Re: [Xen-devel] [PATCH 4/4] SVM: streamline entry.S code

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 08/23/2013 10:04 AM, Jan Beulich wrote:
>           mov  UREGS_eflags(%rsp),%rax
>           mov  %rax,VMCB_rflags(%rcx)
>   
> -        mov  VCPU_svm_vmcb_pa(%rbx),%rax
> -
>           pop  %r15
>           pop  %r14
>           pop  %r13
>           pop  %r12
>           pop  %rbp
> +        mov  VCPU_svm_vmcb_pa(%rbx),%rax
>           pop  %rbx
>           pop  %r11
>           pop  %r10
> @@ -92,25 +97,26 @@ UNLIKELY_END(svm_trace)
>   
>           VMRUN
>   
> +        GET_CURRENT(%rax)
>           push %rdi
>           push %rsi
>           push %rdx
>           push %rcx
> +        mov  VCPU_svm_vmcb(%rax),%rcx
>           push %rax
>           push %r8
>           push %r9
>           push %r10
>           push %r11
>           push %rbx
> +        mov  %rax,%rbx
Can you continue with using %rax as 'current' pointer below and not save it
to %rbx? %rax appears to be a temp register so perhaps you can use, say,
%rdi, for that purpose.

-boris

>           push %rbp
>           push %r12
>           push %r13
>           push %r14
>           push %r15
>   
> -        GET_CURRENT(%rbx)
>           movb $0,VCPU_svm_vmcb_in_sync(%rbx)
> -        mov  VCPU_svm_vmcb(%rbx),%rcx
>           mov  VMCB_rax(%rcx),%rax
>           mov  %rax,UREGS_rax(%rsp)
>           mov  VMCB_rip(%rcx),%rax
> @@ -120,33 +126,14 @@ UNLIKELY_END(svm_trace)
>           mov  VMCB_rflags(%rcx),%rax
>           mov  %rax,UREGS_eflags(%rsp)
>   
> -#ifndef NDEBUG
> -        mov  $0xbeef,%ax
> -        mov  %ax,UREGS_error_code(%rsp)
> -        mov  %ax,UREGS_entry_vector(%rsp)
> -        mov  %ax,UREGS_saved_upcall_mask(%rsp)
> -        mov  %ax,UREGS_cs(%rsp)
> -        mov  %ax,UREGS_ds(%rsp)
> -        mov  %ax,UREGS_es(%rsp)
> -        mov  %ax,UREGS_fs(%rsp)
> -        mov  %ax,UREGS_gs(%rsp)
> -        mov  %ax,UREGS_ss(%rsp)
> -#endif
> -
>           STGI
>   .globl svm_stgi_label
>   svm_stgi_label:
>           mov  %rsp,%rdi
>           call svm_vmexit_handler
> -        jmp  svm_asm_do_resume
> +        jmp  .Lsvm_do_resume
>   

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