| Message ID | 20210521102449.21505-2-ilstam@amazon.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Implement nested TSC scaling | expand |
On Fri, 2021-05-21 at 11:24 +0100, Ilias Stamatis wrote: > This function is needed for KVM's nested virtualization. The nested TSC > scaling implementation requires multiplying 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(+) > > 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) > { Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky
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 KVM's nested virtualization. The nested TSC scaling implementation requires multiplying 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(+)