[lkml]   [2020]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2 4/5] virtio-mmio: add MSI interrupt feature support

On 2020/2/10 下午5:05, Zha Bin wrote:
> From: Liu Jiang<>
> Userspace VMMs (e.g. Qemu microvm, Firecracker) take advantage of using
> virtio over mmio devices as a lightweight machine model for modern
> cloud. The standard virtio over MMIO transport layer only supports one
> legacy interrupt, which is much heavier than virtio over PCI transport
> layer using MSI. Legacy interrupt has long work path and causes specific
> VMExits in following cases, which would considerably slow down the
> performance:
> 1) read interrupt status register
> 2) update interrupt status register
> 3) write IOAPIC EOI register
> We proposed to add MSI support for virtio over MMIO via new feature
> bit VIRTIO_F_MMIO_MSI[1] which increases the interrupt performance.
> With the VIRTIO_F_MMIO_MSI feature bit supported, the virtio-mmio MSI
> uses msi_sharing[1] to indicate the event and vector mapping.
> Bit 1 is 0: device uses non-sharing and fixed vector per event mapping.
> Bit 1 is 1: device uses sharing mode and dynamic mapping.

I believe dynamic mapping should cover the case of fixed vector?


 \ /
  Last update: 2020-02-11 04:18    [W:0.261 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site