mirror of
https://github.com/hanzoai/visor.git
synced 2026-09-24 17:04:14 +00:00
Tianyu Zhou
fc1afc9de5
SlimVM is a lightweight VMX-based platform for gVisor that accelerates sentry system calls by eliminating unnecessary user/kernel context switches. In a traditional gVisor + KVM setup, every guest syscall triggers a full VM exit to userspace, then re-enters the kernel via a regular syscall: gr0 -> hr0 (vm_exit) -> hr3 (ioctl return) -> hr0 (re-invoke syscall) SlimVM eliminates this overhead. When the guest executes a VMCALL, the VM exits into VMX root mode where SlimVM directly invokes the host kernel's syscall handler, then immediately resumes the guest: gr0 -> hr0 (vmcall + direct function call) SlimVM requires a companion kernel module that provides the /dev/slimvm device interface. See https://github.com/antgroup/slimvm for the kernel module and full documentation. A sentry->host getpid microbenchmark (Xeon 6982P-C, host kernel 5.10.134) shows the effect: │ ns/op │ vs base │ base 82.5 1.0x slimvm 420.9 5.1x kvm 3566.1 43.2x slimvm is ~8.5x faster than the kvm platform on this path. See the issue for details. Updates: https://github.com/google/gvisor/issues/13330 Co-developed-by: Chenggang <[email protected]> Co-developed-by: Robin Luk <[email protected]> Co-developed-by: Tiwei Bie <[email protected]> Co-developed-by: Jianfeng Tan <[email protected]> Co-developed-by: liushi.ls <[email protected]> Co-developed-by: Yong He <[email protected]> Co-developed-by: Aaron Lu <[email protected]> Co-developed-by: chris.zn <[email protected]> Co-developed-by: Lai Jiangshan <[email protected]> Co-developed-by: Lingfu <[email protected]> Co-developed-by: Min Le <[email protected]> Co-developed-by: Quan Xu <[email protected]> Co-developed-by: Zhang Haoyu <[email protected]> Co-developed-by: Dawei Shen <[email protected]> Signed-off-by: Tianyu Zhou <[email protected]>
59 lines
1.7 KiB
Go
59 lines
1.7 KiB
Go
// Copyright 2026 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package slimvm
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import (
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/hostarch"
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"gvisor.dev/gvisor/pkg/hostsyscall"
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)
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// yield yields the CPU.
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//
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//go:nosplit
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func yield() {
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hostsyscall.RawSyscallErrno(unix.SYS_SCHED_YIELD, 0, 0, 0)
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}
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// calculateBluepillFault calculates the fault address range.
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//
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//go:nosplit
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func calculateBluepillFault(physical uintptr) (virtualStart, physicalStart, length uintptr, ok bool) {
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alignedPhysical := physical &^ uintptr(hostarch.PageSize-1)
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for _, pr := range physicalRegions {
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end := pr.physical + pr.length
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if physical < pr.physical || physical >= end {
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continue
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}
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// Adjust the block to match our size.
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physicalStart = alignedPhysical
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if physicalStart < pr.physical {
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// Bound the starting point to the start of the region.
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physicalStart = pr.physical
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}
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virtualStart = pr.virtual + (physicalStart - pr.physical)
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physicalEnd := physicalStart + pr.length
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if physicalEnd > end {
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physicalEnd = end
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}
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length = physicalEnd - physicalStart
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return virtualStart, physicalStart, length, true
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}
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return 0, 0, 0, false
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}
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