Re: [RFC PATCH 09/27] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code

From: David Brazdil <dbrazdil@google.com>
To: Quentin Perret <qperret@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	"moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
	<linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" 
	<kvmarm@lists.cs.columbia.edu>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
	<devicetree@vger.kernel.org>,
	kernel-team@android.com, android-kvm@google.com
Subject: Re: [RFC PATCH 09/27] KVM: arm64: Allow using kvm_nvhe_sym() in hyp code
Date: Mon, 23 Nov 2020 12:57:23 +0000	[thread overview]
Message-ID: <20201123125723.4mnodg3tnal4q4v2@google.com> (raw)
In-Reply-To: <20201117181607.1761516-10-qperret@google.com>

On Tue, Nov 17, 2020 at 06:15:49PM +0000, 'Quentin Perret' via kernel-team wrote:
> In order to allow the usage of code shared by the host and the hyp in
> static inline library function, allow the usage of kvm_nvhe_sym() at el2
> by defaulting to the raw symbol name.
> 
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/include/asm/hyp_image.h | 4 ++++
>  arch/arm64/include/asm/kvm_asm.h   | 4 ++--
>  arch/arm64/kvm/arm.c               | 2 +-
>  3 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
> index daa1a1da539e..8b807b646b8f 100644
> --- a/arch/arm64/include/asm/hyp_image.h
> +++ b/arch/arm64/include/asm/hyp_image.h
> @@ -7,11 +7,15 @@
>  #ifndef __ARM64_HYP_IMAGE_H__
>  #define __ARM64_HYP_IMAGE_H__
>  
> +#ifndef __KVM_NVHE_HYPERVISOR__
>  /*
>   * KVM nVHE code has its own symbol namespace prefixed with __kvm_nvhe_,
>   * to separate it from the kernel proper.
>   */
>  #define kvm_nvhe_sym(sym)	__kvm_nvhe_##sym
> +#else
> +#define kvm_nvhe_sym(sym)	sym
> +#endif
>  
>  #ifdef LINKER_SCRIPT
>  
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 1a86581e581e..e4934f5e4234 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -173,11 +173,11 @@ struct kvm_s2_mmu;
>  DECLARE_KVM_NVHE_SYM(__kvm_hyp_init);
>  DECLARE_KVM_NVHE_SYM(__kvm_hyp_host_vector);
>  DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
> -DECLARE_KVM_NVHE_SYM(__kvm_hyp_psci_cpu_entry);
>  #define __kvm_hyp_init			CHOOSE_NVHE_SYM(__kvm_hyp_init)
>  #define __kvm_hyp_host_vector		CHOOSE_NVHE_SYM(__kvm_hyp_host_vector)
>  #define __kvm_hyp_vector		CHOOSE_HYP_SYM(__kvm_hyp_vector)
> -#define __kvm_hyp_psci_cpu_entry	CHOOSE_NVHE_SYM(__kvm_hyp_psci_cpu_entry)
> +
> +void kvm_nvhe_sym(__kvm_hyp_psci_cpu_entry)(void);
>  
>  extern unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
>  DECLARE_KVM_NVHE_SYM(__per_cpu_start);
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 882eb383bd75..391cf6753a13 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1369,7 +1369,7 @@ static void cpu_prepare_hyp_mode(int cpu)
>  
>  	params->vector_hyp_va = kern_hyp_va((unsigned long)kvm_ksym_ref(__kvm_hyp_host_vector));
>  	params->stack_hyp_va = kern_hyp_va(per_cpu(kvm_arm_hyp_stack_page, cpu) + PAGE_SIZE);
> -	params->entry_hyp_va = kern_hyp_va((unsigned long)kvm_ksym_ref(__kvm_hyp_psci_cpu_entry));
> +	params->entry_hyp_va = kern_hyp_va((unsigned long)kvm_ksym_ref_nvhe(__kvm_hyp_psci_cpu_entry));

Why is this change needed?

>  	params->pgd_pa = kvm_mmu_get_httbr();
>  
>  	/*
> -- 
> 2.29.2.299.gdc1121823c-goog
> 
> -- 
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