VirtualBox

source: vbox/trunk/src/VBox/VMM/VMMR0/CPUMR0.cpp@ 12559

Last change on this file since 12559 was 12227, checked in by vboxsync, 16 years ago

CPUMR0: ASMGetDR7 assumption.
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1/* $Id: CPUMR0.cpp 12227 2008-09-08 13:24:05Z vboxsync $ */
2/** @file
3 * CPUM - Host Context Ring 0.
4 */
5
6/*
7 * Copyright (C) 2006-2007 Sun Microsystems, Inc.
8 *
9 * This file is part of VirtualBox Open Source Edition (OSE), as
10 * available from http://www.virtualbox.org. This file is free software;
11 * you can redistribute it and/or modify it under the terms of the GNU
12 * General Public License (GPL) as published by the Free Software
13 * Foundation, in version 2 as it comes in the "COPYING" file of the
14 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16 *
17 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
18 * Clara, CA 95054 USA or visit http://www.sun.com if you need
19 * additional information or have any questions.
20 */
21
22
23/*******************************************************************************
24* Header Files *
25*******************************************************************************/
26#define LOG_GROUP LOG_GROUP_CPUM
27#include <VBox/cpum.h>
28#include "CPUMInternal.h"
29#include <VBox/vm.h>
30#include <VBox/x86.h>
31#include <VBox/err.h>
32#include <VBox/log.h>
33#include <iprt/assert.h>
34#include <iprt/asm.h>
35
36
37
38
39/**
40 * Does Ring-0 CPUM initialization.
41 *
42 * This is mainly to check that the Host CPU mode is compatible
43 * with VBox.
44 *
45 * @returns VBox status code.
46 * @param pVM The VM to operate on.
47 */
48CPUMR0DECL(int) CPUMR0Init(PVM pVM)
49{
50 LogFlow(("CPUMR0Init: %p\n", pVM));
51
52 /*
53 * Check CR0 & CR4 flags.
54 */
55 uint32_t u32CR0 = ASMGetCR0();
56 if ((u32CR0 & (X86_CR0_PE | X86_CR0_PG)) != (X86_CR0_PE | X86_CR0_PG)) /* a bit paranoid perhaps.. */
57 {
58 Log(("CPUMR0Init: PE or PG not set. cr0=%#x\n", u32CR0));
59 return VERR_UNSUPPORTED_CPU_MODE;
60 }
61
62 /*
63 * Check for sysenter if it's used.
64 */
65 if (ASMHasCpuId())
66 {
67 uint32_t u32CpuVersion;
68 uint32_t u32Dummy;
69 uint32_t u32Features;
70 ASMCpuId(1, &u32CpuVersion, &u32Dummy, &u32Dummy, &u32Features);
71 uint32_t u32Family = u32CpuVersion >> 8;
72 uint32_t u32Model = (u32CpuVersion >> 4) & 0xF;
73 uint32_t u32Stepping = u32CpuVersion & 0xF;
74
75 /*
76 * Intel docs claim you should test both the flag and family, model & stepping.
77 * Some Pentium Pro cpus have the SEP cpuid flag set, but don't support it.
78 */
79 if ( (u32Features & X86_CPUID_FEATURE_EDX_SEP)
80 && !(u32Family == 6 && u32Model < 3 && u32Stepping < 3))
81 {
82 /*
83 * Read the MSR and see if it's in use or not.
84 */
85 uint32_t u32 = ASMRdMsr_Low(MSR_IA32_SYSENTER_CS);
86 if (u32)
87 {
88 pVM->cpum.s.fUseFlags |= CPUM_USE_SYSENTER;
89 Log(("CPUMR0Init: host uses sysenter cs=%08x%08x\n", ASMRdMsr_High(MSR_IA32_SYSENTER_CS), u32));
90 }
91 }
92
93 /** @todo check for AMD and syscall!!!!!! */
94 }
95
96
97 /*
98 * Check if debug registers are armed.
99 * This ASSUMES that DR7.GD is not set, or that it's handled transparently!
100 */
101 uint32_t u32DR7 = ASMGetDR7();
102 if (u32DR7 & X86_DR7_ENABLED_MASK)
103 {
104 pVM->cpum.s.fUseFlags |= CPUM_USE_DEBUG_REGS_HOST;
105 Log(("CPUMR0Init: host uses debug registers (dr7=%x)\n", u32DR7));
106 }
107
108 return VINF_SUCCESS;
109}
110
111
112/**
113 * Lazily sync in the FPU/XMM state
114 *
115 * @returns VBox status code.
116 * @param pVM VM handle.
117 * @param pCtx CPU context
118 */
119CPUMR0DECL(int) CPUMR0LoadGuestFPU(PVM pVM, PCPUMCTX pCtx)
120{
121 Assert(pVM->cpum.s.CPUFeatures.edx.u1FXSR);
122 Assert(ASMGetCR4() & X86_CR4_OSFSXR);
123
124 /* If the FPU state has already been loaded, then it's a guest trap. */
125 if (pVM->cpum.s.fUseFlags & CPUM_USED_FPU)
126 {
127 Assert( ((pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) == (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS))
128 || ((pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) == (X86_CR0_MP | X86_CR0_TS)));
129 return VINF_EM_RAW_GUEST_TRAP;
130 }
131
132 /*
133 * There are two basic actions:
134 * 1. Save host fpu and restore guest fpu.
135 * 2. Generate guest trap.
136 *
137 * When entering the hypervisor we'll always enable MP (for proper wait
138 * trapping) and TS (for intercepting all fpu/mmx/sse stuff). The EM flag
139 * is taken from the guest OS in order to get proper SSE handling.
140 *
141 *
142 * Actions taken depending on the guest CR0 flags:
143 *
144 * 3 2 1
145 * TS | EM | MP | FPUInstr | WAIT :: VMM Action
146 * ------------------------------------------------------------------------
147 * 0 | 0 | 0 | Exec | Exec :: Clear TS & MP, Save HC, Load GC.
148 * 0 | 0 | 1 | Exec | Exec :: Clear TS, Save HC, Load GC.
149 * 0 | 1 | 0 | #NM | Exec :: Clear TS & MP, Save HC, Load GC.
150 * 0 | 1 | 1 | #NM | Exec :: Clear TS, Save HC, Load GC.
151 * 1 | 0 | 0 | #NM | Exec :: Clear MP, Save HC, Load GC. (EM is already cleared.)
152 * 1 | 0 | 1 | #NM | #NM :: Go to guest taking trap there.
153 * 1 | 1 | 0 | #NM | Exec :: Clear MP, Save HC, Load GC. (EM is already set.)
154 * 1 | 1 | 1 | #NM | #NM :: Go to guest taking trap there.
155 */
156
157 switch(pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS))
158 {
159 case X86_CR0_MP | X86_CR0_TS:
160 case X86_CR0_MP | X86_CR0_EM | X86_CR0_TS:
161 return VINF_EM_RAW_GUEST_TRAP;
162
163 default:
164 break;
165 }
166
167#ifndef CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE
168 uint64_t oldMsrEFERHost;
169 uint32_t oldCR0 = ASMGetCR0();
170
171 /* Clear MSR_K6_EFER_FFXSR or else we'll be unable to save/restore the XMM state with fxsave/fxrstor. */
172 if (pVM->cpum.s.CPUFeaturesExt.edx & X86_CPUID_AMD_FEATURE_EDX_FFXSR)
173 {
174 /* @todo Do we really need to read this every time?? The host could change this on the fly though. */
175 oldMsrEFERHost = ASMRdMsr(MSR_K6_EFER);
176
177 if (oldMsrEFERHost & MSR_K6_EFER_FFXSR)
178 {
179 ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost & ~MSR_K6_EFER_FFXSR);
180 pVM->cpum.s.fUseFlags |= CPUM_MANUAL_XMM_RESTORE;
181 }
182 }
183
184 /* If we sync the FPU/XMM state on-demand, then we can continue execution as if nothing has happened. */
185 int rc = CPUMHandleLazyFPU(pVM);
186 AssertRC(rc);
187 Assert(CPUMIsGuestFPUStateActive(pVM));
188
189 /* Restore EFER MSR */
190 if (pVM->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE)
191 ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost);
192
193 /* CPUMHandleLazyFPU could have changed CR0; restore it. */
194 ASMSetCR0(oldCR0);
195#else
196 /* Save the FPU control word and MXCSR, so we can restore the properly afterwards.
197 * We don't want the guest to be able to trigger floating point/SSE exceptions on the host.
198 */
199 pVM->cpum.s.Host.fpu.FCW = CPUMGetFCW();
200 if (pVM->cpum.s.CPUFeatures.edx.u1SSE)
201 pVM->cpum.s.Host.fpu.MXCSR = CPUMGetMXCSR();
202
203 CPUMLoadFPUAsm(pCtx);
204
205 /* The MSR_K6_EFER_FFXSR feature is AMD only so far, but check the cpuid just in case Intel adds it in the future.
206 *
207 * MSR_K6_EFER_FFXSR changes the behaviour of fxsave and fxrstore: the XMM state isn't saved/restored
208 */
209 if (pVM->cpum.s.CPUFeaturesExt.edx & X86_CPUID_AMD_FEATURE_EDX_FFXSR)
210 {
211 /* @todo Do we really need to read this every time?? The host could change this on the fly though. */
212 uint64_t msrEFERHost = ASMRdMsr(MSR_K6_EFER);
213
214 if (msrEFERHost & MSR_K6_EFER_FFXSR)
215 {
216 /* fxrstor doesn't restore the XMM state! */
217 CPUMLoadXMMAsm(pCtx);
218 pVM->cpum.s.fUseFlags |= CPUM_MANUAL_XMM_RESTORE;
219 }
220 }
221#endif
222
223 pVM->cpum.s.fUseFlags |= CPUM_USED_FPU;
224 return VINF_SUCCESS;
225}
226
227
228/**
229 * Save guest FPU/XMM state
230 *
231 * @returns VBox status code.
232 * @param pVM VM handle.
233 * @param pCtx CPU context
234 */
235CPUMR0DECL(int) CPUMR0SaveGuestFPU(PVM pVM, PCPUMCTX pCtx)
236{
237 Assert(pVM->cpum.s.CPUFeatures.edx.u1FXSR);
238 Assert(ASMGetCR4() & X86_CR4_OSFSXR);
239 AssertReturn((pVM->cpum.s.fUseFlags & CPUM_USED_FPU), VINF_SUCCESS);
240
241#ifndef CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE
242 uint64_t oldMsrEFERHost;
243
244 /* Clear MSR_K6_EFER_FFXSR or else we'll be unable to save/restore the XMM state with fxsave/fxrstor. */
245 if (pVM->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE)
246 {
247 oldMsrEFERHost = ASMRdMsr(MSR_K6_EFER);
248 ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost & ~MSR_K6_EFER_FFXSR);
249 }
250 CPUMRestoreHostFPUState(pVM);
251
252 /* Restore EFER MSR */
253 if (pVM->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE)
254 ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost | MSR_K6_EFER_FFXSR);
255
256#else
257 CPUMSaveFPUAsm(pCtx);
258 if (pVM->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE)
259 {
260 /* fxsave doesn't save the XMM state! */
261 CPUMSaveXMMAsm(pCtx);
262 }
263 /* Restore the original FPU control word and MXCSR.
264 * We don't want the guest to be able to trigger floating point/SSE exceptions on the host.
265 */
266 CPUMSetFCW(pVM->cpum.s.Host.fpu.FCW);
267 if (pVM->cpum.s.CPUFeatures.edx.u1SSE)
268 CPUMSetMXCSR(pVM->cpum.s.Host.fpu.MXCSR);
269#endif
270
271 pVM->cpum.s.fUseFlags &= ~(CPUM_USED_FPU|CPUM_MANUAL_XMM_RESTORE);
272 return VINF_SUCCESS;
273}
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