KVM: PPC: Book3S HV: Increase KVMPPC_NR_LPIDS on POWER8 and POWER9

POWER8 and POWER9 have 12-bit LPIDs. Change LPID_RSVD to support up to
(4096 - 2) guests on these processors. POWER7 is kept the same with a
limitation of (1024 - 2), but it might be time to drop KVM support for
POWER7.

Tested with 2048 guests * 4 vCPUs on a witherspoon system with 512G
RAM and a bit of swap.

Signed-off-by: Cédric Le Goater <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/include/asm/reg.h

···
 #ifndef SPRN_LPID
 #define SPRN_LPID	0x13F	/* Logical Partition Identifier */
 #endif
-#define   LPID_RSVD	0x3ff		/* Reserved LPID for partn switching */
+#define   LPID_RSVD_POWER7	0x3ff	/* Reserved LPID for partn switching */
+#define   LPID_RSVD		0xfff	/* Reserved LPID for partn switching */
 #define	SPRN_HMER	0x150	/* Hypervisor maintenance exception reg */
 #define   HMER_DEBUG_TRIG	(1ul << (63 - 17)) /* Debug trigger */
 #define	SPRN_HMEER	0x151	/* Hyp maintenance exception enable reg */

arch/powerpc/kvm/book3s_64_mmu_hv.c

···
 	if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE))
 		return -EINVAL;
 
-	/* POWER7 has 10-bit LPIDs (12-bit in POWER8) */
 	host_lpid = 0;
 	if (cpu_has_feature(CPU_FTR_HVMODE))
 		host_lpid = mfspr(SPRN_LPID);
-	rsvd_lpid = LPID_RSVD;
+
+	/* POWER8 and above have 12-bit LPIDs (10-bit in POWER7) */
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		rsvd_lpid = LPID_RSVD;
+	else
+		rsvd_lpid = LPID_RSVD_POWER7;
 
 	kvmppc_init_lpid(rsvd_lpid + 1);