Merge 216da0b7 (automated)

1 files changed, 161 insertions, 0 deletions

diff --git a/pkg/sentry/platform/kvm/machine_amd64_unsafe.go b/pkg/sentry/platform/kvm/machine_amd64_unsafe.go
new file mode 100644
index 000000000..06a2e3b0c
--- /dev/null
+++ b/pkg/sentry/platform/kvm/machine_amd64_unsafe.go
@@ -0,0 +1,161 @@
+// 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.
+
+// +build amd64
+
+package kvm
+
+import (
+	"fmt"
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/time"
+)
+
+// setMemoryRegion initializes a region.
+//
+// This may be called from bluepillHandler, and therefore returns an errno
+// directly (instead of wrapping in an error) to avoid allocations.
+//
+//go:nosplit
+func (m *machine) setMemoryRegion(slot int, physical, length, virtual uintptr) syscall.Errno {
+	userRegion := userMemoryRegion{
+		slot:          uint32(slot),
+		flags:         0,
+		guestPhysAddr: uint64(physical),
+		memorySize:    uint64(length),
+		userspaceAddr: uint64(virtual),
+	}
+
+	// Set the region.
+	_, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(m.fd),
+		_KVM_SET_USER_MEMORY_REGION,
+		uintptr(unsafe.Pointer(&userRegion)))
+	return errno
+}
+
+// loadSegments copies the current segments.
+//
+// This may be called from within the signal context and throws on error.
+//
+//go:nosplit
+func (c *vCPU) loadSegments(tid uint64) {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_ARCH_PRCTL,
+		linux.ARCH_GET_FS,
+		uintptr(unsafe.Pointer(&c.CPU.Registers().Fs_base)),
+		0); errno != 0 {
+		throw("getting FS segment")
+	}
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_ARCH_PRCTL,
+		linux.ARCH_GET_GS,
+		uintptr(unsafe.Pointer(&c.CPU.Registers().Gs_base)),
+		0); errno != 0 {
+		throw("getting GS segment")
+	}
+	atomic.StoreUint64(&c.tid, tid)
+}
+
+// setCPUID sets the CPUID to be used by the guest.
+func (c *vCPU) setCPUID() error {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_SET_CPUID2,
+		uintptr(unsafe.Pointer(&cpuidSupported))); errno != 0 {
+		return fmt.Errorf("error setting CPUID: %v", errno)
+	}
+	return nil
+}
+
+// setSystemTime sets the TSC for the vCPU.
+//
+// This has to make the call many times in order to minimize the intrinstic
+// error in the offset. Unfortunately KVM does not expose a relative offset via
+// the API, so this is an approximation. We do this via an iterative algorithm.
+// This has the advantage that it can generally deal with highly variable
+// system call times and should converge on the correct offset.
+func (c *vCPU) setSystemTime() error {
+	const (
+		_MSR_IA32_TSC  = 0x00000010
+		calibrateTries = 10
+	)
+	registers := modelControlRegisters{
+		nmsrs: 1,
+	}
+	registers.entries[0] = modelControlRegister{
+		index: _MSR_IA32_TSC,
+	}
+	target := uint64(^uint32(0))
+	for done := 0; done < calibrateTries; {
+		start := uint64(time.Rdtsc())
+		registers.entries[0].data = start + target
+		if _, _, errno := syscall.RawSyscall(
+			syscall.SYS_IOCTL,
+			uintptr(c.fd),
+			_KVM_SET_MSRS,
+			uintptr(unsafe.Pointer(&registers))); errno != 0 {
+			return fmt.Errorf("error setting system time: %v", errno)
+		}
+		// See if this is our new minimum call time. Note that this
+		// serves two functions: one, we make sure that we are
+		// accurately predicting the offset we need to set. Second, we
+		// don't want to do the final set on a slow call, which could
+		// produce a really bad result. So we only count attempts
+		// within +/- 6.25% of our minimum as an attempt.
+		end := uint64(time.Rdtsc())
+		if end < start {
+			continue // Totally bogus.
+		}
+		half := (end - start) / 2
+		if half < target {
+			target = half
+		}
+		if (half - target) < target/8 {
+			done++
+		}
+	}
+	return nil
+}
+
+// setSignalMask sets the vCPU signal mask.
+//
+// This must be called prior to running the vCPU.
+func (c *vCPU) setSignalMask() error {
+	// The layout of this structure implies that it will not necessarily be
+	// the same layout chosen by the Go compiler. It gets fudged here.
+	var data struct {
+		length uint32
+		mask1  uint32
+		mask2  uint32
+		_      uint32
+	}
+	data.length = 8 // Fixed sigset size.
+	data.mask1 = ^uint32(bounceSignalMask & 0xffffffff)
+	data.mask2 = ^uint32(bounceSignalMask >> 32)
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_SET_SIGNAL_MASK,
+		uintptr(unsafe.Pointer(&data))); errno != 0 {
+		return fmt.Errorf("error setting signal mask: %v", errno)
+	}
+	return nil
+}