/* $Id: GIMAllKvm.cpp 93725 2022-02-14 13:46:16Z vboxsync $ */ /** @file * GIM - Guest Interface Manager, KVM, All Contexts. */ /* * Copyright (C) 2015-2022 Oracle Corporation * * 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. */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #define LOG_GROUP LOG_GROUP_GIM #include #include #include #include #include #include #include #include "GIMKvmInternal.h" #include "GIMInternal.h" #include #include #include #include #include /** * Handles the KVM hypercall. * * @returns Strict VBox status code. * @retval VINF_SUCCESS if the hypercall succeeded (even if its operation * failed). * @retval VINF_GIM_R3_HYPERCALL re-start the hypercall from ring-3. * @retval VERR_GIM_HYPERCALL_ACCESS_DENIED CPL is insufficient. * * @param pVCpu The cross context virtual CPU structure. * @param pCtx Pointer to the guest-CPU context. * * @thread EMT(pVCpu). */ VMM_INT_DECL(VBOXSTRICTRC) gimKvmHypercall(PVMCPUCC pVCpu, PCPUMCTX pCtx) { VMCPU_ASSERT_EMT(pVCpu); PVMCC pVM = pVCpu->CTX_SUFF(pVM); STAM_REL_COUNTER_INC(&pVM->gim.s.StatHypercalls); /* * Get the hypercall operation and arguments. */ bool const fIs64BitMode = CPUMIsGuestIn64BitCodeEx(pCtx); uint64_t uHyperOp = pCtx->rax; uint64_t uHyperArg0 = pCtx->rbx; uint64_t uHyperArg1 = pCtx->rcx; uint64_t uHyperArg2 = pCtx->rdi; uint64_t uHyperArg3 = pCtx->rsi; uint64_t uHyperRet = KVM_HYPERCALL_RET_ENOSYS; uint64_t uAndMask = UINT64_C(0xffffffffffffffff); if (!fIs64BitMode) { uAndMask = UINT64_C(0xffffffff); uHyperOp &= UINT64_C(0xffffffff); uHyperArg0 &= UINT64_C(0xffffffff); uHyperArg1 &= UINT64_C(0xffffffff); uHyperArg2 &= UINT64_C(0xffffffff); uHyperArg3 &= UINT64_C(0xffffffff); uHyperRet &= UINT64_C(0xffffffff); } /* * Verify that guest ring-0 is the one making the hypercall. */ uint32_t uCpl = CPUMGetGuestCPL(pVCpu); if (RT_UNLIKELY(uCpl)) { pCtx->rax = KVM_HYPERCALL_RET_EPERM & uAndMask; return VERR_GIM_HYPERCALL_ACCESS_DENIED; } /* * Do the work. */ int rc = VINF_SUCCESS; switch (uHyperOp) { case KVM_HYPERCALL_OP_KICK_CPU: { if (uHyperArg1 < pVM->cCpus) { PVMCPUCC pVCpuDst = VMCC_GET_CPU(pVM, uHyperArg1); /* ASSUMES pVCpu index == ApicId of the VCPU. */ EMUnhaltAndWakeUp(pVM, pVCpuDst); uHyperRet = KVM_HYPERCALL_RET_SUCCESS; } else { /* Shouldn't ever happen! If it does, throw a guru, as otherwise it'll lead to deadlocks in the guest anyway! */ rc = VERR_GIM_HYPERCALL_FAILED; } break; } case KVM_HYPERCALL_OP_VAPIC_POLL_IRQ: uHyperRet = KVM_HYPERCALL_RET_SUCCESS; break; default: break; } /* * Place the result in rax/eax. */ pCtx->rax = uHyperRet & uAndMask; return rc; } /** * Returns whether the guest has configured and enabled the use of KVM's * hypercall interface. * * @returns true if hypercalls are enabled, false otherwise. * @param pVCpu The cross context virtual CPU structure. */ VMM_INT_DECL(bool) gimKvmAreHypercallsEnabled(PVMCPU pVCpu) { NOREF(pVCpu); /* KVM paravirt interface doesn't have hypercall control bits (like Hyper-V does) that guests can control, i.e. hypercalls are always enabled. */ return true; } /** * Returns whether the guest has configured and enabled the use of KVM's * paravirtualized TSC. * * @returns true if paravirt. TSC is enabled, false otherwise. * @param pVM The cross context VM structure. */ VMM_INT_DECL(bool) gimKvmIsParavirtTscEnabled(PVMCC pVM) { uint32_t const cCpus = pVM->cCpus; for (uint32_t idCpu = 0; idCpu < cCpus; idCpu++) { PVMCPUCC pVCpu = pVM->CTX_SUFF(apCpus)[idCpu]; PGIMKVMCPU pGimKvmCpu = &pVCpu->gim.s.u.KvmCpu; if (MSR_GIM_KVM_SYSTEM_TIME_IS_ENABLED(pGimKvmCpu->u64SystemTimeMsr)) return true; } return false; } /** * MSR read handler for KVM. * * @returns Strict VBox status code like CPUMQueryGuestMsr(). * @retval VINF_CPUM_R3_MSR_READ * @retval VERR_CPUM_RAISE_GP_0 * * @param pVCpu The cross context virtual CPU structure. * @param idMsr The MSR being read. * @param pRange The range this MSR belongs to. * @param puValue Where to store the MSR value read. */ VMM_INT_DECL(VBOXSTRICTRC) gimKvmReadMsr(PVMCPUCC pVCpu, uint32_t idMsr, PCCPUMMSRRANGE pRange, uint64_t *puValue) { NOREF(pRange); PVM pVM = pVCpu->CTX_SUFF(pVM); PGIMKVM pKvm = &pVM->gim.s.u.Kvm; PGIMKVMCPU pKvmCpu = &pVCpu->gim.s.u.KvmCpu; switch (idMsr) { case MSR_GIM_KVM_SYSTEM_TIME: case MSR_GIM_KVM_SYSTEM_TIME_OLD: *puValue = pKvmCpu->u64SystemTimeMsr; return VINF_SUCCESS; case MSR_GIM_KVM_WALL_CLOCK: case MSR_GIM_KVM_WALL_CLOCK_OLD: *puValue = pKvm->u64WallClockMsr; return VINF_SUCCESS; default: { #ifdef IN_RING3 static uint32_t s_cTimes = 0; if (s_cTimes++ < 20) LogRel(("GIM: KVM: Unknown/invalid RdMsr (%#x) -> #GP(0)\n", idMsr)); #endif LogFunc(("Unknown/invalid RdMsr (%#RX32) -> #GP(0)\n", idMsr)); break; } } return VERR_CPUM_RAISE_GP_0; } /** * MSR write handler for KVM. * * @returns Strict VBox status code like CPUMSetGuestMsr(). * @retval VINF_CPUM_R3_MSR_WRITE * @retval VERR_CPUM_RAISE_GP_0 * * @param pVCpu The cross context virtual CPU structure. * @param idMsr The MSR being written. * @param pRange The range this MSR belongs to. * @param uRawValue The raw value with the ignored bits not masked. */ VMM_INT_DECL(VBOXSTRICTRC) gimKvmWriteMsr(PVMCPUCC pVCpu, uint32_t idMsr, PCCPUMMSRRANGE pRange, uint64_t uRawValue) { NOREF(pRange); switch (idMsr) { case MSR_GIM_KVM_SYSTEM_TIME: case MSR_GIM_KVM_SYSTEM_TIME_OLD: { #ifndef IN_RING3 RT_NOREF2(pVCpu, uRawValue); return VINF_CPUM_R3_MSR_WRITE; #else PVMCC pVM = pVCpu->CTX_SUFF(pVM); PGIMKVMCPU pKvmCpu = &pVCpu->gim.s.u.KvmCpu; if (uRawValue & MSR_GIM_KVM_SYSTEM_TIME_ENABLE_BIT) gimR3KvmEnableSystemTime(pVM, pVCpu, uRawValue); else gimR3KvmDisableSystemTime(pVM); pKvmCpu->u64SystemTimeMsr = uRawValue; return VINF_SUCCESS; #endif /* IN_RING3 */ } case MSR_GIM_KVM_WALL_CLOCK: case MSR_GIM_KVM_WALL_CLOCK_OLD: { #ifndef IN_RING3 RT_NOREF2(pVCpu, uRawValue); return VINF_CPUM_R3_MSR_WRITE; #else /* Enable the wall-clock struct. */ RTGCPHYS GCPhysWallClock = MSR_GIM_KVM_WALL_CLOCK_GUEST_GPA(uRawValue); if (RT_LIKELY(RT_ALIGN_64(GCPhysWallClock, 4) == GCPhysWallClock)) { PVMCC pVM = pVCpu->CTX_SUFF(pVM); int rc = gimR3KvmEnableWallClock(pVM, GCPhysWallClock); if (RT_SUCCESS(rc)) { PGIMKVM pKvm = &pVM->gim.s.u.Kvm; pKvm->u64WallClockMsr = uRawValue; return VINF_SUCCESS; } } return VERR_CPUM_RAISE_GP_0; #endif /* IN_RING3 */ } default: { #ifdef IN_RING3 static uint32_t s_cTimes = 0; if (s_cTimes++ < 20) LogRel(("GIM: KVM: Unknown/invalid WrMsr (%#x,%#x`%08x) -> #GP(0)\n", idMsr, uRawValue & UINT64_C(0xffffffff00000000), uRawValue & UINT64_C(0xffffffff))); #endif LogFunc(("Unknown/invalid WrMsr (%#RX32,%#RX64) -> #GP(0)\n", idMsr, uRawValue)); break; } } return VERR_CPUM_RAISE_GP_0; } /** * Whether we need to trap \#UD exceptions in the guest. * * On AMD-V we need to trap them because paravirtualized Linux/KVM guests use * the Intel VMCALL instruction to make hypercalls and we need to trap and * optionally patch them to the AMD-V VMMCALL instruction and handle the * hypercall. * * I guess this was done so that guest teleporation between an AMD and an Intel * machine would working without any changes at the time of teleporation. * However, this also means we -always- need to intercept \#UD exceptions on one * of the two CPU models (Intel or AMD). Hyper-V solves this problem more * elegantly by letting the hypervisor supply an opaque hypercall page. * * For raw-mode VMs, this function will always return true. See gimR3KvmInit(). * * @param pVM The cross context VM structure. */ VMM_INT_DECL(bool) gimKvmShouldTrapXcptUD(PVM pVM) { return pVM->gim.s.u.Kvm.fTrapXcptUD; } /** * Checks the instruction and executes the hypercall if it's a valid hypercall * instruction. * * This interface is used by \#UD handlers and IEM. * * @returns Strict VBox status code. * @param pVCpu The cross context virtual CPU structure. * @param pCtx Pointer to the guest-CPU context. * @param uDisOpcode The disassembler opcode. * @param cbInstr The instruction length. * * @thread EMT(pVCpu). */ VMM_INT_DECL(VBOXSTRICTRC) gimKvmHypercallEx(PVMCPUCC pVCpu, PCPUMCTX pCtx, unsigned uDisOpcode, uint8_t cbInstr) { Assert(pVCpu); Assert(pCtx); VMCPU_ASSERT_EMT(pVCpu); /* * If the instruction at RIP is the Intel VMCALL instruction or * the AMD VMMCALL instruction handle it as a hypercall. * * Linux/KVM guests always uses the Intel VMCALL instruction but we patch * it to the host-native one whenever we encounter it so subsequent calls * will not require disassembly (when coming from HM). */ if ( uDisOpcode == OP_VMCALL || uDisOpcode == OP_VMMCALL) { /* * Perform the hypercall. * * For HM, we can simply resume guest execution without performing the hypercall now and * do it on the next VMCALL/VMMCALL exit handler on the patched instruction. * * For raw-mode we need to do this now anyway. So we do it here regardless with an added * advantage is that it saves one world-switch for the HM case. */ VBOXSTRICTRC rcStrict = gimKvmHypercall(pVCpu, pCtx); if (rcStrict == VINF_SUCCESS) { /* * Patch the instruction to so we don't have to spend time disassembling it each time. * Makes sense only for HM as with raw-mode we will be getting a #UD regardless. */ PVM pVM = pVCpu->CTX_SUFF(pVM); PCGIMKVM pKvm = &pVM->gim.s.u.Kvm; if ( uDisOpcode != pKvm->uOpcodeNative && cbInstr == sizeof(pKvm->abOpcodeNative) ) { /** @todo r=ramshankar: we probably should be doing this in an * EMT rendezvous. */ /** @todo Add stats for patching. */ int rc = PGMPhysSimpleWriteGCPtr(pVCpu, pCtx->rip, pKvm->abOpcodeNative, sizeof(pKvm->abOpcodeNative)); AssertRC(rc); } } else { /* The KVM provider doesn't have any concept of continuing hypercalls. */ Assert(rcStrict != VINF_GIM_HYPERCALL_CONTINUING); #ifdef IN_RING3 Assert(rcStrict != VINF_GIM_R3_HYPERCALL); #endif } return rcStrict; } return VERR_GIM_INVALID_HYPERCALL_INSTR; } /** * Exception handler for \#UD. * * @returns Strict VBox status code. * @retval VINF_SUCCESS if the hypercall succeeded (even if its operation * failed). * @retval VINF_GIM_R3_HYPERCALL re-start the hypercall from ring-3. * @retval VERR_GIM_HYPERCALL_ACCESS_DENIED CPL is insufficient. * @retval VERR_GIM_INVALID_HYPERCALL_INSTR instruction at RIP is not a valid * hypercall instruction. * * @param pVM The cross context VM structure. * @param pVCpu The cross context virtual CPU structure. * @param pCtx Pointer to the guest-CPU context. * @param pDis Pointer to the disassembled instruction state at RIP. * Optional, can be NULL. * @param pcbInstr Where to store the instruction length of the hypercall * instruction. Optional, can be NULL. * * @thread EMT(pVCpu). */ VMM_INT_DECL(VBOXSTRICTRC) gimKvmXcptUD(PVMCC pVM, PVMCPUCC pVCpu, PCPUMCTX pCtx, PDISCPUSTATE pDis, uint8_t *pcbInstr) { VMCPU_ASSERT_EMT(pVCpu); /* * If we didn't ask for #UD to be trapped, bail. */ if (RT_UNLIKELY(!pVM->gim.s.u.Kvm.fTrapXcptUD)) return VERR_GIM_IPE_3; if (!pDis) { unsigned cbInstr; DISCPUSTATE Dis; int rc = EMInterpretDisasCurrent(pVM, pVCpu, &Dis, &cbInstr); if (RT_SUCCESS(rc)) { if (pcbInstr) *pcbInstr = (uint8_t)cbInstr; return gimKvmHypercallEx(pVCpu, pCtx, Dis.pCurInstr->uOpcode, Dis.cbInstr); } Log(("GIM: KVM: Failed to disassemble instruction at CS:RIP=%04x:%08RX64. rc=%Rrc\n", pCtx->cs.Sel, pCtx->rip, rc)); return rc; } return gimKvmHypercallEx(pVCpu, pCtx, pDis->pCurInstr->uOpcode, pDis->cbInstr); }