Re: [PATCH 1/3] arm: KVM: define headers and offsets to mange VFP state

[Mario Smarduch <m.smarduch@samsung.com>]

On 07/05/2015 12:27 PM, Christoffer Dall wrote:
> On Wed, Jun 24, 2015 at 08:30:26PM -0700, Mario Smarduch wrote:
>> Define the required kvm_vcpu_arch fields, and offsets to manage VFP state. And
>> declary Hyp interface function to switch VFP registers.
>>
>>
>> Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
>> ---
>>  arch/arm/include/asm/kvm_asm.h  |    1 +
>>  arch/arm/include/asm/kvm_host.h |    3 +++
>>  arch/arm/kernel/asm-offsets.c   |    1 +
>>  3 files changed, 5 insertions(+)
>>
>> diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
>> index 25410b2..08dda8c 100644
>> --- a/arch/arm/include/asm/kvm_asm.h
>> +++ b/arch/arm/include/asm/kvm_asm.h
>> @@ -97,6 +97,7 @@ extern char __kvm_hyp_code_end[];
>>  extern void __kvm_flush_vm_context(void);
>>  extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
>>  extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
>> +extern void __kvm_restore_host_vfp_state(struct kvm_vcpu *vcpu);
>>  
>>  extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);
>>  #endif
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index d71607c..22cea72 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -111,6 +111,9 @@ struct kvm_vcpu_arch {
>>  	/* Interrupt related fields */
>>  	u32 irq_lines;		/* IRQ and FIQ levels */
>>  
>> +	/* Track if VFP registers are occupied by Guest while in KVM host mode*/
> 
> why capitalize guest?
I guess just highlight we're holding guest state outside of hyp mode
no issues can change.

> 
> missing space at the end of the line.
> 
> I don't really understand what the semantics of this field is by just
> lookint at this patch.  I would probably define a u32 flags field in
> stead and define a patch akin to what we do for the debug registers and
> call it 'vfp_dirty', and in a comment for the flag offset define say
> something like:
> 
> The vfp_dirty flag must be set if the host VFP register state is
> modified.

Yes agree, this was put together quickly to get comments.
> 
>> +	u32 vfp_guest_saved;
>> +
>>  	/* Exception Information */
>>  	struct kvm_vcpu_fault_info fault;
>>  
>> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
>> index 871b826..35093d0 100644
>> --- a/arch/arm/kernel/asm-offsets.c
>> +++ b/arch/arm/kernel/asm-offsets.c
>> @@ -191,6 +191,7 @@ int main(void)
>>    DEFINE(VCPU_HPFAR,		offsetof(struct kvm_vcpu, arch.fault.hpfar));
>>    DEFINE(VCPU_HYP_PC,		offsetof(struct kvm_vcpu, arch.fault.hyp_pc));
>>    DEFINE(VCPU_VGIC_CPU,		offsetof(struct kvm_vcpu, arch.vgic_cpu));
>> +  DEFINE(VCPU_VFP_SAVED,	offsetof(struct kvm_vcpu, arch.vfp_guest_saved));
>>    DEFINE(VGIC_V2_CPU_HCR,	offsetof(struct vgic_cpu, vgic_v2.vgic_hcr));
>>    DEFINE(VGIC_V2_CPU_VMCR,	offsetof(struct vgic_cpu, vgic_v2.vgic_vmcr));
>>    DEFINE(VGIC_V2_CPU_MISR,	offsetof(struct vgic_cpu, vgic_v2.vgic_misr));
>> -- 
>> 1.7.9.5
>>