[PATCH 17/37] KVM: arm64: Move userspace system registers into separate function

[cdall@linaro.org (Christoffer Dall)]

On Wed, Nov 08, 2017 at 10:32:30AM +0100, Andrew Jones wrote:
> On Thu, Oct 12, 2017 at 12:41:21PM +0200, Christoffer Dall wrote:
> > There's a semantic difference between the EL1 registers that control
> > operation of a kernel running in EL1 and EL1 registers that only control
> > userspace execution in EL0.  Since we can defer saving/restoring the
> > latter, move them into their own function.
> > 
> > We also take this chance to rename the function saving/restoring the
> > remaining system register to make it clear this function deals with
> > the EL1 system registers.
> > 
> > No functional change.
> > 
> > Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> > ---
> >  arch/arm64/kvm/hyp/sysreg-sr.c | 34 +++++++++++++++++++++++-----------
> >  1 file changed, 23 insertions(+), 11 deletions(-)
> > 
> > diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
> > index c4a3714..193c2b0 100644
> > --- a/arch/arm64/kvm/hyp/sysreg-sr.c
> > +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> > @@ -34,14 +34,18 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
> >  
> >  static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
> >  {
> > +	ctxt->sys_regs[MDSCR_EL1]	= read_sysreg(mdscr_el1);
> > +	ctxt->gp_regs.regs.sp		= read_sysreg(sp_el0);
> 
> Maybe a comment stating that sp_el0 is here, instead of down in user
> state, because arm64 Linux chooses to use it for the 'current' pointer.
> At least that's why I think it's been promoted to common state, but maybe
> there was a different reason I missed.
> 

That is the reason.  I can add a comment.

> > +}
> > +
> > +static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
> > +{
> >  	ctxt->sys_regs[ACTLR_EL1]	= read_sysreg(actlr_el1);
> >  	ctxt->sys_regs[TPIDR_EL0]	= read_sysreg(tpidr_el0);
> >  	ctxt->sys_regs[TPIDRRO_EL0]	= read_sysreg(tpidrro_el0);
> > -	ctxt->sys_regs[MDSCR_EL1]	= read_sysreg(mdscr_el1);
> > -	ctxt->gp_regs.regs.sp		= read_sysreg(sp_el0);
> >  }
> >  
> > -static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
> > +static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
> >  {
> >  	ctxt->sys_regs[MPIDR_EL1]	= read_sysreg(vmpidr_el2);
> >  	ctxt->sys_regs[CSSELR_EL1]	= read_sysreg(csselr_el1);
> > @@ -70,31 +74,37 @@ static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
> >  }
> >  
> >  static hyp_alternate_select(__sysreg_call_save_host_state,
> > -			    __sysreg_save_state, __sysreg_do_nothing,
> > +			    __sysreg_save_el1_state, __sysreg_do_nothing,
> >  			    ARM64_HAS_VIRT_HOST_EXTN);
> >  
> >  void __hyp_text __sysreg_save_host_state(struct kvm_cpu_context *ctxt)
> >  {
> >  	__sysreg_call_save_host_state()(ctxt);
> >  	__sysreg_save_common_state(ctxt);
> > +	__sysreg_save_user_state(ctxt);
> >  }
> >  
> >  void __hyp_text __sysreg_save_guest_state(struct kvm_cpu_context *ctxt)
> >  {
> > -	__sysreg_save_state(ctxt);
> > +	__sysreg_save_el1_state(ctxt);
> >  	__sysreg_save_common_state(ctxt);
> > +	__sysreg_save_user_state(ctxt);
> >  }
> >  
> >  static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
> >  {
> > -	write_sysreg(ctxt->sys_regs[ACTLR_EL1],	  actlr_el1);
> > -	write_sysreg(ctxt->sys_regs[TPIDR_EL0],	  tpidr_el0);
> > -	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
> >  	write_sysreg(ctxt->sys_regs[MDSCR_EL1],	  mdscr_el1);
> >  	write_sysreg(ctxt->gp_regs.regs.sp,	  sp_el0);
> >  }
> >  
> > -static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
> > +static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
> > +{
> > +	write_sysreg(ctxt->sys_regs[ACTLR_EL1],	  	actlr_el1);
> > +	write_sysreg(ctxt->sys_regs[TPIDR_EL0],	  	tpidr_el0);
> > +	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], 	tpidrro_el0);
> > +}
> > +
> > +static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
> >  {
> >  	write_sysreg(ctxt->sys_regs[MPIDR_EL1],		vmpidr_el2);
> >  	write_sysreg(ctxt->sys_regs[CSSELR_EL1],	csselr_el1);
> > @@ -123,19 +133,21 @@ static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
> >  }
> >  
> >  static hyp_alternate_select(__sysreg_call_restore_host_state,
> > -			    __sysreg_restore_state, __sysreg_do_nothing,
> > +			    __sysreg_restore_el1_state, __sysreg_do_nothing,
> >  			    ARM64_HAS_VIRT_HOST_EXTN);
> >  
> >  void __hyp_text __sysreg_restore_host_state(struct kvm_cpu_context *ctxt)
> >  {
> >  	__sysreg_call_restore_host_state()(ctxt);
> >  	__sysreg_restore_common_state(ctxt);
> > +	__sysreg_restore_user_state(ctxt);
> >  }
> >  
> >  void __hyp_text __sysreg_restore_guest_state(struct kvm_cpu_context *ctxt)
> >  {
> > -	__sysreg_restore_state(ctxt);
> > +	__sysreg_restore_el1_state(ctxt);
> >  	__sysreg_restore_common_state(ctxt);
> > +	__sysreg_restore_user_state(ctxt);
> >  }
> >  
> >  static void __hyp_text __fpsimd32_save_state(struct kvm_cpu_context *ctxt)
> > -- 
> > 2.9.0
> >
> 
> Otherwise
>  
> Reviewed-by: Andrew Jones <drjones@redhat.com>

Thanks,
-Christoffer