linux-kernel - Re: [PATCH v2 12/21] arm64: KVM: VHE: Enable minimal sysreg save/restore

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Date:	Mon, 1 Feb 2016 15:02:13 +0100
From:	Christoffer Dall <christoffer.dall@...aro.org>
To:	Marc Zyngier <marc.zyngier@....com>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu
Subject: Re: [PATCH v2 12/21] arm64: KVM: VHE: Enable minimal sysreg
 save/restore

On Mon, Jan 25, 2016 at 03:53:46PM +0000, Marc Zyngier wrote:
> We're now in a position where we can introduce VHE's minimal
> save/restore, which is limited to the handful of shared sysregs.
> 
> Add the required alternative function calls that result in a
> "do nothing" call on VHE, and the normal save/restore for non-VHE.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  arch/arm64/kvm/hyp/sysreg-sr.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> index 7d7d757..36bbdec 100644
> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> @@ -23,6 +23,9 @@
>  
>  #include "hyp.h"
>  
> +/* Yes, this does nothing, on purpose */
> +static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
> +
>  /*
>   * Non-VHE: Both host and guest must save everything.
>   *
> @@ -67,9 +70,13 @@ static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
>  	ctxt->gp_regs.spsr[KVM_SPSR_EL1]= read_sysreg_el1(spsr);
>  }
>  
> +static hyp_alternate_select(__sysreg_call_save_state,

__sysreg_call_save_host_state for symmetry with the restore path below?

> +			    __sysreg_save_state, __sysreg_do_nothing,
> +			    ARM64_HAS_VIRT_HOST_EXTN);
> +
>  void __hyp_text __sysreg_save_host_state(struct kvm_cpu_context *ctxt)
>  {
> -	__sysreg_save_state(ctxt);
> +	__sysreg_call_save_state()(ctxt);
>  	__sysreg_save_common_state(ctxt);
>  }
>  
> @@ -116,9 +123,13 @@ static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
>  	write_sysreg_el1(ctxt->gp_regs.spsr[KVM_SPSR_EL1],spsr);
>  }
>  
> +static hyp_alternate_select(__sysreg_call_restore_host_state,
> +			    __sysreg_restore_state, __sysreg_do_nothing,
> +			    ARM64_HAS_VIRT_HOST_EXTN);
> +
>  void __hyp_text __sysreg_restore_host_state(struct kvm_cpu_context *ctxt)
>  {
> -	__sysreg_restore_state(ctxt);
> +	__sysreg_call_restore_host_state()(ctxt);
>  	__sysreg_restore_common_state(ctxt);
>  }
>  
> -- 
> 2.1.4
> 

Otherwise:

Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>