KVM: PPC: Book3S HV: Introduce low level MSR accessor

kvmppc_get_msr() and kvmppc_set_msr_fast() serve as accessors for the
MSR. However because the MSR is kept in the shared regs they include a
conditional check for kvmppc_shared_big_endian() and endian conversion.

Within the Book3S HV specific code there are direct reads and writes of
shregs::msr. In preparation for Nested APIv2 these accesses need to be
replaced with accessor functions so it is possible to extend their
behavior. However, using the kvmppc_get_msr() and kvmppc_set_msr_fast()
functions is undesirable because it would introduce a conditional branch
and endian conversion that is not currently present.

kvmppc_set_msr_hv() already exists, it is used for the
kvmppc_ops::set_msr callback.

Introduce a low level accessor __kvmppc_{s,g}et_msr_hv() that simply
gets and sets shregs::msr. This will be extend for Nested APIv2 support.

Signed-off-by: Jordan Niethe <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://msgid.link/[e-mail]

arch/powerpc/kvm/book3s_64_mmu_hv.c

···
 #include <asm/pte-walk.h>
 
 #include "book3s.h"
+#include "book3s_hv.h"
 #include "trace_hv.h"
 
 //#define DEBUG_RESIZE_HPT	1
···
 	unsigned long v, orig_v, gr;
 	__be64 *hptep;
 	long int index;
-	int virtmode = vcpu->arch.shregs.msr & (data ? MSR_DR : MSR_IR);
+	int virtmode = __kvmppc_get_msr_hv(vcpu) & (data ? MSR_DR : MSR_IR);
 
 	if (kvm_is_radix(vcpu->kvm))
 		return kvmppc_mmu_radix_xlate(vcpu, eaddr, gpte, data, iswrite);
···
 
 	/* Get PP bits and key for permission check */
 	pp = gr & (HPTE_R_PP0 | HPTE_R_PP);
-	key = (vcpu->arch.shregs.msr & MSR_PR) ? SLB_VSID_KP : SLB_VSID_KS;
+	key = (__kvmppc_get_msr_hv(vcpu) & MSR_PR) ? SLB_VSID_KP : SLB_VSID_KS;
 	key &= slb_v;
 
 	/* Calculate permissions */

arch/powerpc/kvm/book3s_hv.c

···
  */
 static void kvmppc_cede(struct kvm_vcpu *vcpu)
 {
-	vcpu->arch.shregs.msr |= MSR_EE;
+	__kvmppc_set_msr_hv(vcpu, __kvmppc_get_msr_hv(vcpu) | MSR_EE);
 	vcpu->arch.ceded = 1;
 	smp_mb();
 	if (vcpu->arch.prodded) {
···
 	 * That can happen due to a bug, or due to a machine check
 	 * occurring at just the wrong time.
 	 */
-	if (vcpu->arch.shregs.msr & MSR_HV) {
+	if (__kvmppc_get_msr_hv(vcpu) & MSR_HV) {
 		printk(KERN_EMERG "KVM trap in HV mode!\n");
 		printk(KERN_EMERG "trap=0x%x | pc=0x%lx | msr=0x%llx\n",
 			vcpu->arch.trap, kvmppc_get_pc(vcpu),
···
 		 * so that it knows that the machine check occurred.
 		 */
 		if (!vcpu->kvm->arch.fwnmi_enabled) {
-			ulong flags = (vcpu->arch.shregs.msr & 0x083c0000) |
+			ulong flags = (__kvmppc_get_msr_hv(vcpu) & 0x083c0000) |
 					(kvmppc_get_msr(vcpu) & SRR1_PREFIXED);
 			kvmppc_core_queue_machine_check(vcpu, flags);
 			r = RESUME_GUEST;
···
 		 * as a result of a hypervisor emulation interrupt
 		 * (e40) getting turned into a 700 by BML RTAS.
 		 */
-		flags = (vcpu->arch.shregs.msr & 0x1f0000ull) |
+		flags = (__kvmppc_get_msr_hv(vcpu) & 0x1f0000ull) |
 			(kvmppc_get_msr(vcpu) & SRR1_PREFIXED);
 		kvmppc_core_queue_program(vcpu, flags);
 		r = RESUME_GUEST;
···
 	{
 		int i;
 
-		if (unlikely(vcpu->arch.shregs.msr & MSR_PR)) {
+		if (unlikely(__kvmppc_get_msr_hv(vcpu) & MSR_PR)) {
 			/*
 			 * Guest userspace executed sc 1. This can only be
 			 * reached by the P9 path because the old path
···
 			break;
 		}
 
-		if (!(vcpu->arch.shregs.msr & MSR_DR))
+		if (!(__kvmppc_get_msr_hv(vcpu) & MSR_DR))
 			vsid = vcpu->kvm->arch.vrma_slb_v;
 		else
 			vsid = vcpu->arch.fault_gpa;
···
 		long err;
 
 		vcpu->arch.fault_dar = kvmppc_get_pc(vcpu);
-		vcpu->arch.fault_dsisr = vcpu->arch.shregs.msr &
+		vcpu->arch.fault_dsisr = __kvmppc_get_msr_hv(vcpu) &
 			DSISR_SRR1_MATCH_64S;
 		if (kvm_is_radix(vcpu->kvm) || !cpu_has_feature(CPU_FTR_ARCH_300)) {
 			/*
···
 			 * hash fault handling below is v3 only (it uses ASDR
 			 * via fault_gpa).
 			 */
-			if (vcpu->arch.shregs.msr & HSRR1_HISI_WRITE)
+			if (__kvmppc_get_msr_hv(vcpu) & HSRR1_HISI_WRITE)
 				vcpu->arch.fault_dsisr |= DSISR_ISSTORE;
 			r = RESUME_PAGE_FAULT;
 			break;
···
 			break;
 		}
 
-		if (!(vcpu->arch.shregs.msr & MSR_IR))
+		if (!(__kvmppc_get_msr_hv(vcpu) & MSR_IR))
 			vsid = vcpu->kvm->arch.vrma_slb_v;
 		else
 			vsid = vcpu->arch.fault_gpa;
···
 		kvmppc_dump_regs(vcpu);
 		printk(KERN_EMERG "trap=0x%x | pc=0x%lx | msr=0x%llx\n",
 			vcpu->arch.trap, kvmppc_get_pc(vcpu),
-			vcpu->arch.shregs.msr);
+			__kvmppc_get_msr_hv(vcpu));
 		run->hw.hardware_exit_reason = vcpu->arch.trap;
 		r = RESUME_HOST;
 		break;
···
 	 * That can happen due to a bug, or due to a machine check
 	 * occurring at just the wrong time.
 	 */
-	if (vcpu->arch.shregs.msr & MSR_HV) {
+	if (__kvmppc_get_msr_hv(vcpu) & MSR_HV) {
 		pr_emerg("KVM trap in HV mode while nested!\n");
 		pr_emerg("trap=0x%x | pc=0x%lx | msr=0x%llx\n",
 			 vcpu->arch.trap, kvmppc_get_pc(vcpu),
-			 vcpu->arch.shregs.msr);
+			 __kvmppc_get_msr_hv(vcpu));
 		kvmppc_dump_regs(vcpu);
 		return RESUME_HOST;
 	}
···
 		vcpu->arch.fault_dar = kvmppc_get_pc(vcpu);
 		vcpu->arch.fault_dsisr = kvmppc_get_msr(vcpu) &
 					 DSISR_SRR1_MATCH_64S;
-		if (vcpu->arch.shregs.msr & HSRR1_HISI_WRITE)
+		if (__kvmppc_get_msr_hv(vcpu) & HSRR1_HISI_WRITE)
 			vcpu->arch.fault_dsisr |= DSISR_ISSTORE;
 		srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 		r = kvmhv_nested_page_fault(vcpu);
···
 	spin_lock_init(&vcpu->arch.vpa_update_lock);
 	spin_lock_init(&vcpu->arch.tbacct_lock);
 	vcpu->arch.busy_preempt = TB_NIL;
-	vcpu->arch.shregs.msr = MSR_ME;
+	__kvmppc_set_msr_hv(vcpu, MSR_ME);
 	vcpu->arch.intr_msr = MSR_SF | MSR_ME;
 
 	/*
···
 		__this_cpu_write(cpu_in_guest, NULL);
 
 		if (trap == BOOK3S_INTERRUPT_SYSCALL &&
-		    !(vcpu->arch.shregs.msr & MSR_PR)) {
+		    !(__kvmppc_get_msr_hv(vcpu) & MSR_PR)) {
 			unsigned long req = kvmppc_get_gpr(vcpu, 3);
 
 			/*
···
 
 	if (!nested) {
 		kvmppc_core_prepare_to_enter(vcpu);
-		if (vcpu->arch.shregs.msr & MSR_EE) {
+		if (__kvmppc_get_msr_hv(vcpu) & MSR_EE) {
 			if (xive_interrupt_pending(vcpu))
 				kvmppc_inject_interrupt_hv(vcpu,
 						BOOK3S_INTERRUPT_EXTERNAL, 0);
···
 		if (run->exit_reason == KVM_EXIT_PAPR_HCALL) {
 			accumulate_time(vcpu, &vcpu->arch.hcall);
 
-			if (WARN_ON_ONCE(vcpu->arch.shregs.msr & MSR_PR)) {
+			if (WARN_ON_ONCE(__kvmppc_get_msr_hv(vcpu) & MSR_PR)) {
 				/*
 				 * These should have been caught reflected
 				 * into the guest by now. Final sanity check:

arch/powerpc/kvm/book3s_hv.h

···
 #define end_timing(vcpu) do {} while (0)
 #endif
 
+static inline void __kvmppc_set_msr_hv(struct kvm_vcpu *vcpu, u64 val)
+{
+	vcpu->arch.shregs.msr = val;
+}
+
+static inline u64 __kvmppc_get_msr_hv(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.shregs.msr;
+}
+
 #define KVMPPC_BOOK3S_HV_VCPU_ACCESSOR_SET(reg, size)			\
 static inline void kvmppc_set_##reg ##_hv(struct kvm_vcpu *vcpu, u##size val)	\
 {									\

arch/powerpc/kvm/book3s_hv_builtin.c

···
 
 #include "book3s_xics.h"
 #include "book3s_xive.h"
+#include "book3s_hv.h"
 
 /*
  * Hash page table alignment on newer cpus(CPU_FTR_ARCH_206)
···
 	 */
 	if ((msr & MSR_TS_MASK) == MSR_TS_MASK)
 		msr &= ~MSR_TS_MASK;
-	vcpu->arch.shregs.msr = msr;
+	__kvmppc_set_msr_hv(vcpu, msr);
 	kvmppc_end_cede(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvmppc_set_msr_hv);
···
 	kvmppc_set_srr0(vcpu, pc);
 	kvmppc_set_srr1(vcpu, (msr & SRR1_MSR_BITS) | srr1_flags);
 	kvmppc_set_pc(vcpu, new_pc);
-	vcpu->arch.shregs.msr = new_msr;
+	__kvmppc_set_msr_hv(vcpu, new_msr);
 }
 
 void kvmppc_inject_interrupt_hv(struct kvm_vcpu *vcpu, int vec, u64 srr1_flags)