KVM: PPC: Book3S HV: Add new POWER9 guest-accessible SPRs

This adds code to handle two new guest-accessible special-purpose
registers on POWER9: TIDR (thread ID register) and PSSCR (processor
stop status and control register).  They are context-switched
between host and guest, and the guest values can be read and set
via the one_reg interface.

The PSSCR contains some fields which are guest-accessible and some
which are only accessible in hypervisor mode.  We only allow the
guest-accessible fields to be read or set by userspace.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Documentation/virtual/kvm/api.txt

@@ -2023,6 +2023,8 @@ registers, find a list below:
   PPC   | KVM_REG_PPC_WORT              | 64
   PPC	| KVM_REG_PPC_SPRG9             | 64
   PPC	| KVM_REG_PPC_DBSR              | 32
+  PPC   | KVM_REG_PPC_TIDR              | 64
+  PPC   | KVM_REG_PPC_PSSCR             | 64
   PPC   | KVM_REG_PPC_TM_GPR0           | 64
           ...
   PPC   | KVM_REG_PPC_TM_GPR31          | 64

arch/powerpc/include/asm/kvm_host.h

@@ -517,6 +517,8 @@ struct kvm_vcpu_arch {
 	ulong tcscr;
 	ulong acop;
 	ulong wort;
+	ulong tid;
+	ulong psscr;
 	ulong shadow_srr1;
 #endif
 	u32 vrsave; /* also USPRG0 */

arch/powerpc/include/uapi/asm/kvm.h

@@ -573,6 +573,10 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
 #define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)
 
+/* POWER9 registers */
+#define KVM_REG_PPC_TIDR	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xbc)
+#define KVM_REG_PPC_PSSCR	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xbd)
+
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs
  */

arch/powerpc/kernel/asm-offsets.c

@@ -548,6 +548,8 @@ int main(void)
 	DEFINE(VCPU_TCSCR, offsetof(struct kvm_vcpu, arch.tcscr));
 	DEFINE(VCPU_ACOP, offsetof(struct kvm_vcpu, arch.acop));
 	DEFINE(VCPU_WORT, offsetof(struct kvm_vcpu, arch.wort));
+	DEFINE(VCPU_TID, offsetof(struct kvm_vcpu, arch.tid));
+	DEFINE(VCPU_PSSCR, offsetof(struct kvm_vcpu, arch.psscr));
 	DEFINE(VCORE_ENTRY_EXIT, offsetof(struct kvmppc_vcore, entry_exit_map));
 	DEFINE(VCORE_IN_GUEST, offsetof(struct kvmppc_vcore, in_guest));
 	DEFINE(VCORE_NAPPING_THREADS, offsetof(struct kvmppc_vcore, napping_threads));

arch/powerpc/kvm/book3s_hv.c

@@ -1230,6 +1230,12 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_WORT:
 		*val = get_reg_val(id, vcpu->arch.wort);
 		break;
+	case KVM_REG_PPC_TIDR:
+		*val = get_reg_val(id, vcpu->arch.tid);
+		break;
+	case KVM_REG_PPC_PSSCR:
+		*val = get_reg_val(id, vcpu->arch.psscr);
+		break;
 	case KVM_REG_PPC_VPA_ADDR:
 		spin_lock(&vcpu->arch.vpa_update_lock);
 		*val = get_reg_val(id, vcpu->arch.vpa.next_gpa);
@@ -1431,6 +1437,12 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id,
 	case KVM_REG_PPC_WORT:
 		vcpu->arch.wort = set_reg_val(id, *val);
 		break;
+	case KVM_REG_PPC_TIDR:
+		vcpu->arch.tid = set_reg_val(id, *val);
+		break;
+	case KVM_REG_PPC_PSSCR:
+		vcpu->arch.psscr = set_reg_val(id, *val) & PSSCR_GUEST_VIS;
+		break;
 	case KVM_REG_PPC_VPA_ADDR:
 		addr = set_reg_val(id, *val);
 		r = -EINVAL;

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -523,6 +523,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
  *                                                                            *
  *****************************************************************************/
 
+/* Stack frame offsets */
+#define STACK_SLOT_TID		(112-16)
+#define STACK_SLOT_PSSCR	(112-24)
+
 .global kvmppc_hv_entry
 kvmppc_hv_entry:
 
@@ -700,6 +704,14 @@ kvmppc_got_guest:
 	mtspr	SPRN_PURR,r7
 	mtspr	SPRN_SPURR,r8
 
+	/* Save host values of some registers */
+BEGIN_FTR_SECTION
+	mfspr	r5, SPRN_TIDR
+	mfspr	r6, SPRN_PSSCR
+	std	r5, STACK_SLOT_TID(r1)
+	std	r6, STACK_SLOT_PSSCR(r1)
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
+
 BEGIN_FTR_SECTION
 	/* Set partition DABR */
 	/* Do this before re-enabling PMU to avoid P7 DABR corruption bug */
@@ -824,6 +836,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
 	mtspr	SPRN_PID, r7
 	mtspr	SPRN_WORT, r8
 BEGIN_FTR_SECTION
+	/* POWER8-only registers */
 	ld	r5, VCPU_TCSCR(r4)
 	ld	r6, VCPU_ACOP(r4)
 	ld	r7, VCPU_CSIGR(r4)
@@ -832,7 +845,14 @@ BEGIN_FTR_SECTION
 	mtspr	SPRN_ACOP, r6
 	mtspr	SPRN_CSIGR, r7
 	mtspr	SPRN_TACR, r8
-END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
+FTR_SECTION_ELSE
+	/* POWER9-only registers */
+	ld	r5, VCPU_TID(r4)
+	ld	r6, VCPU_PSSCR(r4)
+	oris	r6, r6, PSSCR_EC@h	/* This makes stop trap to HV */
+	mtspr	SPRN_TIDR, r5
+	mtspr	SPRN_PSSCR, r6
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
 8:
 
 	/*
@@ -1362,7 +1382,14 @@ BEGIN_FTR_SECTION
 	std	r6, VCPU_ACOP(r9)
 	std	r7, VCPU_CSIGR(r9)
 	std	r8, VCPU_TACR(r9)
-END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
+FTR_SECTION_ELSE
+	mfspr	r5, SPRN_TIDR
+	mfspr	r6, SPRN_PSSCR
+	std	r5, VCPU_TID(r9)
+	rldicl	r6, r6, 4, 50		/* r6 &= PSSCR_GUEST_VIS */
+	rotldi	r6, r6, 60
+	std	r6, VCPU_PSSCR(r9)
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
 	/*
 	 * Restore various registers to 0, where non-zero values
 	 * set by the guest could disrupt the host.
@@ -1531,6 +1558,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	slbia
 	ptesync
 
+	/* Restore host values of some registers */
+BEGIN_FTR_SECTION
+	ld	r5, STACK_SLOT_TID(r1)
+	ld	r6, STACK_SLOT_PSSCR(r1)
+	mtspr	SPRN_TIDR, r5
+	mtspr	SPRN_PSSCR, r6
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
+
 	/*
 	 * POWER7/POWER8 guest -> host partition switch code.
 	 * We don't have to lock against tlbies but we do