KVM: x86 emulator: Move string pio emulation into emulator.c

Currently emulation is done outside of emulator so things like doing
ins/outs to/from mmio are broken it also makes it hard (if not impossible)
to implement single stepping in the future. The implementation in this
patch is not efficient since it exits to userspace for each IO while
previous implementation did 'ins' in batches. Further patch that
implements pio in string read ahead address this problem.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -224,14 +224,9 @@ struct kvm_pv_mmu_op_buffer {
 
 struct kvm_pio_request {
 	unsigned long count;
-	int cur_count;
-	gva_t guest_gva;
 	int in;
 	int port;
 	int size;
-	int string;
-	int down;
-	int rep;
 };
 
 /*
@@ -591,9 +586,6 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 struct x86_emulate_ctxt;
 
 int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size, unsigned short port);
-int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, int in,
-			   int size, unsigned long count, int down,
-			    gva_t address, int rep, unsigned port);
 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu);
 int kvm_emulate_halt(struct kvm_vcpu *vcpu);
 int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address);

arch/x86/kvm/emulate.c

@@ -153,8 +153,8 @@ static u32 opcode_table[256] = {
 	0, 0, 0, 0,
 	/* 0x68 - 0x6F */
 	SrcImm | Mov | Stack, 0, SrcImmByte | Mov | Stack, 0,
-	SrcNone  | ByteOp  | ImplicitOps, SrcNone  | ImplicitOps, /* insb, insw/insd */
-	SrcNone  | ByteOp  | ImplicitOps, SrcNone  | ImplicitOps, /* outsb, outsw/outsd */
+	DstDI | ByteOp | Mov | String, DstDI | Mov | String, /* insb, insw/insd */
+	SrcSI | ByteOp | ImplicitOps | String, SrcSI | ImplicitOps | String, /* outsb, outsw/outsd */
 	/* 0x70 - 0x77 */
 	SrcImmByte, SrcImmByte, SrcImmByte, SrcImmByte,
 	SrcImmByte, SrcImmByte, SrcImmByte, SrcImmByte,
@@ -2615,47 +2615,29 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 		break;
 	case 0x6c:		/* insb */
 	case 0x6d:		/* insw/insd */
+		c->dst.bytes = min(c->dst.bytes, 4u);
 		if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
-					  (c->d & ByteOp) ? 1 : c->op_bytes)) {
+					  c->dst.bytes)) {
 			kvm_inject_gp(ctxt->vcpu, 0);
 			goto done;
 		}
-		if (kvm_emulate_pio_string(ctxt->vcpu,
-				1,
-				(c->d & ByteOp) ? 1 : c->op_bytes,
-				c->rep_prefix ?
-				address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
-				(ctxt->eflags & EFLG_DF),
-				register_address(c, es_base(ctxt),
-						 c->regs[VCPU_REGS_RDI]),
-				c->rep_prefix,
-				c->regs[VCPU_REGS_RDX]) == 0) {
-			c->eip = saved_eip;
-			return -1;
-		}
-		return 0;
+		if (!ops->pio_in_emulated(c->dst.bytes, c->regs[VCPU_REGS_RDX],
+					  &c->dst.val, 1, ctxt->vcpu))
+			goto done; /* IO is needed, skip writeback */
+		break;
 	case 0x6e:		/* outsb */
 	case 0x6f:		/* outsw/outsd */
+		c->src.bytes = min(c->src.bytes, 4u);
 		if (!emulator_io_permited(ctxt, ops, c->regs[VCPU_REGS_RDX],
-					  (c->d & ByteOp) ? 1 : c->op_bytes)) {
+					  c->src.bytes)) {
 			kvm_inject_gp(ctxt->vcpu, 0);
 			goto done;
 		}
-		if (kvm_emulate_pio_string(ctxt->vcpu,
-				0,
-				(c->d & ByteOp) ? 1 : c->op_bytes,
-				c->rep_prefix ?
-				address_mask(c, c->regs[VCPU_REGS_RCX]) : 1,
-				(ctxt->eflags & EFLG_DF),
-					 register_address(c,
-					  seg_override_base(ctxt, c),
-						 c->regs[VCPU_REGS_RSI]),
-				c->rep_prefix,
-				c->regs[VCPU_REGS_RDX]) == 0) {
-			c->eip = saved_eip;
-			return -1;
-		}
-		return 0;
+		ops->pio_out_emulated(c->src.bytes, c->regs[VCPU_REGS_RDX],
+				      &c->src.val, 1, ctxt->vcpu);
+
+		c->dst.type = OP_NONE; /* nothing to writeback */
+		break;
 	case 0x70 ... 0x7f: /* jcc (short) */
 		if (test_cc(c->b, ctxt->eflags))
 			jmp_rel(c, c->src.val);

arch/x86/kvm/x86.c

@@ -3150,18 +3150,17 @@ static int kvm_read_guest_virt_system(gva_t addr, void *val, unsigned int bytes,
 	return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, 0, error);
 }
 
-static int kvm_write_guest_virt_helper(gva_t addr, void *val,
+static int kvm_write_guest_virt_system(gva_t addr, void *val,
 				       unsigned int bytes,
-				       struct kvm_vcpu *vcpu, u32 access,
+				       struct kvm_vcpu *vcpu,
 				       u32 *error)
 {
 	void *data = val;
 	int r = X86EMUL_CONTINUE;
 
-	access |= PFERR_WRITE_MASK;
-
 	while (bytes) {
-		gpa_t gpa =  vcpu->arch.mmu.gva_to_gpa(vcpu, addr, access, error);
+		gpa_t gpa =  vcpu->arch.mmu.gva_to_gpa(vcpu, addr,
+						       PFERR_WRITE_MASK, error);
 		unsigned offset = addr & (PAGE_SIZE-1);
 		unsigned towrite = min(bytes, (unsigned)PAGE_SIZE - offset);
 		int ret;
@@ -3184,20 +3183,6 @@ static int kvm_write_guest_virt_helper(gva_t addr, void *val,
 	return r;
 }
 
-static int kvm_write_guest_virt(gva_t addr, void *val, unsigned int bytes,
-				struct kvm_vcpu *vcpu, u32 *error)
-{
-	u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
-	return kvm_write_guest_virt_helper(addr, val, bytes, vcpu, access, error);
-}
-
-static int kvm_write_guest_virt_system(gva_t addr, void *val,
-				       unsigned int bytes,
-				       struct kvm_vcpu *vcpu, u32 *error)
-{
-	return kvm_write_guest_virt_helper(addr, val, bytes, vcpu, 0, error);
-}
-
 static int emulator_read_emulated(unsigned long addr,
 				  void *val,
 				  unsigned int bytes,
@@ -3423,23 +3408,20 @@ static int kernel_pio(struct kvm_vcpu *vcpu, void *pd)
 static int emulator_pio_in_emulated(int size, unsigned short port, void *val,
 			     unsigned int count, struct kvm_vcpu *vcpu)
 {
-	if (vcpu->arch.pio.cur_count)
+	if (vcpu->arch.pio.count)
 		goto data_avail;
 
 	trace_kvm_pio(1, port, size, 1);
 
 	vcpu->arch.pio.port = port;
 	vcpu->arch.pio.in = 1;
-	vcpu->arch.pio.string = 0;
-	vcpu->arch.pio.down = 0;
-	vcpu->arch.pio.rep = 0;
-	vcpu->arch.pio.count = vcpu->arch.pio.cur_count = count;
+	vcpu->arch.pio.count  = count;
 	vcpu->arch.pio.size = size;
 
 	if (!kernel_pio(vcpu, vcpu->arch.pio_data)) {
 	data_avail:
 		memcpy(val, vcpu->arch.pio_data, size * count);
-		vcpu->arch.pio.cur_count = 0;
+		vcpu->arch.pio.count = 0;
 		return 1;
 	}
 
@@ -3461,16 +3443,13 @@ static int emulator_pio_out_emulated(int size, unsigned short port,
 
 	vcpu->arch.pio.port = port;
 	vcpu->arch.pio.in = 0;
-	vcpu->arch.pio.string = 0;
-	vcpu->arch.pio.down = 0;
-	vcpu->arch.pio.rep = 0;
-	vcpu->arch.pio.count = vcpu->arch.pio.cur_count = count;
+	vcpu->arch.pio.count = count;
 	vcpu->arch.pio.size = size;
 
 	memcpy(vcpu->arch.pio_data, val, size * count);
 
 	if (!kernel_pio(vcpu, vcpu->arch.pio_data)) {
-		vcpu->arch.pio.cur_count = 0;
+		vcpu->arch.pio.count = 0;
 		return 1;
 	}
 
@@ -3717,7 +3696,6 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 	cache_all_regs(vcpu);
 
 	vcpu->mmio_is_write = 0;
-	vcpu->arch.pio.string = 0;
 
 	if (!(emulation_type & EMULTYPE_NO_DECODE)) {
 		int cs_db, cs_l;
@@ -3783,12 +3761,9 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 	if (r == 0)
 		kvm_x86_ops->set_interrupt_shadow(vcpu, shadow_mask);
 
-	if (vcpu->arch.pio.string)
-		return EMULATE_DO_MMIO;
-
-	if (vcpu->arch.pio.cur_count && !vcpu->arch.pio.string) {
+	if (vcpu->arch.pio.count) {
 		if (!vcpu->arch.pio.in)
-			vcpu->arch.pio.cur_count = 0;
+			vcpu->arch.pio.count = 0;
 		return EMULATE_DO_MMIO;
 	}
 
@@ -3821,158 +3796,12 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
 }
 EXPORT_SYMBOL_GPL(emulate_instruction);
 
-static int pio_copy_data(struct kvm_vcpu *vcpu)
-{
-	void *p = vcpu->arch.pio_data;
-	gva_t q = vcpu->arch.pio.guest_gva;
-	unsigned bytes;
-	int ret;
-	u32 error_code;
-
-	bytes = vcpu->arch.pio.size * vcpu->arch.pio.cur_count;
-	if (vcpu->arch.pio.in)
-		ret = kvm_write_guest_virt(q, p, bytes, vcpu, &error_code);
-	else
-		ret = kvm_read_guest_virt(q, p, bytes, vcpu, &error_code);
-
-	if (ret == X86EMUL_PROPAGATE_FAULT)
-		kvm_inject_page_fault(vcpu, q, error_code);
-
-	return ret;
-}
-
-int complete_pio(struct kvm_vcpu *vcpu)
-{
-	struct kvm_pio_request *io = &vcpu->arch.pio;
-	long delta;
-	int r;
-	unsigned long val;
-
-	if (io->in) {
-		r = pio_copy_data(vcpu);
-		if (r)
-			goto out;
-	}
-
-	delta = 1;
-	if (io->rep) {
-		delta *= io->cur_count;
-		/*
-		 * The size of the register should really depend on
-		 * current address size.
-		 */
-		val = kvm_register_read(vcpu, VCPU_REGS_RCX);
-		val -= delta;
-		kvm_register_write(vcpu, VCPU_REGS_RCX, val);
-	}
-	if (io->down)
-		delta = -delta;
-	delta *= io->size;
-	if (io->in) {
-		val = kvm_register_read(vcpu, VCPU_REGS_RDI);
-		val += delta;
-		kvm_register_write(vcpu, VCPU_REGS_RDI, val);
-	} else {
-		val = kvm_register_read(vcpu, VCPU_REGS_RSI);
-		val += delta;
-		kvm_register_write(vcpu, VCPU_REGS_RSI, val);
-	}
-
-out:
-	io->count -= io->cur_count;
-	io->cur_count = 0;
-
-	return 0;
-}
-
-static int pio_string_write(struct kvm_vcpu *vcpu)
-{
-	struct kvm_pio_request *io = &vcpu->arch.pio;
-	void *pd = vcpu->arch.pio_data;
-	int i, r = 0;
-
-	for (i = 0; i < io->cur_count; i++) {
-		if (kvm_io_bus_write(vcpu->kvm, KVM_PIO_BUS,
-				     io->port, io->size, pd)) {
-			r = -EOPNOTSUPP;
-			break;
-		}
-		pd += io->size;
-	}
-	return r;
-}
-
-int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, int in,
-		  int size, unsigned long count, int down,
-		  gva_t address, int rep, unsigned port)
-{
-	unsigned now, in_page;
-	int ret = 0;
-
-	trace_kvm_pio(!in, port, size, count);
-
-	vcpu->run->exit_reason = KVM_EXIT_IO;
-	vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT;
-	vcpu->run->io.size = vcpu->arch.pio.size = size;
-	vcpu->run->io.data_offset = KVM_PIO_PAGE_OFFSET * PAGE_SIZE;
-	vcpu->run->io.count = vcpu->arch.pio.count = vcpu->arch.pio.cur_count = count;
-	vcpu->run->io.port = vcpu->arch.pio.port = port;
-	vcpu->arch.pio.in = in;
-	vcpu->arch.pio.string = 1;
-	vcpu->arch.pio.down = down;
-	vcpu->arch.pio.rep = rep;
-
-	if (!count) {
-		kvm_x86_ops->skip_emulated_instruction(vcpu);
-		return 1;
-	}
-
-	if (!down)
-		in_page = PAGE_SIZE - offset_in_page(address);
-	else
-		in_page = offset_in_page(address) + size;
-	now = min(count, (unsigned long)in_page / size);
-	if (!now)
-		now = 1;
-	if (down) {
-		/*
-		 * String I/O in reverse.  Yuck.  Kill the guest, fix later.
-		 */
-		pr_unimpl(vcpu, "guest string pio down\n");
-		kvm_inject_gp(vcpu, 0);
-		return 1;
-	}
-	vcpu->run->io.count = now;
-	vcpu->arch.pio.cur_count = now;
-
-	if (vcpu->arch.pio.cur_count == vcpu->arch.pio.count)
-		kvm_x86_ops->skip_emulated_instruction(vcpu);
-
-	vcpu->arch.pio.guest_gva = address;
-
-	if (!vcpu->arch.pio.in) {
-		/* string PIO write */
-		ret = pio_copy_data(vcpu);
-		if (ret == X86EMUL_PROPAGATE_FAULT)
-			return 1;
-		if (ret == 0 && !pio_string_write(vcpu)) {
-			complete_pio(vcpu);
-			if (vcpu->arch.pio.count == 0)
-				ret = 1;
-		}
-	}
-	/* no string PIO read support yet */
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(kvm_emulate_pio_string);
-
 int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size, unsigned short port)
 {
 	unsigned long val = kvm_register_read(vcpu, VCPU_REGS_RAX);
 	int ret = emulator_pio_out_emulated(size, port, &val, 1, vcpu);
 	/* do not return to emulator after return from userspace */
-	vcpu->arch.pio.cur_count = 0;
+	vcpu->arch.pio.count = 0;
 	return ret;
 }
 EXPORT_SYMBOL_GPL(kvm_fast_pio_out);
@@ -4705,15 +4534,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	if (!irqchip_in_kernel(vcpu->kvm))
 		kvm_set_cr8(vcpu, kvm_run->cr8);
 
-	if (vcpu->arch.pio.cur_count) {
+	if (vcpu->arch.pio.count) {
 		vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
-		if (!vcpu->arch.pio.string)
-			r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE);
-		else
-			r = complete_pio(vcpu);
+		r = emulate_instruction(vcpu, 0, 0, EMULTYPE_NO_DECODE);
 		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
-		if (r == EMULATE_DO_MMIO)
+		if (r == EMULATE_DO_MMIO) {
+			r = 0;
 			goto out;
+		}
 	}
 	if (vcpu->mmio_needed) {
 		memcpy(vcpu->mmio_data, kvm_run->mmio.data, 8);