On Thu, Sep 1, 2022 at 5:40 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > 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. Sure, please go ahead. Thanks, Uros.
