Re: [PATCH v4 3/4] pci-assign: Use PCI-2.3-based shared legacy interrupts

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 2012-03-08 at 11:10 +0100, Jan Kiszka wrote:
> Enable the new KVM feature that allows legacy interrupt sharing for
> PCI-2.3-compliant devices. This requires to synchronize any guest
> change of the INTx mask bit to the kernel.
> 
> The feature is controlled by the property 'share_intx' and is off by
> default for now.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  hw/device-assignment.c |   25 +++++++++++++++++++++++++
>  hw/device-assignment.h |   10 ++++++----
>  qemu-kvm.c             |    9 +++++++++
>  qemu-kvm.h             |    2 ++
>  4 files changed, 42 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> index a5f1abb..b7cabd4 100644
> --- a/hw/device-assignment.c
> +++ b/hw/device-assignment.c
> @@ -782,6 +782,13 @@ static int assign_device(AssignedDevice *dev)
>                  "cause host memory corruption if the device issues DMA write "
>                  "requests!\n");
>      }
> +    if (dev->features & ASSIGNED_DEVICE_SHARE_INTX_MASK) {
> +        assigned_dev_data.flags |= KVM_DEV_ASSIGN_PCI_2_3;
> +
> +        /* hide host-side INTx masking from the guest */
> +        dev->emulate_config_read[PCI_COMMAND + 1] |=
> +            PCI_COMMAND_INTX_DISABLE >> 8;
> +    }

I think this also needs a kvm_has_intx_set_mask() check or else we're
emulating pci2.3 intx disable support without actually backing it.
Thanks,

Alex

>  
>      r = kvm_assign_pci_device(kvm_state, &assigned_dev_data);
>      if (r < 0) {
> @@ -1121,10 +1128,26 @@ static void assigned_dev_pci_write_config(PCIDevice *pci_dev, uint32_t address,
>                                            uint32_t val, int len)
>  {
>      AssignedDevice *assigned_dev = DO_UPCAST(AssignedDevice, dev, pci_dev);
> +    uint16_t old_cmd = pci_get_word(pci_dev->config + PCI_COMMAND);
>      uint32_t emulate_mask, full_emulation_mask;
> +    int ret;
>  
>      pci_default_write_config(pci_dev, address, val, len);
>  
> +    if (kvm_has_intx_set_mask() &&
> +        range_covers_byte(address, len, PCI_COMMAND + 1)) {
> +        bool intx_masked = (pci_get_word(pci_dev->config + PCI_COMMAND) &
> +                            PCI_COMMAND_INTX_DISABLE);
> +
> +        if (intx_masked != !!(old_cmd & PCI_COMMAND_INTX_DISABLE)) {
> +            ret = kvm_device_intx_set_mask(kvm_state,
> +                                           calc_assigned_dev_id(assigned_dev),
> +                                           intx_masked);
> +            if (ret) {
> +                perror("assigned_dev_pci_write_config: set intx mask");
> +            }
> +        }
> +    }
>      if (assigned_dev->cap.available & ASSIGNED_DEVICE_CAP_MSI) {
>          if (range_covers_byte(address, len,
>                                pci_dev->msi_cap + PCI_MSI_FLAGS)) {
> @@ -1748,6 +1771,8 @@ static Property da_properties[] =
>                     ASSIGNED_DEVICE_USE_IOMMU_BIT, true),
>      DEFINE_PROP_BIT("prefer_msi", AssignedDevice, features,
>                     ASSIGNED_DEVICE_PREFER_MSI_BIT, true),
> +    DEFINE_PROP_BIT("share_intx", AssignedDevice, features,
> +                    ASSIGNED_DEVICE_SHARE_INTX_BIT, false),
>      DEFINE_PROP_INT32("bootindex", AssignedDevice, bootindex, -1),
>      DEFINE_PROP_STRING("configfd", AssignedDevice, configfd_name),
>      DEFINE_PROP_END_OF_LIST(),
> diff --git a/hw/device-assignment.h b/hw/device-assignment.h
> index b4bcfa6..5d271d5 100644
> --- a/hw/device-assignment.h
> +++ b/hw/device-assignment.h
> @@ -74,11 +74,13 @@ typedef struct {
>      PCIRegion *region;
>  } AssignedDevRegion;
>  
> -#define ASSIGNED_DEVICE_USE_IOMMU_BIT	0
> -#define ASSIGNED_DEVICE_PREFER_MSI_BIT	1
> +#define ASSIGNED_DEVICE_USE_IOMMU_BIT   0
> +#define ASSIGNED_DEVICE_PREFER_MSI_BIT  1
> +#define ASSIGNED_DEVICE_SHARE_INTX_BIT  2
>  
> -#define ASSIGNED_DEVICE_USE_IOMMU_MASK	(1 << ASSIGNED_DEVICE_USE_IOMMU_BIT)
> -#define ASSIGNED_DEVICE_PREFER_MSI_MASK	(1 << ASSIGNED_DEVICE_PREFER_MSI_BIT)
> +#define ASSIGNED_DEVICE_USE_IOMMU_MASK  (1 << ASSIGNED_DEVICE_USE_IOMMU_BIT)
> +#define ASSIGNED_DEVICE_PREFER_MSI_MASK (1 << ASSIGNED_DEVICE_PREFER_MSI_BIT)
> +#define ASSIGNED_DEVICE_SHARE_INTX_MASK (1 << ASSIGNED_DEVICE_SHARE_INTX_BIT)
>  
>  typedef struct {
>      uint32_t addr_lo;
> diff --git a/qemu-kvm.c b/qemu-kvm.c
> index 09a35f0..2047ebb 100644
> --- a/qemu-kvm.c
> +++ b/qemu-kvm.c
> @@ -54,6 +54,15 @@ static int kvm_old_assign_irq(KVMState *s,
>      return kvm_vm_ioctl(s, KVM_ASSIGN_IRQ, assigned_irq);
>  }
>  
> +int kvm_device_intx_set_mask(KVMState *s, uint32_t dev_id, bool masked)
> +{
> +    struct kvm_assigned_pci_dev assigned_dev;
> +
> +    assigned_dev.assigned_dev_id = dev_id;
> +    assigned_dev.flags = masked ? KVM_DEV_ASSIGN_MASK_INTX : 0;
> +    return kvm_vm_ioctl(s, KVM_ASSIGN_SET_INTX_MASK, &assigned_dev);
> +}
> +
>  #ifdef KVM_CAP_ASSIGN_DEV_IRQ
>  int kvm_assign_irq(KVMState *s, struct kvm_assigned_irq *assigned_irq)
>  {
> diff --git a/qemu-kvm.h b/qemu-kvm.h
> index 3c4f023..2b23daf 100644
> --- a/qemu-kvm.h
> +++ b/qemu-kvm.h
> @@ -114,6 +114,8 @@ int kvm_assign_irq(KVMState *s, struct kvm_assigned_irq *assigned_irq);
>   */
>  int kvm_deassign_irq(KVMState *s, struct kvm_assigned_irq *assigned_irq);
>  
> +int kvm_device_intx_set_mask(KVMState *s, uint32_t dev_id, bool masked);
> +
>  /*!
>   * \brief Notifies host kernel about a PCI device to be deassigned from a guest
>   *