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2013-03-11kvm: remove cast for kmalloc return valueIoan Orghici1-2/+1
Signed-off-by: Ioan Orghici<ioan.orghici@gmail.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-03-07KVM: nVMX: Fix setting of CR0 and CR4 in guest modeJan Kiszka1-15/+33
The logic for calculating the value with which we call kvm_set_cr0/4 was broken (will definitely be visible with nested unrestricted guest mode support). Also, we performed the check regarding CR0_ALWAYSON too early when in guest mode. What really needs to be done on both CR0 and CR4 is to mask out L1-owned bits and merge them in from L1's guest_cr0/4. In contrast, arch.cr0/4 and arch.cr0/4_guest_owned_bits contain the mangled L0+L1 state and, thus, are not suited as input. For both CRs, we can then apply the check against VMXON_CRx_ALWAYSON and refuse the update if it fails. To be fully consistent, we implement this check now also for CR4. For CR4, we move the check into vmx_set_cr4 while we keep it in handle_set_cr0. This is because the CR0 checks for vmxon vs. guest mode will diverge soon when adding unrestricted guest mode support. Finally, we have to set the shadow to the value L2 wanted to write originally. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-03-07KVM: nVMX: Fix content of MSR_IA32_VMX_ENTRY/EXIT_CTLSJan Kiszka1-3/+10
Properly set those bits to 1 that the spec demands in case bit 55 of VMX_BASIC is 0 - like in our case. Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-03-05KVM: nVMX: Reset RFLAGS on VM-exitJan Kiszka1-0/+1
Ouch, how could this work so well that far? We need to clear RFLAGS to the reset value as specified by the SDM. Particularly, IF must be off after VM-exit! Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-03-04KVM: nVMX: Fix switching of debug stateJan Kiszka1-1/+4
First of all, do not blindly overwrite GUEST_DR7 on L2 entry. The host may have guest debugging enabled. Then properly reset DR7 and DEBUG_CTL on L2->L1 switch as specified in the SDM. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-03-04KVM: set_memory_region: Drop user_alloc from set_memory_region()Takuya Yoshikawa1-3/+3
Except ia64's stale code, KVM_SET_MEMORY_REGION support, this is only used for sanity checks in __kvm_set_memory_region() which can easily be changed to use slot id instead. Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-02-28KVM: VMX: Pass vcpu to __vmx_complete_interruptsJan Kiszka1-17/+14
Cleanup: __vmx_complete_interrupts has no use for the vmx structure. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-28KVM: nVMX: Avoid one redundant vmcs_read in prepare_vmcs12Jan Kiszka1-2/+1
IDT_VECTORING_INFO_FIELD was already read right after vmexit. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-27KVM: nVMX: Use cached exit reasonJan Kiszka1-2/+2
No need to re-read what vmx_vcpu_run already picked up for us. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-27KVM: nVMX: Clear segment cache after switching between L1 and L2Jan Kiszka1-0/+4
Switching the VMCS obviously invalidates what may have been cached about the guest segments. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-27KVM: nVMX: Advertise PAUSE and WBINVD exiting supportJan Kiszka1-1/+3
These exits have no preconditions, and we already process the corresponding reasons in nested_vmx_exit_handled correctly. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-27KVM: VMX: Make prepare_vmcs12 and load_vmcs12_host_state staticJan Kiszka1-2/+3
Both are only used locally. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-22KVM: nVMX: Trap unconditionally if msr bitmap access failsJan Kiszka1-1/+2
This avoids basing decisions on uninitialized variables, potentially leaking kernel data to the L1 guest. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-02-22KVM: nVMX: Improve I/O exit handlingJan Kiszka1-2/+47
This prevents trapping L2 I/O exits if L1 has neither unconditional nor bitmap-based exiting enabled. Furthermore, it implements I/O bitmap handling. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-02-14KVM: nVMX: Remove redundant get_vmcs12 from nested_vmx_exit_handled_msrJan Kiszka1-1/+1
We already pass vmcs12 as argument. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-11KVM: VMX: disable apicv by defaultYang Zhang1-2/+1
Without Posted Interrupt, current code is broken. Just disable by default until Posted Interrupt is ready. Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-02-06KVM: VMX: cleanup vmx_set_cr0().Gleb Natapov1-9/+5
When calculating hw_cr0 teh current code masks bits that should be always on and re-adds them back immediately after. Cleanup the code by masking only those bits that should be dropped from hw_cr0. This allow us to get rid of some defines. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-02-05KVM: VMX: disable SMEP feature when guest is in non-paging modeDongxiao Xu1-0/+8
SMEP is disabled if CPU is in non-paging mode in hardware. However KVM always uses paging mode to emulate guest non-paging mode with TDP. To emulate this behavior, SMEP needs to be manually disabled when guest switches to non-paging mode. We met an issue that, SMP Linux guest with recent kernel (enable SMEP support, for example, 3.5.3) would crash with triple fault if setting unrestricted_guest=0. This is because KVM uses an identity mapping page table to emulate the non-paging mode, where the page table is set with USER flag. If SMEP is still enabled in this case, guest will meet unhandlable page fault and then crash. Reviewed-by: Gleb Natapov <gleb@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com> Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-29x86, apicv: add virtual interrupt delivery supportYang Zhang1-10/+109
Virtual interrupt delivery avoids KVM to inject vAPIC interrupts manually, which is fully taken care of by the hardware. This needs some special awareness into existing interrupr injection path: - for pending interrupt, instead of direct injection, we may need update architecture specific indicators before resuming to guest. - A pending interrupt, which is masked by ISR, should be also considered in above update action, since hardware will decide when to inject it at right time. Current has_interrupt and get_interrupt only returns a valid vector from injection p.o.v. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-01-29x86, apicv: add virtual x2apic supportYang Zhang1-20/+178
basically to benefit from apicv, we need to enable virtualized x2apic mode. Currently, we only enable it when guest is really using x2apic. Also, clear MSR bitmap for corresponding x2apic MSRs when guest enabled x2apic: 0x800 - 0x8ff: no read intercept for apicv register virtualization, except APIC ID and TMCCT which need software's assistance to get right value. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-01-29x86, apicv: add APICv register virtualization supportYang Zhang1-1/+32
- APIC read doesn't cause VM-Exit - APIC write becomes trap-like Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Yang Zhang <yang.z.zhang@intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-01-24KVM: VMX: set vmx->emulation_required only when needed.Gleb Natapov1-7/+12
If emulate_invalid_guest_state=false vmx->emulation_required is never actually used, but it ends up to be always set to true since handle_invalid_guest_state(), the only place it is reset back to false, is never called. This, besides been not very clean, makes vmexit and vmentry path to check emulate_invalid_guest_state needlessly. The patch fixes that by keeping emulation_required coherent with emulate_invalid_guest_state setting. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: rename fix_pmode_dataseg to fix_pmode_seg.Gleb Natapov1-7/+7
The function deals with code segment too. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: don't clobber segment AR of unusable segments.Gleb Natapov1-2/+0
Usability is returned in unusable field, so not need to clobber entire AR. Callers have to know how to deal with unusable segments already since if emulate_invalid_guest_state=true AR is not zeroed. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: skip vmx->rmode.vm86_active check on cr0 write if unrestricted ↵Gleb Natapov1-8/+6
guest is enabled vmx->rmode.vm86_active is never true is unrestricted guest is enabled. Make it more explicit that neither enter_pmode() nor enter_rmode() is called in this case. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: remove hack that disables emulation on vcpu reset/initGleb Natapov1-3/+0
There is no reason for it. If state is suitable for vmentry it will be detected during guest entry and no emulation will happen. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: if unrestricted guest is enabled vcpu state is always valid.Gleb Natapov1-0/+3
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: reset CPL only on CS register write.Gleb Natapov1-1/+2
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-24KVM: VMX: remove special CPL cache access during transition to real mode.Gleb Natapov1-8/+4
Since vmx_get_cpl() always returns 0 when VCPU is in real mode it is no longer needed. Also reset CPL cache to zero during transaction to protected mode since transaction may happen while CS.selectors & 3 != 0, but in reality CPL is 0. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-08KVM: VMX: fix incorrect cached cpl value with real/v8086 modesMarcelo Tosatti1-11/+4
CPL is always 0 when in real mode, and always 3 when virtual 8086 mode. Using values other than those can cause failures on operations that check CPL. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-02KVM: VMX: handle IO when emulation is due to #GP in real mode.Gleb Natapov1-34/+41
With emulate_invalid_guest_state=0 if a vcpu is in real mode VMX can enter the vcpu with smaller segment limit than guest configured. If the guest tries to access pass this limit it will get #GP at which point instruction will be emulated with correct segment limit applied. If during the emulation IO is detected it is not handled correctly. Vcpu thread should exit to userspace to serve the IO, but it returns to the guest instead. Since emulation is not completed till userspace completes the IO the faulty instruction is re-executed ad infinitum. The patch fixes that by exiting to userspace if IO happens during instruction emulation. Reported-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-02KVM: VMX: Do not fix segment register during vcpu initialization.Gleb Natapov1-13/+5
Segment registers will be fixed according to current emulation policy during switching to real mode for the first time. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-02KVM: VMX: fix emulation of invalid guest state.Gleb Natapov1-54/+68
Currently when emulation of invalid guest state is enable (emulate_invalid_guest_state=1) segment registers are still fixed for entry to vm86 mode some times. Segment register fixing is avoided in enter_rmode(), but vmx_set_segment() still does it unconditionally. The patch fixes it. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2013-01-02KVM: VMX: make rmode_segment_valid() more strict.Gleb Natapov1-3/+1
Currently it allows entering vm86 mode if segment limit is greater than 0xffff and db bit is set. Both of those can cause incorrect execution of instruction by cpu since in vm86 mode limit will be set to 0xffff and db will be forced to 0. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-12-23KVM: VMX: remove unneeded temporary variable from vmx_set_segment()Gleb Natapov1-4/+2
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: clean-up vmx_set_segment()Gleb Natapov1-18/+9
Move all vm86_active logic into one place. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: remove redundant code from vmx_set_segment()Gleb Natapov1-9/+3
Segment descriptor's base is fixed by call to fix_rmode_seg(). Not need to do it twice. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: use fix_rmode_seg() to fix all code/data segmentsGleb Natapov1-24/+2
The code for SS and CS does the same thing fix_rmode_seg() is doing. Use it instead of hand crafted code. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: return correct segment limit and flags for CS/SS registers in real ↵Gleb Natapov1-4/+3
mode VMX without unrestricted mode cannot virtualize real mode, so if emulate_invalid_guest_state=0 kvm uses vm86 mode to approximate it. Sometimes, when guest moves from protected mode to real mode, it leaves segment descriptors in a state not suitable for use by vm86 mode virtualization, so we keep shadow copy of segment descriptors for internal use and load fake register to VMCS for guest entry to succeed. Till now we kept shadow for all segments except SS and CS (for SS and CS we returned parameters directly from VMCS), but since commit a5625189f6810 emulator enforces segment limits in real mode. This causes #GP during move from protected mode to real mode when emulator fetches first instruction after moving to real mode since it uses incorrect CS base and limit to linearize the %rip. Fix by keeping shadow for SS and CS too. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: relax check for CS register in rmode_segment_valid()Gleb Natapov1-0/+2
rmode_segment_valid() checks if segment descriptor can be used to enter vm86 mode. VMX spec mandates that in vm86 mode CS register will be of type data, not code. Lets allow guest entry with vm86 mode if the only problem with CS register is incorrect type. Otherwise entire real mode will be emulated. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-23KVM: VMX: cleanup rmode_segment_valid()Gleb Natapov1-1/+4
Set segment fields explicitly instead of using binary operations. No behaviour changes. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-13KVM: struct kvm_memory_slot.user_alloc -> boolAlex Williamson1-3/+3
There's no need for this to be an int, it holds a boolean. Move to the end of the struct for alignment. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-12-13Merge tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-58/+145
Pull KVM updates from Marcelo Tosatti: "Considerable KVM/PPC work, x86 kvmclock vsyscall support, IA32_TSC_ADJUST MSR emulation, amongst others." Fix up trivial conflict in kernel/sched/core.c due to cross-cpu migration notifier added next to rq migration call-back. * tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (156 commits) KVM: emulator: fix real mode segment checks in address linearization VMX: remove unneeded enable_unrestricted_guest check KVM: VMX: fix DPL during entry to protected mode x86/kexec: crash_vmclear_local_vmcss needs __rcu kvm: Fix irqfd resampler list walk KVM: VMX: provide the vmclear function and a bitmap to support VMCLEAR in kdump x86/kexec: VMCLEAR VMCSs loaded on all cpus if necessary KVM: MMU: optimize for set_spte KVM: PPC: booke: Get/set guest EPCR register using ONE_REG interface KVM: PPC: bookehv: Add EPCR support in mtspr/mfspr emulation KVM: PPC: bookehv: Add guest computation mode for irq delivery KVM: PPC: Make EPCR a valid field for booke64 and bookehv KVM: PPC: booke: Extend MAS2 EPN mask for 64-bit KVM: PPC: e500: Mask MAS2 EPN high 32-bits in 32/64 tlbwe emulation KVM: PPC: Mask ea's high 32-bits in 32/64 instr emulation KVM: PPC: e500: Add emulation helper for getting instruction ea KVM: PPC: bookehv64: Add support for interrupt handling KVM: PPC: bookehv: Remove GET_VCPU macro from exception handler KVM: PPC: booke: Fix get_tb() compile error on 64-bit KVM: PPC: e500: Silence bogus GCC warning in tlb code ...
2012-12-11VMX: remove unneeded enable_unrestricted_guest checkGleb Natapov1-1/+1
If enable_unrestricted_guest is true vmx->rmode.vm86_active will always be false. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-12-11KVM: VMX: fix DPL during entry to protected modeGleb Natapov1-0/+1
On CPUs without support for unrestricted guests DPL cannot be smaller than RPL for data segments during guest entry, but this state can occurs if a data segment selector changes while vcpu is in real mode to a value with lowest two bits != 00. Fix that by forcing DPL == RPL on transition to protected mode. This is a regression introduced by c865c43de66dc97. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-12-06KVM: VMX: provide the vmclear function and a bitmap to support VMCLEAR in kdumpZhang Yanfei1-0/+67
The vmclear function will be assigned to the callback function pointer when loading kvm-intel module. And the bitmap indicates whether we should do VMCLEAR operation in kdump. The bits in the bitmap are set/unset according to different conditions. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Acked-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-05KVM: x86: Make register state after reset conform to specificationJulian Stecklina1-8/+0
VMX behaves now as SVM wrt to FPU initialization. Code has been moved to generic code path. General-purpose registers are now cleared on reset and INIT. SVM code properly initializes EDX. Signed-off-by: Julian Stecklina <jsteckli@os.inf.tu-dresden.de> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-05kvm: don't use bit24 for detecting address-specific invalidation capabilityZhang Xiantao1-16/+0
Bit24 in VMX_EPT_VPID_CAP_MASI is not used for address-specific invalidation capability reporting, so remove it from KVM to avoid conflicts in future. Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-12-05kvm: remove unnecessary bit checking for ept violationZhang Xiantao1-5/+0
Bit 6 in EPT vmexit's exit qualification is not defined in SDM, so remove it. Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2012-11-30KVM: x86: Emulate IA32_TSC_ADJUST MSRWill Auld1-0/+9
CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported Basic design is to emulate the MSR by allowing reads and writes to a guest vcpu specific location to store the value of the emulated MSR while adding the value to the vmcs tsc_offset. In this way the IA32_TSC_ADJUST value will be included in all reads to the TSC MSR whether through rdmsr or rdtsc. This is of course as long as the "use TSC counter offsetting" VM-execution control is enabled as well as the IA32_TSC_ADJUST control. However, because hardware will only return the TSC + IA32_TSC_ADJUST + vmsc tsc_offset for a guest process when it does and rdtsc (with the correct settings) the value of our virtualized IA32_TSC_ADJUST must be stored in one of these three locations. The argument against storing it in the actual MSR is performance. This is likely to be seldom used while the save/restore is required on every transition. IA32_TSC_ADJUST was created as a way to solve some issues with writing TSC itself so that is not an option either. The remaining option, defined above as our solution has the problem of returning incorrect vmcs tsc_offset values (unless we intercept and fix, not done here) as mentioned above. However, more problematic is that storing the data in vmcs tsc_offset will have a different semantic effect on the system than does using the actual MSR. This is illustrated in the following example: The hypervisor set the IA32_TSC_ADJUST, then the guest sets it and a guest process performs a rdtsc. In this case the guest process will get TSC + IA32_TSC_ADJUST_hyperviser + vmsc tsc_offset including IA32_TSC_ADJUST_guest. While the total system semantics changed the semantics as seen by the guest do not and hence this will not cause a problem. Signed-off-by: Will Auld <will.auld@intel.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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