Re: [PATCH v3 2/6] KVM: VMX: Extend BUILD_CONTROLS_SHADOW macro to support 64-bit variation

[Zeng Guang]

On 8/6/2021 6:32 AM, Sean Christopherson wrote:
> On Thu, Aug 05, 2021, Zeng Guang wrote:
> > From: Robert Hoo <robert.hu@xxxxxxxxxxxxxxx>
> >
> > The Tertiary VM-Exec Control, different from previous control fields, is 64
> > bit. So extend BUILD_CONTROLS_SHADOW() by adding a 'bit' parameter, to
> > support both 32 bit and 64 bit fields' auxiliary functions building.
> > Also, define the auxiliary functions for Tertiary control field here, using
> > the new BUILD_CONTROLS_SHADOW().
> >
> > Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> > Signed-off-by: Robert Hoo <robert.hu@xxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/vmx/vmx.h | 23 ++++++++++++-----------
> >   1 file changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> > index 3979a947933a..945c6639ce24 100644
> > --- a/arch/x86/kvm/vmx/vmx.h
> > +++ b/arch/x86/kvm/vmx/vmx.h
> > @@ -413,31 +413,32 @@ static inline u8 vmx_get_rvi(void)
> >   	return vmcs_read16(GUEST_INTR_STATUS) & 0xff;
> >   }
> >   
> > -#define BUILD_CONTROLS_SHADOW(lname, uname)				    \
> > -static inline void lname##_controls_set(struct vcpu_vmx *vmx, u32 val)	    \
> > +#define BUILD_CONTROLS_SHADOW(lname, uname, bits)			    \
> > +static inline void lname##_controls_set(struct vcpu_vmx *vmx, u##bits val) \
> Align the trailing backslashes (with tabs when possible).  It's a lot of unfortunate
> churn, but it really does make the code easier to read.  An alternative is to split
> "static inline" to a separate line.
>
> >   {									    \
> >   	if (vmx->loaded_vmcs->controls_shadow.lname != val) {		    \
> > -		vmcs_write32(uname, val);				    \
> > +		vmcs_write##bits(uname, val);				    \
> >   		vmx->loaded_vmcs->controls_shadow.lname = val;		    \
> >   	}								    \
> >   }									    \
> > -static inline u32 lname##_controls_get(struct vcpu_vmx *vmx)		    \
> > +static inline u##bits lname##_controls_get(struct vcpu_vmx *vmx)	    \
> >   {									    \
> >   	return vmx->loaded_vmcs->controls_shadow.lname;			    \
> >   }									    \
> > -static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u32 val)   \
> > +static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u##bits val)   \
> >   {									    \
> >   	lname##_controls_set(vmx, lname##_controls_get(vmx) | val);	    \
> >   }									    \
> > -static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u32 val) \
> > +static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u##bits val) \
> >   {									    \
> >   	lname##_controls_set(vmx, lname##_controls_get(vmx) & ~val);	    \
> >   }
> > -BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS)
> > -BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS)
> > -BUILD_CONTROLS_SHADOW(pin, PIN_BASED_VM_EXEC_CONTROL)
> > -BUILD_CONTROLS_SHADOW(exec, CPU_BASED_VM_EXEC_CONTROL)
> > -BUILD_CONTROLS_SHADOW(secondary_exec, SECONDARY_VM_EXEC_CONTROL)
> > +BUILD_CONTROLS_SHADOW(vm_entry, VM_ENTRY_CONTROLS, 32)
> > +BUILD_CONTROLS_SHADOW(vm_exit, VM_EXIT_CONTROLS, 32)
> > +BUILD_CONTROLS_SHADOW(pin, PIN_BASED_VM_EXEC_CONTROL, 32)
> > +BUILD_CONTROLS_SHADOW(exec, CPU_BASED_VM_EXEC_CONTROL, 32)
> > +BUILD_CONTROLS_SHADOW(secondary_exec, SECONDARY_VM_EXEC_CONTROL, 32)
> > +BUILD_CONTROLS_SHADOW(tertiary_exec, TERTIARY_VM_EXEC_CONTROL, 64)
> This fails to compile because all the TERTIARY collateral is in a later patch.


Alternative to derive relative TERTIARY collateral and prepare them in 
this patch. Ok for that ?

> I think I'd also prefer hiding the 32/64 param via more macros, e.g.
>
> #define __BUILD_CONTROLS_SHADOW(lname, uname, bits)				\
> static inline void lname##_controls_set(struct vcpu_vmx *vmx, u##bits val)	\
> {										\
> 	if (vmx->loaded_vmcs->controls_shadow.lname != val) {			\
> 		vmcs_write##bits(uname, val);					\
> 		vmx->loaded_vmcs->controls_shadow.lname = val;			\
> 	}									\
> }										\
> static inline u##bits lname##_controls_get(struct vcpu_vmx *vmx)		\
> {										\
> 	return vmx->loaded_vmcs->controls_shadow.lname;				\
> }										\
> static inline void lname##_controls_setbit(struct vcpu_vmx *vmx, u##bits val)	\
> {										\
> 	lname##_controls_set(vmx, lname##_controls_get(vmx) | val);		\
> }										\
> static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u##bits val)	\
> {										\
> 	lname##_controls_set(vmx, lname##_controls_get(vmx) & ~val);		\
> }
> #define BUILD_CONTROLS_SHADOW(lname, uname)   __BUILD_CONTROLS_SHADOW(lname, uname, 32)
> #define BUILD_CONTROLS_SHADOW64(lname, uname) __BUILD_CONTROLS_SHADOW(lname, uname, 64)