On Wednesday 17 November 2010 03:45:22 Marcelo Tosatti wrote:
> On Mon, Nov 15, 2010 at 05:15:32PM +0800, Sheng Yang wrote:
> > This patch enable per-vector mask for assigned devices using MSI-X.
> >
> > This patch provided two new APIs: one is for guest to specific device's
> > MSI-X table address in MMIO, the other is for userspace to get
> > information about mask bit.
> >
> > All the mask bit operation are kept in kernel, in order to accelerate.
> > Userspace shouldn't access the device MMIO directly for the information,
> > instead it should uses provided API to do so.
> >
> > Signed-off-by: Sheng Yang <[email protected]>
> > ---
> >
> > arch/x86/kvm/x86.c | 1 +
> > include/linux/kvm.h | 32 +++++
> > include/linux/kvm_host.h | 5 +
> > virt/kvm/assigned-dev.c | 318
> > +++++++++++++++++++++++++++++++++++++++++++++- 4 files changed,
355
> > insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index fc29223..37602e2 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -1966,6 +1966,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> >
> > case KVM_CAP_X86_ROBUST_SINGLESTEP:
> > case KVM_CAP_XSAVE:
> >
> > case KVM_CAP_ASYNC_PF:
> > + case KVM_CAP_MSIX_MASK:
> > r = 1;
> > break;
> >
> > case KVM_CAP_COALESCED_MMIO:
> > diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> > index ea2dc1a..b3e5ffe 100644
> > --- a/include/linux/kvm.h
> > +++ b/include/linux/kvm.h
> > @@ -541,6 +541,9 @@ struct kvm_ppc_pvinfo {
> >
> > #define KVM_CAP_PPC_GET_PVINFO 57
> > #define KVM_CAP_PPC_IRQ_LEVEL 58
> > #define KVM_CAP_ASYNC_PF 59
> >
> > +#ifdef __KVM_HAVE_MSIX
> > +#define KVM_CAP_MSIX_MASK 60
> > +#endif
> >
> > #ifdef KVM_CAP_IRQ_ROUTING
> >
> > @@ -672,6 +675,9 @@ struct kvm_clock_data {
> >
> > #define KVM_XEN_HVM_CONFIG _IOW(KVMIO, 0x7a, struct
> > kvm_xen_hvm_config) #define KVM_SET_CLOCK _IOW(KVMIO,
> > 0x7b, struct kvm_clock_data) #define KVM_GET_CLOCK
> > _IOR(KVMIO, 0x7c, struct kvm_clock_data)
> >
> > +/* Available with KVM_CAP_MSIX_MASK */
> > +#define KVM_GET_MSIX_ENTRY _IOWR(KVMIO, 0x7d, struct
> > kvm_msix_entry) +#define KVM_UPDATE_MSIX_MMIO _IOW(KVMIO, 0x7e,
> > struct kvm_msix_mmio)
> >
> > /* Available with KVM_CAP_PIT_STATE2 */
> > #define KVM_GET_PIT2 _IOR(KVMIO, 0x9f, struct
> > kvm_pit_state2) #define KVM_SET_PIT2 _IOW(KVMIO, 0xa0,
> > struct kvm_pit_state2)
> >
> > @@ -795,4 +801,30 @@ struct kvm_assigned_msix_entry {
> >
> > __u16 padding[3];
> >
> > };
> >
> > +#define KVM_MSIX_TYPE_ASSIGNED_DEV 1
> > +
> > +#define KVM_MSIX_FLAG_MASKBIT (1 << 0)
> > +#define KVM_MSIX_FLAG_QUERY_MASKBIT (1 << 0)
> > +
> > +struct kvm_msix_entry {
> > + __u32 id;
> > + __u32 type;
>
> Is type really necessary? Will it ever differ from
> KVM_MSIX_TYPE_ASSIGNED_DEV?
This is the suggestion from Michael. He want it to be reused by emulated/pv
devices. So I add the type field here.
>
> > + __u32 entry; /* The index of entry in the MSI-X table */
> > + __u32 flags;
> > + __u32 query_flags;
> > + __u32 reserved[5];
> > +};
> > +
> > +#define KVM_MSIX_MMIO_FLAG_REGISTER (1 << 0)
> > +#define KVM_MSIX_MMIO_FLAG_UNREGISTER (1 << 1)
> > +
> > +struct kvm_msix_mmio {
> > + __u32 id;
> > + __u32 type;
> > + __u64 base_addr;
> > + __u32 max_entries_nr;
> > + __u32 flags;
> > + __u32 reserved[6];
> > +};
> > +
> >
> > #endif /* __LINUX_KVM_H */
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index f09db87..57a437a 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -501,6 +501,7 @@ struct kvm_guest_msix_entry {
> >
> > };
> >
> > #define KVM_ASSIGNED_ENABLED_IOMMU (1 << 0)
> >
> > +#define KVM_ASSIGNED_ENABLED_MSIX_MMIO (1 << 1)
> >
> > struct kvm_assigned_dev_kernel {
> >
> > struct kvm_irq_ack_notifier ack_notifier;
> > struct work_struct interrupt_work;
> >
> > @@ -521,6 +522,10 @@ struct kvm_assigned_dev_kernel {
> >
> > struct pci_dev *dev;
> > struct kvm *kvm;
> > spinlock_t assigned_dev_lock;
> >
> > + DECLARE_BITMAP(msix_mask_bitmap, KVM_MAX_MSIX_PER_DEV);
> > + gpa_t msix_mmio_base;
> > + struct kvm_io_device msix_mmio_dev;
> > + int msix_max_entries_nr;
> >
> > };
> >
> > struct kvm_irq_mask_notifier {
> >
> > diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
> > index 5c6b96d..76a1f12 100644
> > --- a/virt/kvm/assigned-dev.c
> > +++ b/virt/kvm/assigned-dev.c
> > @@ -226,12 +226,27 @@ static void kvm_free_assigned_irq(struct kvm *kvm,
> >
> > kvm_deassign_irq(kvm, assigned_dev, assigned_dev->irq_requested_type);
> >
> > }
> >
> > +static void unregister_msix_mmio(struct kvm *kvm,
> > + struct kvm_assigned_dev_kernel *adev)
> > +{
> > + if (adev->flags & KVM_ASSIGNED_ENABLED_MSIX_MMIO) {
> > + mutex_lock(&kvm->slots_lock);
> > + kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
> > + &adev->msix_mmio_dev);
> > + mutex_unlock(&kvm->slots_lock);
> > + adev->flags &= ~KVM_ASSIGNED_ENABLED_MSIX_MMIO;
> > + }
> > +}
> > +
> >
> > static void kvm_free_assigned_device(struct kvm *kvm,
> >
> > struct kvm_assigned_dev_kernel
> > *assigned_dev)
> >
> > {
> >
> > kvm_free_assigned_irq(kvm, assigned_dev);
> >
> > +#ifdef __KVM_HAVE_MSIX
> > + unregister_msix_mmio(kvm, assigned_dev);
> > +#endif
> >
> > pci_reset_function(assigned_dev->dev);
> >
> > pci_release_regions(assigned_dev->dev);
> >
> > @@ -504,7 +519,7 @@ out:
> > static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
> >
> > struct kvm_assigned_pci_dev *assigned_dev)
> >
> > {
> >
> > - int r = 0, idx;
> > + int r = 0, idx, i;
> >
> > struct kvm_assigned_dev_kernel *match;
> > struct pci_dev *dev;
> >
> > @@ -564,6 +579,10 @@ static int kvm_vm_ioctl_assign_device(struct kvm
> > *kvm,
> >
> > list_add(&match->list, &kvm->arch.assigned_dev_head);
> >
> > + /* The state after reset of MSI-X table is all masked */
> > + for (i = 0; i < KVM_MAX_MSIX_PER_DEV; i++)
> > + set_bit(i, match->msix_mask_bitmap);
> > +
> >
> > if (assigned_dev->flags & KVM_ASSIGNED_ENABLED_IOMMU) {
> >
> > if (!kvm->arch.iommu_domain) {
> >
> > r = kvm_iommu_map_guest(kvm);
> >
> > @@ -667,6 +686,43 @@ msix_nr_out:
> > return r;
> >
> > }
> >
> > +static void update_msix_mask(struct kvm_assigned_dev_kernel *adev,
> > + int idx, bool new_mask_flag)
> > +{
> > + int irq;
> > + bool old_mask_flag, need_flush = false;
> > +
> > + spin_lock_irq(&adev->assigned_dev_lock);
> > +
> > + if (!adev->dev->msix_enabled ||
> > + !(adev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX))
> > + goto out;
> > +
> > + old_mask_flag = test_bit(adev->guest_msix_entries[idx].entry,
> > + adev->msix_mask_bitmap);
> > + if (old_mask_flag == new_mask_flag)
> > + goto out;
> > +
> > + irq = adev->host_msix_entries[idx].vector;
> > + BUG_ON(irq == 0);
> > +
> > + if (new_mask_flag) {
> > + set_bit(adev->guest_msix_entries[idx].entry,
> > + adev->msix_mask_bitmap);
> > + disable_irq_nosync(irq);
> > + need_flush = true;
> > + } else {
> > + clear_bit(adev->guest_msix_entries[idx].entry,
> > + adev->msix_mask_bitmap);
> > + enable_irq(irq);
> > + }
> > +out:
> > + spin_unlock_irq(&adev->assigned_dev_lock);
> > +
> > + if (need_flush)
> > + flush_work(&adev->interrupt_work);
> > +}
> > +
> >
> > static int kvm_vm_ioctl_set_msix_entry(struct kvm *kvm,
> >
> > struct kvm_assigned_msix_entry *entry)
> >
> > {
> >
> > @@ -701,6 +757,235 @@ msix_entry_out:
> > return r;
> >
> > }
> >
> > +
> > +static int kvm_vm_ioctl_get_msix_entry(struct kvm *kvm,
> > + struct kvm_msix_entry *entry)
> > +{
> > + int r = 0;
> > + struct kvm_assigned_dev_kernel *adev;
> > +
> > + if (entry->type != KVM_MSIX_TYPE_ASSIGNED_DEV)
> > + return -EINVAL;
> > +
> > + if (!entry->query_flags)
> > + return -EINVAL;
> > +
> > + mutex_lock(&kvm->lock);
> > +
> > + adev = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
> > + entry->id);
> > +
> > + if (!adev) {
> > + r = -EINVAL;
> > + goto out;
> > + }
> > +
> > + if (entry->entry >= adev->msix_max_entries_nr) {
> > + r = -ENOSPC;
> > + goto out;
> > + }
> > +
> > + if (entry->query_flags & KVM_MSIX_FLAG_QUERY_MASKBIT) {
> > + if (test_bit(entry->entry, adev->msix_mask_bitmap))
> > + entry->flags |= KVM_MSIX_FLAG_MASKBIT;
> > + else
> > + entry->flags &= ~KVM_MSIX_FLAG_MASKBIT;
> > + }
> > +
> > +out:
> > + mutex_unlock(&kvm->lock);
> > +
> > + return r;
> > +}
> > +
> > +static bool msix_mmio_in_range(struct kvm_assigned_dev_kernel *adev,
> > + gpa_t addr, int len)
> > +{
> > + gpa_t start, end;
> > +
> > + BUG_ON(!(adev->flags & KVM_ASSIGNED_ENABLED_MSIX_MMIO));
> > + start = adev->msix_mmio_base;
> > + end = adev->msix_mmio_base + PCI_MSIX_ENTRY_SIZE *
> > + adev->msix_max_entries_nr;
> > + if (addr >= start && addr + len <= end)
> > + return true;
> > +
> > + return false;
> > +}
> > +
> > +static int msix_get_enabled_idx(struct kvm_assigned_dev_kernel *adev,
> > + gpa_t addr, int len)
> > +{
> > + int i, index = (addr - adev->msix_mmio_base) / PCI_MSIX_ENTRY_SIZE;
> > +
> > + for (i = 0; i < adev->entries_nr; i++)
> > + if (adev->guest_msix_entries[i].entry == index)
> > + return i;
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int msix_mmio_read(struct kvm_io_device *this, gpa_t addr, int
> > len, + void *val)
> > +{
> > + struct kvm_assigned_dev_kernel *adev =
> > + container_of(this, struct kvm_assigned_dev_kernel,
> > + msix_mmio_dev);
> > + int idx, r = 0;
> > + u32 entry[4];
> > + struct kvm_kernel_irq_routing_entry e;
> > +
> > + /* TODO: Get big-endian machine work */
> > + mutex_lock(&adev->kvm->lock);
> > + if (!msix_mmio_in_range(adev, addr, len)) {
> > + r = -EOPNOTSUPP;
> > + goto out;
> > + }
>
> The unregister path does:
>
> mutex_lock(kvm->lock)
> kvm_io_bus_unregister_dev()
> synchronize_srcu()
>
> If an instance of msix_mmio_read/msix_mmio_write is waiting on
> kvm->lock, synchronize_srcu will never complete.
>
> You should use a separate lock for the in range check (and have it mind
> that reads/writes can trigger after kvm_io_bus_register_dev, so all
> state accessible in the r/w handlers should be complete by that time).
Good point! Would update it.
>
> > + if ((addr & 0x3) || len != 4)
> > + goto out;
> > +
> > + idx = msix_get_enabled_idx(adev, addr, len);
> > + if (idx < 0) {
> > + idx = (addr - adev->msix_mmio_base) / PCI_MSIX_ENTRY_SIZE;
> > + if ((addr % PCI_MSIX_ENTRY_SIZE) ==
> > + PCI_MSIX_ENTRY_VECTOR_CTRL)
> > + *(unsigned long *)val =
> > + test_bit(idx, adev->msix_mask_bitmap) ?
> > + PCI_MSIX_ENTRY_CTRL_MASKBIT : 0;
> > + else
> > + r = -EOPNOTSUPP;
> > + goto out;
> > + }
> > +
> > + r = kvm_get_irq_routing_entry(adev->kvm,
> > + adev->guest_msix_entries[idx].vector, &e);
> > + if (r || e.type != KVM_IRQ_ROUTING_MSI) {
> > + r = -EOPNOTSUPP;
> > + goto out;
> > + }
> > + entry[0] = e.msi.address_lo;
> > + entry[1] = e.msi.address_hi;
> > + entry[2] = e.msi.data;
> > + entry[3] = test_bit(adev->guest_msix_entries[idx].entry,
> > + adev->msix_mask_bitmap);
> > + memcpy(val, &entry[addr % PCI_MSIX_ENTRY_SIZE / sizeof *entry], len);
>
> Division by zero?
Not quite understand. You mean sizeof *entry or PCI_MSIX_ENTRY_SIZE? Both of
them
should be positive integer I think... Maybe I should use sizeof u32 here?
--
regards
Yang, Sheng
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