KVM: PPC: Convert MSR to shared page

One of the most obvious registers to share with the guest directly is the
MSR. The MSR contains the "interrupts enabled" flag which the guest has to
toggle in critical sections.

So in order to bring the overhead of interrupt en- and disabling down, let's
put msr into the shared page. Keep in mind that even though you can fully read
its contents, writing to it doesn't always update all state. There are a few
safe fields that don't require hypervisor interaction. See the documentation
for a list of MSR bits that are safe to be set from inside the guest.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/include/asm/kvm_host.h

@@ -211,7 +211,6 @@ struct kvm_vcpu_arch {
 	u32 cr;
 #endif
 
-	ulong msr;
 #ifdef CONFIG_PPC_BOOK3S
 	ulong shadow_msr;
 	ulong hflags;

arch/powerpc/include/asm/kvm_para.h

@@ -23,6 +23,7 @@
 #include <linux/types.h>
 
 struct kvm_vcpu_arch_shared {
+	__u64 msr;
 };
 
 #ifdef __KERNEL__

arch/powerpc/kernel/asm-offsets.c

@@ -394,13 +394,13 @@ int main(void)
 	DEFINE(VCPU_HOST_STACK, offsetof(struct kvm_vcpu, arch.host_stack));
 	DEFINE(VCPU_HOST_PID, offsetof(struct kvm_vcpu, arch.host_pid));
 	DEFINE(VCPU_GPRS, offsetof(struct kvm_vcpu, arch.gpr));
-	DEFINE(VCPU_MSR, offsetof(struct kvm_vcpu, arch.msr));
 	DEFINE(VCPU_SPRG4, offsetof(struct kvm_vcpu, arch.sprg4));
 	DEFINE(VCPU_SPRG5, offsetof(struct kvm_vcpu, arch.sprg5));
 	DEFINE(VCPU_SPRG6, offsetof(struct kvm_vcpu, arch.sprg6));
 	DEFINE(VCPU_SPRG7, offsetof(struct kvm_vcpu, arch.sprg7));
 	DEFINE(VCPU_SHADOW_PID, offsetof(struct kvm_vcpu, arch.shadow_pid));
 	DEFINE(VCPU_SHARED, offsetof(struct kvm_vcpu, arch.shared));
+	DEFINE(VCPU_SHARED_MSR, offsetof(struct kvm_vcpu_arch_shared, msr));
 
 	/* book3s */
 #ifdef CONFIG_PPC_BOOK3S

arch/powerpc/kvm/44x_tlb.c

@@ -221,14 +221,14 @@ gpa_t kvmppc_mmu_xlate(struct kvm_vcpu *vcpu, unsigned int gtlb_index,
 
 int kvmppc_mmu_itlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
 {
-	unsigned int as = !!(vcpu->arch.msr & MSR_IS);
+	unsigned int as = !!(vcpu->arch.shared->msr & MSR_IS);
 
 	return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
 }
 
 int kvmppc_mmu_dtlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
 {
-	unsigned int as = !!(vcpu->arch.msr & MSR_DS);
+	unsigned int as = !!(vcpu->arch.shared->msr & MSR_DS);
 
 	return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
 }
@@ -354,7 +354,7 @@ void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gpa_t gpaddr,
 
 	stlbe.word1 = (hpaddr & 0xfffffc00) | ((hpaddr >> 32) & 0xf);
 	stlbe.word2 = kvmppc_44x_tlb_shadow_attrib(flags,
-	                                            vcpu->arch.msr & MSR_PR);
+	                                            vcpu->arch.shared->msr & MSR_PR);
 	stlbe.tid = !(asid & 0xff);
 
 	/* Keep track of the reference so we can properly release it later. */
@@ -423,7 +423,7 @@ static int tlbe_is_host_safe(const struct kvm_vcpu *vcpu,
 
 	/* Does it match current guest AS? */
 	/* XXX what about IS != DS? */
-	if (get_tlb_ts(tlbe) != !!(vcpu->arch.msr & MSR_IS))
+	if (get_tlb_ts(tlbe) != !!(vcpu->arch.shared->msr & MSR_IS))
 		return 0;
 
 	gpa = get_tlb_raddr(tlbe);

arch/powerpc/kvm/book3s.c

@@ -115,31 +115,31 @@ static u32 kvmppc_get_dec(struct kvm_vcpu *vcpu)
 
 static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
 {
-	vcpu->arch.shadow_msr = vcpu->arch.msr;
+	ulong smsr = vcpu->arch.shared->msr;
+
 	/* Guest MSR values */
-	vcpu->arch.shadow_msr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE |
-				 MSR_BE | MSR_DE;
+	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_DE;
 	/* Process MSR values */
-	vcpu->arch.shadow_msr |= MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_PR |
-				 MSR_EE;
+	smsr |= MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_PR | MSR_EE;
 	/* External providers the guest reserved */
-	vcpu->arch.shadow_msr |= (vcpu->arch.msr & vcpu->arch.guest_owned_ext);
+	smsr |= (vcpu->arch.shared->msr & vcpu->arch.guest_owned_ext);
 	/* 64-bit Process MSR values */
 #ifdef CONFIG_PPC_BOOK3S_64
-	vcpu->arch.shadow_msr |= MSR_ISF | MSR_HV;
+	smsr |= MSR_ISF | MSR_HV;
 #endif
+	vcpu->arch.shadow_msr = smsr;
 }
 
 void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
 {
-	ulong old_msr = vcpu->arch.msr;
+	ulong old_msr = vcpu->arch.shared->msr;
 
 #ifdef EXIT_DEBUG
 	printk(KERN_INFO "KVM: Set MSR to 0x%llx\n", msr);
 #endif
 
 	msr &= to_book3s(vcpu)->msr_mask;
-	vcpu->arch.msr = msr;
+	vcpu->arch.shared->msr = msr;
 	kvmppc_recalc_shadow_msr(vcpu);
 
 	if (msr & (MSR_WE|MSR_POW)) {
@@ -149,21 +149,21 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
 		}
 	}
 
-	if ((vcpu->arch.msr & (MSR_PR|MSR_IR|MSR_DR)) !=
+	if ((vcpu->arch.shared->msr & (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));
 	}
 
 	/* Preload FPU if it's enabled */
-	if (vcpu->arch.msr & MSR_FP)
+	if (vcpu->arch.shared->msr & MSR_FP)
 		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
 }
 
 void kvmppc_inject_interrupt(struct kvm_vcpu *vcpu, int vec, u64 flags)
 {
 	vcpu->arch.srr0 = kvmppc_get_pc(vcpu);
-	vcpu->arch.srr1 = vcpu->arch.msr | flags;
+	vcpu->arch.srr1 = vcpu->arch.shared->msr | flags;
 	kvmppc_set_pc(vcpu, to_book3s(vcpu)->hior + vec);
 	vcpu->arch.mmu.reset_msr(vcpu);
 }
@@ -254,11 +254,11 @@ int kvmppc_book3s_irqprio_deliver(struct kvm_vcpu *vcpu, unsigned int priority)
 
 	switch (priority) {
 	case BOOK3S_IRQPRIO_DECREMENTER:
-		deliver = vcpu->arch.msr & MSR_EE;
+		deliver = vcpu->arch.shared->msr & MSR_EE;
 		vec = BOOK3S_INTERRUPT_DECREMENTER;
 		break;
 	case BOOK3S_IRQPRIO_EXTERNAL:
-		deliver = vcpu->arch.msr & MSR_EE;
+		deliver = vcpu->arch.shared->msr & MSR_EE;
 		vec = BOOK3S_INTERRUPT_EXTERNAL;
 		break;
 	case BOOK3S_IRQPRIO_SYSTEM_RESET:
@@ -437,7 +437,7 @@ static void kvmppc_patch_dcbz(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
 static int kvmppc_xlate(struct kvm_vcpu *vcpu, ulong eaddr, bool data,
 			 struct kvmppc_pte *pte)
 {
-	int relocated = (vcpu->arch.msr & (data ? MSR_DR : MSR_IR));
+	int relocated = (vcpu->arch.shared->msr & (data ? MSR_DR : MSR_IR));
 	int r;
 
 	if (relocated) {
@@ -545,8 +545,8 @@ 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.msr & MSR_DR) ? true : false;
-	bool ir = (vcpu->arch.msr & MSR_IR) ? true : false;
+	bool dr = (vcpu->arch.shared->msr & MSR_DR) ? true : false;
+	bool ir = (vcpu->arch.shared->msr & MSR_IR) ? true : false;
 	u64 vsid;
 
 	relocated = data ? dr : ir;
@@ -563,15 +563,15 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		pte.vpage = eaddr >> 12;
 	}
 
-	switch (vcpu->arch.msr & (MSR_DR|MSR_IR)) {
+	switch (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
 	case 0:
 		pte.vpage |= ((u64)VSID_REAL << (SID_SHIFT - 12));
 		break;
 	case MSR_DR:
 	case MSR_IR:
 		vcpu->arch.mmu.esid_to_vsid(vcpu, eaddr >> SID_SHIFT, &vsid);
 
-		if ((vcpu->arch.msr & (MSR_DR|MSR_IR)) == MSR_DR)
+		if ((vcpu->arch.shared->msr & (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));
@@ -596,14 +596,16 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		/* Page not found in guest PTE entries */
 		vcpu->arch.dear = kvmppc_get_fault_dar(vcpu);
 		to_book3s(vcpu)->dsisr = to_svcpu(vcpu)->fault_dsisr;
-		vcpu->arch.msr |= (to_svcpu(vcpu)->shadow_srr1 & 0x00000000f8000000ULL);
+		vcpu->arch.shared->msr |=
+			(to_svcpu(vcpu)->shadow_srr1 & 0x00000000f8000000ULL);
 		kvmppc_book3s_queue_irqprio(vcpu, vec);
 	} else if (page_found == -EPERM) {
 		/* Storage protection */
 		vcpu->arch.dear = kvmppc_get_fault_dar(vcpu);
 		to_book3s(vcpu)->dsisr = to_svcpu(vcpu)->fault_dsisr & ~DSISR_NOHPTE;
 		to_book3s(vcpu)->dsisr |= DSISR_PROTFAULT;
-		vcpu->arch.msr |= (to_svcpu(vcpu)->shadow_srr1 & 0x00000000f8000000ULL);
+		vcpu->arch.shared->msr |=
+			(to_svcpu(vcpu)->shadow_srr1 & 0x00000000f8000000ULL);
 		kvmppc_book3s_queue_irqprio(vcpu, vec);
 	} else if (page_found == -EINVAL) {
 		/* Page not found in guest SLB */
@@ -695,9 +697,11 @@ static int kvmppc_read_inst(struct kvm_vcpu *vcpu)
 
 	ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
 	if (ret == -ENOENT) {
-		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 33, 33, 1);
-		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 34, 36, 0);
-		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 42, 47, 0);
+		ulong msr = vcpu->arch.shared->msr;
+
+		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);
 		kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_INST_STORAGE);
 		return EMULATE_AGAIN;
 	}
@@ -736,7 +740,7 @@ 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.msr & msr)) {
+	if (!(vcpu->arch.shared->msr & msr)) {
 		kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 		return RESUME_GUEST;
 	}
@@ -804,7 +808,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	if ((exit_nr != 0x900) && (exit_nr != 0x500))
 		printk(KERN_EMERG "exit_nr=0x%x | pc=0x%lx | dar=0x%lx | msr=0x%lx\n",
 			exit_nr, kvmppc_get_pc(vcpu), kvmppc_get_fault_dar(vcpu),
-			vcpu->arch.msr);
+			vcpu->arch.shared->msr);
 #endif
 	kvm_resched(vcpu);
 	switch (exit_nr) {
@@ -836,7 +840,8 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			kvmppc_mmu_pte_flush(vcpu, kvmppc_get_pc(vcpu), ~0xFFFUL);
 			r = RESUME_GUEST;
 		} else {
-			vcpu->arch.msr |= to_svcpu(vcpu)->shadow_srr1 & 0x58000000;
+			vcpu->arch.shared->msr |=
+				to_svcpu(vcpu)->shadow_srr1 & 0x58000000;
 			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
 			kvmppc_mmu_pte_flush(vcpu, kvmppc_get_pc(vcpu), ~0xFFFUL);
 			r = RESUME_GUEST;
@@ -904,7 +909,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 program_interrupt:
 		flags = to_svcpu(vcpu)->shadow_srr1 & 0x1f0000ull;
 
-		if (vcpu->arch.msr & MSR_PR) {
+		if (vcpu->arch.shared->msr & 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
@@ -1052,7 +1057,7 @@ int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 	regs->ctr = kvmppc_get_ctr(vcpu);
 	regs->lr = kvmppc_get_lr(vcpu);
 	regs->xer = kvmppc_get_xer(vcpu);
-	regs->msr = vcpu->arch.msr;
+	regs->msr = vcpu->arch.shared->msr;
 	regs->srr0 = vcpu->arch.srr0;
 	regs->srr1 = vcpu->arch.srr1;
 	regs->pid = vcpu->arch.pid;
@@ -1353,7 +1358,7 @@ int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 	local_irq_enable();
 
 	/* Preload FPU if it's enabled */
-	if (vcpu->arch.msr & MSR_FP)
+	if (vcpu->arch.shared->msr & MSR_FP)
 		kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
 
 	ret = __kvmppc_vcpu_entry(kvm_run, vcpu);

arch/powerpc/kvm/book3s_32_mmu.c

@@ -133,7 +133,7 @@ static int kvmppc_mmu_book3s_32_xlate_bat(struct kvm_vcpu *vcpu, gva_t eaddr,
 		else
 			bat = &vcpu_book3s->ibat[i];
 
-		if (vcpu->arch.msr & MSR_PR) {
+		if (vcpu->arch.shared->msr & MSR_PR) {
 			if (!bat->vp)
 				continue;
 		} else {
@@ -214,8 +214,8 @@ static int kvmppc_mmu_book3s_32_xlate_pte(struct kvm_vcpu *vcpu, gva_t eaddr,
 			pte->raddr = (pteg[i+1] & ~(0xFFFULL)) | (eaddr & 0xFFF);
 			pp = pteg[i+1] & 3;
 
-			if ((sre->Kp &&  (vcpu->arch.msr & MSR_PR)) ||
-			    (sre->Ks && !(vcpu->arch.msr & MSR_PR)))
+			if ((sre->Kp &&  (vcpu->arch.shared->msr & MSR_PR)) ||
+			    (sre->Ks && !(vcpu->arch.shared->msr & MSR_PR)))
 				pp |= 4;
 
 			pte->may_write = false;
@@ -334,7 +334,7 @@ static int kvmppc_mmu_book3s_32_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
 	struct kvmppc_sr *sr;
 	u64 gvsid = esid;
 
-	if (vcpu->arch.msr & (MSR_DR|MSR_IR)) {
+	if (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
 		sr = find_sr(to_book3s(vcpu), ea);
 		if (sr->valid)
 			gvsid = sr->vsid;
@@ -343,7 +343,7 @@ static int kvmppc_mmu_book3s_32_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
 	/* In case we only have one of MSR_IR or MSR_DR set, let's put
 	   that in the real-mode context (and hope RM doesn't access
 	   high memory) */
-	switch (vcpu->arch.msr & (MSR_DR|MSR_IR)) {
+	switch (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
 	case 0:
 		*vsid = VSID_REAL | esid;
 		break;
@@ -363,7 +363,7 @@ static int kvmppc_mmu_book3s_32_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
 		BUG();
 	}
 
-	if (vcpu->arch.msr & MSR_PR)
+	if (vcpu->arch.shared->msr & MSR_PR)
 		*vsid |= VSID_PR;
 
 	return 0;

arch/powerpc/kvm/book3s_32_mmu_host.c

@@ -86,7 +86,7 @@ static struct kvmppc_sid_map *find_sid_vsid(struct kvm_vcpu *vcpu, u64 gvsid)
 	struct kvmppc_sid_map *map;
 	u16 sid_map_mask;
 
-	if (vcpu->arch.msr & MSR_PR)
+	if (vcpu->arch.shared->msr & MSR_PR)
 		gvsid |= VSID_PR;
 
 	sid_map_mask = kvmppc_sid_hash(vcpu, gvsid);
@@ -253,7 +253,7 @@ static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
 	u16 sid_map_mask;
 	static int backwards_map = 0;
 
-	if (vcpu->arch.msr & MSR_PR)
+	if (vcpu->arch.shared->msr & MSR_PR)
 		gvsid |= VSID_PR;
 
 	/* We might get collisions that trap in preceding order, so let's

arch/powerpc/kvm/book3s_64_mmu.c

@@ -180,9 +180,9 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
 		goto no_page_found;
 	}
 
-	if ((vcpu->arch.msr & MSR_PR) && slbe->Kp)
+	if ((vcpu->arch.shared->msr & MSR_PR) && slbe->Kp)
 		key = 4;
-	else if (!(vcpu->arch.msr & MSR_PR) && slbe->Ks)
+	else if (!(vcpu->arch.shared->msr & MSR_PR) && slbe->Ks)
 		key = 4;
 
 	for (i=0; i<16; i+=2) {
@@ -381,7 +381,7 @@ static void kvmppc_mmu_book3s_64_slbia(struct kvm_vcpu *vcpu)
 	for (i = 1; i < vcpu_book3s->slb_nr; i++)
 		vcpu_book3s->slb[i].valid = false;
 
-	if (vcpu->arch.msr & MSR_IR) {
+	if (vcpu->arch.shared->msr & MSR_IR) {
 		kvmppc_mmu_flush_segments(vcpu);
 		kvmppc_mmu_map_segment(vcpu, kvmppc_get_pc(vcpu));
 	}
@@ -446,13 +446,13 @@ static int kvmppc_mmu_book3s_64_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
 	struct kvmppc_slb *slb;
 	u64 gvsid = esid;
 
-	if (vcpu->arch.msr & (MSR_DR|MSR_IR)) {
+	if (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
 		slb = kvmppc_mmu_book3s_64_find_slbe(to_book3s(vcpu), ea);
 		if (slb)
 			gvsid = slb->vsid;
 	}
 
-	switch (vcpu->arch.msr & (MSR_DR|MSR_IR)) {
+	switch (vcpu->arch.shared->msr & (MSR_DR|MSR_IR)) {
 	case 0:
 		*vsid = VSID_REAL | esid;
 		break;
@@ -473,7 +473,7 @@ static int kvmppc_mmu_book3s_64_esid_to_vsid(struct kvm_vcpu *vcpu, ulong esid,
 		break;
 	}
 
-	if (vcpu->arch.msr & MSR_PR)
+	if (vcpu->arch.shared->msr & MSR_PR)
 		*vsid |= VSID_PR;
 
 	return 0;