It seems that a lot of complexity and trickiness with iosignalfd is
handling the group/item relationship, which comes about because kvm does
not currently let a device on the bus claim a write transaction based on the
value written.  This could be greatly simplified if the value written
was passed to the in_range check for write operation.  We could then
simply make each kvm_iosignalfd a device on the bus.

What does everyone think of the following lightly tested patch?

-->

Subject: kvm: pass value to in_range callback

For write transactions, pass the value written to in_range checks so
that we can make each iosignalfd a separate device on kvm bus.

Signed-off-by: Michael S. Tsirkin <m...@redhat.com>

---


diff --git a/virt/kvm/iodev.h b/virt/kvm/iodev.h
index 55e8846..98a25af 100644
--- a/virt/kvm/iodev.h
+++ b/virt/kvm/iodev.h
@@ -28,7 +28,7 @@ struct kvm_io_device {
                      int len,
                      const void *val);
        int (*in_range)(struct kvm_io_device *this, gpa_t addr, int len,
-                       int is_write);
+                       int is_write, void *write_val);
        void (*destructor)(struct kvm_io_device *this);
 
        void             *private;
@@ -51,9 +51,10 @@ static inline void kvm_iodevice_write(struct kvm_io_device 
*dev,
 }
 
 static inline int kvm_iodevice_inrange(struct kvm_io_device *dev,
-                                      gpa_t addr, int len, int is_write)
+                                      gpa_t addr, int len, int is_write,
+                                      void *write_val)
 {
-       return dev->in_range(dev, addr, len, is_write);
+       return dev->in_range(dev, addr, len, is_write, write_val);
 }
 
 static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 80c57b0..8cfdf9d 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -211,11 +211,13 @@ 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)
+                                       gpa_t addr, int len, int is_write,
+                                       void *write_val)
 {
        struct kvm_io_device *dev;
 
-       dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr, len, is_write);
+       dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr, len, is_write,
+                                 write_val);
 
        return dev;
 }
@@ -247,7 +247,8 @@ 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);
+       mmio_dev = vcpu_find_mmio_dev(vcpu, p->addr, p->size,
+                                     !p->dir, &p->data);
        if (mmio_dev) {
                if (!p->dir)
                        kvm_iodevice_write(mmio_dev, p->addr, p->size,
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4d6f0d2..5ba21ff 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -485,7 +485,7 @@ static void pit_ioport_read(struct kvm_io_device *this,
 }
 
 static int pit_in_range(struct kvm_io_device *this, gpa_t addr,
-                       int len, int is_write)
+                       int len, int is_write, void *write_val)
 {
        return ((addr >= KVM_PIT_BASE_ADDRESS) &&
                (addr < KVM_PIT_BASE_ADDRESS + KVM_PIT_MEM_LENGTH));
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ae99d83..456fd53 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -721,7 +721,7 @@ static void apic_mmio_write(struct kvm_io_device *this,
 }
 
 static int apic_mmio_range(struct kvm_io_device *this, gpa_t addr,
-                          int len, int size)
+                          int len, int is_write, void *write_val)
 {
        struct kvm_lapic *apic = (struct kvm_lapic *)this->private;
        int ret = 0;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 249540f..9d29017 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2043,13 +2043,13 @@ static void kvm_init_msr_list(void)
  */
 static struct kvm_io_device *vcpu_find_pervcpu_dev(struct kvm_vcpu *vcpu,
                                                gpa_t addr, int len,
-                                               int is_write)
+                                               int is_write, void *write_val)
 {
        struct kvm_io_device *dev;
 
        if (vcpu->arch.apic) {
                dev = &vcpu->arch.apic->dev;
-               if (dev->in_range(dev, addr, len, is_write))
+               if (dev->in_range(dev, addr, len, is_write, write_val))
                        return dev;
        }
        return NULL;
@@ -2058,14 +2058,14 @@ static struct kvm_io_device 
*vcpu_find_pervcpu_dev(struct kvm_vcpu *vcpu,
 
 static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
                                                gpa_t addr, int len,
-                                               int is_write)
+                                               int is_write, void *write_val)
 {
        struct kvm_io_device *dev;
 
-       dev = vcpu_find_pervcpu_dev(vcpu, addr, len, is_write);
+       dev = vcpu_find_pervcpu_dev(vcpu, addr, len, is_write, write_val);
        if (dev == NULL)
                dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr, len,
-                                         is_write);
+                                         is_write, write_val);
        return dev;
 }
 
@@ -2161,7 +2161,7 @@ mmio:
         * Is this MMIO handled locally?
         */
        mutex_lock(&vcpu->kvm->lock);
-       mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 0);
+       mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 0, NULL);
        if (mmio_dev) {
                kvm_iodevice_read(mmio_dev, gpa, bytes, val);
                mutex_unlock(&vcpu->kvm->lock);
@@ -2216,7 +2216,7 @@ mmio:
         * Is this MMIO handled locally?
         */
        mutex_lock(&vcpu->kvm->lock);
-       mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 1);
+       mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 1, val);
        if (mmio_dev) {
                kvm_iodevice_write(mmio_dev, gpa, bytes, val);
                mutex_unlock(&vcpu->kvm->lock);
@@ -2576,9 +2576,10 @@ static void pio_string_write(struct kvm_io_device 
*pio_dev,
 
 static struct kvm_io_device *vcpu_find_pio_dev(struct kvm_vcpu *vcpu,
                                               gpa_t addr, int len,
-                                              int is_write)
+                                              int is_write, void *write_val)
 {
-       return kvm_io_bus_find_dev(&vcpu->kvm->pio_bus, addr, len, is_write);
+       return kvm_io_bus_find_dev(&vcpu->kvm->pio_bus, addr, len, is_write,
+                                  write_val);
 }
 
 int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
@@ -2608,7 +2608,8 @@ 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);
 
-       pio_dev = vcpu_find_pio_dev(vcpu, port, size, !in);
+       pio_dev = vcpu_find_pio_dev(vcpu, port, size, !in,
+                                   vcpu->arch.pio_data);
        if (pio_dev) {
                kernel_pio(pio_dev, vcpu, vcpu->arch.pio_data);
                complete_pio(vcpu);
@@ -2624,7 +2625,6 @@ 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;
@@ -2672,9 +2672,6 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct 
kvm_run *run, int in,
 
        vcpu->arch.pio.guest_gva = address;
 
-       pio_dev = vcpu_find_pio_dev(vcpu, port,
-                                   vcpu->arch.pio.cur_count,
-                                   !vcpu->arch.pio.in);
        if (!vcpu->arch.pio.in) {
                /* string PIO write */
                ret = pio_copy_data(vcpu);
@@ -2682,13 +2679,20 @@ 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);
-                       complete_pio(vcpu);
-                       if (vcpu->arch.pio.count == 0)
-                               ret = 1;
+               if (ret == 0) {
+                       struct kvm_io_device *pio_dev;
+                       pio_dev = vcpu_find_pio_dev(vcpu, port,
+                                                   vcpu->arch.pio.cur_count,
+                                                   1, vcpu->arch.pio_data);
+                       if (pio_dev) {
+                               pio_string_write(pio_dev, vcpu);
+                               complete_pio(vcpu);
+                               if (vcpu->arch.pio.count == 0)
+                                       ret = 1;
+                       }
                }
-       } else if (pio_dev)
+       } else if (vcpu_find_pio_dev(vcpu, port, vcpu->arch.pio.cur_count, 0,
+                                    NULL))
                pr_unimpl(vcpu, "no string pio read support yet, "
                       "port %x size %d count %ld\n",
                        port, size, count);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index aacc544..0fb7938 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -60,7 +60,8 @@ 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);
+                                         gpa_t addr, int len, int is_write,
+                                         void *write_val);
 void kvm_io_bus_register_dev(struct kvm_io_bus *bus,
                             struct kvm_io_device *dev);
 
diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
index 5ae620d..3a1cbfd 100644
--- a/virt/kvm/coalesced_mmio.c
+++ b/virt/kvm/coalesced_mmio.c
@@ -15,7 +15,8 @@
 #include "coalesced_mmio.h"
 
 static int coalesced_mmio_in_range(struct kvm_io_device *this,
-                                  gpa_t addr, int len, int is_write)
+                                  gpa_t addr, int len, int is_write,
+                                  void *write_val)
 {
        struct kvm_coalesced_mmio_dev *dev =
                                (struct kvm_coalesced_mmio_dev*)this->private;
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 1eddae9..2adbb1b 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -221,7 +221,8 @@ void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int 
trigger_mode)
 }
 
 static int ioapic_in_range(struct kvm_io_device *this, gpa_t addr,
-                          int len, int is_write)
+                          int len, int is_write,
+                          void *write_val)
 {
        struct kvm_ioapic *ioapic = (struct kvm_ioapic *)this->private;
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7645543..b97e390 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2445,14 +2445,15 @@ 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)
+                                         gpa_t addr, int len, int is_write,
+                                         void *write_val)
 {
        int i;
 
        for (i = 0; i < bus->dev_count; i++) {
                struct kvm_io_device *pos = bus->devs[i];
 
-               if (pos->in_range(pos, addr, len, is_write))
+               if (pos->in_range(pos, addr, len, is_write, write_val))
                        return pos;
        }
 
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