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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package kvm
import (
"fmt"
"gvisor.dev/gvisor/pkg/ring0/pagetables"
)
type allocator struct {
base pagetables.RuntimeAllocator
// cpu must be set prior to any pagetable operation.
//
// Due to the way KVM's shadow paging implementation works,
// modifications to the page tables while in host mode may not be
// trapped, leading to the shadow pages being out of sync. Therefore,
// we need to ensure that we are in guest mode for page table
// modifications. See the call to bluepill, below.
cpu *vCPU
}
// newAllocator is used to define the allocator.
func newAllocator() *allocator {
a := new(allocator)
a.base.Init()
return a
}
// NewPTEs implements pagetables.Allocator.NewPTEs.
//
// +checkescape:all
//
//go:nosplit
func (a *allocator) NewPTEs() *pagetables.PTEs {
ptes := a.base.NewPTEs() // escapes: bluepill below.
if a.cpu != nil {
bluepill(a.cpu)
}
return ptes
}
// PhysicalFor returns the physical address for a set of PTEs.
//
// +checkescape:all
//
//go:nosplit
func (a *allocator) PhysicalFor(ptes *pagetables.PTEs) uintptr {
virtual := a.base.PhysicalFor(ptes)
physical, _, ok := translateToPhysical(virtual)
if !ok {
panic(fmt.Sprintf("PhysicalFor failed for %p", ptes)) // escapes: panic.
}
return physical
}
// LookupPTEs implements pagetables.Allocator.LookupPTEs.
//
// +checkescape:all
//
//go:nosplit
func (a *allocator) LookupPTEs(physical uintptr) *pagetables.PTEs {
virtualStart, physicalStart, _, ok := calculateBluepillFault(physical, physicalRegions)
if !ok {
panic(fmt.Sprintf("LookupPTEs failed for 0x%x", physical)) // escapes: panic.
}
return a.base.LookupPTEs(virtualStart + (physical - physicalStart))
}
// FreePTEs implements pagetables.Allocator.FreePTEs.
//
// +checkescape:all
//
//go:nosplit
func (a *allocator) FreePTEs(ptes *pagetables.PTEs) {
a.base.FreePTEs(ptes) // escapes: bluepill below.
if a.cpu != nil {
bluepill(a.cpu)
}
}
// Recycle implements pagetables.Allocator.Recycle.
//
//go:nosplit
func (a *allocator) Recycle() {
a.base.Recycle()
}
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