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KVM: Allow host IRQ sharing for assigned PCI 2.3 devices

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PCI 2.3 allows to generically disable IRQ sources at device level. This
enables us to share legacy IRQs of such devices with other host devices
when passing them to a guest.

The new IRQ sharing feature introduced here is optional, user space has
to request it explicitly. Moreover, user space can inform us about its
view of PCI_COMMAND_INTX_DISABLE so that we can avoid unmasking the
interrupt and signaling it if the guest masked it via the virtualized
PCI config space.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Jan Kiszka
2012-02-28 14:19:54 +01:00
committed by Avi Kivity
parent 3e515705a1
commit 07700a94b0
5 changed files with 230 additions and 29 deletions
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41
Documentation/virtual/kvm/api.txt
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@@ -1169,6 +1169,14 @@ following flags are specified:
/* Depends on KVM_CAP_IOMMU */
#define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
/* The following two depend on KVM_CAP_PCI_2_3 */
#define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)
#define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)
If KVM_DEV_ASSIGN_PCI_2_3 is set, the kernel will manage legacy INTx interrupts
via the PCI-2.3-compliant device-level mask, thus enable IRQ sharing with other
assigned devices or host devices. KVM_DEV_ASSIGN_MASK_INTX specifies the
guest's view on the INTx mask, see KVM_ASSIGN_SET_INTX_MASK for details.
The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure
isolation of the device. Usages not specifying this flag are deprecated.
@@ -1441,6 +1449,39 @@ The "num_dirty" field is a performance hint for KVM to determine whether it
should skip processing the bitmap and just invalidate everything. It must
be set to the number of set bits in the bitmap.
4.60 KVM_ASSIGN_SET_INTX_MASK
Capability: KVM_CAP_PCI_2_3
Architectures: x86
Type: vm ioctl
Parameters: struct kvm_assigned_pci_dev (in)
Returns: 0 on success, -1 on error
Allows userspace to mask PCI INTx interrupts from the assigned device. The
kernel will not deliver INTx interrupts to the guest between setting and
clearing of KVM_ASSIGN_SET_INTX_MASK via this interface. This enables use of
and emulation of PCI 2.3 INTx disable command register behavior.
This may be used for both PCI 2.3 devices supporting INTx disable natively and
older devices lacking this support. Userspace is responsible for emulating the
read value of the INTx disable bit in the guest visible PCI command register.
When modifying the INTx disable state, userspace should precede updating the
physical device command register by calling this ioctl to inform the kernel of
the new intended INTx mask state.
Note that the kernel uses the device INTx disable bit to internally manage the
device interrupt state for PCI 2.3 devices. Reads of this register may
therefore not match the expected value. Writes should always use the guest
intended INTx disable value rather than attempting to read-copy-update the
current physical device state. Races between user and kernel updates to the
INTx disable bit are handled lazily in the kernel. It's possible the device
may generate unintended interrupts, but they will not be injected into the
guest.
See KVM_ASSIGN_DEV_IRQ for the data structure. The target device is specified
by assigned_dev_id. In the flags field, only KVM_DEV_ASSIGN_MASK_INTX is
evaluated.
4.62 KVM_CREATE_SPAPR_TCE
Capability: KVM_CAP_SPAPR_TCE