KVM: PPC: Book3S PR: Fix MSR setting when delivering interrupts

This makes sure that MSR "partial-function" bits are not transferred
to SRR1 when delivering an interrupt.  This was causing failures in
guests running kernels that include commit f3d96e69 ("powerpc/mm:
Overhaul handling of bad page faults", 2017-07-19), which added code
to check bits of SRR1 on instruction storage interrupts (ISIs) that
indicate a bad page fault.  The symptom was that a guest user program
that handled a signal and attempted to return from the signal handler
would get a SIGBUS signal and die.

The code that generated ISIs and some other interrupts would
previously set bits in the guest MSR to indicate the interrupt status
and then call kvmppc_book3s_queue_irqprio().  This technique no
longer works now that kvmppc_inject_interrupt() is masking off those
bits.  Instead we make kvmppc_core_queue_data_storage() and
kvmppc_core_queue_inst_storage() call kvmppc_inject_interrupt()
directly, and make sure that all the places that generate ISIs or
DSIs call kvmppc_core_queue_{data,inst}_storage instead of
kvmppc_book3s_queue_irqprio().
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/kvm/book3s.c

@@ -134,7 +134,7 @@ void kvmppc_inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 flags)
 {
 	kvmppc_unfixup_split_real(vcpu);
 	kvmppc_set_srr0(vcpu, kvmppc_get_pc(vcpu));
-	kvmppc_set_srr1(vcpu, kvmppc_get_msr(vcpu) | flags);
+	kvmppc_set_srr1(vcpu, (kvmppc_get_msr(vcpu) & ~0x783f0000ul) | flags);
 	kvmppc_set_pc(vcpu, kvmppc_interrupt_offset(vcpu) + vec);
 	vcpu->arch.mmu.reset_msr(vcpu);
 }
@@ -256,18 +256,15 @@ void kvmppc_core_queue_data_storage(struct kvm_vcpu *vcpu, ulong dar,
 {
 	kvmppc_set_dar(vcpu, dar);
 	kvmppc_set_dsisr(vcpu, flags);
-	kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_DATA_STORAGE);
+	kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_DATA_STORAGE, 0);
 }
-EXPORT_SYMBOL_GPL(kvmppc_core_queue_data_storage);	/* used by kvm_hv */
+EXPORT_SYMBOL_GPL(kvmppc_core_queue_data_storage);
 
 void kvmppc_core_queue_inst_storage(struct kvm_vcpu *vcpu, ulong flags)
 {
-	u64 msr = kvmppc_get_msr(vcpu);
-	msr &= ~(SRR1_ISI_NOPT | SRR1_ISI_N_OR_G | SRR1_ISI_PROT);
-	msr |= flags & (SRR1_ISI_NOPT | SRR1_ISI_N_OR_G | SRR1_ISI_PROT);
-	kvmppc_set_msr_fast(vcpu, msr);
-	kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_INST_STORAGE);
+	kvmppc_inject_interrupt(vcpu, BOOK3S_INTERRUPT_INST_STORAGE, flags);
 }
+EXPORT_SYMBOL_GPL(kvmppc_core_queue_inst_storage);
 
 static int kvmppc_book3s_irqprio_deliver(struct kvm_vcpu *vcpu,
 					 unsigned int priority)

arch/powerpc/kvm/book3s_pr.c

@@ -728,24 +728,20 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		pte.may_execute = !data;
 	}
 
-	if (page_found == -ENOENT) {
-		/* Page not found in guest PTE entries */
-		u64 ssrr1 = vcpu->arch.shadow_srr1;
-		u64 msr = kvmppc_get_msr(vcpu);
-		kvmppc_set_dar(vcpu, kvmppc_get_fault_dar(vcpu));
-		kvmppc_set_dsisr(vcpu, vcpu->arch.fault_dsisr);
-		kvmppc_set_msr_fast(vcpu, msr | (ssrr1 & 0xf8000000ULL));
-		kvmppc_book3s_queue_irqprio(vcpu, vec);
-	} else if (page_found == -EPERM) {
-		/* Storage protection */
-		u32 dsisr = vcpu->arch.fault_dsisr;
-		u64 ssrr1 = vcpu->arch.shadow_srr1;
-		u64 msr = kvmppc_get_msr(vcpu);
-		kvmppc_set_dar(vcpu, kvmppc_get_fault_dar(vcpu));
-		dsisr = (dsisr & ~DSISR_NOHPTE) | DSISR_PROTFAULT;
-		kvmppc_set_dsisr(vcpu, dsisr);
-		kvmppc_set_msr_fast(vcpu, msr | (ssrr1 & 0xf8000000ULL));
-		kvmppc_book3s_queue_irqprio(vcpu, vec);
+	if (page_found == -ENOENT || page_found == -EPERM) {
+		/* Page not found in guest PTE entries, or protection fault */
+		u64 flags;
+
+		if (page_found == -EPERM)
+			flags = DSISR_PROTFAULT;
+		else
+			flags = DSISR_NOHPTE;
+		if (data) {
+			flags |= vcpu->arch.fault_dsisr & DSISR_ISSTORE;
+			kvmppc_core_queue_data_storage(vcpu, eaddr, flags);
+		} else {
+			kvmppc_core_queue_inst_storage(vcpu, flags);
+		}
 	} else if (page_found == -EINVAL) {
 		/* Page not found in guest SLB */
 		kvmppc_set_dar(vcpu, kvmppc_get_fault_dar(vcpu));
@@ -1178,10 +1174,8 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			kvmppc_mmu_pte_flush(vcpu, kvmppc_get_pc(vcpu), ~0xFFFUL);
 			r = RESUME_GUEST;
 		} else {
-			u64 msr = kvmppc_get_msr(vcpu);
-			msr |= shadow_srr1 & 0x58000000;
-			kvmppc_set_msr_fast(vcpu, msr);
-			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
+			kvmppc_core_queue_inst_storage(vcpu,
+						shadow_srr1 & 0x58000000);
 			r = RESUME_GUEST;
 		}
 		break;
@@ -1220,9 +1214,7 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			r = kvmppc_handle_pagefault(run, vcpu, dar, exit_nr);
 			srcu_read_unlock(&vcpu->kvm->srcu, idx);
 		} else {
-			kvmppc_set_dar(vcpu, dar);
-			kvmppc_set_dsisr(vcpu, fault_dsisr);
-			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
+			kvmppc_core_queue_data_storage(vcpu, dar, fault_dsisr);
 			r = RESUME_GUEST;
 		}
 		break;