/* $Id: CPUMR0.cpp 21942 2009-08-03 14:39:00Z vboxsync $ */ /** @file * CPUM - Host Context Ring 0. */ /* * Copyright (C) 2006-2007 Sun Microsystems, Inc. * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa * Clara, CA 95054 USA or visit http://www.sun.com if you need * additional information or have any questions. */ /******************************************************************************* * Header Files * *******************************************************************************/ #define LOG_GROUP LOG_GROUP_CPUM #include #include "CPUMInternal.h" #include #include #include #include #include #include #include /** * Does Ring-0 CPUM initialization. * * This is mainly to check that the Host CPU mode is compatible * with VBox. * * @returns VBox status code. * @param pVM The VM to operate on. */ VMMR0DECL(int) CPUMR0Init(PVM pVM) { LogFlow(("CPUMR0Init: %p\n", pVM)); /* * Check CR0 & CR4 flags. */ uint32_t u32CR0 = ASMGetCR0(); if ((u32CR0 & (X86_CR0_PE | X86_CR0_PG)) != (X86_CR0_PE | X86_CR0_PG)) /* a bit paranoid perhaps.. */ { Log(("CPUMR0Init: PE or PG not set. cr0=%#x\n", u32CR0)); return VERR_UNSUPPORTED_CPU_MODE; } /* * Check for sysenter and syscall usage. */ if (ASMHasCpuId()) { /* * SYSENTER/SYSEXIT * * Intel docs claim you should test both the flag and family, model & * stepping because some Pentium Pro CPUs have the SEP cpuid flag set, * but don't support it. AMD CPUs may support this feature in legacy * mode, they've banned it from long mode. Since we switch to 32-bit * mode when entering raw-mode context the feature would become * accessible again on AMD CPUs, so we have to check regardless of * host bitness. */ uint32_t u32CpuVersion; uint32_t u32Dummy; uint32_t fFeatures; ASMCpuId(1, &u32CpuVersion, &u32Dummy, &u32Dummy, &fFeatures); uint32_t u32Family = u32CpuVersion >> 8; uint32_t u32Model = (u32CpuVersion >> 4) & 0xF; uint32_t u32Stepping = u32CpuVersion & 0xF; if ( (fFeatures & X86_CPUID_FEATURE_EDX_SEP) && ( u32Family != 6 /* (> pentium pro) */ || u32Model >= 3 || u32Stepping >= 3 || !ASMIsIntelCpu()) ) { /* * Read the MSR and see if it's in use or not. */ uint32_t u32 = ASMRdMsr_Low(MSR_IA32_SYSENTER_CS); if (u32) { pVM->cpum.s.fHostUseFlags |= CPUM_USE_SYSENTER; Log(("CPUMR0Init: host uses sysenter cs=%08x%08x\n", ASMRdMsr_High(MSR_IA32_SYSENTER_CS), u32)); } } /* * SYSCALL/SYSRET * * This feature is indicated by the SEP bit returned in EDX by CPUID * function 0x80000001. Intel CPUs only supports this feature in * long mode. Since we're not running 64-bit guests in raw-mode there * are no issues with 32-bit intel hosts. */ uint32_t cExt = 0; ASMCpuId(0x80000000, &cExt, &u32Dummy, &u32Dummy, &u32Dummy); if ( cExt >= 0x80000001 && cExt <= 0x8000ffff) { uint32_t fExtFeaturesEDX = ASMCpuId_EDX(0x80000001); if (fExtFeaturesEDX & X86_CPUID_AMD_FEATURE_EDX_SEP) { #ifdef RT_ARCH_X86 # ifdef VBOX_WITH_HYBRID_32BIT_KERNEL if (fExtFeaturesEDX & X86_CPUID_AMD_FEATURE_EDX_LONG_MODE) # else if (!ASMIsIntelCpu()) # endif #endif { uint64_t fEfer = ASMRdMsr(MSR_K6_EFER); if (fEfer & MSR_K6_EFER_SCE) { pVM->cpum.s.fHostUseFlags |= CPUM_USE_SYSCALL; Log(("CPUMR0Init: host uses syscall\n")); } } } } } /* * Check if debug registers are armed. * This ASSUMES that DR7.GD is not set, or that it's handled transparently! */ uint32_t u32DR7 = ASMGetDR7(); if (u32DR7 & X86_DR7_ENABLED_MASK) { for (unsigned i=0;icCPUs;i++) pVM->aCpus[i].cpum.s.fUseFlags |= CPUM_USE_DEBUG_REGS_HOST; Log(("CPUMR0Init: host uses debug registers (dr7=%x)\n", u32DR7)); } return VINF_SUCCESS; } /** * Lazily sync in the FPU/XMM state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. * @param pCtx CPU context */ VMMR0DECL(int) CPUMR0LoadGuestFPU(PVM pVM, PVMCPU pVCpu, PCPUMCTX pCtx) { Assert(pVM->cpum.s.CPUFeatures.edx.u1FXSR); Assert(ASMGetCR4() & X86_CR4_OSFSXR); /* If the FPU state has already been loaded, then it's a guest trap. */ if (pVCpu->cpum.s.fUseFlags & CPUM_USED_FPU) { Assert( ((pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) == (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) || ((pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) == (X86_CR0_MP | X86_CR0_TS))); return VINF_EM_RAW_GUEST_TRAP; } /* * There are two basic actions: * 1. Save host fpu and restore guest fpu. * 2. Generate guest trap. * * When entering the hypervisor we'll always enable MP (for proper wait * trapping) and TS (for intercepting all fpu/mmx/sse stuff). The EM flag * is taken from the guest OS in order to get proper SSE handling. * * * Actions taken depending on the guest CR0 flags: * * 3 2 1 * TS | EM | MP | FPUInstr | WAIT :: VMM Action * ------------------------------------------------------------------------ * 0 | 0 | 0 | Exec | Exec :: Clear TS & MP, Save HC, Load GC. * 0 | 0 | 1 | Exec | Exec :: Clear TS, Save HC, Load GC. * 0 | 1 | 0 | #NM | Exec :: Clear TS & MP, Save HC, Load GC. * 0 | 1 | 1 | #NM | Exec :: Clear TS, Save HC, Load GC. * 1 | 0 | 0 | #NM | Exec :: Clear MP, Save HC, Load GC. (EM is already cleared.) * 1 | 0 | 1 | #NM | #NM :: Go to guest taking trap there. * 1 | 1 | 0 | #NM | Exec :: Clear MP, Save HC, Load GC. (EM is already set.) * 1 | 1 | 1 | #NM | #NM :: Go to guest taking trap there. */ switch (pCtx->cr0 & (X86_CR0_MP | X86_CR0_EM | X86_CR0_TS)) { case X86_CR0_MP | X86_CR0_TS: case X86_CR0_MP | X86_CR0_EM | X86_CR0_TS: return VINF_EM_RAW_GUEST_TRAP; default: break; } #if HC_ARCH_BITS == 32 && defined(VBOX_WITH_64_BITS_GUESTS) && !defined(VBOX_WITH_HYBRID_32BIT_KERNEL) if (CPUMIsGuestInLongModeEx(pCtx)) { Assert(!(pVCpu->cpum.s.fUseFlags & CPUM_SYNC_FPU_STATE)); /* Save the host state and record the fact (CPUM_USED_FPU | CPUM_USED_FPU_SINCE_REM). */ cpumR0SaveHostFPUState(&pVCpu->cpum.s); /* Restore the state on entry as we need to be in 64 bits mode to access the full state. */ pVCpu->cpum.s.fUseFlags |= CPUM_SYNC_FPU_STATE; } else #endif { #ifndef CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE # if defined(VBOX_WITH_HYBRID_32BIT_KERNEL) || defined(VBOX_WITH_KERNEL_USING_XMM) /** @todo remove the #else here and move cpumHandleLazyFPUAsm back to VMMGC after branching out 3.0!!. */ Assert(!(pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE)); /** @todo Move the FFXR handling down into * cpumR0SaveHostRestoreguestFPUState to optimize the * VBOX_WITH_KERNEL_USING_XMM handling. */ /* Clear MSR_K6_EFER_FFXSR or else we'll be unable to save/restore the XMM state with fxsave/fxrstor. */ uint64_t SavedEFER = 0; if (pVM->cpum.s.CPUFeaturesExt.edx & X86_CPUID_AMD_FEATURE_EDX_FFXSR) { SavedEFER = ASMRdMsr(MSR_K6_EFER); if (SavedEFER & MSR_K6_EFER_FFXSR) { ASMWrMsr(MSR_K6_EFER, SavedEFER & ~MSR_K6_EFER_FFXSR); pVCpu->cpum.s.fUseFlags |= CPUM_MANUAL_XMM_RESTORE; } } /* Do the job and record that we've switched FPU state. */ cpumR0SaveHostRestoreGuestFPUState(&pVCpu->cpum.s); /* Restore EFER. */ if (pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE) ASMWrMsr(MSR_K6_EFER, SavedEFER); # else uint64_t oldMsrEFERHost = 0; uint32_t oldCR0 = ASMGetCR0(); /* Clear MSR_K6_EFER_FFXSR or else we'll be unable to save/restore the XMM state with fxsave/fxrstor. */ if (pVM->cpum.s.CPUFeaturesExt.edx & X86_CPUID_AMD_FEATURE_EDX_FFXSR) { /** @todo Do we really need to read this every time?? The host could change this on the fly though. * bird: what about starting by skipping the ASMWrMsr below if we didn't * change anything? Ditto for the stuff in CPUMR0SaveGuestFPU. */ oldMsrEFERHost = ASMRdMsr(MSR_K6_EFER); if (oldMsrEFERHost & MSR_K6_EFER_FFXSR) { ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost & ~MSR_K6_EFER_FFXSR); pVCpu->cpum.s.fUseFlags |= CPUM_MANUAL_XMM_RESTORE; } } /* If we sync the FPU/XMM state on-demand, then we can continue execution as if nothing has happened. */ int rc = CPUMHandleLazyFPU(pVCpu); AssertRC(rc); Assert(CPUMIsGuestFPUStateActive(pVCpu)); /* Restore EFER MSR */ if (pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE) ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost); /* CPUMHandleLazyFPU could have changed CR0; restore it. */ ASMSetCR0(oldCR0); # endif #else /* CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE */ /* * Save the FPU control word and MXCSR, so we can restore the state properly afterwards. * We don't want the guest to be able to trigger floating point/SSE exceptions on the host. */ pVCpu->cpum.s.Host.fpu.FCW = CPUMGetFCW(); if (pVM->cpum.s.CPUFeatures.edx.u1SSE) pVCpu->cpum.s.Host.fpu.MXCSR = CPUMGetMXCSR(); cpumR0LoadFPU(pCtx); /* * The MSR_K6_EFER_FFXSR feature is AMD only so far, but check the cpuid just in case Intel adds it in the future. * * MSR_K6_EFER_FFXSR changes the behaviour of fxsave and fxrstore: the XMM state isn't saved/restored */ if (pVM->cpum.s.CPUFeaturesExt.edx & X86_CPUID_AMD_FEATURE_EDX_FFXSR) { /** @todo Do we really need to read this every time?? The host could change this on the fly though. */ uint64_t msrEFERHost = ASMRdMsr(MSR_K6_EFER); if (msrEFERHost & MSR_K6_EFER_FFXSR) { /* fxrstor doesn't restore the XMM state! */ cpumR0LoadXMM(pCtx); pVCpu->cpum.s.fUseFlags |= CPUM_MANUAL_XMM_RESTORE; } } #endif /* CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE */ } Assert((pVCpu->cpum.s.fUseFlags & (CPUM_USED_FPU | CPUM_USED_FPU_SINCE_REM)) == (CPUM_USED_FPU | CPUM_USED_FPU_SINCE_REM)); return VINF_SUCCESS; } /** * Save guest FPU/XMM state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. * @param pCtx CPU context */ VMMR0DECL(int) CPUMR0SaveGuestFPU(PVM pVM, PVMCPU pVCpu, PCPUMCTX pCtx) { Assert(pVM->cpum.s.CPUFeatures.edx.u1FXSR); Assert(ASMGetCR4() & X86_CR4_OSFSXR); AssertReturn((pVCpu->cpum.s.fUseFlags & CPUM_USED_FPU), VINF_SUCCESS); #if HC_ARCH_BITS == 32 && defined(VBOX_WITH_64_BITS_GUESTS) && !defined(VBOX_WITH_HYBRID_32BIT_KERNEL) if (CPUMIsGuestInLongModeEx(pCtx)) { if (!(pVCpu->cpum.s.fUseFlags & CPUM_SYNC_FPU_STATE)) { HWACCMR0SaveFPUState(pVM, pVCpu, pCtx); cpumR0RestoreHostFPUState(&pVCpu->cpum.s); } /* else nothing to do; we didn't perform a world switch */ } else #endif { #ifndef CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE # ifdef VBOX_WITH_KERNEL_USING_XMM /* * We've already saved the XMM registers in the assembly wrapper, so * we have to save them before saving the entire FPU state and put them * back afterwards. */ /** @todo This could be skipped if MSR_K6_EFER_FFXSR is set, but * I'm not able to test such an optimization tonight. * We could just all this in assembly. */ uint128_t aGuestXmmRegs[16]; memcpy(&aGuestXmmRegs[0], &pVCpu->cpum.s.Guest.fpu.aXMM[0], sizeof(aGuestXmmRegs)); # endif /* Clear MSR_K6_EFER_FFXSR or else we'll be unable to save/restore the XMM state with fxsave/fxrstor. */ uint64_t oldMsrEFERHost = 0; if (pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE) { oldMsrEFERHost = ASMRdMsr(MSR_K6_EFER); ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost & ~MSR_K6_EFER_FFXSR); } cpumR0SaveGuestRestoreHostFPUState(&pVCpu->cpum.s); /* Restore EFER MSR */ if (pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE) ASMWrMsr(MSR_K6_EFER, oldMsrEFERHost | MSR_K6_EFER_FFXSR); # ifdef VBOX_WITH_KERNEL_USING_XMM memcpy(&pVCpu->cpum.s.Guest.fpu.aXMM[0], &aGuestXmmRegs[0], sizeof(aGuestXmmRegs)); # endif #else /* CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE */ # ifdef VBOX_WITH_KERNEL_USING_XMM # error "Fix all the NM_TRAPS_IN_KERNEL_MODE code path. I'm not going to fix unused code now." # endif cpumR0SaveFPU(pCtx); if (pVCpu->cpum.s.fUseFlags & CPUM_MANUAL_XMM_RESTORE) { /* fxsave doesn't save the XMM state! */ cpumR0SaveXMM(pCtx); } /* * Restore the original FPU control word and MXCSR. * We don't want the guest to be able to trigger floating point/SSE exceptions on the host. */ cpumR0SetFCW(pVCpu->cpum.s.Host.fpu.FCW); if (pVM->cpum.s.CPUFeatures.edx.u1SSE) cpumR0SetMXCSR(pVCpu->cpum.s.Host.fpu.MXCSR); #endif /* CPUM_CAN_HANDLE_NM_TRAPS_IN_KERNEL_MODE */ } pVCpu->cpum.s.fUseFlags &= ~(CPUM_USED_FPU | CPUM_SYNC_FPU_STATE | CPUM_MANUAL_XMM_RESTORE); return VINF_SUCCESS; } /** * Save guest debug state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. * @param pCtx CPU context * @param fDR6 Include DR6 or not */ VMMR0DECL(int) CPUMR0SaveGuestDebugState(PVM pVM, PVMCPU pVCpu, PCPUMCTX pCtx, bool fDR6) { Assert(pVCpu->cpum.s.fUseFlags & CPUM_USE_DEBUG_REGS); /* Save the guest's debug state. The caller is responsible for DR7. */ #if HC_ARCH_BITS == 32 && defined(VBOX_WITH_64_BITS_GUESTS) && !defined(VBOX_WITH_HYBRID_32BIT_KERNEL) if (CPUMIsGuestInLongModeEx(pCtx)) { if (!(pVCpu->cpum.s.fUseFlags & CPUM_SYNC_DEBUG_STATE)) { uint64_t dr6 = pCtx->dr[6]; HWACCMR0SaveDebugState(pVM, pVCpu, pCtx); if (!fDR6) /* dr6 was already up-to-date */ pCtx->dr[6] = dr6; } } else #endif { #ifdef VBOX_WITH_HYBRID_32BIT_KERNEL cpumR0SaveDRx(&pCtx->dr[0]); #else pCtx->dr[0] = ASMGetDR0(); pCtx->dr[1] = ASMGetDR1(); pCtx->dr[2] = ASMGetDR2(); pCtx->dr[3] = ASMGetDR3(); #endif if (fDR6) pCtx->dr[6] = ASMGetDR6(); } /* * Restore the host's debug state. DR0-3, DR6 and only then DR7! * DR7 contains 0x400 right now. */ CPUMR0LoadHostDebugState(pVM, pVCpu); Assert(!(pVCpu->cpum.s.fUseFlags & CPUM_USE_DEBUG_REGS)); return VINF_SUCCESS; } /** * Lazily sync in the debug state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. * @param pCtx CPU context * @param fDR6 Include DR6 or not */ VMMR0DECL(int) CPUMR0LoadGuestDebugState(PVM pVM, PVMCPU pVCpu, PCPUMCTX pCtx, bool fDR6) { /* Save the host state. */ CPUMR0SaveHostDebugState(pVM, pVCpu); Assert(ASMGetDR7() == X86_DR7_INIT_VAL); /* Activate the guest state DR0-3; DR7 is left to the caller. */ #if HC_ARCH_BITS == 32 && defined(VBOX_WITH_64_BITS_GUESTS) && !defined(VBOX_WITH_HYBRID_32BIT_KERNEL) if (CPUMIsGuestInLongModeEx(pCtx)) { /* Restore the state on entry as we need to be in 64 bits mode to access the full state. */ pVCpu->cpum.s.fUseFlags |= CPUM_SYNC_DEBUG_STATE; } else #endif { #ifdef VBOX_WITH_HYBRID_32BIT_KERNEL cpumR0LoadDRx(&pCtx->dr[0]); #else ASMSetDR0(pCtx->dr[0]); ASMSetDR1(pCtx->dr[1]); ASMSetDR2(pCtx->dr[2]); ASMSetDR3(pCtx->dr[3]); #endif if (fDR6) ASMSetDR6(pCtx->dr[6]); } pVCpu->cpum.s.fUseFlags |= CPUM_USE_DEBUG_REGS; return VINF_SUCCESS; } /** * Save the host debug state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. */ VMMR0DECL(int) CPUMR0SaveHostDebugState(PVM pVM, PVMCPU pVCpu) { /* Save the host state. */ #ifdef VBOX_WITH_HYBRID_32BIT_KERNEL AssertCompile((uintptr_t)&pVCpu->cpum.s.Host.dr3 - (uintptr_t)&pVCpu->cpum.s.Host.dr0 == sizeof(uint64_t) * 3); cpumR0SaveDRx(&pVCpu->cpum.s.Host.dr0); #else pVCpu->cpum.s.Host.dr0 = ASMGetDR0(); pVCpu->cpum.s.Host.dr1 = ASMGetDR1(); pVCpu->cpum.s.Host.dr2 = ASMGetDR2(); pVCpu->cpum.s.Host.dr3 = ASMGetDR3(); #endif pVCpu->cpum.s.Host.dr6 = ASMGetDR6(); /** @todo dr7 might already have been changed to 0x400; don't care right now as it's harmless. */ pVCpu->cpum.s.Host.dr7 = ASMGetDR7(); /* Make sure DR7 is harmless or else we could trigger breakpoints when restoring dr0-3 (!) */ ASMSetDR7(X86_DR7_INIT_VAL); return VINF_SUCCESS; } /** * Load the host debug state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. */ VMMR0DECL(int) CPUMR0LoadHostDebugState(PVM pVM, PVMCPU pVCpu) { Assert(pVCpu->cpum.s.fUseFlags & (CPUM_USE_DEBUG_REGS | CPUM_USE_DEBUG_REGS_HYPER)); /* * Restore the host's debug state. DR0-3, DR6 and only then DR7! * DR7 contains 0x400 right now. */ #ifdef VBOX_WITH_HYBRID_32BIT_KERNEL AssertCompile((uintptr_t)&pVCpu->cpum.s.Host.dr3 - (uintptr_t)&pVCpu->cpum.s.Host.dr0 == sizeof(uint64_t) * 3); cpumR0LoadDRx(&pVCpu->cpum.s.Host.dr0); #else ASMSetDR0(pVCpu->cpum.s.Host.dr0); ASMSetDR1(pVCpu->cpum.s.Host.dr1); ASMSetDR2(pVCpu->cpum.s.Host.dr2); ASMSetDR3(pVCpu->cpum.s.Host.dr3); #endif ASMSetDR6(pVCpu->cpum.s.Host.dr6); ASMSetDR7(pVCpu->cpum.s.Host.dr7); pVCpu->cpum.s.fUseFlags &= ~(CPUM_USE_DEBUG_REGS | CPUM_USE_DEBUG_REGS_HYPER); return VINF_SUCCESS; } /** * Lazily sync in the hypervisor debug state * * @returns VBox status code. * @param pVM VM handle. * @param pVCpu VMCPU handle. * @param pCtx CPU context * @param fDR6 Include DR6 or not */ VMMR0DECL(int) CPUMR0LoadHyperDebugState(PVM pVM, PVMCPU pVCpu, PCPUMCTX pCtx, bool fDR6) { /* Save the host state. */ CPUMR0SaveHostDebugState(pVM, pVCpu); Assert(ASMGetDR7() == X86_DR7_INIT_VAL); /* Activate the guest state DR0-3; DR7 is left to the caller. */ #if HC_ARCH_BITS == 32 && defined(VBOX_WITH_64_BITS_GUESTS) && !defined(VBOX_WITH_HYBRID_32BIT_KERNEL) if (CPUMIsGuestInLongModeEx(pCtx)) { AssertFailed(); return VERR_NOT_IMPLEMENTED; } else #endif { #ifdef VBOX_WITH_HYBRID_32BIT_KERNEL AssertFailed(); return VERR_NOT_IMPLEMENTED; #else ASMSetDR0(CPUMGetHyperDR0(pVCpu)); ASMSetDR1(CPUMGetHyperDR1(pVCpu)); ASMSetDR2(CPUMGetHyperDR2(pVCpu)); ASMSetDR3(CPUMGetHyperDR3(pVCpu)); #endif if (fDR6) ASMSetDR6(CPUMGetHyperDR6(pVCpu)); } pVCpu->cpum.s.fUseFlags |= CPUM_USE_DEBUG_REGS_HYPER; return VINF_SUCCESS; }