On Wed, Aug 17, 2022, Uros Bizjak wrote: > There is no need to declare vmread_error asmlinkage, its arguments > can be passed via registers for both, 32-bit and 64-bit targets. > Function argument registers are considered call-clobbered registers, > they are saved in the trampoline just before the function call and > restored afterwards. > > Note that asmlinkage and __attribute__((regparm(0))) have no effect > on 64-bit targets. The trampoline is called from the assembler glue > code that implements its own stack-passing function calling convention, > so the attribute on the trampoline declaration does not change anything > for 64-bit as well as 32-bit targets. We can declare it asmlinkage for > documentation purposes. ... > diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h > index 5cfc49ddb1b4..550a89394d9f 100644 > --- a/arch/x86/kvm/vmx/vmx_ops.h > +++ b/arch/x86/kvm/vmx/vmx_ops.h > @@ -10,9 +10,9 @@ > #include "vmcs.h" > #include "../x86.h" > > -asmlinkage void vmread_error(unsigned long field, bool fault); > -__attribute__((regparm(0))) void vmread_error_trampoline(unsigned long field, > - bool fault); > +void vmread_error(unsigned long field, bool fault); > +asmlinkage void vmread_error_trampoline(unsigned long field, > + bool fault); > void vmwrite_error(unsigned long field, unsigned long value); > void vmclear_error(struct vmcs *vmcs, u64 phys_addr); > void vmptrld_error(struct vmcs *vmcs, u64 phys_addr); If it's ok with you, I'll split this into two patches. One to drop asmlinkage from vmread_error(), and one to convert the open coded regparm to asmlinkage.
