KVM: PPC: Remove kvmppc_claim_lpid

Removing kvmppc_claim_lpid makes the lpid allocator API a bit simpler to
change the underlying implementation in a future patch.

The host LPID is always 0, so that can be a detail of the allocator. If
the allocator range is restricted, that can reserve LPIDs at the top of
the range. This allows kvmppc_claim_lpid to be removed.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220123120043.3586018-2-npiggin@gmail.com

arch/powerpc/include/asm/kvm_ppc.h

@@ -877,7 +877,6 @@ int kvm_vcpu_ioctl_dirty_tlb(struct kvm_vcpu *vcpu,
 			     struct kvm_dirty_tlb *cfg);
 
 long kvmppc_alloc_lpid(void);
-void kvmppc_claim_lpid(long lpid);
 void kvmppc_free_lpid(long lpid);
 void kvmppc_init_lpid(unsigned long nr_lpids);
 

arch/powerpc/kvm/book3s_64_mmu_hv.c

@@ -256,14 +256,15 @@ void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
 
 int kvmppc_mmu_hv_init(void)
 {
-	unsigned long host_lpid, rsvd_lpid;
+	unsigned long rsvd_lpid;
 
 	if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE))
 		return -EINVAL;
 
-	host_lpid = 0;
-	if (cpu_has_feature(CPU_FTR_HVMODE))
-		host_lpid = mfspr(SPRN_LPID);
+	if (cpu_has_feature(CPU_FTR_HVMODE)) {
+		if (WARN_ON(mfspr(SPRN_LPID) != 0))
+			return -EINVAL;
+	}
 
 	/* POWER8 and above have 12-bit LPIDs (10-bit in POWER7) */
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
@@ -271,11 +272,8 @@ int kvmppc_mmu_hv_init(void)
 	else
 		rsvd_lpid = LPID_RSVD_POWER7;
 
-	kvmppc_init_lpid(rsvd_lpid + 1);
-
-	kvmppc_claim_lpid(host_lpid);
 	/* rsvd_lpid is reserved for use in partition switching */
-	kvmppc_claim_lpid(rsvd_lpid);
+	kvmppc_init_lpid(rsvd_lpid);
 
 	return 0;
 }

arch/powerpc/kvm/e500mc.c

@@ -399,7 +399,6 @@ static int __init kvmppc_e500mc_init(void)
 	 * allocator.
 	 */
 	kvmppc_init_lpid(KVMPPC_NR_LPIDS/threads_per_core);
-	kvmppc_claim_lpid(0); /* host */
 
 	r = kvm_init(NULL, sizeof(struct kvmppc_vcpu_e500), 0, THIS_MODULE);
 	if (r)

arch/powerpc/kvm/powerpc.c

@@ -2515,12 +2515,6 @@ long kvmppc_alloc_lpid(void)
 }
 EXPORT_SYMBOL_GPL(kvmppc_alloc_lpid);
 
-void kvmppc_claim_lpid(long lpid)
-{
-	set_bit(lpid, lpid_inuse);
-}
-EXPORT_SYMBOL_GPL(kvmppc_claim_lpid);
-
 void kvmppc_free_lpid(long lpid)
 {
 	clear_bit(lpid, lpid_inuse);
@@ -2531,6 +2525,7 @@ void kvmppc_init_lpid(unsigned long nr_lpids_param)
 {
 	nr_lpids = min_t(unsigned long, KVMPPC_NR_LPIDS, nr_lpids_param);
 	memset(lpid_inuse, 0, sizeof(lpid_inuse));
+	set_bit(0, lpid_inuse); /* The host LPID must always be 0 */
 }
 EXPORT_SYMBOL_GPL(kvmppc_init_lpid);