KVM: PPC: Book3S PR: Handle Facility interrupt and FSCR

POWER8 introduced a new interrupt type called "Facility unavailable interrupt"
which contains its status message in a new register called FSCR.

Handle these exits and try to emulate instructions for unhandled facilities.
Follow-on patches enable KVM to expose specific facilities into the guest.

Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/include/asm/kvm_asm.h

@@ -102,6 +102,7 @@
 #define BOOK3S_INTERRUPT_PERFMON	0xf00
 #define BOOK3S_INTERRUPT_ALTIVEC	0xf20
 #define BOOK3S_INTERRUPT_VSX		0xf40
+#define BOOK3S_INTERRUPT_FAC_UNAVAIL	0xf60
 #define BOOK3S_INTERRUPT_H_FAC_UNAVAIL	0xf80
 
 #define BOOK3S_IRQPRIO_SYSTEM_RESET		0
@@ -114,14 +115,15 @@
 #define BOOK3S_IRQPRIO_FP_UNAVAIL		7
 #define BOOK3S_IRQPRIO_ALTIVEC			8
 #define BOOK3S_IRQPRIO_VSX			9
-#define BOOK3S_IRQPRIO_SYSCALL			10
-#define BOOK3S_IRQPRIO_MACHINE_CHECK		11
-#define BOOK3S_IRQPRIO_DEBUG			12
-#define BOOK3S_IRQPRIO_EXTERNAL			13
-#define BOOK3S_IRQPRIO_DECREMENTER		14
-#define BOOK3S_IRQPRIO_PERFORMANCE_MONITOR	15
-#define BOOK3S_IRQPRIO_EXTERNAL_LEVEL		16
-#define BOOK3S_IRQPRIO_MAX			17
+#define BOOK3S_IRQPRIO_FAC_UNAVAIL		10
+#define BOOK3S_IRQPRIO_SYSCALL			11
+#define BOOK3S_IRQPRIO_MACHINE_CHECK		12
+#define BOOK3S_IRQPRIO_DEBUG			13
+#define BOOK3S_IRQPRIO_EXTERNAL			14
+#define BOOK3S_IRQPRIO_DECREMENTER		15
+#define BOOK3S_IRQPRIO_PERFORMANCE_MONITOR	16
+#define BOOK3S_IRQPRIO_EXTERNAL_LEVEL		17
+#define BOOK3S_IRQPRIO_MAX			18
 
 #define BOOK3S_HFLAG_DCBZ32			0x1
 #define BOOK3S_HFLAG_SLB			0x2

arch/powerpc/include/asm/kvm_book3s_asm.h

@@ -104,6 +104,7 @@ struct kvmppc_host_state {
 #ifdef CONFIG_PPC_BOOK3S_64
 	u64 cfar;
 	u64 ppr;
+	u64 host_fscr;
 #endif
 };
 
@@ -133,6 +134,7 @@ struct kvmppc_book3s_shadow_vcpu {
 		u64     esid;
 		u64     vsid;
 	} slb[64];			/* guest SLB */
+	u64 shadow_fscr;
 #endif
 };
 

arch/powerpc/include/asm/kvm_host.h

@@ -475,6 +475,7 @@ struct kvm_vcpu_arch {
 	ulong ppr;
 	ulong pspb;
 	ulong fscr;
+	ulong shadow_fscr;
 	ulong ebbhr;
 	ulong ebbrr;
 	ulong bescr;

arch/powerpc/kernel/asm-offsets.c

@@ -537,6 +537,7 @@ int main(void)
 	DEFINE(VCPU_CFAR, offsetof(struct kvm_vcpu, arch.cfar));
 	DEFINE(VCPU_PPR, offsetof(struct kvm_vcpu, arch.ppr));
 	DEFINE(VCPU_FSCR, offsetof(struct kvm_vcpu, arch.fscr));
+	DEFINE(VCPU_SHADOW_FSCR, offsetof(struct kvm_vcpu, arch.shadow_fscr));
 	DEFINE(VCPU_PSPB, offsetof(struct kvm_vcpu, arch.pspb));
 	DEFINE(VCPU_EBBHR, offsetof(struct kvm_vcpu, arch.ebbhr));
 	DEFINE(VCPU_EBBRR, offsetof(struct kvm_vcpu, arch.ebbrr));
@@ -618,6 +619,7 @@ int main(void)
 #ifdef CONFIG_PPC64
 	SVCPU_FIELD(SVCPU_SLB, slb);
 	SVCPU_FIELD(SVCPU_SLB_MAX, slb_max);
+	SVCPU_FIELD(SVCPU_SHADOW_FSCR, shadow_fscr);
 #endif
 
 	HSTATE_FIELD(HSTATE_HOST_R1, host_r1);
@@ -653,6 +655,7 @@ int main(void)
 #ifdef CONFIG_PPC_BOOK3S_64
 	HSTATE_FIELD(HSTATE_CFAR, cfar);
 	HSTATE_FIELD(HSTATE_PPR, ppr);
+	HSTATE_FIELD(HSTATE_HOST_FSCR, host_fscr);
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 #else /* CONFIG_PPC_BOOK3S */

arch/powerpc/kvm/book3s.c

@@ -145,6 +145,7 @@ static int kvmppc_book3s_vec2irqprio(unsigned int vec)
 	case 0xd00: prio = BOOK3S_IRQPRIO_DEBUG;		break;
 	case 0xf20: prio = BOOK3S_IRQPRIO_ALTIVEC;		break;
 	case 0xf40: prio = BOOK3S_IRQPRIO_VSX;			break;
+	case 0xf60: prio = BOOK3S_IRQPRIO_FAC_UNAVAIL;		break;
 	default:    prio = BOOK3S_IRQPRIO_MAX;			break;
 	}
 
@@ -275,6 +276,9 @@ int kvmppc_book3s_irqprio_deliver(struct kvm_vcpu *vcpu, unsigned int priority)
 	case BOOK3S_IRQPRIO_PERFORMANCE_MONITOR:
 		vec = BOOK3S_INTERRUPT_PERFMON;
 		break;
+	case BOOK3S_IRQPRIO_FAC_UNAVAIL:
+		vec = BOOK3S_INTERRUPT_FAC_UNAVAIL;
+		break;
 	default:
 		deliver = 0;
 		printk(KERN_ERR "KVM: Unknown interrupt: 0x%x\n", priority);
@@ -627,6 +631,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 			val = get_reg_val(reg->id, kvmppc_xics_get_icp(vcpu));
 			break;
 #endif /* CONFIG_KVM_XICS */
+		case KVM_REG_PPC_FSCR:
+			val = get_reg_val(reg->id, vcpu->arch.fscr);
+			break;
 		default:
 			r = -EINVAL;
 			break;
@@ -716,6 +723,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 						set_reg_val(reg->id, val));
 			break;
 #endif /* CONFIG_KVM_XICS */
+		case KVM_REG_PPC_FSCR:
+			vcpu->arch.fscr = set_reg_val(reg->id, val);
+			break;
 		default:
 			r = -EINVAL;
 			break;

arch/powerpc/kvm/book3s_emulate.c

@@ -438,6 +438,9 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 	case SPRN_GQR7:
 		to_book3s(vcpu)->gqr[sprn - SPRN_GQR0] = spr_val;
 		break;
+	case SPRN_FSCR:
+		vcpu->arch.fscr = spr_val;
+		break;
 	case SPRN_ICTC:
 	case SPRN_THRM1:
 	case SPRN_THRM2:
@@ -545,6 +548,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
 	case SPRN_GQR7:
 		*spr_val = to_book3s(vcpu)->gqr[sprn - SPRN_GQR0];
 		break;
+	case SPRN_FSCR:
+		*spr_val = vcpu->arch.fscr;
+		break;
 	case SPRN_THRM1:
 	case SPRN_THRM2:
 	case SPRN_THRM3:

arch/powerpc/kvm/book3s_hv.c

@@ -879,9 +879,6 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_IAMR:
 		*val = get_reg_val(id, vcpu->arch.iamr);
 		break;
-	case KVM_REG_PPC_FSCR:
-		*val = get_reg_val(id, vcpu->arch.fscr);
-		break;
 	case KVM_REG_PPC_PSPB:
 		*val = get_reg_val(id, vcpu->arch.pspb);
 		break;
@@ -1091,9 +1088,6 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_IAMR:
 		vcpu->arch.iamr = set_reg_val(id, *val);
 		break;
-	case KVM_REG_PPC_FSCR:
-		vcpu->arch.fscr = set_reg_val(id, *val);
-		break;
 	case KVM_REG_PPC_PSPB:
 		vcpu->arch.pspb = set_reg_val(id, *val);
 		break;

arch/powerpc/kvm/book3s_pr.c

@@ -53,6 +53,7 @@
 
 static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
 			     ulong msr);
+static void kvmppc_giveup_fac(struct kvm_vcpu *vcpu, ulong fac);
 
 /* Some compatibility defines */
 #ifdef CONFIG_PPC_BOOK3S_32
@@ -115,6 +116,9 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
 	svcpu->ctr = vcpu->arch.ctr;
 	svcpu->lr  = vcpu->arch.lr;
 	svcpu->pc  = vcpu->arch.pc;
+#ifdef CONFIG_PPC_BOOK3S_64
+	svcpu->shadow_fscr = vcpu->arch.shadow_fscr;
+#endif
 	svcpu->in_use = true;
 }
 
@@ -158,6 +162,9 @@ void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu,
 	vcpu->arch.fault_dar   = svcpu->fault_dar;
 	vcpu->arch.fault_dsisr = svcpu->fault_dsisr;
 	vcpu->arch.last_inst   = svcpu->last_inst;
+#ifdef CONFIG_PPC_BOOK3S_64
+	vcpu->arch.shadow_fscr = svcpu->shadow_fscr;
+#endif
 	svcpu->in_use = false;
 
 out:
@@ -610,6 +617,17 @@ void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr)
 	kvmppc_recalc_shadow_msr(vcpu);
 }
 
+/* Give up facility (TAR / EBB / DSCR) */
+static void kvmppc_giveup_fac(struct kvm_vcpu *vcpu, ulong fac)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+	if (!(vcpu->arch.shadow_fscr & (1ULL << fac))) {
+		/* Facility not available to the guest, ignore giveup request*/
+		return;
+	}
+#endif
+}
+
 static int kvmppc_read_inst(struct kvm_vcpu *vcpu)
 {
 	ulong srr0 = kvmppc_get_pc(vcpu);
@@ -741,6 +759,50 @@ static void kvmppc_handle_lost_ext(struct kvm_vcpu *vcpu)
 	current->thread.regs->msr |= lost_ext;
 }
 
+#ifdef CONFIG_PPC_BOOK3S_64
+
+static void kvmppc_trigger_fac_interrupt(struct kvm_vcpu *vcpu, ulong fac)
+{
+	/* Inject the Interrupt Cause field and trigger a guest interrupt */
+	vcpu->arch.fscr &= ~(0xffULL << 56);
+	vcpu->arch.fscr |= (fac << 56);
+	kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_FAC_UNAVAIL);
+}
+
+static void kvmppc_emulate_fac(struct kvm_vcpu *vcpu, ulong fac)
+{
+	enum emulation_result er = EMULATE_FAIL;
+
+	if (!(kvmppc_get_msr(vcpu) & MSR_PR))
+		er = kvmppc_emulate_instruction(vcpu->run, vcpu);
+
+	if ((er != EMULATE_DONE) && (er != EMULATE_AGAIN)) {
+		/* Couldn't emulate, trigger interrupt in guest */
+		kvmppc_trigger_fac_interrupt(vcpu, fac);
+	}
+}
+
+/* Enable facilities (TAR, EBB, DSCR) for the guest */
+static int kvmppc_handle_fac(struct kvm_vcpu *vcpu, ulong fac)
+{
+	BUG_ON(!cpu_has_feature(CPU_FTR_ARCH_207S));
+
+	if (!(vcpu->arch.fscr & (1ULL << fac))) {
+		/* Facility not enabled by the guest */
+		kvmppc_trigger_fac_interrupt(vcpu, fac);
+		return RESUME_GUEST;
+	}
+
+	switch (fac) {
+	default:
+		kvmppc_emulate_fac(vcpu, fac);
+		break;
+	}
+
+	return RESUME_GUEST;
+}
+#endif
+
 int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			  unsigned int exit_nr)
 {
@@ -1015,6 +1077,12 @@ program_interrupt:
 		}
 		r = RESUME_GUEST;
 		break;
+#ifdef CONFIG_PPC_BOOK3S_64
+	case BOOK3S_INTERRUPT_FAC_UNAVAIL:
+		kvmppc_handle_fac(vcpu, vcpu->arch.shadow_fscr >> 56);
+		r = RESUME_GUEST;
+		break;
+#endif
 	case BOOK3S_INTERRUPT_MACHINE_CHECK:
 	case BOOK3S_INTERRUPT_TRACE:
 		kvmppc_book3s_queue_irqprio(vcpu, exit_nr);

arch/powerpc/kvm/book3s_segment.S

@@ -90,6 +90,15 @@ kvmppc_handler_trampoline_enter:
 	LOAD_GUEST_SEGMENTS
 
 #ifdef CONFIG_PPC_BOOK3S_64
+BEGIN_FTR_SECTION
+	/* Save host FSCR */
+	mfspr	r8, SPRN_FSCR
+	std	r8, HSTATE_HOST_FSCR(r13)
+	/* Set FSCR during guest execution */
+	ld	r9, SVCPU_SHADOW_FSCR(r13)
+	mtspr	SPRN_FSCR, r9
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
+
 	/* Some guests may need to have dcbz set to 32 byte length.
 	 *
 	 * Usually we ensure that by patching the guest's instructions
@@ -255,6 +264,10 @@ BEGIN_FTR_SECTION
 	cmpwi	r12, BOOK3S_INTERRUPT_H_EMUL_ASSIST
 	beq-	ld_last_inst
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
+BEGIN_FTR_SECTION
+	cmpwi	r12, BOOK3S_INTERRUPT_FAC_UNAVAIL
+	beq-	ld_last_inst
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 #endif
 
 	b	no_ld_last_inst
@@ -311,6 +324,18 @@ no_ld_last_inst:
 
 no_dcbz32_off:
 
+BEGIN_FTR_SECTION
+	/* Save guest FSCR on a FAC_UNAVAIL interrupt */
+	cmpwi	r12, BOOK3S_INTERRUPT_FAC_UNAVAIL
+	bne+	no_fscr_save
+	mfspr	r7, SPRN_FSCR
+	std	r7, SVCPU_SHADOW_FSCR(r13)
+no_fscr_save:
+	/* Restore host FSCR */
+	ld	r8, HSTATE_HOST_FSCR(r13)
+	mtspr	SPRN_FSCR, r8
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
+
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 	/*