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6be27cdcab
Some passthrough devices require multiple MSI vectors, but don't
support MSI-X. In meanwhile, Linux kernel doesn't support continuous
vector allocation.
On native platform, this issue can be mitigated by IOMMU via interrupt
remapping. However, on ACRN, there is no vIOMMU.
vMSI-X on MSI emulation is one solution to mitigate this problem on ACRN.
This patch adds MSI-X emulation on MSI capability.
For the device needs to do MSI-X emulation, HV will hide MSI capability
and present MSI-X capability to guest.
The guest driver may need to modify to reqeust MSI-X vector.
For example:
ret = pci_alloc_irq_vectors(pdev, 1, STMMAC_MSI_VEC_MAX,
- PCI_IRQ_MSI);
+ PCI_IRQ_MSI | PCI_IRQ_MSIX);
To enable MSI-X emulation, the device should:
- 1. The device should be in vmsix_on_msi_devs array.
- 2. Support MSI, but don't support MSI-X.
- 3. MSI capability should support per-vector mask.
- 4. The device should have an unused BAR.
- 5. The device driver should not rely on PBA for functionality.
Tracked-On: #4831
Signed-off-by: Binbin Wu <binbin.wu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
ACRN Hypervisor ############### The open source `Project ACRN`_ defines a device hypervisor reference stack and an architecture for running multiple software subsystems, managed securely, on a consolidated system by means of a virtual machine manager. It also defines a reference framework implementation for virtual device emulation, called the "ACRN Device Model". The ACRN Hypervisor is a Type 1 reference hypervisor stack, running directly on the bare-metal hardware, and is suitable for a variety of IoT and embedded device solutions. The ACRN hypervisor addresses the gap that currently exists between datacenter hypervisors, and hard partitioning hypervisors. The ACRN hypervisor architecture partitions the system into different functional domains, with carefully selected guest OS sharing optimizations for IoT and embedded devices. You can find out more about Project ACRN on the `Project ACRN documentation`_ website. .. _`Project ACRN`: https://projectacrn.org .. _`ACRN Hypervisor`: https://github.com/projectacrn/acrn-hypervisor .. _`Project ACRN documentation`: https://projectacrn.github.io/