Re: [PATCH v7 2/5] arm64: KVM: encapsulate kvm_cpu_context in kvm_host_data

[Christoffer Dall <christoffer.dall@arm.com>]

On Tue, Dec 11, 2018 at 12:13:37PM +0000, Andrew Murray wrote:
> The virt/arm core allocates a percpu structure as per the kvm_cpu_context_t
> type, at present this is typedef'd to kvm_cpu_context and used to store
> host cpu context. The kvm_cpu_context structure is also used elsewhere to
> hold vcpu context. In order to use the percpu to hold additional future
> host information we encapsulate kvm_cpu_context in a new structure.
> 
> Signed-off-by: Andrew Murray <andrew.murray@arm.com>
> ---
>  arch/arm64/include/asm/kvm_host.h | 8 ++++++--
>  arch/arm64/kernel/asm-offsets.c   | 3 ++-
>  virt/kvm/arm/arm.c                | 4 +++-
>  3 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 1550192..bcf9d60 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -205,7 +205,11 @@ struct kvm_cpu_context {
>  	struct kvm_vcpu *__hyp_running_vcpu;
>  };
>  
> -typedef struct kvm_cpu_context kvm_cpu_context_t;
> +struct kvm_host_data {
> +	struct kvm_cpu_context __kvm_cpu_state;
> +};
> +
> +typedef struct kvm_host_data kvm_cpu_context_t;

Now I'm confused based on the conversation on the last version.

I think it's bizarre to use the typedef to rename things in this way.

Can you please make this:

   struct kvm_cpu_context;
   typedef struct kvm_cpu_context kvm_cpu_context_t;

   struct kvm_host_data;
   typedef struct kvm_host_data kvm_host_data_t;

And change the code with the fallout from that.


>  
>  struct kvm_vcpu_arch {
>  	struct kvm_cpu_context ctxt;
> @@ -241,7 +245,7 @@ struct kvm_vcpu_arch {
>  	struct kvm_guest_debug_arch external_debug_state;
>  
>  	/* Pointer to host CPU context */
> -	kvm_cpu_context_t *host_cpu_context;
> +	struct kvm_cpu_context *host_cpu_context;
>  
>  	struct thread_info *host_thread_info;	/* hyp VA */
>  	struct user_fpsimd_state *host_fpsimd_state;	/* hyp VA */
> diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
> index 323aeb5..da34022 100644
> --- a/arch/arm64/kernel/asm-offsets.c
> +++ b/arch/arm64/kernel/asm-offsets.c
> @@ -142,7 +142,8 @@ int main(void)
>    DEFINE(CPU_FP_REGS,		offsetof(struct kvm_regs, fp_regs));
>    DEFINE(VCPU_FPEXC32_EL2,	offsetof(struct kvm_vcpu, arch.ctxt.sys_regs[FPEXC32_EL2]));
>    DEFINE(VCPU_HOST_CONTEXT,	offsetof(struct kvm_vcpu, arch.host_cpu_context));
> -  DEFINE(HOST_CONTEXT_VCPU,	offsetof(struct kvm_cpu_context, __hyp_running_vcpu));
> +  DEFINE(HOST_CONTEXT_VCPU,	offsetof(struct kvm_cpu_context, __hyp_running_vcpu)
> +				+ offsetof(struct kvm_host_data, __kvm_cpu_state));

This should be HOST_DATA_VCPU, then.


Thanks,

    Christoffer

>  #endif
>  #ifdef CONFIG_CPU_PM
>    DEFINE(CPU_SUSPEND_SZ,	sizeof(struct cpu_suspend_ctx));
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 150c8a6..4f2e534 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -361,8 +361,10 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  {
>  	int *last_ran;
> +	kvm_cpu_context_t *cpu_ctxt;
>  
>  	last_ran = this_cpu_ptr(vcpu->kvm->arch.last_vcpu_ran);
> +	cpu_ctxt = this_cpu_ptr(&kvm_host_cpu_state);
>  
>  	/*
>  	 * We might get preempted before the vCPU actually runs, but
> @@ -374,7 +376,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>  	}
>  
>  	vcpu->cpu = cpu;
> -	vcpu->arch.host_cpu_context = this_cpu_ptr(&kvm_host_cpu_state);
> +	vcpu->arch.host_cpu_context = &cpu_ctxt->__kvm_cpu_state;
>  
>  	kvm_arm_set_running_vcpu(vcpu);
>  	kvm_vgic_load(vcpu);
> -- 
> 2.7.4
>