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Re: [Xen-devel] [PATCH v7 04/19] x86/VPMU: Make vpmu marcos a bit more efficient

On 06/06/2014 02:13 PM, Andrew Cooper wrote:
On 06/06/14 18:40, Boris Ostrovsky wrote:
Update macros that modify VPMU flags to allow changing multiple bits at once.
Modify how?  It appears to only be an introduction of "vcpu_are_all_set()".

I meant "vpmu_is_set(foo) + vpmu_is_set(bar)" ==> vpmu_are_all_set(foo|bar).

So probably "Introduce macro that allows testing multiple bits at one".

--- a/xen/include/asm-x86/hvm/vpmu.h
+++ b/xen/include/asm-x86/hvm/vpmu.h
@@ -81,10 +81,11 @@ struct vpmu_struct {
  #define VPMU_CPU_HAS_BTS                    0x200 /* Has Branch Trace Store */
-#define vpmu_set(_vpmu, _x) ((_vpmu)->flags |= (_x))
-#define vpmu_reset(_vpmu, _x)  ((_vpmu)->flags &= ~(_x))
-#define vpmu_is_set(_vpmu, _x) ((_vpmu)->flags & (_x))
-#define vpmu_clear(_vpmu)      ((_vpmu)->flags = 0)
+#define vpmu_set(_vpmu, _x)         ((_vpmu)->flags |= (_x))
+#define vpmu_reset(_vpmu, _x)       ((_vpmu)->flags &= ~(_x))
+#define vpmu_is_set(_vpmu, _x)      ((_vpmu)->flags & (_x))
+#define vpmu_are_all_set(_vpmu, _x) (((_vpmu)->flags & (_x)) == (_x))
+#define vpmu_clear(_vpmu)           ((_vpmu)->flags = 0)
These macros' implicit types don't quite match their implementation.

set, reset and clear are implicitly void. (and frankly clear and reset
are confusing given the other bitopt nomenclature, but I don't suggest
changing them).

is_set and are_all_set are implicitly bool, but don't have !!'s

I realise I am straying vastly into personal preference here, but I feel
these would be much nicer as static inlines with proper types, and const
correctness for {is,are_all}_set().

I don't have a preference here. If there is no difference binary-wise (code size) between the two I can change these to inlines.


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