diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-01-22 11:39:22 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-02-09 13:24:37 +0100 |
| commit | b51012deb390528d89d426f328d84618683f5d73 (patch) | |
| tree | 7c1b7c78064df33f353c5875e645ebf1fe381190 /arch/x86/kvm/x86.h | |
| parent | 765bdb406de4b6132e349c5d4e077866536a9cc0 (diff) | |
KVM: x86: introduce do_shl32_div32
This is similar to the existing div_frac function, but it returns the
remainder too. Unlike div_frac, it can be used to implement long
division, e.g. (a << 64) / b for 32-bit a and b.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.h')
| -rw-r--r-- | arch/x86/kvm/x86.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index f2afa5fe48a6..34f416427143 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -192,4 +192,19 @@ extern unsigned int min_timer_period_us; extern unsigned int lapic_timer_advance_ns; extern struct static_key kvm_no_apic_vcpu; + +/* Same "calling convention" as do_div: + * - divide (n << 32) by base + * - put result in n + * - return remainder + */ +#define do_shl32_div32(n, base) \ + ({ \ + u32 __quot, __rem; \ + asm("divl %2" : "=a" (__quot), "=d" (__rem) \ + : "rm" (base), "0" (0), "1" ((u32) n)); \ + n = __quot; \ + __rem; \ + }) + #endif |