Re: [PATCH v5 1/8] KVM: arm64: Pass struct kvm to per-EC handlers

[Marc Zyngier <maz@kernel.org>]

On Fri, 27 Aug 2021 11:16:02 +0100,
Fuad Tabba <tabba@google.com> wrote:
> 
> We need struct kvm to check for protected VMs to be able to pick
> the right handlers for them.
> 
> Mark the handler functions inline, since some handlers will be
> called in future code from the protected VM handlers.
> 
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
>  arch/arm64/kvm/hyp/include/hyp/switch.h | 16 ++++++++--------
>  arch/arm64/kvm/hyp/nvhe/switch.c        |  2 +-
>  arch/arm64/kvm/hyp/vhe/switch.c         |  2 +-
>  3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index 0397606c0951..7cbff0ee59a5 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -163,7 +163,7 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
>   * If FP/SIMD is not implemented, handle the trap and inject an undefined
>   * instruction exception to the guest. Similarly for trapped SVE accesses.
>   */
> -static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)

No, please don't do that. We already have function pointers for each
of these, so by doing that you are forcing the compiler to emit the
code *twice*.

Instead, call into the relevant EC handler by using the base array
that already does the non-protected handling.

>  {
>  	bool sve_guest, sve_host;
>  	u8 esr_ec;
> @@ -318,7 +318,7 @@ static inline bool esr_is_ptrauth_trap(u32 esr)
>  
>  DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
>  
> -static bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
>  {
>  	struct kvm_cpu_context *ctxt;
>  	u64 val;
> @@ -343,7 +343,7 @@ static bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
>  	return true;
>  }
>  
> -static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
>  {
>  	if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
>  	    handle_tx2_tvm(vcpu))
> @@ -356,7 +356,7 @@ static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
>  	return false;
>  }
>  
> -static bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 *exit_code)
>  {
>  	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
>  	    __vgic_v3_perform_cpuif_access(vcpu) == 1)
> @@ -365,7 +365,7 @@ static bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 *exit_code)
>  	return false;
>  }
>  
> -static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
>  {
>  	if (!__populate_fault_info(vcpu))
>  		return true;
> @@ -373,7 +373,7 @@ static bool kvm_hyp_handle_iabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
>  	return false;
>  }
>  
> -static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
> +static inline bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
>  {
>  	if (!__populate_fault_info(vcpu))
>  		return true;
> @@ -403,7 +403,7 @@ static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code)
>  
>  typedef bool (*exit_handler_fn)(struct kvm_vcpu *, u64 *);
>  
> -static const exit_handler_fn *kvm_get_exit_handler_array(void);
> +const exit_handler_fn *kvm_get_exit_handler_array(struct kvm *kvm);

Why? What breaks if when this is static? There really shouldn't be
anything else referencing this array.

Thanks,

	M.

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