Subject: [PATCH v2 02/10] arm64: KVM: allows discrimination of AArch32 sysreg access

From: [email-masked] (Christoffer Dall)
Date: Wed, 29 Jan 2014 12:06:47 -0800

On Wed, Jan 22, 2014 at 02:56:34PM +0000, Marc Zyngier wrote:
> The current handling of AArch32 trapping is slightly less than
> perfect, as it is not possible (from a handler point of view)
> to distinguish it from an AArch64 access, nor to tell a 32bit
> from a 64bit access either.
> 
> Fix this by introducing two additional flags:
> - is_aarch32: true if the access was made in AArch32 mode
> - is_32bit: true if is_aarch32 == true and a MCR/MRC instruction
>   was used to perform the access (as opposed to MCRR/MRRC).
> 
> This allows a handler to cover all the possible conditions in which
> a system register gets trapped.
> 
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  arch/arm64/kvm/sys_regs.c | 5 +++++
>  arch/arm64/kvm/sys_regs.h | 2 ++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 02e9d09..f063750 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -437,6 +437,8 @@ int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	u32 hsr = kvm_vcpu_get_hsr(vcpu);
>  	int Rt2 = (hsr >> 10) & 0xf;
>  
> +	params.is_aarch32 = true;
> +	params.is_32bit = false;
>  	params.CRm = (hsr >> 1) & 0xf;
>  	params.Rt = (hsr >> 5) & 0xf;
>  	params.is_write = ((hsr & 1) == 0);
> @@ -480,6 +482,8 @@ int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	struct sys_reg_params params;
>  	u32 hsr = kvm_vcpu_get_hsr(vcpu);
>  
> +	params.is_aarch32 = true;
> +	params.is_32bit = true;
>  	params.CRm = (hsr >> 1) & 0xf;
>  	params.Rt  = (hsr >> 5) & 0xf;
>  	params.is_write = ((hsr & 1) == 0);
> @@ -549,6 +553,7 @@ int kvm_handle_sys_reg(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	struct sys_reg_params params;
>  	unsigned long esr = kvm_vcpu_get_hsr(vcpu);
>  
> +	params.is_aarch32 = false;

I'm wondering if we should set is_32bit = false, just for clarity...

>  	params.Op0 = (esr >> 20) & 3;
>  	params.Op1 = (esr >> 14) & 0x7;
>  	params.CRn = (esr >> 10) & 0xf;
> diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
> index d50d372..d411e25 100644
> --- a/arch/arm64/kvm/sys_regs.h
> +++ b/arch/arm64/kvm/sys_regs.h
> @@ -30,6 +30,8 @@ struct sys_reg_params {
>  	u8	Op2;
>  	u8	Rt;
>  	bool	is_write;
> +	bool	is_aarch32;
> +	bool	is_32bit;	/* Only valid if is_aarch32 is true */
>  };
>  
>  struct sys_reg_desc {
> -- 
> 1.8.3.4
> 

Acked-by: Christoffer Dall <[email-masked]>