[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 4/4] SVM: streamline entry.S code
On 09/04/2013 11:20 AM, Jan Beulich wrote: On 04.09.13 at 17:09, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:I meant something like this: diff --git a/xen/arch/x86/hvm/svm/entry.S b/xen/arch/x86/hvm/svm/entry.S index 1969629..b362637 100644 --- a/xen/arch/x86/hvm/svm/entry.S +++ b/xen/arch/x86/hvm/svm/entry.S @@ -92,10 +92,12 @@ 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 @@ -108,17 +110,15 @@ UNLIKELY_END(svm_trace) 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 - mov %rax,UREGS_rip(%rsp) - mov VMCB_rsp(%rcx),%rax - mov %rax,UREGS_rsp(%rsp) - mov VMCB_rflags(%rcx),%rax - mov %rax,UREGS_eflags(%rsp) + movb $0,VCPU_svm_vmcb_in_sync(%rax) + mov VMCB_rax(%rcx),%rdi + mov %rdi,UREGS_rax(%rsp) + mov VMCB_rip(%rcx),%rdi + mov %rdi,UREGS_rip(%rsp) + mov VMCB_rsp(%rcx),%rdi + mov %rdi,UREGS_rsp(%rsp) + mov VMCB_rflags(%rcx),%rdi + mov %rdi,UREGS_eflags(%rsp) #ifndef NDEBUG mov $0xbeef,%ax ostr@workbase> %rax is clobbered anyway by ' mov VMCB_rax(%rcx),%rax'But the "current" pointer also isn't needed anymore after the clearing of VCPU_svm_vmcb_in_sync and before doing the first function call (it's needed after the function call, but for that it's can't be in %rax). So yes, that clearing of VCPU_svm_vmcb_in_sync could certainly be done using %rax instead of %rbx, but no other code change would seem necessary/desirable. If you agree, I'd be willing to do this one line adjustment. Oh, yes, that's right, no reason to change other lines. My only reason for suggesting this change though was to eliminate 'mov %rax,%rbx' instruction (in your patch, not in the code above). If you want to keep it in though then I don't think the line adjustment that you are talking about is needed. -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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