From: Andrew Cooper Date: Tue, 12 Feb 2019 18:33:30 +0000 (+0000) Subject: x86/svm: Improve code generation from cpu_has_svm_feature() X-Git-Tag: archive/raspbian/4.14.0+80-gd101b417b7-1+rpi1^2~63^2~2455 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=1e780ef5a527661d1d6106ccacf65706e3ed664d;p=xen.git x86/svm: Improve code generation from cpu_has_svm_feature() Taking svm_feature_flags by pointer and using test_bit() results in generated code which loads svm_feature_flags into a 32bit register, then does a bitwise operation. The logic can be expressed in terms of a straight bitwise operation, resulting in the following minor improvement. add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-136 (-136) Function old new delta svm_nested_features_on_efer_update 281 273 -8 svm_create_vmcb 1404 1388 -16 svm_vmexit_handler 6271 6239 -32 start_svm 818 738 -80 Total: Before=3347569, After=3347433, chg -0.00% Signed-off-by: Andrew Cooper Reviewed-by: Boris Ostrovsky --- diff --git a/xen/include/asm-x86/hvm/svm/svm.h b/xen/include/asm-x86/hvm/svm/svm.h index 49dca39e0b..6e688a8e10 100644 --- a/xen/include/asm-x86/hvm/svm/svm.h +++ b/xen/include/asm-x86/hvm/svm/svm.h @@ -21,7 +21,6 @@ #define __ASM_X86_HVM_SVM_H__ #include -#include #define svm_vmload(x) svm_vmload_pa(__pa(x)) #define svm_vmsave(x) svm_vmsave_pa(__pa(x)) @@ -77,7 +76,7 @@ extern u32 svm_feature_flags; #define SVM_FEATURE_VLOADSAVE 15 /* virtual vmload/vmsave */ #define SVM_FEATURE_VGIF 16 /* Virtual GIF */ -#define cpu_has_svm_feature(f) test_bit(f, &svm_feature_flags) +#define cpu_has_svm_feature(f) (svm_feature_flags & (1u << (f))) #define cpu_has_svm_npt cpu_has_svm_feature(SVM_FEATURE_NPT) #define cpu_has_svm_lbrv cpu_has_svm_feature(SVM_FEATURE_LBRV) #define cpu_has_svm_svml cpu_has_svm_feature(SVM_FEATURE_SVML)