msr-index.h>
 #include <asm/asm.h>
+#include <asm/irq_remapping.h>
 #include <asm/kvm_page_track.h>
 #include <asm/kvm_vcpu_regs.h>
 #include <asm/reboot.h>
@@ -2423,4 +2424,9 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
  */
 #define KVM_EXIT_HYPERCALL_MBZ		GENMASK_ULL(31, 1)
 
+static inline bool kvm_arch_has_irq_bypass(void)
+{
+	return enable_apicv && irq_remapping_cap(IRQ_POSTING_CAP);
+}
+
 #endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3712dde0bf9d..c1fdd527044c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13556,11 +13556,6 @@ bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
 }
 EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
 
-bool kvm_arch_has_irq_bypass(void)
-{
-	return enable_apicv && irq_remapping_cap(IRQ_POSTING_CAP);
-}
-
 int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
 				      struct irq_bypass_producer *prod)
 {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 291d49b9bf05..82f044e4b3f5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2383,7 +2383,6 @@ struct kvm_vcpu *kvm_get_running_vcpu(void);
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
 
 #if IS_ENABLED(CONFIG_HAVE_KVM_IRQ_BYPASS)
-bool kvm_arch_has_irq_bypass(void);
 int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *,
 			   struct irq_bypass_producer *);
 void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
-- 
2.43.5
Re: [PATCH] KVM: arm64, x86: make kvm_arch_has_irq_bypass() inline
Posted by Sean Christopherson 7 months, 4 weeks ago 
On Fri, Apr 18, 2025, Paolo Bonzini wrote:
> kvm_arch_has_irq_bypass() is a small function and even though it does
> not appear in any *really* hot paths, it's also not entirely rare.
> Make it inline---it also works out nicely in preparation for using it in
> kvm-intel.ko and kvm-amd.ko, since the function is not currently exported.
> 
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/arm64/include/asm/kvm_host.h   | 5 +++++
>  arch/arm64/kvm/arm.c                | 5 -----
>  arch/powerpc/include/asm/kvm_host.h | 2 ++
>  arch/x86/include/asm/kvm_host.h     | 6 ++++++
>  arch/x86/kvm/x86.c                  | 5 -----
>  include/linux/kvm_host.h            | 1 -
>  6 files changed, 13 insertions(+), 11 deletions(-)

...

> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 2d139c807577..6f761b77b813 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -907,4 +907,6 @@ static inline void kvm_arch_flush_shadow_all(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
>  
> +bool kvm_arch_has_irq_bypass(void);

...

> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 291d49b9bf05..82f044e4b3f5 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2383,7 +2383,6 @@ struct kvm_vcpu *kvm_get_running_vcpu(void);
>  struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
>  
>  #if IS_ENABLED(CONFIG_HAVE_KVM_IRQ_BYPASS)
> -bool kvm_arch_has_irq_bypass(void);

Moving the declaration to PPC is unnecessary, and IMO undesirable.  It's perfectly
legal to have a non-static declaration follow a "static inline", and asm/kvm_host.h
is included by linux/kvm_host.h, i.e. the per-arch "static inline" is guaranteed
to be processed first.

And KVM already have multiple instances of this, e.g. kvm_arch_vcpu_blocking().
If only for consistency, I vote to keep the common declaration.

>  int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *,
>  			   struct irq_bypass_producer *);
>  void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
> -- 
> 2.43.5
>
Re: [PATCH] KVM: arm64, x86: make kvm_arch_has_irq_bypass() inline
Posted by Oliver Upton 7 months, 4 weeks ago 
On Fri, Apr 18, 2025 at 01:16:09PM -0400, Paolo Bonzini wrote:
> kvm_arch_has_irq_bypass() is a small function and even though it does
> not appear in any *really* hot paths, it's also not entirely rare.
> Make it inline---it also works out nicely in preparation for using it in
> kvm-intel.ko and kvm-amd.ko, since the function is not currently exported.
> 
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

LOL, surprised this wasn't the case already.

Acked-by: Oliver Upton <oliver.upton@linux.dev>

> ---
>  arch/arm64/include/asm/kvm_host.h   | 5 +++++
>  arch/arm64/kvm/arm.c                | 5 -----
>  arch/powerpc/include/asm/kvm_host.h | 2 ++
>  arch/x86/include/asm/kvm_host.h     | 6 ++++++
>  arch/x86/kvm/x86.c                  | 5 -----
>  include/linux/kvm_host.h            | 1 -
>  6 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index e98cfe7855a6..08ba91e6fb03 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -1588,4 +1588,9 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val);
>  #define kvm_has_s1poe(k)				\
>  	(kvm_has_feat((k), ID_AA64MMFR3_EL1, S1POE, IMP))
>  
> +static inline bool kvm_arch_has_irq_bypass(void)
> +{
> +	return true;
> +}
> +
>  #endif /* __ARM64_KVM_HOST_H__ */
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 68fec8c95fee..19ca57def629 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -2743,11 +2743,6 @@ bool kvm_arch_irqchip_in_kernel(struct kvm *kvm)
>  	return irqchip_in_kernel(kvm);
>  }
>  
> -bool kvm_arch_has_irq_bypass(void)
> -{
> -	return true;
> -}
> -
>  int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
>  				      struct irq_bypass_producer *prod)
>  {
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 2d139c807577..6f761b77b813 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -907,4 +907,6 @@ static inline void kvm_arch_flush_shadow_all(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
>  static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
>  
> +bool kvm_arch_has_irq_bypass(void);
> +
>  #endif /* __POWERPC_KVM_HOST_H__ */
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 3bdae454a959..7bc174a1f1cb 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -35,6 +35,7 @@
>  #include <asm/mtrr.h>
>  #include <asm/msr-index.h>
>  #include <asm/asm.h>
> +#include <asm/irq_remapping.h>
>  #include <asm/kvm_page_track.h>
>  #include <asm/kvm_vcpu_regs.h>
>  #include <asm/reboot.h>
> @@ -2423,4 +2424,9 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
>   */
>  #define KVM_EXIT_HYPERCALL_MBZ		GENMASK_ULL(31, 1)
>  
> +static inline bool kvm_arch_has_irq_bypass(void)
> +{
> +	return enable_apicv && irq_remapping_cap(IRQ_POSTING_CAP);
> +}
> +
>  #endif /* _ASM_X86_KVM_HOST_H */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3712dde0bf9d..c1fdd527044c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -13556,11 +13556,6 @@ bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
>  }
>  EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);
>  
> -bool kvm_arch_has_irq_bypass(void)
> -{
> -	return enable_apicv && irq_remapping_cap(IRQ_POSTING_CAP);
> -}
> -
>  int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
>  				      struct irq_bypass_producer *prod)
>  {
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 291d49b9bf05..82f044e4b3f5 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -2383,7 +2383,6 @@ struct kvm_vcpu *kvm_get_running_vcpu(void);
>  struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
>  
>  #if IS_ENABLED(CONFIG_HAVE_KVM_IRQ_BYPASS)
> -bool kvm_arch_has_irq_bypass(void);
>  int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *,
>  			   struct irq_bypass_producer *);
>  void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
> -- 
> 2.43.5
> 
>

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