From: Alexander Graf Date: Fri, 19 Feb 2010 10:00:42 +0000 (+0100) Subject: KVM: PPC: Add helpers to modify ppc fields X-Git-Tag: v2.6.35-rc1~436^2~239 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0564ee8a8611326f28bae2a0455182b458826762;p=karo-tx-linux.git KVM: PPC: Add helpers to modify ppc fields The PowerPC specification always lists bits from MSB to LSB. That is really confusing when you're trying to write C code, because it fits in pretty badly with the normal (1 << xx) schemes. So I came up with some nice wrappers that allow to get and set fields in a u64 with bit numbers exactly as given in the spec. That makes the code in KVM and the spec easier comparable. Signed-off-by: Alexander Graf Signed-off-by: Avi Kivity --- diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 07612189eb8b..c7fcdd751f14 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -103,6 +103,39 @@ extern void kvmppc_booke_exit(void); extern void kvmppc_core_destroy_mmu(struct kvm_vcpu *vcpu); +/* + * Cuts out inst bits with ordering according to spec. + * That means the leftmost bit is zero. All given bits are included. + */ +static inline u32 kvmppc_get_field(u64 inst, int msb, int lsb) +{ + u32 r; + u32 mask; + + BUG_ON(msb > lsb); + + mask = (1 << (lsb - msb + 1)) - 1; + r = (inst >> (63 - lsb)) & mask; + + return r; +} + +/* + * Replaces inst bits with ordering according to spec. + */ +static inline u32 kvmppc_set_field(u64 inst, int msb, int lsb, int value) +{ + u32 r; + u32 mask; + + BUG_ON(msb > lsb); + + mask = ((1 << (lsb - msb + 1)) - 1) << (63 - lsb); + r = (inst & ~mask) | ((value << (63 - lsb)) & mask); + + return r; +} + #ifdef CONFIG_PPC_BOOK3S /* We assume we're always acting on the current vcpu */