| Message ID | 20210512150945.4591-2-ilstam@amazon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Implement nested TSC scaling | expand |
On Wed, May 12, 2021, Ilias Stamatis wrote: > This function is needed for the nested TSC scaling code where we need to s/the nested/KVM's nested virtualization. Non-KVM folk will have no idea what "nested" means without context. They may know not what nested virtualization is, but this will at least give them a starting point for asking the right questions. > multiply the signed TSC offset with the unsigned TSC multiplier.
diff --git a/include/linux/math64.h b/include/linux/math64.h index 66deb1fdc2ef..2928f03d6d46 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -3,6 +3,7 @@ #define _LINUX_MATH64_H #include <linux/types.h> +#include <linux/math.h> #include <vdso/math64.h> #include <asm/div64.h> @@ -234,6 +235,24 @@ static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift) #endif +#ifndef mul_s64_u64_shr +static inline u64 mul_s64_u64_shr(s64 a, u64 b, unsigned int shift) +{ + u64 ret; + + /* + * Extract the sign before the multiplication and put it back + * afterwards if needed. + */ + ret = mul_u64_u64_shr(abs(a), b, shift); + + if (a < 0) + ret = -((s64) ret); + + return ret; +} +#endif /* mul_s64_u64_shr */ + #ifndef mul_u64_u32_div static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor) {
This function is needed for the nested TSC scaling code where we need to multiply the signed TSC offset with the unsigned TSC multiplier. Signed-off-by: Ilias Stamatis <ilstam@amazon.com> --- include/linux/math64.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)