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| author | Ilias Stamatis <ilstam@amazon.com> | 2021-05-26 21:44:08 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-17 20:09:27 +0300 |
| commit | 605a140a49099effc069f0fd509db34d91f48496 (patch) | |
| tree | ee3632b91c72fda9366bb2e05a21df7320f3e247 /include/linux/math64.h | |
| parent | d501f747ef5c0ac0c917f9a6781d04ae4ae39d63 (diff) | |
| download | linux-605a140a49099effc069f0fd509db34d91f48496.tar.xz | |
math64.h: Add mul_s64_u64_shr()
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>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210526184418.28881-2-ilstam@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/linux/math64.h')
| -rw-r--r-- | include/linux/math64.h | 19 |
1 files changed, 19 insertions, 0 deletions
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) { |