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, 1 insertions, 107 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 8053efdf7ea7..f3d3183249fe 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -277,8 +277,7 @@ void kvmhv_commence_exit(int trap)
 	struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
 	int ptid = local_paca->kvm_hstate.ptid;
 	struct kvm_split_mode *sip = local_paca->kvm_hstate.kvm_split_mode;
-	int me, ee, i, t;
-	int cpu0;
+	int me, ee, i;
 
 	/* Set our bit in the threads-exiting-guest map in the 0xff00
 	   bits of vcore->entry_exit_map */
@@ -320,22 +319,6 @@ void kvmhv_commence_exit(int trap)
 		if ((ee >> 8) == 0)
 			kvmhv_interrupt_vcore(vc, ee);
 	}
-
-	/*
-	 * On POWER9 when running a HPT guest on a radix host (sip != NULL),
-	 * we have to interrupt inactive CPU threads to get them to
-	 * restore the host LPCR value.
-	 */
-	if (sip->lpcr_req) {
-		if (cmpxchg(&sip->do_restore, 0, 1) == 0) {
-			vc = local_paca->kvm_hstate.kvm_vcore;
-			cpu0 = vc->pcpu + ptid - local_paca->kvm_hstate.tid;
-			for (t = 1; t < threads_per_core; ++t) {
-				if (sip->napped[t])
-					kvmhv_rm_send_ipi(cpu0 + t);
-			}
-		}
-	}
 }
 
 struct kvmppc_host_rm_ops *kvmppc_host_rm_ops_hv;
@@ -667,95 +650,6 @@ void kvmppc_bad_interrupt(struct pt_regs *regs)
 	panic("Bad KVM trap");
 }
 
-/*
- * Functions used to switch LPCR HR and UPRT bits on all threads
- * when entering and exiting HPT guests on a radix host.
- */
-
-#define PHASE_REALMODE		1	/* in real mode */
-#define PHASE_SET_LPCR		2	/* have set LPCR */
-#define PHASE_OUT_OF_GUEST	4	/* have finished executing in guest */
-#define PHASE_RESET_LPCR	8	/* have reset LPCR to host value */
-
-#define ALL(p)		(((p) << 24) | ((p) << 16) | ((p) << 8) | (p))
-
-static void wait_for_sync(struct kvm_split_mode *sip, int phase)
-{
-	int thr = local_paca->kvm_hstate.tid;
-
-	sip->lpcr_sync.phase[thr] |= phase;
-	phase = ALL(phase);
-	while ((sip->lpcr_sync.allphases & phase) != phase) {
-		HMT_low();
-		barrier();
-	}
-	HMT_medium();
-}
-
-void kvmhv_p9_set_lpcr(struct kvm_split_mode *sip)
-{
-	int num_sets;
-	unsigned long rb, set;
-
-	/* wait for every other thread to get to real mode */
-	wait_for_sync(sip, PHASE_REALMODE);
-
-	/* Set LPCR and LPIDR */
-	mtspr(SPRN_LPCR, sip->lpcr_req);
-	mtspr(SPRN_LPID, sip->lpidr_req);
-	isync();
-
-	/*
-	 * P10 will flush all the congruence class with a single tlbiel
-	 */
-	if (cpu_has_feature(CPU_FTR_ARCH_31))
-		num_sets =  1;
-	else
-		num_sets = POWER9_TLB_SETS_RADIX;
-
-	/* Invalidate the TLB on thread 0 */
-	if (local_paca->kvm_hstate.tid == 0) {
-		sip->do_set = 0;
-		asm volatile("ptesync" : : : "memory");
-		for (set = 0; set < num_sets; ++set) {
-			rb = TLBIEL_INVAL_SET_LPID +
-				(set << TLBIEL_INVAL_SET_SHIFT);
-			asm volatile(PPC_TLBIEL(%0, %1, 0, 0, 0) : :
-				     "r" (rb), "r" (0));
-		}
-		asm volatile("ptesync" : : : "memory");
-	}
-
-	/* indicate that we have done so and wait for others */
-	wait_for_sync(sip, PHASE_SET_LPCR);
-	/* order read of sip->lpcr_sync.allphases vs. sip->do_set */
-	smp_rmb();
-}
-
-/*
- * Called when a thread that has been in the guest needs
- * to reload the host LPCR value - but only on POWER9 when
- * running a HPT guest on a radix host.
- */
-void kvmhv_p9_restore_lpcr(struct kvm_split_mode *sip)
-{
-	/* we're out of the guest... */
-	wait_for_sync(sip, PHASE_OUT_OF_GUEST);
-
-	mtspr(SPRN_LPID, 0);
-	mtspr(SPRN_LPCR, sip->host_lpcr);
-	isync();
-
-	if (local_paca->kvm_hstate.tid == 0) {
-		sip->do_restore = 0;
-		smp_wmb();	/* order store of do_restore vs. phase */
-	}
-
-	wait_for_sync(sip, PHASE_RESET_LPCR);
-	smp_mb();
-	local_paca->kvm_hstate.kvm_split_mode = NULL;
-}
-
 static void kvmppc_end_cede(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.ceded = 0;