KVM: PPC: Book3S HV: Remove support for running HPT guest on RPT host without mixed mode support

This reverts much of commit c01015091a770 ("KVM: PPC: Book3S HV: Run HPT
guests on POWER9 radix hosts"), which was required to run HPT guests on
RPT hosts on early POWER9 CPUs without support for "mixed mode", which
meant the host could not run with MMU on while guests were running.

This code has some corner case bugs, e.g., when the guest hits a machine
check or HMI the primary locks up waiting for secondaries to switch LPCR
to host, which they never do. This could all be fixed in software, but
most CPUs in production have mixed mode support, and those that don't
are believed to be all in installations that don't use this capability.
So simplify things and remove support.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

1 files changed, 19 insertions, 61 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 65161c062dc5..565464e3f9a5 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -87,19 +87,6 @@ _GLOBAL_TOC(kvmppc_hv_entry_trampoline)
 	RFI_TO_KERNEL
 
 kvmppc_call_hv_entry:
-BEGIN_FTR_SECTION
-	/* On P9, do LPCR setting, if necessary */
-	ld	r3, HSTATE_SPLIT_MODE(r13)
-	cmpdi	r3, 0
-	beq	46f
-	lwz	r4, KVM_SPLIT_DO_SET(r3)
-	cmpwi	r4, 0
-	beq	46f
-	bl	kvmhv_p9_set_lpcr
-	nop
-46:
-END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
-
 	ld	r4, HSTATE_KVM_VCPU(r13)
 	bl	kvmppc_hv_entry
 
@@ -363,11 +350,11 @@ kvm_secondary_got_guest:
 	LOAD_REG_ADDR(r6, decrementer_max)
 	ld	r6, 0(r6)
 	mtspr	SPRN_HDEC, r6
+BEGIN_FTR_SECTION
 	/* and set per-LPAR registers, if doing dynamic micro-threading */
 	ld	r6, HSTATE_SPLIT_MODE(r13)
 	cmpdi	r6, 0
 	beq	63f
-BEGIN_FTR_SECTION
 	ld	r0, KVM_SPLIT_RPR(r6)
 	mtspr	SPRN_RPR, r0
 	ld	r0, KVM_SPLIT_PMMAR(r6)
@@ -375,16 +362,7 @@ BEGIN_FTR_SECTION
 	ld	r0, KVM_SPLIT_LDBAR(r6)
 	mtspr	SPRN_LDBAR, r0
 	isync
-FTR_SECTION_ELSE
-	/* On P9 we use the split_info for coordinating LPCR changes */
-	lwz	r4, KVM_SPLIT_DO_SET(r6)
-	cmpwi	r4, 0
-	beq	1f
-	mr	r3, r6
-	bl	kvmhv_p9_set_lpcr
-	nop
-1:
-ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 63:
 	/* Order load of vcpu after load of vcore */
 	lwsync
@@ -454,19 +432,15 @@ kvm_no_guest:
 	mtcr	r5
 	blr
 
-53:	HMT_LOW
+53:
+BEGIN_FTR_SECTION
+	HMT_LOW
 	ld	r5, HSTATE_KVM_VCORE(r13)
 	cmpdi	r5, 0
 	bne	60f
 	ld	r3, HSTATE_SPLIT_MODE(r13)
 	cmpdi	r3, 0
 	beq	kvm_no_guest
-	lwz	r0, KVM_SPLIT_DO_SET(r3)
-	cmpwi	r0, 0
-	bne	kvmhv_do_set
-	lwz	r0, KVM_SPLIT_DO_RESTORE(r3)
-	cmpwi	r0, 0
-	bne	kvmhv_do_restore
 	lbz	r0, KVM_SPLIT_DO_NAP(r3)
 	cmpwi	r0, 0
 	beq	kvm_no_guest
@@ -474,24 +448,19 @@ kvm_no_guest:
 	b	kvm_unsplit_nap
 60:	HMT_MEDIUM
 	b	kvm_secondary_got_guest
+FTR_SECTION_ELSE
+	HMT_LOW
+	ld	r5, HSTATE_KVM_VCORE(r13)
+	cmpdi	r5, 0
+	beq	kvm_no_guest
+	HMT_MEDIUM
+	b	kvm_secondary_got_guest
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
 
 54:	li	r0, KVM_HWTHREAD_IN_KVM
 	stb	r0, HSTATE_HWTHREAD_STATE(r13)
 	b	kvm_no_guest
 
-kvmhv_do_set:
-	/* Set LPCR, LPIDR etc. on P9 */
-	HMT_MEDIUM
-	bl	kvmhv_p9_set_lpcr
-	nop
-	b	kvm_no_guest
-
-kvmhv_do_restore:
-	HMT_MEDIUM
-	bl	kvmhv_p9_restore_lpcr
-	nop
-	b	kvm_no_guest
-
 /*
  * Here the primary thread is trying to return the core to
  * whole-core mode, so we need to nap.
@@ -529,7 +498,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	/* Set kvm_split_mode.napped[tid] = 1 */
 	ld	r3, HSTATE_SPLIT_MODE(r13)
 	li	r0, 1
-	lbz	r4, HSTATE_TID(r13)
+	lhz	r4, PACAPACAINDEX(r13)
+	clrldi	r4, r4, 61	/* micro-threading => P8 => 8 threads/core */
 	addi	r4, r4, KVM_SPLIT_NAPPED
 	stbx	r0, r3, r4
 	/* Check the do_nap flag again after setting napped[] */
@@ -1958,24 +1928,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 19:	lis	r8,0x7fff		/* MAX_INT@h */
 	mtspr	SPRN_HDEC,r8
 
-16:
-BEGIN_FTR_SECTION
-	/* On POWER9 with HPT-on-radix we need to wait for all other threads */
-	ld	r3, HSTATE_SPLIT_MODE(r13)
-	cmpdi	r3, 0
-	beq	47f
-	lwz	r8, KVM_SPLIT_DO_RESTORE(r3)
-	cmpwi	r8, 0
-	beq	47f
-	bl	kvmhv_p9_restore_lpcr
-	nop
-	b	48f
-47:
-END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
-	ld	r8,KVM_HOST_LPCR(r4)
+16:	ld	r8,KVM_HOST_LPCR(r4)
 	mtspr	SPRN_LPCR,r8
 	isync
-48:
+
 #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
 	/* Finish timing, if we have a vcpu */
 	ld	r4, HSTATE_KVM_VCPU(r13)
@@ -2799,8 +2755,10 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
 	beq	kvm_end_cede
 	cmpwi	r0, NAPPING_NOVCPU
 	beq	kvm_novcpu_wakeup
+BEGIN_FTR_SECTION
 	cmpwi	r0, NAPPING_UNSPLIT
 	beq	kvm_unsplit_wakeup
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
 	twi	31,0,0 /* Nap state must not be zero */
 
 33:	mr	r4, r3