Commit 0564ee8a authored by Alexander Graf's avatar Alexander Graf Committed by Avi Kivity
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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: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent dba2e123

arch/powerpc/include/asm/kvm_ppc.h

+33 −0
Original line number Diff line number Diff line
@@ -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 */