KVM: remove in_range from io devices

This changes bus accesses to use high-level kvm_io_bus_read/kvm_io_bus_write
functions. in_range now becomes unused so it is removed from device ops in
favor of read/write callbacks performing range checks internally.

This allows aliasing (mostly for in-kernel virtio), as well as better error
handling by making it possible to pass errors up to userspace.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

4 files changed, 90 insertions, 133 deletions

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4082cdd468ed..8c3ac30ef9bd 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -358,8 +358,14 @@ static inline struct kvm_pit *speaker_to_pit(struct kvm_io_device *dev)
         return container_of(dev, struct kvm_pit, speaker_dev);
 }
 
-static void pit_ioport_write(struct kvm_io_device *this,
-                             gpa_t addr, int len, const void *data)
+static inline int pit_in_range(gpa_t addr)
+{
+        return ((addr >= KVM_PIT_BASE_ADDRESS) &&
+                (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
+}
+
+static int pit_ioport_write(struct kvm_io_device *this,
+                            gpa_t addr, int len, const void *data)
 {
         struct kvm_pit *pit = dev_to_pit(this);
         struct kvm_kpit_state *pit_state = &pit->pit_state;
@@ -367,6 +373,8 @@ static void pit_ioport_write(struct kvm_io_device *this,
         int channel, access;
         struct kvm_kpit_channel_state *s;
         u32 val = *(u32 *) data;
+        if (!pit_in_range(addr))
+                return -EOPNOTSUPP;
 
         val  &= 0xff;
         addr &= KVM_PIT_CHANNEL_MASK;
@@ -429,16 +437,19 @@ static void pit_ioport_write(struct kvm_io_device *this,
         }
 
         mutex_unlock(&pit_state->lock);
+        return 0;
 }
 
-static void pit_ioport_read(struct kvm_io_device *this,
-                            gpa_t addr, int len, void *data)
+static int pit_ioport_read(struct kvm_io_device *this,
+                           gpa_t addr, int len, void *data)
 {
         struct kvm_pit *pit = dev_to_pit(this);
         struct kvm_kpit_state *pit_state = &pit->pit_state;
         struct kvm *kvm = pit->kvm;
         int ret, count;
         struct kvm_kpit_channel_state *s;
+        if (!pit_in_range(addr))
+                return -EOPNOTSUPP;
 
         addr &= KVM_PIT_CHANNEL_MASK;
         s = &pit_state->channels[addr];
@@ -493,37 +504,36 @@ static void pit_ioport_read(struct kvm_io_device *this,
         memcpy(data, (char *)&ret, len);
 
         mutex_unlock(&pit_state->lock);
+        return 0;
 }
 
-static int pit_in_range(struct kvm_io_device *this, gpa_t addr,
-                        int len, int is_write)
-{
-        return ((addr >= KVM_PIT_BASE_ADDRESS) &&
-                (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
-}
-
-static void speaker_ioport_write(struct kvm_io_device *this,
-                                 gpa_t addr, int len, const void *data)
+static int speaker_ioport_write(struct kvm_io_device *this,
+                                gpa_t addr, int len, const void *data)
 {
         struct kvm_pit *pit = speaker_to_pit(this);
         struct kvm_kpit_state *pit_state = &pit->pit_state;
         struct kvm *kvm = pit->kvm;
         u32 val = *(u32 *) data;
+        if (addr != KVM_SPEAKER_BASE_ADDRESS)
+                return -EOPNOTSUPP;
 
         mutex_lock(&pit_state->lock);
         pit_state->speaker_data_on = (val >> 1) & 1;
         pit_set_gate(kvm, 2, val & 1);
         mutex_unlock(&pit_state->lock);
+        return 0;
 }
 
-static void speaker_ioport_read(struct kvm_io_device *this,
-                                gpa_t addr, int len, void *data)
+static int speaker_ioport_read(struct kvm_io_device *this,
+                               gpa_t addr, int len, void *data)
 {
         struct kvm_pit *pit = speaker_to_pit(this);
         struct kvm_kpit_state *pit_state = &pit->pit_state;
         struct kvm *kvm = pit->kvm;
         unsigned int refresh_clock;
         int ret;
+        if (addr != KVM_SPEAKER_BASE_ADDRESS)
+                return -EOPNOTSUPP;
 
         /* Refresh clock toggles at about 15us. We approximate as 2^14ns. */
         refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
@@ -535,12 +545,7 @@ static void speaker_ioport_read(struct kvm_io_device *this,
                 len = sizeof(ret);
         memcpy(data, (char *)&ret, len);
         mutex_unlock(&pit_state->lock);
-}
-
-static int speaker_in_range(struct kvm_io_device *this, gpa_t addr,
-                            int len, int is_write)
-{
-        return (addr == KVM_SPEAKER_BASE_ADDRESS);
+        return 0;
 }
 
 void kvm_pit_reset(struct kvm_pit *pit)
@@ -574,13 +579,11 @@ static void pit_mask_notifer(struct kvm_irq_mask_notifier *kimn, bool mask)
 static const struct kvm_io_device_ops pit_dev_ops = {
         .read     = pit_ioport_read,
         .write    = pit_ioport_write,
-        .in_range = pit_in_range,
 };
 
 static const struct kvm_io_device_ops speaker_dev_ops = {
         .read     = speaker_ioport_read,
         .write    = speaker_ioport_write,
-        .in_range = speaker_in_range,
 };
 
 /* Caller must have writers lock on slots_lock */
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 1851aec8a7da..1d1bb75dc7bc 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -430,8 +430,7 @@ static u32 elcr_ioport_read(void *opaque, u32 addr1)
         return s->elcr;
 }
 
-static int picdev_in_range(struct kvm_io_device *this, gpa_t addr,
-                           int len, int is_write)
+static int picdev_in_range(gpa_t addr)
 {
         switch (addr) {
         case 0x20:
@@ -451,16 +450,18 @@ static inline struct kvm_pic *to_pic(struct kvm_io_device *dev)
         return container_of(dev, struct kvm_pic, dev);
 }
 
-static void picdev_write(struct kvm_io_device *this,
+static int picdev_write(struct kvm_io_device *this,
                          gpa_t addr, int len, const void *val)
 {
         struct kvm_pic *s = to_pic(this);
         unsigned char data = *(unsigned char *)val;
+        if (!picdev_in_range(addr))
+                return -EOPNOTSUPP;
 
         if (len != 1) {
                 if (printk_ratelimit())
                         printk(KERN_ERR "PIC: non byte write\n");
-                return;
+                return 0;
         }
         pic_lock(s);
         switch (addr) {
@@ -476,18 +477,21 @@ static void picdev_write(struct kvm_io_device *this,
                 break;
         }
         pic_unlock(s);
+        return 0;
 }
 
-static void picdev_read(struct kvm_io_device *this,
-                        gpa_t addr, int len, void *val)
+static int picdev_read(struct kvm_io_device *this,
+                       gpa_t addr, int len, void *val)
 {
         struct kvm_pic *s = to_pic(this);
         unsigned char data = 0;
+        if (!picdev_in_range(addr))
+                return -EOPNOTSUPP;
 
         if (len != 1) {
                 if (printk_ratelimit())
                         printk(KERN_ERR "PIC: non byte read\n");
-                return;
+                return 0;
         }
         pic_lock(s);
         switch (addr) {
@@ -504,6 +508,7 @@ static void picdev_read(struct kvm_io_device *this,
         }
         *(unsigned char *)val = data;
         pic_unlock(s);
+        return 0;
 }
 
 /*
@@ -526,7 +531,6 @@ static void pic_irq_request(void *opaque, int level)
 static const struct kvm_io_device_ops picdev_ops = {
         .read     = picdev_read,
         .write    = picdev_write,
-        .in_range = picdev_in_range,
 };
 
 struct kvm_pic *kvm_create_pic(struct kvm *kvm)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2e0286596387..265a765f038f 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -546,18 +546,27 @@ static inline struct kvm_lapic *to_lapic(struct kvm_io_device *dev)
         return container_of(dev, struct kvm_lapic, dev);
 }
 
-static void apic_mmio_read(struct kvm_io_device *this,
-                           gpa_t address, int len, void *data)
+static int apic_mmio_in_range(struct kvm_lapic *apic, gpa_t addr)
+{
+        return apic_hw_enabled(apic) &&
+            addr >= apic->base_address &&
+            addr < apic->base_address + LAPIC_MMIO_LENGTH;
+}
+
+static int apic_mmio_read(struct kvm_io_device *this,
+                          gpa_t address, int len, void *data)
 {
         struct kvm_lapic *apic = to_lapic(this);
         unsigned int offset = address - apic->base_address;
         unsigned char alignment = offset & 0xf;
         u32 result;
+        if (!apic_mmio_in_range(apic, address))
+                return -EOPNOTSUPP;
 
         if ((alignment + len) > 4) {
                 printk(KERN_ERR "KVM_APIC_READ: alignment error %lx %d",
                        (unsigned long)address, len);
-                return;
+                return 0;
         }
         result = __apic_read(apic, offset & ~0xf);
 
@@ -574,6 +583,7 @@ static void apic_mmio_read(struct kvm_io_device *this,
                        "should be 1,2, or 4 instead\n", len);
                 break;
         }
+        return 0;
 }
 
 static void update_divide_count(struct kvm_lapic *apic)
@@ -629,13 +639,15 @@ static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
                 apic->vcpu->kvm->arch.vapics_in_nmi_mode--;
 }
 
-static void apic_mmio_write(struct kvm_io_device *this,
-                            gpa_t address, int len, const void *data)
+static int apic_mmio_write(struct kvm_io_device *this,
+                           gpa_t address, int len, const void *data)
 {
         struct kvm_lapic *apic = to_lapic(this);
         unsigned int offset = address - apic->base_address;
         unsigned char alignment = offset & 0xf;
         u32 val;
+        if (!apic_mmio_in_range(apic, address))
+                return -EOPNOTSUPP;
 
         /*
          * APIC register must be aligned on 128-bits boundary.
@@ -646,7 +658,7 @@ static void apic_mmio_write(struct kvm_io_device *this,
                 /* Don't shout loud, $infamous_os would cause only noise. */
                 apic_debug("apic write: bad size=%d %lx\n",
                            len, (long)address);
-                return;
+                return 0;
         }
 
         val = *(u32 *) data;
@@ -729,7 +741,7 @@ static void apic_mmio_write(struct kvm_io_device *this,
                 hrtimer_cancel(&apic->lapic_timer.timer);
                 apic_set_reg(apic, APIC_TMICT, val);
                 start_apic_timer(apic);
-                return;
+                return 0;
 
         case APIC_TDCR:
                 if (val & 4)
@@ -743,22 +755,7 @@ static void apic_mmio_write(struct kvm_io_device *this,
                            offset);
                 break;
         }
-
-}
-
-static int apic_mmio_range(struct kvm_io_device *this, gpa_t addr,
-                           int len, int size)
-{
-        struct kvm_lapic *apic = to_lapic(this);
-        int ret = 0;
-
-
-        if (apic_hw_enabled(apic) &&
-            (addr >= apic->base_address) &&
-            (addr < (apic->base_address + LAPIC_MMIO_LENGTH)))
-                ret = 1;
-
-        return ret;
+        return 0;
 }
 
 void kvm_free_lapic(struct kvm_vcpu *vcpu)
@@ -938,7 +935,6 @@ static struct kvm_timer_ops lapic_timer_ops = {
 static const struct kvm_io_device_ops apic_mmio_ops = {
         .read     = apic_mmio_read,
         .write    = apic_mmio_write,
-        .in_range = apic_mmio_range,
 };
 
 int kvm_create_lapic(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7ce6367c1976..96f0ae7d97b6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2333,35 +2333,23 @@ static void kvm_init_msr_list(void)
         num_msrs_to_save = j;
 }
 
-/*
- * Only apic need an MMIO device hook, so shortcut now..
- */
-static struct kvm_io_device *vcpu_find_pervcpu_dev(struct kvm_vcpu *vcpu,
-                                                gpa_t addr, int len,
-                                                int is_write)
+static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len,
+                           const void *v)
 {
-        struct kvm_io_device *dev;
+        if (vcpu->arch.apic &&
+            !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v))
+                return 0;
 
-        if (vcpu->arch.apic) {
-                dev = &vcpu->arch.apic->dev;
-                if (kvm_iodevice_in_range(dev, addr, len, is_write))
-                        return dev;
-        }
-        return NULL;
+        return kvm_io_bus_write(&vcpu->kvm->mmio_bus, addr, len, v);
 }
 
-
-static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
-                                                gpa_t addr, int len,
-                                                int is_write)
+static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void *v)
 {
-        struct kvm_io_device *dev;
+        if (vcpu->arch.apic &&
+            !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, len, v))
+                return 0;
 
-        dev = vcpu_find_pervcpu_dev(vcpu, addr, len, is_write);
-        if (dev == NULL)
-                dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr, len,
-                                          is_write);
-        return dev;
+        return kvm_io_bus_read(&vcpu->kvm->mmio_bus, addr, len, v);
 }
 
 static int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
@@ -2430,7 +2418,6 @@ static int emulator_read_emulated(unsigned long addr,
                                   unsigned int bytes,
                                   struct kvm_vcpu *vcpu)
 {
-        struct kvm_io_device *mmio_dev;
         gpa_t                 gpa;
 
         if (vcpu->mmio_read_completed) {
@@ -2455,13 +2442,8 @@ mmio:
         /*
          * Is this MMIO handled locally?
          */
-        mutex_lock(&vcpu->kvm->lock);
-        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 0);
-        mutex_unlock(&vcpu->kvm->lock);
-        if (mmio_dev) {
-                kvm_iodevice_read(mmio_dev, gpa, bytes, val);
+        if (!vcpu_mmio_read(vcpu, gpa, bytes, val))
                 return X86EMUL_CONTINUE;
-        }
 
         vcpu->mmio_needed = 1;
         vcpu->mmio_phys_addr = gpa;
@@ -2488,7 +2470,6 @@ static int emulator_write_emulated_onepage(unsigned long addr,
                                            unsigned int bytes,
                                            struct kvm_vcpu *vcpu)
 {
-        struct kvm_io_device *mmio_dev;
         gpa_t                 gpa;
 
         gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, addr);
@@ -2509,13 +2490,8 @@ mmio:
         /*
          * Is this MMIO handled locally?
          */
-        mutex_lock(&vcpu->kvm->lock);
-        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 1);
-        mutex_unlock(&vcpu->kvm->lock);
-        if (mmio_dev) {
-                kvm_iodevice_write(mmio_dev, gpa, bytes, val);
+        if (!vcpu_mmio_write(vcpu, gpa, bytes, val))
                 return X86EMUL_CONTINUE;
-        }
 
         vcpu->mmio_needed = 1;
         vcpu->mmio_phys_addr = gpa;
@@ -2850,48 +2826,40 @@ int complete_pio(struct kvm_vcpu *vcpu)
         return 0;
 }
 
-static void kernel_pio(struct kvm_io_device *pio_dev,
-                       struct kvm_vcpu *vcpu,
-                       void *pd)
+static int kernel_pio(struct kvm_vcpu *vcpu, void *pd)
 {
         /* TODO: String I/O for in kernel device */
+        int r;
 
         if (vcpu->arch.pio.in)
-                kvm_iodevice_read(pio_dev, vcpu->arch.pio.port,
-                                  vcpu->arch.pio.size,
-                                  pd);
+                r = kvm_io_bus_read(&vcpu->kvm->pio_bus, vcpu->arch.pio.port,
+                                    vcpu->arch.pio.size, pd);
         else
-                kvm_iodevice_write(pio_dev, vcpu->arch.pio.port,
-                                   vcpu->arch.pio.size,
-                                   pd);
+                r = kvm_io_bus_write(&vcpu->kvm->pio_bus, vcpu->arch.pio.port,
+                                     vcpu->arch.pio.size, pd);
+        return r;
 }
 
-static void pio_string_write(struct kvm_io_device *pio_dev,
-                             struct kvm_vcpu *vcpu)
+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;
+        int i, r = 0;
 
         for (i = 0; i < io->cur_count; i++) {
-                kvm_iodevice_write(pio_dev, io->port,
-                                   io->size,
-                                   pd);
+                if (kvm_io_bus_write(&vcpu->kvm->pio_bus,
+                                     io->port, io->size, pd)) {
+                        r = -EOPNOTSUPP;
+                        break;
+                }
                 pd += io->size;
         }
-}
-
-static struct kvm_io_device *vcpu_find_pio_dev(struct kvm_vcpu *vcpu,
-                                               gpa_t addr, int len,
-                                               int is_write)
-{
-        return kvm_io_bus_find_dev(&vcpu->kvm->pio_bus, addr, len, is_write);
+        return r;
 }
 
 int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
                   int size, unsigned port)
 {
-        struct kvm_io_device *pio_dev;
         unsigned long val;
 
         vcpu->run->exit_reason = KVM_EXIT_IO;
@@ -2911,11 +2879,7 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
         val = kvm_register_read(vcpu, VCPU_REGS_RAX);
         memcpy(vcpu->arch.pio_data, &val, 4);
 
-        mutex_lock(&vcpu->kvm->lock);
-        pio_dev = vcpu_find_pio_dev(vcpu, port, size, !in);
-        mutex_unlock(&vcpu->kvm->lock);
-        if (pio_dev) {
-                kernel_pio(pio_dev, vcpu, vcpu->arch.pio_data);
+        if (!kernel_pio(vcpu, vcpu->arch.pio_data)) {
                 complete_pio(vcpu);
                 return 1;
         }
@@ -2929,7 +2893,6 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
 {
         unsigned now, in_page;
         int ret = 0;
-        struct kvm_io_device *pio_dev;
 
         vcpu->run->exit_reason = KVM_EXIT_IO;
         vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT;
@@ -2973,12 +2936,6 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
 
         vcpu->arch.pio.guest_gva = address;
 
-        mutex_lock(&vcpu->kvm->lock);
-        pio_dev = vcpu_find_pio_dev(vcpu, port,
-                                    vcpu->arch.pio.cur_count,
-                                    !vcpu->arch.pio.in);
-        mutex_unlock(&vcpu->kvm->lock);
-
         if (!vcpu->arch.pio.in) {
                 /* string PIO write */
                 ret = pio_copy_data(vcpu);
@@ -2986,16 +2943,13 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
                         kvm_inject_gp(vcpu, 0);
                         return 1;
                 }
-                if (ret == 0 && pio_dev) {
-                        pio_string_write(pio_dev, vcpu);
+                if (ret == 0 && !pio_string_write(vcpu)) {
                         complete_pio(vcpu);
                         if (vcpu->arch.pio.count == 0)
                                 ret = 1;
                 }
-        } else if (pio_dev)
-                pr_unimpl(vcpu, "no string pio read support yet, "
-                       "port %x size %d count %ld\n",
-                        port, size, count);
+        }
+        /* no string PIO read support yet */
 
         return ret;
 }