powerpc fixes for 5.16 #3

Fix KVM using a Power9 instruction on earlier CPUs, which could lead to the host SLB being
 incorrectly invalidated and a subsequent host crash.
 
 Fix kernel hardlockup on vmap stack overflow on 32-bit.
 
 Thanks to: Christophe Leroy, Nicholas Piggin, Fabiano Rosas.
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Merge tag 'powerpc-5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "Fix KVM using a Power9 instruction on earlier CPUs, which could lead
  to the host SLB being incorrectly invalidated and a subsequent host
  crash.

  Fix kernel hardlockup on vmap stack overflow on 32-bit.

  Thanks to Christophe Leroy, Nicholas Piggin, and Fabiano Rosas"

* tag 'powerpc-5.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32: Fix hardlockup on vmap stack overflow
  KVM: PPC: Book3S HV: Prevent POWER7/8 TLB flush flushing SLB

arch/powerpc/kernel/head_32.h

@@ -202,11 +202,11 @@ vmap_stack_overflow:
 	mfspr	r1, SPRN_SPRG_THREAD
 	lwz	r1, TASK_CPU - THREAD(r1)
 	slwi	r1, r1, 3
-	addis	r1, r1, emergency_ctx@ha
+	addis	r1, r1, emergency_ctx-PAGE_OFFSET@ha
 #else
-	lis	r1, emergency_ctx@ha
+	lis	r1, emergency_ctx-PAGE_OFFSET@ha
 #endif
-	lwz	r1, emergency_ctx@l(r1)
+	lwz	r1, emergency_ctx-PAGE_OFFSET@l(r1)
 	addi	r1, r1, THREAD_SIZE - INT_FRAME_SIZE
 	EXCEPTION_PROLOG_2 0 vmap_stack_overflow
 	prepare_transfer_to_handler

arch/powerpc/kvm/book3s_hv_builtin.c

@@ -695,6 +695,7 @@ static void flush_guest_tlb(struct kvm *kvm)
 				       "r" (0) : "memory");
 		}
 		asm volatile("ptesync": : :"memory");
+		// POWER9 congruence-class TLBIEL leaves ERAT. Flush it now.
 		asm volatile(PPC_RADIX_INVALIDATE_ERAT_GUEST : : :"memory");
 	} else {
 		for (set = 0; set < kvm->arch.tlb_sets; ++set) {
@@ -705,7 +706,9 @@ static void flush_guest_tlb(struct kvm *kvm)
 			rb += PPC_BIT(51);	/* increment set number */
 		}
 		asm volatile("ptesync": : :"memory");
-		asm volatile(PPC_ISA_3_0_INVALIDATE_ERAT : : :"memory");
+		// POWER9 congruence-class TLBIEL leaves ERAT. Flush it now.
+		if (cpu_has_feature(CPU_FTR_ARCH_300))
+			asm volatile(PPC_ISA_3_0_INVALIDATE_ERAT : : :"memory");
 	}
 }