[PATCHv2] kvm: remove in_range and switch to rwsem for iobus

From: Michael S. Tsirkin
Date: Sun Jun 28 2009 - 15:35:17 EST

This changes bus accesses to use high-level kvm_io_bus_read/kvm_io_bus_write
functions, which utilize read/write semaphore intead of mutex. 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. And it's enough
to look at the diffstat to see that it's a better API anyway.

While we are at it, document locking rules for kvm_io_device_ops.

Note: since the use of the new bus_lock is localized to a small number of
places, it will be easy to switch to srcu in the future if we so desire.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---

OK, here's an updated version of the patch. I punted on rcu and went
with rw semaphore for now, but it will be easy to change now that the
use of the semaphore is fairly isolated. Works for me, but please
review carefully.

arch/ia64/kvm/kvm-ia64.c | 28 +++--------
arch/x86/kvm/i8254.c | 53 +++++++++++----------
arch/x86/kvm/i8259.c | 22 +++++----
arch/x86/kvm/lapic.c | 44 ++++++++----------
arch/x86/kvm/x86.c | 112 ++++++++++++++-------------------------------
include/linux/kvm_host.h | 10 +++-
virt/kvm/coalesced_mmio.c | 28 ++++++------
virt/kvm/ioapic.c | 24 +++++----
virt/kvm/iodev.h | 42 +++++++----------
virt/kvm/kvm_main.c | 41 ++++++++++++-----
10 files changed, 184 insertions(+), 220 deletions(-)

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index c1c5cb6..5bf5100 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -210,16 +210,6 @@ int kvm_dev_ioctl_check_extension(long ext)

}

-static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
- gpa_t addr, int len, int is_write)
-{
- struct kvm_io_device *dev;
-
- dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr, len, is_write);
-
- return dev;
-}
-
static int handle_vm_error(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
kvm_run->exit_reason = KVM_EXIT_UNKNOWN;
@@ -231,6 +221,7 @@ static int handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
struct kvm_mmio_req *p;
struct kvm_io_device *mmio_dev;
+ int r;

p = kvm_get_vcpu_ioreq(vcpu);

@@ -247,16 +238,13 @@ static int handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
kvm_run->exit_reason = KVM_EXIT_MMIO;
return 0;
mmio:
- mmio_dev = vcpu_find_mmio_dev(vcpu, p->addr, p->size, !p->dir);
- if (mmio_dev) {
- if (!p->dir)
- kvm_iodevice_write(mmio_dev, p->addr, p->size,
- &p->data);
- else
- kvm_iodevice_read(mmio_dev, p->addr, p->size,
- &p->data);
-
- } else
+ if (p->dir)
+ r = kvm_io_bus_read(vcpu->kvm, &vcpu->kvm->mmio_bus, p->addr,
+ p->size, &p->data);
+ else
+ r = kvm_io_bus_write(vcpu->kvm, &vcpu->kvm->mmio_bus, p->addr,
+ p->size, &p->data);
+ if (r)
printk(KERN_ERR"kvm: No iodevice found! addr:%lx\n", p->addr);
p->state = STATE_IORESP_READY;

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 331705f..3155ffa 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -357,8 +357,14 @@ 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;
@@ -366,6 +372,8 @@ 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;
@@ -428,16 +436,19 @@ 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];
@@ -492,37 +503,36 @@ 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;
@@ -534,12 +544,7 @@ 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)
@@ -573,13 +578,11 @@ 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,
};

struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
@@ -620,11 +623,11 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier);

kvm_iodevice_init(&pit->dev, &pit_dev_ops);
- kvm_io_bus_register_dev(&kvm->pio_bus, &pit->dev);
+ kvm_io_bus_register_dev(kvm, &kvm->pio_bus, &pit->dev);

if (flags & KVM_PIT_SPEAKER_DUMMY) {
kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops);
- kvm_io_bus_register_dev(&kvm->pio_bus, &pit->speaker_dev);
+ kvm_io_bus_register_dev(kvm, &kvm->pio_bus, &pit->speaker_dev);
}

return pit;
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 148c52a..1d1bb75 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)
@@ -548,6 +552,6 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm)
* Initialize PIO device
*/
kvm_iodevice_init(&s->dev, &picdev_ops);
- kvm_io_bus_register_dev(&kvm->pio_bus, &s->dev);
+ kvm_io_bus_register_dev(kvm, &kvm->pio_bus, &s->dev);
return s;
}
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 2e02865..265a765 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 5a66bb9..badc23f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2260,35 +2260,23 @@ 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, &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, &vcpu->kvm->mmio_bus, addr, len, v);
}

static int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
@@ -2357,7 +2345,6 @@ 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) {
@@ -2382,13 +2369,8 @@ 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;
@@ -2415,7 +2397,6 @@ 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);
@@ -2436,13 +2417,8 @@ 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;
@@ -2758,48 +2734,42 @@ 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, &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, &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, &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;
@@ -2819,11 +2789,7 @@ 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;
}
@@ -2837,7 +2803,6 @@ 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;
@@ -2881,12 +2846,6 @@ 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);
@@ -2894,16 +2853,13 @@ 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;
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2451f48..8337f8e 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -42,6 +42,7 @@

#define KVM_USERSPACE_IRQ_SOURCE_ID 0

+struct kvm;
struct kvm_vcpu;
extern struct kmem_cache *kvm_vcpu_cache;

@@ -59,9 +60,11 @@ struct kvm_io_bus {

void kvm_io_bus_init(struct kvm_io_bus *bus);
void kvm_io_bus_destroy(struct kvm_io_bus *bus);
-struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus,
- gpa_t addr, int len, int is_write);
-void kvm_io_bus_register_dev(struct kvm_io_bus *bus,
+int kvm_io_bus_write(struct kvm *, struct kvm_io_bus *bus, gpa_t addr, int len,
+ const void *val);
+int kvm_io_bus_read(struct kvm *, struct kvm_io_bus *bus, gpa_t addr, int len,
+ void *val);
+void kvm_io_bus_register_dev(struct kvm *, struct kvm_io_bus *bus,
struct kvm_io_device *dev);

struct kvm_vcpu {
@@ -138,6 +141,7 @@ struct kvm {
atomic_t online_vcpus;
struct list_head vm_list;
struct mutex lock;
+ struct rw_semaphore bus_lock;
struct kvm_io_bus mmio_bus;
struct kvm_io_bus pio_bus;
#ifdef CONFIG_HAVE_KVM_EVENTFD
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 397f419..0140218 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -19,17 +19,15 @@ static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
}

-static int coalesced_mmio_in_range(struct kvm_io_device *this,
- gpa_t addr, int len, int is_write)
+static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
+ gpa_t addr, int len)
{
- struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
struct kvm_coalesced_mmio_zone *zone;
struct kvm_coalesced_mmio_ring *ring;
unsigned avail;
int i;

- if (!is_write)
- return 0;
+ /* kvm->bus_lock is taken by the caller */

/* Are we able to batch it ? */

@@ -60,11 +58,13 @@ static int coalesced_mmio_in_range(struct kvm_io_device *this,
return 0;
}

-static void coalesced_mmio_write(struct kvm_io_device *this,
- gpa_t addr, int len, const void *val)
+static int coalesced_mmio_write(struct kvm_io_device *this,
+ gpa_t addr, int len, const void *val)
{
struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
+ if (!coalesced_mmio_in_range(dev, addr, len))
+ return -EOPNOTSUPP;

spin_lock(&dev->lock);

@@ -76,6 +76,7 @@ static void coalesced_mmio_write(struct kvm_io_device *this,
smp_wmb();
ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
spin_unlock(&dev->lock);
+ return 0;
}

static void coalesced_mmio_destructor(struct kvm_io_device *this)
@@ -87,7 +88,6 @@ static void coalesced_mmio_destructor(struct kvm_io_device *this)

static const struct kvm_io_device_ops coalesced_mmio_ops = {
.write = coalesced_mmio_write,
- .in_range = coalesced_mmio_in_range,
.destructor = coalesced_mmio_destructor,
};

@@ -102,7 +102,7 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
dev->kvm = kvm;
kvm->coalesced_mmio_dev = dev;
- kvm_io_bus_register_dev(&kvm->mmio_bus, &dev->dev);
+ kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &dev->dev);

return 0;
}
@@ -115,16 +115,16 @@ int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
if (dev == NULL)
return -EINVAL;

- mutex_lock(&kvm->lock);
+ down_write(&kvm->bus_lock);
if (dev->nb_zones >= KVM_COALESCED_MMIO_ZONE_MAX) {
- mutex_unlock(&kvm->lock);
+ up_write(&kvm->bus_lock);
return -ENOBUFS;
}

dev->zone[dev->nb_zones] = *zone;
dev->nb_zones++;

- mutex_unlock(&kvm->lock);
+ up_write(&kvm->bus_lock);
return 0;
}

@@ -138,7 +138,7 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
if (dev == NULL)
return -EINVAL;

- mutex_lock(&kvm->lock);
+ down_write(&kvm->bus_lock);

i = dev->nb_zones;
while(i) {
@@ -156,7 +156,7 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
i--;
}

- mutex_unlock(&kvm->lock);
+ up_write(&kvm->bus_lock);

return 0;
}
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index d8b2eca..2d352f7 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -227,20 +227,19 @@ static inline struct kvm_ioapic *to_ioapic(struct kvm_io_device *dev)
return container_of(dev, struct kvm_ioapic, dev);
}

-static int ioapic_in_range(struct kvm_io_device *this, gpa_t addr,
- int len, int is_write)
+static inline int ioapic_in_range(struct kvm_ioapic *ioapic, gpa_t addr)
{
- struct kvm_ioapic *ioapic = to_ioapic(this);
-
return ((addr >= ioapic->base_address &&
(addr < ioapic->base_address + IOAPIC_MEM_LENGTH)));
}

-static void ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
- void *val)
+static int ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
+ void *val)
{
struct kvm_ioapic *ioapic = to_ioapic(this);
u32 result;
+ if (!ioapic_in_range(ioapic, addr))
+ return -ENOTSUPP;

ioapic_debug("addr %lx\n", (unsigned long)addr);
ASSERT(!(addr & 0xf)); /* check alignment */
@@ -273,13 +272,16 @@ static void ioapic_mmio_read(struct kvm_io_device *this, gpa_t addr, int len,
printk(KERN_WARNING "ioapic: wrong length %d\n", len);
}
mutex_unlock(&ioapic->kvm->irq_lock);
+ return 0;
}

-static void ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
- const void *val)
+static int ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
+ const void *val)
{
struct kvm_ioapic *ioapic = to_ioapic(this);
u32 data;
+ if (!ioapic_in_range(ioapic, addr))
+ return -ENOTSUPP;

ioapic_debug("ioapic_mmio_write addr=%p len=%d val=%p\n",
(void*)addr, len, val);
@@ -290,7 +292,7 @@ static void ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
data = *(u32 *) val;
else {
printk(KERN_WARNING "ioapic: Unsupported size %d\n", len);
- return;
+ return 0;
}

addr &= 0xff;
@@ -312,6 +314,7 @@ static void ioapic_mmio_write(struct kvm_io_device *this, gpa_t addr, int len,
break;
}
mutex_unlock(&ioapic->kvm->irq_lock);
+ return 0;
}

void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
@@ -329,7 +332,6 @@ void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
static const struct kvm_io_device_ops ioapic_mmio_ops = {
.read = ioapic_mmio_read,
.write = ioapic_mmio_write,
- .in_range = ioapic_in_range,
};

int kvm_ioapic_init(struct kvm *kvm)
@@ -343,7 +345,7 @@ int kvm_ioapic_init(struct kvm *kvm)
kvm_ioapic_reset(ioapic);
kvm_iodevice_init(&ioapic->dev, &ioapic_mmio_ops);
ioapic->kvm = kvm;
- kvm_io_bus_register_dev(&kvm->mmio_bus, &ioapic->dev);
+ kvm_io_bus_register_dev(kvm, &kvm->mmio_bus, &ioapic->dev);
return 0;
}

diff --git a/virt/kvm/iodev.h b/virt/kvm/iodev.h
index 2c67f5a..c4b07eb 100644
--- a/virt/kvm/iodev.h
+++ b/virt/kvm/iodev.h
@@ -17,20 +17,24 @@
#define __KVM_IODEV_H__

#include <linux/kvm_types.h>
+#include <asm/errno.h>

struct kvm_io_device;

+/**
+ * read and write handlers are called under kvm bus_lock.
+ * They return 0 if the transaction has been handled,
+ * or non-zero to have it passed to the next device.
+ **/
struct kvm_io_device_ops {
- void (*read)(struct kvm_io_device *this,
+ int (*read)(struct kvm_io_device *this,
+ gpa_t addr,
+ int len,
+ void *val);
+ int (*write)(struct kvm_io_device *this,
gpa_t addr,
int len,
- void *val);
- void (*write)(struct kvm_io_device *this,
- gpa_t addr,
- int len,
- const void *val);
- int (*in_range)(struct kvm_io_device *this, gpa_t addr, int len,
- int is_write);
+ const void *val);
void (*destructor)(struct kvm_io_device *this);
};

@@ -45,26 +49,16 @@ static inline void kvm_iodevice_init(struct kvm_io_device *dev,
dev->ops = ops;
}

-static inline void kvm_iodevice_read(struct kvm_io_device *dev,
- gpa_t addr,
- int len,
- void *val)
+static inline int kvm_iodevice_read(struct kvm_io_device *dev,
+ gpa_t addr, int l, void *v)
{
- dev->ops->read(dev, addr, len, val);
+ return dev->ops->read ? dev->ops->read(dev, addr, l, v) : -EOPNOTSUPP;
}

-static inline void kvm_iodevice_write(struct kvm_io_device *dev,
- gpa_t addr,
- int len,
- const void *val)
+static inline int kvm_iodevice_write(struct kvm_io_device *dev,
+ gpa_t addr, int l, const void *v)
{
- dev->ops->write(dev, addr, len, val);
-}
-
-static inline int kvm_iodevice_in_range(struct kvm_io_device *dev,
- gpa_t addr, int len, int is_write)
-{
- return dev->ops->in_range(dev, addr, len, is_write);
+ return dev->ops->write ? dev->ops->write(dev, addr, l, v) : -EOPNOTSUPP;
}

static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 58d6bc6..3b19839 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -981,6 +981,7 @@ static struct kvm *kvm_create_vm(void)
kvm_io_bus_init(&kvm->pio_bus);
kvm_irqfd_init(kvm);
mutex_init(&kvm->lock);
+ init_rwsem(&kvm->bus_lock);
mutex_init(&kvm->irq_lock);
kvm_io_bus_init(&kvm->mmio_bus);
init_rwsem(&kvm->slots_lock);
@@ -2484,26 +2485,42 @@ void kvm_io_bus_destroy(struct kvm_io_bus *bus)
}
}

-struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus,
- gpa_t addr, int len, int is_write)
+int kvm_io_bus_write(struct kvm *kvm, struct kvm_io_bus *bus, gpa_t addr,
+ int len, const void *val)
{
- int i;
-
- for (i = 0; i < bus->dev_count; i++) {
- struct kvm_io_device *pos = bus->devs[i];
-
- if (kvm_iodevice_in_range(pos, addr, len, is_write))
- return pos;
- }
+ int i, r = -EOPNOTSUPP;
+ down_read(&kvm->bus_lock);
+ for (i = 0; i < bus->dev_count; i++)
+ if (!kvm_iodevice_write(bus->devs[i], addr, len, val)) {
+ r = 0;
+ break;
+ }
+ up_read(&kvm->bus_lock);
+ return r;
+}

- return NULL;
+int kvm_io_bus_read(struct kvm *kvm, struct kvm_io_bus *bus, gpa_t addr,
+ int len, void *val)
+{
+ int i, r = -EOPNOTSUPP;
+ down_read(&kvm->bus_lock);
+ for (i = 0; i < bus->dev_count; i++)
+ if (!kvm_iodevice_read(bus->devs[i], addr, len, val)) {
+ r = 0;
+ break;
+ }
+ up_read(&kvm->bus_lock);
+ return r;
}

-void kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
+void kvm_io_bus_register_dev(struct kvm *kvm, struct kvm_io_bus *bus,
+ struct kvm_io_device *dev)
{
+ down_write(&kvm->bus_lock);
BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));

bus->devs[bus->dev_count++] = dev;
+ up_write(&kvm->bus_lock);
}

static struct notifier_block kvm_cpu_notifier = {
--
1.6.2.2
--
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