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2022-05-25i386: docs: Convert hyperv.txt to rSTVitaly Kuznetsov
rSTify docs/hyperv.txt and link it from docs/system/target-i386.rst. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220525115949.1294004-7-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-25i386: Hyper-V Direct TLB flush hypercallVitaly Kuznetsov
Hyper-V TLFS allows for L0 and L1 hypervisors to collaborate on L2's TLB flush hypercalls handling. With the correct setup, L2's TLB flush hypercalls can be handled by L0 directly, without the need to exit to L1. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220525115949.1294004-6-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-25i386: Hyper-V Support extended GVA ranges for TLB flush hypercallsVitaly Kuznetsov
KVM kind of supported "extended GVA ranges" (up to 4095 additional GFNs per hypercall) since the implementation of Hyper-V PV TLB flush feature (Linux-4.18) as regardless of the request, full TLB flush was always performed. "Extended GVA ranges for TLB flush hypercalls" feature bit wasn't exposed then. Now, as KVM gains support for fine-grained TLB flush handling, exposing this feature starts making sense. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220525115949.1294004-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-25i386: Hyper-V XMM fast hypercall input featureVitaly Kuznetsov
Hyper-V specification allows to pass parameters for certain hypercalls using XMM registers ("XMM Fast Hypercall Input"). When the feature is in use, it allows for faster hypercalls processing as KVM can avoid reading guest's memory. KVM supports the feature since v5.14. Rename HV_HYPERCALL_{PARAMS_XMM_AVAILABLE -> XMM_INPUT_AVAILABLE} to comply with KVM. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220525115949.1294004-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-25i386: Hyper-V Enlightened MSR bitmap featureVitaly Kuznetsov
The newly introduced enlightenment allow L0 (KVM) and L1 (Hyper-V) hypervisors to collaborate to avoid unnecessary updates to L2 MSR-Bitmap upon vmexits. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220525115949.1294004-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-06hyperv: Add support to process syndbg commandsJon Doron
SynDbg commands can come from two different flows: 1. Hypercalls, in this mode the data being sent is fully encapsulated network packets. 2. SynDbg specific MSRs, in this mode only the data that needs to be transfered is passed. Signed-off-by: Jon Doron <arilou@gmail.com> Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Message-Id: <20220216102500.692781-4-arilou@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-11-22Fix some typos in documentation (found by codespell)Stefan Weil
Signed-off-by: Stefan Weil <sw@weilnetz.de> Message-Id: <20211117210702.1393570-1-sw@weilnetz.de> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> [thuth: "what's" --> "what is" as suggested by philmd] Signed-off-by: Thomas Huth <thuth@redhat.com>
2021-10-01i386: Change the default Hyper-V version to match WS2016Vitaly Kuznetsov
KVM implements some Hyper-V 2016 functions so providing WS2008R2 version is somewhat incorrect. While generally guests shouldn't care about it and always check feature bits, it is known that some tools in Windows actually check version info. For compatibility reasons make the change for 6.2 machine types only. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210902093530.345756-9-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-01i386: Make Hyper-V version id configurableVitaly Kuznetsov
Currently, we hardcode Hyper-V version id (CPUID 0x40000002) to WS2008R2 and it is known that certain tools in Windows check this. It seems useful to provide some flexibility by making it possible to change this info at will. CPUID information is defined in TLFS as: EAX: Build Number EBX Bits 31-16: Major Version Bits 15-0: Minor Version ECX Service Pack EDX Bits 31-24: Service Branch Bits 23-0: Service Number Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210902093530.345756-8-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-01i386: Implement pseudo 'hv-avic' ('hv-apicv') enlightenmentVitaly Kuznetsov
The enlightenment allows to use Hyper-V SynIC with hardware APICv/AVIC enabled. Normally, Hyper-V SynIC disables these hardware features and suggests the guest to use paravirtualized AutoEOI feature. Linux-4.15 gains support for conditional APICv/AVIC disablement, the feature stays on until the guest tries to use AutoEOI feature with SynIC. With 'HV_DEPRECATING_AEOI_RECOMMENDED' bit exposed, modern enough Windows/ Hyper-V versions should follow the recommendation and not use the (unwanted) feature. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210902093530.345756-7-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-10-01i386: Support KVM_CAP_HYPERV_ENFORCE_CPUIDVitaly Kuznetsov
By default, KVM allows the guest to use all currently supported Hyper-V enlightenments when Hyper-V CPUID interface was exposed, regardless of if some features were not announced in guest visible CPUIDs. hv-enforce-cpuid feature alters this behavior and only allows the guest to use exposed Hyper-V enlightenments. The feature is supported by Linux >= 5.14 and is not enabled by default in QEMU. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210902093530.345756-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-07-13i386: hardcode supported eVMCS version to '1'Vitaly Kuznetsov
Currently, the only eVMCS version, supported by KVM (and described in TLFS) is '1'. When Enlightened VMCS feature is enabled, QEMU takes the supported eVMCS version range (from KVM_CAP_HYPERV_ENLIGHTENED_VMCS enablement) and puts it to guest visible CPUIDs. When (and if) eVMCS ver.2 appears a problem on migration is expected: it doesn't seem to be possible to migrate from a host supporting eVMCS ver.2 to a host, which only support eVMCS ver.1. Hardcode eVMCS ver.1 as the result of 'hv-evmcs' enablement for now. Newer eVMCS versions will have to have their own enablement options (e.g. 'hv-evmcs=2'). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com> Message-Id: <20210608120817.1325125-4-vkuznets@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
2021-07-13i386: clarify 'hv-passthrough' behaviorVitaly Kuznetsov
Clarify the fact that 'hv-passthrough' only enables features which are already known to QEMU and that it overrides all other 'hv-*' settings. Reviewed-by: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210608120817.1325125-3-vkuznets@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
2021-03-19i386: Make migration fail when Hyper-V reenlightenment was enabled but ↵Vitaly Kuznetsov
'user_tsc_khz' is unset KVM doesn't fully support Hyper-V reenlightenment notifications on migration. In particular, it doesn't support emulating TSC frequency of the source host by trapping all TSC accesses so unless TSC scaling is supported on the destination host and KVM_SET_TSC_KHZ succeeds, it is unsafe to proceed with migration. KVM_SET_TSC_KHZ is called from two sites: kvm_arch_init_vcpu() and kvm_arch_put_registers(). The later (intentionally) doesn't propagate errors allowing migrations to succeed even when TSC scaling is not supported on the destination. This doesn't suit 're-enlightenment' use-case as we have to guarantee that TSC frequency stays constant. Require 'tsc-frequency=' command line option to be specified for successful migration when re-enlightenment was enabled by the guest. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20210319123801.1111090-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-09-18i386/kvm: correct the meaning of '0xffffffff' value for hv-spinlocksVitaly Kuznetsov
Hyper-V TLFS prior to version 6.0 had a mistake in it: special value '0xffffffff' for CPUID 0x40000004.EBX was called 'never to retry', this looked weird (like why it's not '0' which supposedly have the same effect?) but nobody raised the question. In TLFS version 6.0 the mistake was corrected to 'never notify' which sounds logical. Fix QEMU accordingly. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20200515114847.74523-1-vkuznets@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
2019-10-22i386/kvm: add NoNonArchitecturalCoreSharing Hyper-V enlightenmentVitaly Kuznetsov
Hyper-V TLFS specifies this enlightenment as: "NoNonArchitecturalCoreSharing - Indicates that a virtual processor will never share a physical core with another virtual processor, except for virtual processors that are reported as sibling SMT threads. This can be used as an optimization to avoid the performance overhead of STIBP". However, STIBP is not the only implication. It was found that Hyper-V on KVM doesn't pass MD_CLEAR bit to its guests if it doesn't see NoNonArchitecturalCoreSharing bit. KVM reports NoNonArchitecturalCoreSharing in KVM_GET_SUPPORTED_HV_CPUID to indicate that SMT on the host is impossible (not supported of forcefully disabled). Implement NoNonArchitecturalCoreSharing support in QEMU as tristate: 'off' - the feature is disabled (default) 'on' - the feature is enabled. This is only safe if vCPUS are properly pinned and correct topology is exposed. As CPU pinning is done outside of QEMU the enablement decision will be made on a higher level. 'auto' - copy KVM setting. As during live migration SMT settings on the source and destination host may differ this requires us to add a migration blocker. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20191018163908.10246-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-06-21i386/kvm: add support for Direct Mode for Hyper-V synthetic timersVitaly Kuznetsov
Hyper-V on KVM can only use Synthetic timers with Direct Mode (opting for an interrupt instead of VMBus message). This new capability is only announced in KVM_GET_SUPPORTED_HV_CPUID. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20190517141924.19024-10-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-06-21i386/kvm: implement 'hv-passthrough' modeVitaly Kuznetsov
In many case we just want to give Windows guests all currently supported Hyper-V enlightenments and that's where this new mode may come handy. We pass through what was returned by KVM_GET_SUPPORTED_HV_CPUID. hv_cpuid_check_and_set() is modified to also set cpu->hyperv_* flags as we may want to check them later (and we actually do for hv_runtime, hv_synic,...). 'hv-passthrough' is a development only feature, a migration blocker is added to prevent issues while migrating between hosts with different feature sets. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20190517141924.19024-6-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-06-21i386/kvm: document existing Hyper-V enlightenmentsVitaly Kuznetsov
Currently, there is no doc describing hv-* CPU flags, people are encouraged to get the information from Microsoft Hyper-V Top Level Functional specification (TLFS). There is, however, a bit of QEMU specifics. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20190517141924.19024-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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