- 17 Jun, 2021 40 commits
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Vitaly Kuznetsov authored
VMCS12 is used to keep the authoritative state during nested state migration. In case 'need_vmcs12_to_shadow_sync' flag is set, we're in between L2->L1 vmexit and L1 guest run when actual sync to enlightened (or shadow) VMCS happens. Nested state, however, has no flag for 'need_vmcs12_to_shadow_sync' so vmx_set_nested_state()-> set_current_vmptr() always sets it. Enlightened vmptrld path, however, doesn't have the quirk so some VMCS12 changes may not get properly reflected to eVMCS and L1 will see an incorrect state. Note, during L2 execution or when need_vmcs12_to_shadow_sync is not set the change is effectively a nop: in the former case all changes will get reflected during the first L2->L1 vmexit and in the later case VMCS12 and eVMCS are already in sync (thanks to copy_enlightened_to_vmcs12() in vmx_get_nested_state()). Reviewed-by:
Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210526132026.270394-11-vkuznets@redhat.com> Signed-off-by:
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Vitaly Kuznetsov authored
When nested state migration happens during L1's execution, it is incorrect to modify eVMCS as it is L1 who 'owns' it at the moment. At least genuine Hyper-V seems to not be very happy when 'clean fields' data changes underneath it. 'Clean fields' data is used in KVM twice: by copy_enlightened_to_vmcs12() and prepare_vmcs02_rare() so we can reset it from prepare_vmcs02() instead. While at it, update a comment stating why exactly we need to reset 'hv_clean_fields' data from L0. Signed-off-by:
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Vitaly Kuznetsov authored
'need_vmcs12_to_shadow_sync' is used for both shadow and enlightened VMCS sync when we exit to L1. The comment in nested_vmx_failValid() validly states why shadow vmcs sync can be omitted but this doesn't apply to enlightened VMCS as it 'shadows' all VMCS12 fields. Reviewed-by:
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Vitaly Kuznetsov authored
'Clean fields' data from enlightened VMCS is only valid upon vmentry: L1 hypervisor is not obliged to keep it up-to-date while it is mangling L2's state, KVM_GET_NESTED_STATE request may come at a wrong moment when actual eVMCS changes are unsynchronized with 'hv_clean_fields'. As upon migration VMCS12 is used as a source of ultimate truth, we must make sure we pick all the changes to eVMCS and thus 'clean fields' data must be ignored. Signed-off-by:
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Vitaly Kuznetsov authored
Unlike VMREAD/VMWRITE/VMPTRLD, VMCLEAR is a valid instruction when enlightened VMCS is in use. TLFS has the following brief description: "The L1 hypervisor can execute a VMCLEAR instruction to transition an enlightened VMCS from the active to the non-active state". Normally, this change can be ignored as unmapping active eVMCS can be postponed until the next VMLAUNCH instruction but in case nested state is migrated with KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE, keeping eVMCS mapped may result in its synchronization with VMCS12 and this is incorrect: L1 hypervisor is free to reuse inactive eVMCS memory for something else. Inactive eVMCS after VMCLEAR can just be unmapped. Reviewed-by:
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Vitaly Kuznetsov authored
Unlike regular set_current_vmptr(), nested_vmx_handle_enlightened_vmptrld() can not be called directly from vmx_set_nested_state() as KVM may not have all the information yet (e.g. HV_X64_MSR_VP_ASSIST_PAGE MSR may not be restored yet). Enlightened VMCS is mapped later while getting nested state pages. In the meantime, vmx->nested.hv_evmcs_vmptr remains 'EVMPTR_INVALID' and it's indistinguishable from 'evmcs is not in use' case. This leads to certain issues, in particular, if KVM_GET_NESTED_STATE is called right after KVM_SET_NESTED_STATE, KVM_STATE_NESTED_EVMCS flag in the resulting state will be unset (and such state will later fail to load). Introduce 'EVMPTR_MAP_PENDING' state to detect not-yet-mapped eVMCS after restore. With this, the 'is_guest_mode(vcpu)' hack in vmx_has_valid_vmcs12() is no longer needed. Signed-off-by:
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Vitaly Kuznetsov authored
copy_vmcs12_to_enlightened()/copy_enlightened_to_vmcs12() don't return any result, make them return 'void'. No functional change intended. Suggested-by:
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Vitaly Kuznetsov authored
In theory, L1 can try to disable enlightened VMENTRY in VP assist page and try to issue VMLAUNCH/VMRESUME. While nested_vmx_handle_enlightened_vmptrld() properly handles this as 'EVMPTRLD_DISABLED', previously mapped eVMCS remains mapped and thus all evmptr_is_valid() checks will still pass and nested_vmx_run() will proceed when it shouldn't. Release eVMCS immediately when we detect that enlightened vmentry was disabled by L1. Signed-off-by:
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Vitaly Kuznetsov authored
'dirty_vmcs12' is only checked in prepare_vmcs02_early()/prepare_vmcs02() and both checks look like: 'vmx->nested.dirty_vmcs12 || evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)' so for eVMCS case the flag changes nothing. Drop the assignment to avoid the confusion. No functional change intended. Reported-by:
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Vitaly Kuznetsov authored
Instead of checking 'vmx->nested.hv_evmcs' use '-1' in 'vmx->nested.hv_evmcs_vmptr' to indicate 'evmcs is not in use' state. This matches how we check 'vmx->nested.current_vmptr'. Introduce EVMPTR_INVALID and evmptr_is_valid() and use it instead of raw '-1' check as a preparation to adding other 'special' values. No functional change intended. Suggested-by:
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Maxim Levitsky authored
if new KVM_*_SREGS2 ioctls are used, the PDPTRs are a part of the migration state and are correctly restored by those ioctls. Signed-off-by:
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Maxim Levitsky authored
This is a new version of KVM_GET_SREGS / KVM_SET_SREGS. It has the following changes: * Has flags for future extensions * Has vcpu's PDPTRs, allowing to save/restore them on migration. * Lacks obsolete interrupt bitmap (done now via KVM_SET_VCPU_EVENTS) New capability, KVM_CAP_SREGS2 is added to signal the userspace of this ioctl. Signed-off-by:
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Maxim Levitsky authored
Small refactoring that will be used in the next patch. Signed-off-by:
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Maxim Levitsky authored
Similar to the rest of guest page accesses after a migration, this access should be delayed to KVM_REQ_GET_NESTED_STATE_PAGES. Signed-off-by:
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Maxim Levitsky authored
Document the actual reason why we need to do it on migration and move the call to svm_set_nested_state to be closer to VMX code. To avoid loading the PDPTRs from possibly not up to date memory map, in nested_svm_load_cr3 after the move, move this code to .get_nested_state_pages. Signed-off-by:
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Sean Christopherson authored
Kill off pdptrs_changed() and instead go through the full kvm_set_cr3() for PAE guest, even if the new CR3 is the same as the current CR3. For VMX, and SVM with NPT enabled, the PDPTRs are unconditionally marked as unavailable after VM-Exit, i.e. the optimization is dead code except for SVM without NPT. In the unlikely scenario that anyone cares about SVM without NPT _and_ a PAE guest, they've got bigger problems if their guest is loading the same CR3 so frequently that the performance of kvm_set_cr3() is notable, especially since KVM's fast PGD switching means reloading the same CR3 does not require a full rebuild. Given that PAE and PCID are mutually exclusive, i.e. a sync and flush are guaranteed in any case, the actual benefits of the pdptrs_changed() optimization are marginal at best. Signed-off-by:
Sean Christopherson <seanjc@google.com> Message-Id: <20210607090203.133058-4-mlevitsk@redhat.com> Signed-off-by:
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Sean Christopherson authored
Remove the "PDPTRs unchanged" check to skip PDPTR loading during nested SVM transitions as it's not at all an optimization. Reading guest memory to get the PDPTRs isn't magically cheaper by doing it in pdptrs_changed(), and if the PDPTRs did change, KVM will end up doing the read twice. Signed-off-by:
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Sean Christopherson authored
Remove the pdptrs_changed() check when loading L2's CR3. The set of available registers is always reset when switching VMCSes (see commit e5d03de5, "KVM: nVMX: Reset register cache (available and dirty masks) on VMCS switch"), thus the "are PDPTRs available" check will always fail. And even if it didn't fail, reading guest memory to check the PDPTRs is just as expensive as reading guest memory to load 'em. Signed-off-by:
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Vitaly Kuznetsov authored
The initial implementation of the test only tests that access to Hyper-V MSRs and hypercalls is in compliance with guest visible CPUID feature bits. Signed-off-by:
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Vitaly Kuznetsov authored
evmcs.h is x86_64 only thing, move it to x86_64/ subdirectory. Signed-off-by:
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Vitaly Kuznetsov authored
These defines can be shared by multiple tests, move them to a dedicated header. Signed-off-by:
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Vitaly Kuznetsov authored
Hypercalls which use extended processor masks are only available when HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED privilege bit is exposed (and 'RECOMMENDED' is rather a misnomer). Signed-off-by:
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Vitaly Kuznetsov authored
Hyper-V partition must possess 'HV_X64_CLUSTER_IPI_RECOMMENDED' privilege ('recommended' is rather a misnomer) to issue HVCALL_SEND_IPI hypercalls. Signed-off-by: -
Vitaly Kuznetsov authored
Hyper-V partition must possess 'HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED' privilege ('recommended' is rather a misnomer) to issue HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST/SPACE hypercalls. Signed-off-by: -
Vitaly Kuznetsov authored
Hyper-V partition must possess 'HV_DEBUGGING' privilege to issue HVCALL_POST_DEBUG_DATA/HVCALL_RETRIEVE_DEBUG_DATA/ HVCALL_RESET_DEBUG_SESSION hypercalls. Note, when SynDBG is disabled hv_check_hypercall_access() returns 'true' (like for any other unknown hypercall) so the result will be HV_STATUS_INVALID_HYPERCALL_CODE and not HV_STATUS_ACCESS_DENIED. Signed-off-by:
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Vitaly Kuznetsov authored
Hyper-V partition must possess 'HV_SIGNAL_EVENTS' privilege to issue HVCALL_SIGNAL_EVENT hypercalls. Signed-off-by:
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Vitaly Kuznetsov authored
Hyper-V partition must possess 'HV_POST_MESSAGES' privilege to issue HVCALL_POST_MESSAGE hypercalls. Signed-off-by:
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Vitaly Kuznetsov authored
TLFS6.0b states that partition issuing HVCALL_NOTIFY_LONG_SPIN_WAIT must posess 'UseHypercallForLongSpinWait' privilege but there's no corresponding feature bit. Instead, we have "Recommended number of attempts to retry a spinlock failure before notifying the hypervisor about the failures. 0xFFFFFFFF indicates never notify." Use this to check access to the hypercall. Also, check against zero as the corresponding CPUID must be set (and '0' attempts before re-try is weird anyway). Signed-off-by:
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Vitaly Kuznetsov authored
Introduce hv_check_hypercallr_access() to check if the particular hypercall should be available to guest, this will be used with KVM_CAP_HYPERV_ENFORCE_CPUID mode. No functional change intended. Signed-off-by:
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Vitaly Kuznetsov authored
Synthetic timers can only be configured in 'direct' mode when HV_STIMER_DIRECT_MODE_AVAILABLE bit was exposed. Signed-off-by:
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Vitaly Kuznetsov authored
Access to all MSRs is now properly checked. To avoid 'forgetting' to properly check access to new MSRs in the future change the default to 'false' meaning 'no access'. No functional change intended. Signed-off-by:
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Vitaly Kuznetsov authored
Synthetic debugging MSRs (HV_X64_MSR_SYNDBG_CONTROL, HV_X64_MSR_SYNDBG_STATUS, HV_X64_MSR_SYNDBG_SEND_BUFFER, HV_X64_MSR_SYNDBG_RECV_BUFFER, HV_X64_MSR_SYNDBG_PENDING_BUFFER, HV_X64_MSR_SYNDBG_OPTIONS) are only available to guest when HV_FEATURE_DEBUG_MSRS_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4, HV_X64_MSR_CRASH_CTL are only available to guest when HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_REENLIGHTENMENT_CONTROL/HV_X64_MSR_TSC_EMULATION_CONTROL/ HV_X64_MSR_TSC_EMULATION_STATUS are only available to guest when HV_ACCESS_REENLIGHTENMENT bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_TSC_FREQUENCY/HV_X64_MSR_APIC_FREQUENCY are only available to guest when HV_ACCESS_FREQUENCY_MSRS bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_EOI, HV_X64_MSR_ICR, HV_X64_MSR_TPR, and HV_X64_MSR_VP_ASSIST_PAGE are only available to guest when HV_MSR_APIC_ACCESS_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
Synthetic timers MSRs (HV_X64_MSR_STIMER[0-3]_CONFIG, HV_X64_MSR_STIMER[0-3]_COUNT) are only available to guest when HV_MSR_SYNTIMER_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
SynIC MSRs (HV_X64_MSR_SCONTROL, HV_X64_MSR_SVERSION, HV_X64_MSR_SIEFP, HV_X64_MSR_SIMP, HV_X64_MSR_EOM, HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15) are only available to guest when HV_MSR_SYNIC_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_REFERENCE_TSC is only available to guest when HV_MSR_REFERENCE_TSC_AVAILABLE bit is exposed. Signed-off-by:
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Vitaly Kuznetsov authored
HV_X64_MSR_RESET is only available to guest when HV_MSR_RESET_AVAILABLE bit is exposed. Signed-off-by:
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