KVM: PPC: Make shared struct aka magic page guest endian

The shared (magic) page is a data structure that contains often used
supervisor privileged SPRs accessible via memory to the user to reduce
the number of exits we have to take to read/write them.

When we actually share this structure with the guest we have to maintain
it in guest endianness, because some of the patch tricks only work with
native endian load/store operations.

Since we only share the structure with either host or guest in little
endian on book3s_64 pr mode, we don't have to worry about booke or book3s hv.

For booke, the shared struct stays big endian. For book3s_64 hv we maintain
the struct in host native endian, since it never gets shared with the guest.

For book3s_64 pr we introduce a variable that tells us which endianness the
shared struct is in and route every access to it through helper inline
functions that evaluate this variable.

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

1 files changed, 58 insertions, 39 deletions

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index d7b0ad2bffe4..d424ca053765 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -246,14 +246,15 @@ static void kvm_set_spte_hva_pr(struct kvm *kvm, unsigned long hva, pte_t pte)
 
 static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
 {
-	ulong smsr = vcpu->arch.shared->msr;
+	ulong guest_msr = kvmppc_get_msr(vcpu);
+	ulong smsr = guest_msr;
 
 	/* Guest MSR values */
 	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_LE;
 	/* Process MSR values */
 	smsr |= MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_PR | MSR_EE;
 	/* External providers the guest reserved */
-	smsr |= (vcpu->arch.shared->msr & vcpu->arch.guest_owned_ext);
+	smsr |= (guest_msr & vcpu->arch.guest_owned_ext);
 	/* 64-bit Process MSR values */
 #ifdef CONFIG_PPC_BOOK3S_64
 	smsr |= MSR_ISF | MSR_HV;
@@ -263,14 +264,14 @@ static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
 
 static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr)
 {
-	ulong old_msr = vcpu->arch.shared->msr;
+	ulong old_msr = kvmppc_get_msr(vcpu);
 
 #ifdef EXIT_DEBUG
 	printk(KERN_INFO "KVM: Set MSR to 0x%llx\n", msr);
 #endif
 
 	msr &= to_book3s(vcpu)->msr_mask;
-	vcpu->arch.shared->msr = msr;
+	kvmppc_set_msr_fast(vcpu, msr);
 	kvmppc_recalc_shadow_msr(vcpu);
 
 	if (msr & MSR_POW) {
@@ -281,11 +282,11 @@ static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr)
 
 			/* Unset POW bit after we woke up */
 			msr &= ~MSR_POW;
-			vcpu->arch.shared->msr = msr;
+			kvmppc_set_msr_fast(vcpu, msr);
 		}
 	}
 
-	if ((vcpu->arch.shared->msr & (MSR_PR|MSR_IR|MSR_DR)) !=
+	if ((kvmppc_get_msr(vcpu) & (MSR_PR|MSR_IR|MSR_DR)) !=
 		   (old_msr & (MSR_PR|MSR_IR|MSR_DR))) {
 		kvmppc_mmu_flush_segments(vcpu);
 		kvmppc_mmu_map_segment(vcpu, kvmppc_get_pc(vcpu));
@@ -317,7 +318,7 @@ static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr)
 	}
 
 	/* Preload FPU if it's enabled */
-	if (vcpu->arch.shared->msr & MSR_FP)
+	if (kvmppc_get_msr(vcpu) & MSR_FP)
 		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
 }
 
@@ -438,7 +439,7 @@ static int kvmppc_visible_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	ulong mp_pa = vcpu->arch.magic_page_pa;
 
-	if (!(vcpu->arch.shared->msr & MSR_SF))
+	if (!(kvmppc_get_msr(vcpu) & MSR_SF))
 		mp_pa = (uint32_t)mp_pa;
 
 	if (unlikely(mp_pa) &&
@@ -459,8 +460,8 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	int page_found = 0;
 	struct kvmppc_pte pte;
 	bool is_mmio = false;
-	bool dr = (vcpu->arch.shared->msr & MSR_DR) ? true : false;
-	bool ir = (vcpu->arch.shared->msr & MSR_IR) ? true : false;
+	bool dr = (kvmppc_get_msr(vcpu) & MSR_DR) ? true : false;
+	bool ir = (kvmppc_get_msr(vcpu) & MSR_IR) ? true : false;
 	u64 vsid;
 
 	relocated = data ? dr : ir;
@@ -480,7 +481,7 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		pte.page_size = MMU_PAGE_64K;
 	}
 
-	switch (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
+	switch (kvmppc_get_msr(vcpu) & (MSR_DR|MSR_IR)) {
 	case 0:
 		pte.vpage |= ((u64)VSID_REAL << (SID_SHIFT - 12));
 		break;
@@ -488,7 +489,7 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	case MSR_IR:
 		vcpu->arch.mmu.esid_to_vsid(vcpu, eaddr >> SID_SHIFT, &vsid);
 
-		if ((vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) == MSR_DR)
+		if ((kvmppc_get_msr(vcpu) & (MSR_DR|MSR_IR)) == MSR_DR)
 			pte.vpage |= ((u64)VSID_REAL_DR << (SID_SHIFT - 12));
 		else
 			pte.vpage |= ((u64)VSID_REAL_IR << (SID_SHIFT - 12));
@@ -511,22 +512,25 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 
 	if (page_found == -ENOENT) {
 		/* Page not found in guest PTE entries */
-		vcpu->arch.shared->dar = kvmppc_get_fault_dar(vcpu);
-		vcpu->arch.shared->dsisr = vcpu->arch.fault_dsisr;
-		vcpu->arch.shared->msr |=
-			vcpu->arch.shadow_srr1 & 0x00000000f8000000ULL;
+		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 */
-		vcpu->arch.shared->dar = kvmppc_get_fault_dar(vcpu);
-		vcpu->arch.shared->dsisr = vcpu->arch.fault_dsisr & ~DSISR_NOHPTE;
-		vcpu->arch.shared->dsisr |= DSISR_PROTFAULT;
-		vcpu->arch.shared->msr |=
-			vcpu->arch.shadow_srr1 & 0x00000000f8000000ULL;
+		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);
 	} else if (page_found == -EINVAL) {
 		/* Page not found in guest SLB */
-		vcpu->arch.shared->dar = kvmppc_get_fault_dar(vcpu);
+		kvmppc_set_dar(vcpu, kvmppc_get_fault_dar(vcpu));
 		kvmppc_book3s_queue_irqprio(vcpu, vec + 0x80);
 	} else if (!is_mmio &&
 		   kvmppc_visible_gfn(vcpu, pte.raddr >> PAGE_SHIFT)) {
@@ -614,11 +618,12 @@ static int kvmppc_read_inst(struct kvm_vcpu *vcpu)
 
 	ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
 	if (ret == -ENOENT) {
-		ulong msr = vcpu->arch.shared->msr;
+		ulong msr = kvmppc_get_msr(vcpu);
 
 		msr = kvmppc_set_field(msr, 33, 33, 1);
 		msr = kvmppc_set_field(msr, 34, 36, 0);
-		vcpu->arch.shared->msr = kvmppc_set_field(msr, 42, 47, 0);
+		msr = kvmppc_set_field(msr, 42, 47, 0);
+		kvmppc_set_msr_fast(vcpu, msr);
 		kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_INST_STORAGE);
 		return EMULATE_AGAIN;
 	}
@@ -651,7 +656,7 @@ static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
 	if (vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE)
 		return RESUME_GUEST;
 
-	if (!(vcpu->arch.shared->msr & msr)) {
+	if (!(kvmppc_get_msr(vcpu) & msr)) {
 		kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 		return RESUME_GUEST;
 	}
@@ -792,7 +797,9 @@ 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 {
-			vcpu->arch.shared->msr |= shadow_srr1 & 0x58000000;
+			u64 msr = kvmppc_get_msr(vcpu);
+			msr |= shadow_srr1 & 0x58000000;
+			kvmppc_set_msr_fast(vcpu, msr);
 			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 			r = RESUME_GUEST;
 		}
@@ -832,8 +839,8 @@ 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 {
-			vcpu->arch.shared->dar = dar;
-			vcpu->arch.shared->dsisr = fault_dsisr;
+			kvmppc_set_dar(vcpu, dar);
+			kvmppc_set_dsisr(vcpu, fault_dsisr);
 			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 			r = RESUME_GUEST;
 		}
@@ -841,7 +848,7 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	}
 	case BOOK3S_INTERRUPT_DATA_SEGMENT:
 		if (kvmppc_mmu_map_segment(vcpu, kvmppc_get_fault_dar(vcpu)) < 0) {
-			vcpu->arch.shared->dar = kvmppc_get_fault_dar(vcpu);
+			kvmppc_set_dar(vcpu, kvmppc_get_fault_dar(vcpu));
 			kvmppc_book3s_queue_irqprio(vcpu,
 				BOOK3S_INTERRUPT_DATA_SEGMENT);
 		}
@@ -879,7 +886,7 @@ int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
 program_interrupt:
 		flags = vcpu->arch.shadow_srr1 & 0x1f0000ull;
 
-		if (vcpu->arch.shared->msr & MSR_PR) {
+		if (kvmppc_get_msr(vcpu) & MSR_PR) {
 #ifdef EXIT_DEBUG
 			printk(KERN_INFO "Userspace triggered 0x700 exception at 0x%lx (0x%x)\n", kvmppc_get_pc(vcpu), kvmppc_get_last_inst(vcpu));
 #endif
@@ -921,7 +928,7 @@ program_interrupt:
 	case BOOK3S_INTERRUPT_SYSCALL:
 		if (vcpu->arch.papr_enabled &&
 		    (kvmppc_get_last_sc(vcpu) == 0x44000022) &&
-		    !(vcpu->arch.shared->msr & MSR_PR)) {
+		    !(kvmppc_get_msr(vcpu) & MSR_PR)) {
 			/* SC 1 papr hypercalls */
 			ulong cmd = kvmppc_get_gpr(vcpu, 3);
 			int i;
@@ -953,7 +960,7 @@ program_interrupt:
 				gprs[i] = kvmppc_get_gpr(vcpu, i);
 			vcpu->arch.osi_needed = 1;
 			r = RESUME_HOST_NV;
-		} else if (!(vcpu->arch.shared->msr & MSR_PR) &&
+		} else if (!(kvmppc_get_msr(vcpu) & MSR_PR) &&
 		    (((u32)kvmppc_get_gpr(vcpu, 0)) == KVM_SC_MAGIC_R0)) {
 			/* KVM PV hypercalls */
 			kvmppc_set_gpr(vcpu, 3, kvmppc_kvm_pv(vcpu));
@@ -994,10 +1001,16 @@ program_interrupt:
 	}
 	case BOOK3S_INTERRUPT_ALIGNMENT:
 		if (kvmppc_read_inst(vcpu) == EMULATE_DONE) {
-			vcpu->arch.shared->dsisr = kvmppc_alignment_dsisr(vcpu,
-				kvmppc_get_last_inst(vcpu));
-			vcpu->arch.shared->dar = kvmppc_alignment_dar(vcpu,
-				kvmppc_get_last_inst(vcpu));
+			u32 last_inst = kvmppc_get_last_inst(vcpu);
+			u32 dsisr;
+			u64 dar;
+
+			dsisr = kvmppc_alignment_dsisr(vcpu, last_inst);
+			dar = kvmppc_alignment_dar(vcpu, last_inst);
+
+			kvmppc_set_dsisr(vcpu, dsisr);
+			kvmppc_set_dar(vcpu, dar);
+
 			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 		}
 		r = RESUME_GUEST;
@@ -1062,7 +1075,7 @@ static int kvm_arch_vcpu_ioctl_get_sregs_pr(struct kvm_vcpu *vcpu,
 		}
 	} else {
 		for (i = 0; i < 16; i++)
-			sregs->u.s.ppc32.sr[i] = vcpu->arch.shared->sr[i];
+			sregs->u.s.ppc32.sr[i] = kvmppc_get_sr(vcpu, i);
 
 		for (i = 0; i < 8; i++) {
 			sregs->u.s.ppc32.ibat[i] = vcpu3s->ibat[i].raw;
@@ -1198,8 +1211,14 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_pr(struct kvm *kvm,
 		goto uninit_vcpu;
 	/* the real shared page fills the last 4k of our page */
 	vcpu->arch.shared = (void *)(p + PAGE_SIZE - 4096);
-
 #ifdef CONFIG_PPC_BOOK3S_64
+	/* Always start the shared struct in native endian mode */
+#ifdef __BIG_ENDIAN__
+        vcpu->arch.shared_big_endian = true;
+#else
+        vcpu->arch.shared_big_endian = false;
+#endif
+
 	/*
 	 * Default to the same as the host if we're on sufficiently
 	 * recent machine that we have 1TB segments;
@@ -1293,7 +1312,7 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
 
 	/* Preload FPU if it's enabled */
-	if (vcpu->arch.shared->msr & MSR_FP)
+	if (kvmppc_get_msr(vcpu) & MSR_FP)
 		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
 
 	kvmppc_fix_ee_before_entry();