c4ef2c7dd9
Improves virtiofs and VirtioProxy performance by giving each virtio
device its own SWIOTLB aperture instead of sharing a single global
pool. The guest kernel reserves a contiguous physical range at boot,
publishes the (base, size), and the host programs a matching
per-device aperture in wsldevicehost.
1. The WSL kernel allocates a contiguous range at boot
(alloc_contig_pages with __GFP_DMA32 | __GFP_ZERO) and exposes
the chosen physical (base, size) under
/sys/bus/vmbus/drivers/hv_pci/swiotlb_{base,size}
2. mini_init (WSL2) and the WSLC init handler read those sysfs files
and return the values in LX_INIT_GUEST_CAPABILITIES and
WSLC_GET_GUEST_CAPABILITIES_RESULT respectively.
3. WslCoreVm::ReadGuestCapabilities and
WSLCVirtualMachine::ReadGuestCapabilities capture the values.
WSLC forwards them to wslservice via the new
HcsVirtualMachine::ApplyGuestCapabilities IDL method (with a
WSLCGuestCapabilities struct so future kernel-published values
can be added without bumping the interface IID).
4. Both VM owners format "swiotlb=0x{base:x},{size}" once into
m_swiotlbOption and pass it verbatim to AddGuestDevice /
AddSharePath for every virtiofs share and virtio-net adapter
(VirtioProxy networking). wsldevicehost consumes the token and
creates the per-device SWIOTLB aperture.
If the kernel does not publish the sysfs files (older kernel) both
values come back as zero, the host omits the device-options token,
and the WSL2 path emits a one-time user warning via
MessageSwiotlbKernelUnsupported so users understand why performance
is degraded. (The WSLC path always uses the bundled kernel, so the
warning does not apply there.)
Other changes:
* Bump Microsoft.WSL.Kernel to 6.18.26.3-1, which is the first
official kernel that publishes the hv_pci swiotlb_{base,size}
sysfs files this PR consumes.
* Bump Microsoft.WSL.DeviceHost to 1.2.29-0 for the device-side
SWIOTLB aperture support.
* Default pool sizing moves to helpers::ComputeDefaultSwiotlbConfig
and is only requested on the kernel command line when a virtio
device that needs bounce buffers (VirtioFs / Virtio9p /
VirtioProxy) is in use.
* Telemetry: emit GuestKernelInfo / WSLCReadGuestCapabilities /
WSLCApplyGuestCapabilities events with the kernel-chosen base
and size so we can validate the handshake in CI.
Co-authored-by: Ben Hillis <benhill@ntdev.microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Windows Subsystem for Linux (WSL) is a powerful way for you to run your Linux command-line tools, utilities and applications, all unmodified and directly on Windows without the overhead of a traditional virtual machine or dual boot setup.
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Related repositories
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