On Wed, Dec 29, 2010 at 03:18:13PM +0800, Sheng Yang wrote:
> On Tuesday 28 December 2010 20:26:13 Avi Kivity wrote:
> > On 12/22/2010 10:44 AM, Sheng Yang wrote:
> > > Then we can support mask bit operation of assigned devices now.
> > >
> > >
> > > @@ -3817,14 +3819,16 @@ static int
> > > emulator_write_emulated_onepage(unsigned long addr,
> > >
> > > mmio:
> > > trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, bytes, gpa, *(u64 *)val);
> > >
> > > + r = vcpu_mmio_write(vcpu, gpa, bytes, val);
> > >
> > > /*
> > >
> > > * Is this MMIO handled locally?
> > > */
> > >
> > > - if (!vcpu_mmio_write(vcpu, gpa, bytes, val))
> > > + if (!r)
> > >
> > > return X86EMUL_CONTINUE;
> > >
> > > vcpu->mmio_needed = 1;
> > >
> > > - vcpu->run->exit_reason = KVM_EXIT_MMIO;
> > > + vcpu->run->exit_reason = (r == -ENOTSYNC) ?
> > > + KVM_EXIT_MSIX_ROUTING_UPDATE : KVM_EXIT_MMIO;
> >
> > This isn't very pretty, exit_reason should be written in
> > vcpu_mmio_write(). I guess we can refactor it later.
>
> Sure.
> >
> > > +#define KVM_MSIX_MMIO_TYPE_ASSIGNED_DEV (1<< 0)
> > > +
> > > +#define KVM_MSIX_MMIO_TYPE_BASE_TABLE (1<< 8)
> > > +#define KVM_MSIX_MMIO_TYPE_BASE_PBA (1<< 9)
> > > +
> > > +#define KVM_MSIX_MMIO_TYPE_DEV_MASK 0x00ff
> > > +#define KVM_MSIX_MMIO_TYPE_BASE_MASK 0xff00
> >
> > Any explanation of these?
>
> I chose to use assigned device id instead of one specific table id, because every
> device should got at most one MSI MMIO(the same should applied to vfio device as
> well), and if we use specific table ID, we need way to associate with the device
> anyway, to perform mask/unmask or other operation. So I think it's better to use
> device ID here directly.
Table id will be needed to make things work for emulated devices.
My idea was this: we have the device id in kvm_assigned_msix_entry already.
Just put table id and entry number in kvm_irq_routing_entry (create
a new gsi type for this).
The result will also work for irqfd because these are mapped to gsi.
> And for the table and pba address, it's due to the mapping in userspace may know
> the guest MSI-X table address and PBA address at different time(due to different
> BAR, refer to the code in assigned_dev_iomem_map() of qemu). So I purposed this
> API to allow each of them can be passed to kernel space individually.
> >
> > > +struct kvm_msix_mmio_user {
> > > + __u32 dev_id;
> > > + __u16 type;
> > > + __u16 max_entries_nr;
> > > + __u64 base_addr;
> > > + __u64 base_va;
> > > + __u64 flags;
> > > + __u64 reserved[4];
> > > +};
> > > +
> > >
> > >
> > > +int kvm_assigned_device_update_msix_mask_bit(struct kvm *kvm,
> > > + int assigned_dev_id, int entry, u32 flag)
> > > +{
> >
> > Need a better name for 'flag' (and make it a bool).
> >
> > > + int r = -EFAULT;
> > > + struct kvm_assigned_dev_kernel *adev;
> > > + int i;
> > > +
> > > + if (!irqchip_in_kernel(kvm))
> > > + return r;
> > > +
> > > + mutex_lock(&kvm->lock);
> > > + adev = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
> > > + assigned_dev_id);
> > > + if (!adev)
> > > + goto out;
> > > +
> > > + for (i = 0; i< adev->entries_nr; i++)
> > > + if (adev->host_msix_entries[i].entry == entry) {
> > > + if (flag)
> > > + disable_irq_nosync(
> > > + adev->host_msix_entries[i].vector);
> > > + else
> > > + enable_irq(adev->host_msix_entries[i].vector);
> > > + r = 0;
> > > + break;
> > > + }
> > > +out:
> > > + mutex_unlock(&kvm->lock);
> > > + return r;
> > > +}
> > >
> > > @@ -1988,6 +2008,12 @@ static int kvm_dev_ioctl_create_vm(void)
> > >
> > > return r;
> > >
> > > }
> > >
> > > #endif
> > >
> > > + r = kvm_register_msix_mmio_dev(kvm);
> > > + if (r< 0) {
> > > + kvm_put_kvm(kvm);
> > > + return r;
> > > + }
> >
> > Shouldn't this be part of individual KVM_REGISTER_MSIX_MMIO calls?
>
> In fact this MMIO device is more like global one for the VM, not for every
> devices. It should handle all MMIO from all MSI-X enabled devices, so I put it in
> the VM init/destroy process.
>
> > > +static int msix_table_mmio_read(struct kvm_io_device *this, gpa_t addr,
> > > int len, + void *val)
> > > +{
> > > + struct kvm_msix_mmio_dev *mmio_dev =
> > > + container_of(this, struct kvm_msix_mmio_dev, table_dev);
> > > + struct kvm_msix_mmio *mmio;
> > > + int idx, ret = 0, entry, offset, r;
> > > +
> > > + mutex_lock(&mmio_dev->lock);
> > > + idx = get_mmio_table_index(mmio_dev, addr, len);
> > > + if (idx< 0) {
> > > + ret = -EOPNOTSUPP;
> > > + goto out;
> > > + }
> > > + if ((addr& 0x3) || (len != 4&& len != 8))
> > > + goto out;
> >
> > What about (addr & 4) && (len == 8)? Is it supported? It may cross entry
> > boundaries.
>
> Should not supported. But I haven't found words on the PCI spec for it. So I
> didn't add this check.
IMPLEMENTATION NOTE
MSI-X Memory Space Structures in Read/Write Memory
....
For all accesses to MSI-X Table and MSI-X PBA fields, software must use
aligned full
DWORD or aligned full QWORD transactions; otherwise, the result is
undefined.
> >
> > > + mmio =&mmio_dev->mmio[idx];
> > > +
> > > + entry = (addr - mmio->table_base_addr) / PCI_MSIX_ENTRY_SIZE;
> > > + offset = addr& 0xf;
> > > + r = copy_from_user(val, (void *)(mmio->table_base_va +
> > > + entry * PCI_MSIX_ENTRY_SIZE + offset), len);
> > >
> > >
> > > + if (r)
> > > + goto out;
> > > +out:
> > > + mutex_unlock(&mmio_dev->lock);
> > > + return ret;
> > > +}
> > > +
> > > +static int msix_table_mmio_write(struct kvm_io_device *this, gpa_t addr,
> > > + int len, const void *val)
> > > +{
> > > + struct kvm_msix_mmio_dev *mmio_dev =
> > > + container_of(this, struct kvm_msix_mmio_dev, table_dev);
> > > + struct kvm_msix_mmio *mmio;
> > > + int idx, entry, offset, ret = 0, r = 0;
> > > + gpa_t entry_base;
> > > + u32 old_ctrl, new_ctrl;
> > > +
> > > + mutex_lock(&mmio_dev->lock);
> > > + idx = get_mmio_table_index(mmio_dev, addr, len);
> > > + if (idx< 0) {
> > > + ret = -EOPNOTSUPP;
> > > + goto out;
> > > + }
> > > + if ((addr& 0x3) || (len != 4&& len != 8))
> > > + goto out;
> > > + mmio =&mmio_dev->mmio[idx];
> > > + entry = (addr - mmio->table_base_addr) / PCI_MSIX_ENTRY_SIZE;
> > > + entry_base = mmio->table_base_va + entry * PCI_MSIX_ENTRY_SIZE;
> > > + offset = addr& 0xF;
> > > +
> > > + if (copy_from_user(&old_ctrl,
> > > + entry_base + PCI_MSIX_ENTRY_VECTOR_CTRL,
> > > + sizeof old_ctrl))
> > > + goto out;
> >
> > get_user() is easier.
> >
> > > +
> > > + /* No allow writing to other fields when entry is unmasked */
> > > + if (!(old_ctrl& PCI_MSIX_ENTRY_CTRL_MASKBIT)&&
> > > + offset != PCI_MSIX_ENTRY_VECTOR_CTRL)
> > > + goto out;
> > > +
> > > + if (copy_to_user(entry_base + offset, val, len))
> > > + goto out;
> > >
> > > +
> > > + if (copy_from_user(&new_ctrl,
> > > + entry_base + PCI_MSIX_ENTRY_VECTOR_CTRL,
> > > + sizeof new_ctrl))
> > > + goto out;
> >
> > put_user()
> >
> > > +
> > > + if ((offset< PCI_MSIX_ENTRY_VECTOR_CTRL&& len == 4) ||
> > > + (offset< PCI_MSIX_ENTRY_DATA&& len == 8))
> > > + ret = -ENOTSYNC;
> > > + if (old_ctrl == new_ctrl)
> > > + goto out;
> > > + if (!(old_ctrl& PCI_MSIX_ENTRY_CTRL_MASKBIT)&&
> > > + (new_ctrl& PCI_MSIX_ENTRY_CTRL_MASKBIT))
> > > + r = update_msix_mask_bit(mmio_dev->kvm, mmio, entry, 1);
> > > + else if ((old_ctrl& PCI_MSIX_ENTRY_CTRL_MASKBIT)&&
> > > + !(new_ctrl& PCI_MSIX_ENTRY_CTRL_MASKBIT))
> > > + r = update_msix_mask_bit(mmio_dev->kvm, mmio, entry, 0);
> > > + if (r || ret)
> > > + ret = -ENOTSYNC;
> > > +out:
> > > + mutex_unlock(&mmio_dev->lock);
> > > + return ret;
> > > +}
> >
> > blank line...
> >
> > > +static const struct kvm_io_device_ops msix_mmio_table_ops = {
> > > + .read = msix_table_mmio_read,
> > > + .write = msix_table_mmio_write,
> > > +};
> > > +
> > > ++
> > > +int kvm_vm_ioctl_register_msix_mmio(struct kvm *kvm,
> > > + struct kvm_msix_mmio_user *mmio_user)
> > > +{
> > > + struct kvm_msix_mmio_dev *mmio_dev =&kvm->msix_mmio_dev;
> > > + struct kvm_msix_mmio *mmio = NULL;
> > > + int r = 0, i;
> > > +
> > > + mutex_lock(&mmio_dev->lock);
> > > + for (i = 0; i< mmio_dev->mmio_nr; i++) {
> > > + if (mmio_dev->mmio[i].dev_id == mmio_user->dev_id&&
> > > + (mmio_dev->mmio[i].type& KVM_MSIX_MMIO_TYPE_DEV_MASK) ==
> > > + (mmio_user->type& KVM_MSIX_MMIO_TYPE_DEV_MASK)) {
> > > + mmio =&mmio_dev->mmio[i];
> > > + if (mmio->max_entries_nr != mmio_user->max_entries_nr) {
> > > + r = -EINVAL;
> > > + goto out;
> > > + }
> > > + break;
> > > + }
> > > + }
> > > + if (!mmio) {
> > > + if (mmio_dev->mmio_nr == KVM_MSIX_MMIO_MAX) {
> > > + r = -ENOSPC;
> > > + goto out;
> > > + }
> > > + mmio =&mmio_dev->mmio[mmio_dev->mmio_nr];
> > > + mmio_dev->mmio_nr++;
> > > + }
> > > + mmio->max_entries_nr = mmio_user->max_entries_nr;
> >
> > Sanity check to avoid overflow.
> >
> > > + mmio->dev_id = mmio_user->dev_id;
> > > + mmio->flags = mmio_user->flags;
> >
> > Check for unsupported bits (all of them at present?)
> >
> > > + if ((mmio_user->type& KVM_MSIX_MMIO_TYPE_DEV_MASK) ==
> > > + KVM_MSIX_MMIO_TYPE_ASSIGNED_DEV)
> > > + mmio->type = KVM_MSIX_MMIO_TYPE_ASSIGNED_DEV;
> > > +
> > > + if ((mmio_user->type& KVM_MSIX_MMIO_TYPE_BASE_MASK) ==
> > > + KVM_MSIX_MMIO_TYPE_BASE_TABLE) {
> > > + mmio->type |= KVM_MSIX_MMIO_TYPE_BASE_TABLE;
> > > + mmio->table_base_addr = mmio_user->base_addr;
> > > + mmio->table_base_va = mmio_user->base_va;
> >
> > Check for va in kernel space.
> >
> > > + } else if ((mmio_user->type& KVM_MSIX_MMIO_TYPE_BASE_MASK) ==
> > > + KVM_MSIX_MMIO_TYPE_BASE_PBA) {
> > > + mmio->type |= KVM_MSIX_MMIO_TYPE_BASE_PBA;
> > > + mmio->pba_base_addr = mmio_user->base_addr;
> > > + mmio->pba_base_va = mmio_user->base_va;
> > > + }
> > > +out:
> > > + mutex_unlock(&mmio_dev->lock);
> > > + return r;
> > > +}
> > > +
> > > +
> >
> > In all, looks reasonable. I'd like to see documentation for it, and
> > review from the pci people. Alex, mst?
Some general comments:
PBA isn't supported in this version, which is OK, but let's not add a
capability until it is, and let's not try to guess what
the interface will look like. I think keeping PBA in userspace will be hard
because it needs to be modified from interrupt context.
Removing the PBA stub will make the interface simpler.
> Would add the API document soon.
>
> --
> regards
> Yang, Sheng
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