mirror of
https://github.com/hanzoai/visor.git
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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]>
88 lines
2.5 KiB
Go
88 lines
2.5 KiB
Go
// Copyright 2019 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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//go:build arm64
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package hostarch
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import "encoding/binary"
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const (
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// PageSize is the system page size.
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// arm64 support 4K/16K/64K page size,
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// which can be get by unix.Getpagesize().
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// Currently, only 4K page size is supported by default,
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// or 64K pages by using the pagesize_64k build tag.
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PageSize = 1 << PageShift
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// HugePageSize is the system huge page size.
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HugePageSize = 1 << HugePageShift
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// JumboPageSize is the 1GB jumbo page size.
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JumboPageSize = 1 << JumboPageShift
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// CacheLineSize is the size of the cache line.
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CacheLineSize = 1 << CacheLineShift
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// JumboPageShift is the binary log of jumbo page whose size is 1GB.
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JumboPageShift = 30
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// CacheLineShift is the binary log of the cache line size.
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CacheLineShift = 6
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)
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var (
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// ByteOrder is the native byte order (little endian).
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ByteOrder = binary.LittleEndian
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)
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// Arm64: Exception Syndrome Register EL1.
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const (
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_ESR_ELx_EC_SHIFT = 26
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_ESR_ELx_EC_MASK = 0x3F << _ESR_ELx_EC_SHIFT
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_ESR_ELx_EC_IABT_LOW = 0x20
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_ESR_ELx_EC_DABT_LOW = 0x24
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_ESR_ELx_WNR = 1 << 6
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_ESR_ELx_CM = 1 << 8
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)
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// ESRAccessType returns the memory access type for the given ESR (Exception
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// Syndrome Register) code. If code does not represent an invalid memory
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// access from a lower exception level, ESRAccessType returns NoAccess.
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//
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//go:nosplit
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func ESRAccessType(code uint64) AccessType {
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switch (code & _ESR_ELx_EC_MASK) >> _ESR_ELx_EC_SHIFT {
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case _ESR_ELx_EC_IABT_LOW:
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return Execute
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case _ESR_ELx_EC_DABT_LOW:
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// For faults on cache maintenance and address translation
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// instructions, _ESR_ELx_WNR is always set.
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if code&(_ESR_ELx_WNR|_ESR_ELx_CM) == _ESR_ELx_WNR {
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return Write
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}
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return Read
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default:
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return NoAccess
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}
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}
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// UntaggedUserAddr clears the tag from the address pointer. Top-Byte-Ignore (TBI0)
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// is enabled in Linux, so bits[63:56] of user space addresses are ignored.
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func UntaggedUserAddr(addr Addr) Addr {
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return Addr(int64(addr<<8) >> 8)
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}
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