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2023-02-15Merge tag 'kvm-x86-pmu-6.3' of https://github.com/kvm-x86/linux into HEADPaolo Bonzini1-6/+4
KVM x86 PMU changes for 6.3: - Add support for created masked events for the PMU filter to allow userspace to heavily restrict what events the guest can use without needing to create an absurd number of events - Clean up KVM's handling of "PMU MSRs to save", especially when vPMU support is disabled - Add PEBS support for Intel SPR
2023-02-02KVM: x86: hyper-v: Add extended hypercall support in Hyper-vVipin Sharma1-0/+28
Add support for extended hypercall in Hyper-v. Hyper-v TLFS 6.0b describes hypercalls above call code 0x8000 as extended hypercalls. A Hyper-v hypervisor's guest VM finds availability of extended hypercalls via CPUID.0x40000003.EBX BIT(20). If the bit is set then the guest can call extended hypercalls. All extended hypercalls will exit to userspace by default. This allows for easy support of future hypercalls without being dependent on KVM releases. If there will be need to process the hypercall in KVM instead of userspace then KVM can create a capability which userspace can query to know which hypercalls can be handled by the KVM and enable handling of those hypercalls. Signed-off-by: Vipin Sharma <vipinsh@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20221212183720.4062037-10-vipinsh@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-02-02KVM: x86: hyper-v: Use common code for hypercall userspace exitVipin Sharma1-16/+11
Remove duplicate code to exit to userspace for hyper-v hypercalls and use a common place to exit. No functional change intended. Signed-off-by: Vipin Sharma <vipinsh@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20221212183720.4062037-9-vipinsh@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-01-27KVM: x86/pmu: Gate all "unimplemented MSR" prints on report_ignored_msrsSean Christopherson1-6/+4
Add helpers to print unimplemented MSR accesses and condition all such prints on report_ignored_msrs, i.e. honor userspace's request to not print unimplemented MSRs. Even though vcpu_unimpl() is ratelimited, printing can still be problematic, e.g. if a print gets stalled when host userspace is writing MSRs during live migration, an effective stall can result in very noticeable disruption in the guest. E.g. the profile below was taken while calling KVM_SET_MSRS on the PMU counters while the PMU was disabled in KVM. - 99.75% 0.00% [.] __ioctl - __ioctl - 99.74% entry_SYSCALL_64_after_hwframe do_syscall_64 sys_ioctl - do_vfs_ioctl - 92.48% kvm_vcpu_ioctl - kvm_arch_vcpu_ioctl - 85.12% kvm_set_msr_ignored_check svm_set_msr kvm_set_msr_common printk vprintk_func vprintk_default vprintk_emit console_unlock call_console_drivers univ8250_console_write serial8250_console_write uart_console_write Reported-by: Aaron Lewis <aaronlewis@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20230124234905.3774678-3-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2022-12-29KVM: x86: Unify pr_fmt to use module name for all KVM modulesSean Christopherson1-0/+1
Define pr_fmt using KBUILD_MODNAME for all KVM x86 code so that printks use consistent formatting across common x86, Intel, and AMD code. In addition to providing consistent print formatting, using KBUILD_MODNAME, e.g. kvm_amd and kvm_intel, allows referencing SVM and VMX (and SEV and SGX and ...) as technologies without generating weird messages, and without causing naming conflicts with other kernel code, e.g. "SEV: ", "tdx: ", "sgx: " etc.. are all used by the kernel for non-KVM subsystems. Opportunistically move away from printk() for prints that need to be modified anyways, e.g. to drop a manual "kvm: " prefix. Opportunistically convert a few SGX WARNs that are similarly modified to WARN_ONCE; in the very unlikely event that the WARNs fire, odds are good that they would fire repeatedly and spam the kernel log without providing unique information in each print. Note, defining pr_fmt yields undesirable results for code that uses KVM's printk wrappers, e.g. vcpu_unimpl(). But, that's a pre-existing problem as SVM/kvm_amd already defines a pr_fmt, and thankfully use of KVM's wrappers is relatively limited in KVM x86 code. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Paul Durrant <paul@xen.org> Message-Id: <20221130230934.1014142-35-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Hyper-V invariant TSC controlVitaly Kuznetsov1-0/+19
Normally, genuine Hyper-V doesn't expose architectural invariant TSC (CPUID.80000007H:EDX[8]) to its guests by default. A special PV MSR (HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x40000118) and corresponding CPUID feature bit (CPUID.0x40000003.EAX[15]) were introduced. When bit 0 of the PV MSR is set, invariant TSC bit starts to show up in CPUID. When the feature is exposed to Hyper-V guests, reenlightenment becomes unneeded. Add the feature to KVM. Keep CPUID output intact when the feature wasn't exposed to L1 and implement the required logic for hiding invariant TSC when the feature was exposed and invariant TSC control MSR wasn't written to. Copy genuine Hyper-V behavior and forbid to disable the feature once it was enabled. For the reference, for linux guests, support for the feature was added in commit dce7cd62754b ("x86/hyperv: Allow guests to enable InvariantTSC"). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221013095849.705943-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86: hyper-v: Fix 'using uninitialized value' Coverity warningVitaly Kuznetsov1-27/+36
In kvm_hv_flush_tlb(), 'data_offset' and 'consumed_xmm_halves' variables are used in a mutually exclusive way: in 'hc->fast' we count in 'XMM halves' and increase 'data_offset' otherwise. Coverity discovered, that in one case both variables are incremented unconditionally. This doesn't seem to cause any issues as the only user of 'data_offset'/'consumed_xmm_halves' data is kvm_hv_get_tlb_flush_entries() -> kvm_hv_get_hc_data() which also takes into account 'hc->fast' but is still worth fixing. To make things explicit, put 'data_offset' and 'consumed_xmm_halves' to 'struct kvm_hv_hcall' as a union and use at call sites. This allows to remove explicit 'data_offset'/'consumed_xmm_halves' parameters from kvm_hv_get_hc_data()/kvm_get_sparse_vp_set()/kvm_hv_get_tlb_flush_entries() helpers. Note: 'struct kvm_hv_hcall' is allocated on stack in kvm_hv_hypercall() and is not zeroed, consumers are supposed to initialize the appropriate field if needed. Reported-by: coverity-bot <keescook+coverity-bot@chromium.org> Addresses-Coverity-ID: 1527764 ("Uninitialized variables") Fixes: 260970862c88 ("KVM: x86: hyper-v: Handle HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls gently") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221208102700.959630-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: Expose Hyper-V L2 TLB flush featureVitaly Kuznetsov1-0/+1
With both nSVM and nVMX implementations in place, KVM can now expose Hyper-V L2 TLB flush feature to userspace. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-30-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: Make kvm_hv_get_assist_page() return 0/-errnoVitaly Kuznetsov1-4/+4
Convert kvm_hv_get_assist_page() to return 'int' and propagate possible errors from kvm_read_guest_cached(). Suggested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-28-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: nVMX: hyper-v: Cache VP assist page in 'struct kvm_vcpu_hv'Vitaly Kuznetsov1-4/+6
In preparation to enabling L2 TLB flush, cache VP assist page in 'struct kvm_vcpu_hv'. While on it, rename nested_enlightened_vmentry() to nested_get_evmptr() and make it return eVMCS GPA directly. No functional change intended. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-26-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: L2 TLB flushVitaly Kuznetsov1-13/+67
Handle L2 TLB flush requests by going through all vCPUs and checking whether there are vCPUs running the same VM_ID with a VP_ID specified in the requests. Perform synthetic exit to L2 upon finish. Note, while checking VM_ID/VP_ID of running vCPUs seem to be a bit racy, we count on the fact that KVM flushes the whole L2 VPID upon transition. Also, KVM_REQ_HV_TLB_FLUSH request needs to be done upon transition between L1 and L2 to make sure all pending requests are always processed. For the reference, Hyper-V TLFS refers to the feature as "Direct Virtual Flush". Note, nVMX/nSVM code does not handle VMCALL/VMMCALL from L2 yet. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-24-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Use preallocated buffer in 'struct kvm_vcpu_hv' instead ↵Vitaly Kuznetsov1-2/+4
of on-stack 'sparse_banks' To make kvm_hv_flush_tlb() ready to handle L2 TLB flush requests, KVM needs to allow for all 64 sparse vCPU banks regardless of KVM_MAX_VCPUs as L1 may use vCPU overcommit for L2. To avoid growing on-stack allocation, make 'sparse_banks' part of per-vCPU 'struct kvm_vcpu_hv' which is allocated dynamically. Note: sparse_set_to_vcpu_mask() can't currently be used to handle L2 requests as KVM does not keep L2 VM_ID -> L2 VCPU_ID -> L1 vCPU mappings, i.e. its vp_bitmap array is still bounded by the number of L1 vCPUs and so can remain an on-stack allocation. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-19-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Create a separate fifo for L2 TLB flushVitaly Kuznetsov1-4/+7
To handle L2 TLB flush requests, KVM needs to use a separate fifo from regular (L1) Hyper-V TLB flush requests: e.g. when a request to flush something in L2 is made, the target vCPU can transition from L2 to L1, receive a request to flush a GVA for L1 and then try to enter L2 back. The first request needs to be processed at this point. Similarly, requests to flush GVAs in L1 must wait until L2 exits to L1. No functional change as KVM doesn't handle L2 TLB flush requests from L2 yet. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-18-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Don't use sparse_set_to_vcpu_mask() in kvm_hv_send_ipi()Vitaly Kuznetsov1-11/+31
Get rid of on-stack allocation of vcpu_mask and optimize kvm_hv_send_ipi() for a smaller number of vCPUs in the request. When Hyper-V TLB flush is in use, HvSendSyntheticClusterIpi{,Ex} calls are not commonly used to send IPIs to a large number of vCPUs (and are rarely used in general). Introduce hv_is_vp_in_sparse_set() to directly check if the specified VP_ID is present in sparse vCPU set. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-17-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Use HV_MAX_SPARSE_VCPU_BANKS/HV_VCPUS_PER_SPARSE_BANK ↵Vitaly Kuznetsov1-7/+6
instead of raw '64' It may not be clear from where the '64' limit for the maximum sparse bank number comes from, use HV_MAX_SPARSE_VCPU_BANKS define instead. Use HV_VCPUS_PER_SPARSE_BANK in KVM_HV_MAX_SPARSE_VCPU_SET_BITS's definition. Opportunistically adjust the comment around BUILD_BUG_ON(). No functional change. Suggested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-16-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: Prepare kvm_hv_flush_tlb() to handle L2's GPAsVitaly Kuznetsov1-0/+14
To handle L2 TLB flush requests, KVM needs to translate the specified L2 GPA to L1 GPA to read hypercall arguments from there. No functional change as KVM doesn't handle VMCALL/VMMCALL from L2 yet. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-14-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Expose support for extended gva ranges for flush hypercallsVitaly Kuznetsov1-0/+1
Extended GVA ranges support bit seems to indicate whether lower 12 bits of GVA can be used to specify up to 4095 additional consequent GVAs to flush. This is somewhat described in TLFS. Previously, KVM was handling HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} requests by flushing the whole VPID so technically, extended GVA ranges were already supported. As such requests are handled more gently now, advertizing support for extended ranges starts making sense to reduce the size of TLB flush requests. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-13-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Handle HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls gentlyVitaly Kuznetsov1-16/+95
Currently, HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls are handled the exact same way as HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE{,EX}: by flushing the whole VPID and this is sub-optimal. Switch to handling these requests with 'flush_tlb_gva()' hooks instead. Use the newly introduced TLB flush fifo to queue the requests. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-12-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Add helper to read hypercall data for arraySean Christopherson1-20/+33
Move the guts of kvm_get_sparse_vp_set() to a helper so that the code for reading a guest-provided array can be reused in the future, e.g. for getting a list of virtual addresses whose TLB entries need to be flushed. Opportunisticaly swap the order of the data and XMM adjustment so that the XMM/gpa offsets are bundled together. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-11-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Introduce TLB flush fifoVitaly Kuznetsov1-0/+47
To allow flushing individual GVAs instead of always flushing the whole VPID a per-vCPU structure to pass the requests is needed. Use standard 'kfifo' to queue two types of entries: individual GVA (GFN + up to 4095 following GFNs in the lower 12 bits) and 'flush all'. The size of the fifo is arbitrarily set to '16'. Note, kvm_hv_flush_tlb() only queues 'flush all' entries for now and kvm_hv_vcpu_flush_tlb() doesn't actually read the fifo just resets the queue before returning -EOPNOTSUPP (which triggers full TLB flush) so the functional change is very small but the infrastructure is prepared to handle individual GVA flush requests. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-10-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-18KVM: x86: hyper-v: Resurrect dedicated KVM_REQ_HV_TLB_FLUSH flagVitaly Kuznetsov1-2/+2
In preparation to implementing fine-grained Hyper-V TLB flush and L2 TLB flush, resurrect dedicated KVM_REQ_HV_TLB_FLUSH request bit. As KVM_REQ_TLB_FLUSH_GUEST is a stronger operation, clear KVM_REQ_HV_TLB_FLUSH request in kvm_vcpu_flush_tlb_guest(). The flush itself is temporary handled by kvm_vcpu_flush_tlb_guest(). No functional change intended. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20221101145426.251680-9-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26KVM: nVMX: Support PERF_GLOBAL_CTRL with enlightened VMCSVitaly Kuznetsov1-1/+1
Enlightened VMCS v1 got updated and now includes the required fields for loading PERF_GLOBAL_CTRL upon VMENTER/VMEXIT features. For KVM on Hyper-V enablement, KVM can just observe VMX control MSRs and use the features (with or without eVMCS) when possible. Hyper-V on KVM is messier as Windows 11 guests fail to boot if the controls are advertised and a new PV feature flag, CPUID.0x4000000A.EBX BIT(0), is not set. Honor the Hyper-V CPUID feature flag to play nice with Windows guests. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20220830133737.1539624-16-vkuznets@redhat.com Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26KVM: x86: hyper-v: Cache HYPERV_CPUID_NESTED_FEATURES CPUID leafVitaly Kuznetsov1-0/+6
KVM has to check guest visible HYPERV_CPUID_NESTED_FEATURES.EBX CPUID leaf to know which Enlightened VMCS definition to use (original or 2022 update). Cache the leaf along with other Hyper-V CPUID feature leaves to make the check quick. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20220830133737.1539624-12-vkuznets@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26KVM: x86: Report error when setting CPUID if Hyper-V allocation failsSean Christopherson1-16/+14
Return -ENOMEM back to userspace if allocating the Hyper-V vCPU struct fails when enabling Hyper-V in guest CPUID. Silently ignoring failure means that KVM will not have an up-to-date CPUID cache if allocating the struct succeeds later on, e.g. when activating SynIC. Rejecting the CPUID operation also guarantess that vcpu->arch.hyperv is non-NULL if hyperv_enabled is true, which will allow for additional cleanup, e.g. in the eVMCS code. Note, the initialization needs to be done before CPUID is set, and more subtly before kvm_check_cpuid(), which potentially enables dynamic XFEATURES. Sadly, there's no easy way to avoid exposing Hyper-V details to CPUID or vice versa. Expose kvm_hv_vcpu_init() and the Hyper-V CPUID signature to CPUID instead of exposing cpuid_entry2_find() outside of CPUID code. It's hard to envision kvm_hv_vcpu_init() being misused, whereas cpuid_entry2_find() absolutely shouldn't be used outside of core CPUID code. Fixes: 10d7bf1e46dc ("KVM: x86: hyper-v: Cache guest CPUID leaves determining features availability") Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20220830133737.1539624-6-vkuznets@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26KVM: x86: Check for existing Hyper-V vCPU in kvm_hv_vcpu_init()Sean Christopherson1-15/+12
When potentially allocating/initializing the Hyper-V vCPU struct, check for an existing instance in kvm_hv_vcpu_init() instead of requiring callers to perform the check. Relying on callers to do the check is risky as it's all too easy for KVM to overwrite vcpu->arch.hyperv and leak memory, and it adds additional burden on callers without much benefit. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Wei Liu <wei.liu@kernel.org> Link: https://lore.kernel.org/r/20220830133737.1539624-5-vkuznets@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26KVM: x86: Zero out entire Hyper-V CPUID cache before processing entriesVitaly Kuznetsov1-9/+2
Wipe the whole 'hv_vcpu->cpuid_cache' with memset() instead of having to zero each particular member when the corresponding CPUID entry was not found. No functional change intended. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> [sean: split to separate patch] Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Wei Liu <wei.liu@kernel.org> Link: https://lore.kernel.org/r/20220830133737.1539624-4-vkuznets@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-07-14KVM: x86: Add dedicated helper to get CPUID entry with significant indexSean Christopherson1-4/+4
Add a second CPUID helper, kvm_find_cpuid_entry_index(), to handle KVM queries for CPUID leaves whose index _may_ be significant, and drop the index param from the existing kvm_find_cpuid_entry(). Add a WARN in the inner helper, cpuid_entry2_find(), to detect attempts to retrieve a CPUID entry whose index is significant without explicitly providing an index. Using an explicit magic number and letting callers omit the index avoids confusion by eliminating the myriad cases where KVM specifies '0' as a dummy value. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-06-05Merge tag 'bitmap-for-5.19-rc1' of https://github.com/norov/linuxLinus Torvalds1-6/+6
Pull bitmap updates from Yury Norov: - bitmap: optimize bitmap_weight() usage, from me - lib/bitmap.c make bitmap_print_bitmask_to_buf parseable, from Mauro Carvalho Chehab - include/linux/find: Fix documentation, from Anna-Maria Behnsen - bitmap: fix conversion from/to fix-sized arrays, from me - bitmap: Fix return values to be unsigned, from Kees Cook It has been in linux-next for at least a week with no problems. * tag 'bitmap-for-5.19-rc1' of https://github.com/norov/linux: (31 commits) nodemask: Fix return values to be unsigned bitmap: Fix return values to be unsigned KVM: x86: hyper-v: replace bitmap_weight() with hweight64() KVM: x86: hyper-v: fix type of valid_bank_mask ia64: cleanup remove_siblinginfo() drm/amd/pm: use bitmap_{from,to}_arr32 where appropriate KVM: s390: replace bitmap_copy with bitmap_{from,to}_arr64 where appropriate lib/bitmap: add test for bitmap_{from,to}_arr64 lib: add bitmap_{from,to}_arr64 lib/bitmap: extend comment for bitmap_(from,to)_arr32() include/linux/find: Fix documentation lib/bitmap.c make bitmap_print_bitmask_to_buf parseable MAINTAINERS: add cpumask and nodemask files to BITMAP_API arch/x86: replace nodes_weight with nodes_empty where appropriate mm/vmstat: replace cpumask_weight with cpumask_empty where appropriate clocksource: replace cpumask_weight with cpumask_empty in clocksource.c genirq/affinity: replace cpumask_weight with cpumask_empty where appropriate irq: mips: replace cpumask_weight with cpumask_empty where appropriate drm/i915/pmu: replace cpumask_weight with cpumask_empty where appropriate arch/x86: replace cpumask_weight with cpumask_empty where appropriate ...
2022-06-03KVM: x86: hyper-v: replace bitmap_weight() with hweight64()Yury Norov1-2/+2
kvm_hv_flush_tlb() applies bitmap API to a u64 variable valid_bank_mask. Since valid_bank_mask has a fixed size, we can use hweight64() and avoid excessive bloating. CC: Borislav Petkov <bp@alien8.de> CC: Dave Hansen <dave.hansen@linux.intel.com> CC: H. Peter Anvin <hpa@zytor.com> CC: Ingo Molnar <mingo@redhat.com> CC: Jim Mattson <jmattson@google.com> CC: Joerg Roedel <joro@8bytes.org> CC: Paolo Bonzini <pbonzini@redhat.com> CC: Sean Christopherson <seanjc@google.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Vitaly Kuznetsov <vkuznets@redhat.com> CC: Wanpeng Li <wanpengli@tencent.com> CC: kvm@vger.kernel.org CC: linux-kernel@vger.kernel.org CC: x86@kernel.org Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Yury Norov <yury.norov@gmail.com>
2022-06-03KVM: x86: hyper-v: fix type of valid_bank_maskYury Norov1-2/+2
In kvm_hv_flush_tlb(), valid_bank_mask is declared as unsigned long, but is used as u64, which is wrong for i386, and has been spotted by LKP after applying "KVM: x86: hyper-v: replace bitmap_weight() with hweight64()" https://lore.kernel.org/lkml/20220510154750.212913-12-yury.norov@gmail.com/ But it's wrong even without that patch because now bitmap_weight() dereferences a word after valid_bank_mask on i386. >> include/asm-generic/bitops/const_hweight.h:21:76: warning: right shift count >= width of type +[-Wshift-count-overflow] 21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) | ^~ include/asm-generic/bitops/const_hweight.h:10:16: note: in definition of macro '__const_hweight8' 10 | ((!!((w) & (1ULL << 0))) + \ | ^ include/asm-generic/bitops/const_hweight.h:20:31: note: in expansion of macro '__const_hweight16' 20 | #define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16)) | ^~~~~~~~~~~~~~~~~ include/asm-generic/bitops/const_hweight.h:21:54: note: in expansion of macro '__const_hweight32' 21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) | ^~~~~~~~~~~~~~~~~ include/asm-generic/bitops/const_hweight.h:29:49: note: in expansion of macro '__const_hweight64' 29 | #define hweight64(w) (__builtin_constant_p(w) ? __const_hweight64(w) : __arch_hweight64(w)) | ^~~~~~~~~~~~~~~~~ arch/x86/kvm/hyperv.c:1983:36: note: in expansion of macro 'hweight64' 1983 | if (hc->var_cnt != hweight64(valid_bank_mask)) | ^~~~~~~~~ CC: Borislav Petkov <bp@alien8.de> CC: Dave Hansen <dave.hansen@linux.intel.com> CC: H. Peter Anvin <hpa@zytor.com> CC: Ingo Molnar <mingo@redhat.com> CC: Jim Mattson <jmattson@google.com> CC: Joerg Roedel <joro@8bytes.org> CC: Paolo Bonzini <pbonzini@redhat.com> CC: Sean Christopherson <seanjc@google.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Vitaly Kuznetsov <vkuznets@redhat.com> CC: Wanpeng Li <wanpengli@tencent.com> CC: kvm@vger.kernel.org CC: linux-kernel@vger.kernel.org CC: x86@kernel.org Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Yury Norov <yury.norov@gmail.com> Message-Id: <20220519171504.1238724-1-yury.norov@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-20KVM: x86: hyper-v: fix type of valid_bank_maskYury Norov1-2/+2
In kvm_hv_flush_tlb(), valid_bank_mask is declared as unsigned long, but is used as u64, which is wrong for i386, and has been spotted by LKP after applying "KVM: x86: hyper-v: replace bitmap_weight() with hweight64()" https://lore.kernel.org/lkml/20220510154750.212913-12-yury.norov@gmail.com/ But it's wrong even without that patch because now bitmap_weight() dereferences a word after valid_bank_mask on i386. >> include/asm-generic/bitops/const_hweight.h:21:76: warning: right shift count >= width of type +[-Wshift-count-overflow] 21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) | ^~ include/asm-generic/bitops/const_hweight.h:10:16: note: in definition of macro '__const_hweight8' 10 | ((!!((w) & (1ULL << 0))) + \ | ^ include/asm-generic/bitops/const_hweight.h:20:31: note: in expansion of macro '__const_hweight16' 20 | #define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16)) | ^~~~~~~~~~~~~~~~~ include/asm-generic/bitops/const_hweight.h:21:54: note: in expansion of macro '__const_hweight32' 21 | #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) | ^~~~~~~~~~~~~~~~~ include/asm-generic/bitops/const_hweight.h:29:49: note: in expansion of macro '__const_hweight64' 29 | #define hweight64(w) (__builtin_constant_p(w) ? __const_hweight64(w) : __arch_hweight64(w)) | ^~~~~~~~~~~~~~~~~ arch/x86/kvm/hyperv.c:1983:36: note: in expansion of macro 'hweight64' 1983 | if (hc->var_cnt != hweight64(valid_bank_mask)) | ^~~~~~~~~ CC: Borislav Petkov <bp@alien8.de> CC: Dave Hansen <dave.hansen@linux.intel.com> CC: H. Peter Anvin <hpa@zytor.com> CC: Ingo Molnar <mingo@redhat.com> CC: Jim Mattson <jmattson@google.com> CC: Joerg Roedel <joro@8bytes.org> CC: Paolo Bonzini <pbonzini@redhat.com> CC: Sean Christopherson <seanjc@google.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Vitaly Kuznetsov <vkuznets@redhat.com> CC: Wanpeng Li <wanpengli@tencent.com> CC: kvm@vger.kernel.org CC: linux-kernel@vger.kernel.org CC: x86@kernel.org Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Yury Norov <yury.norov@gmail.com> Message-Id: <20220519171504.1238724-1-yury.norov@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-02KVM: x86: replace bitmap_weight with bitmap_empty where appropriateYury Norov1-4/+4
In some places kvm/hyperv.c code calls bitmap_weight() to check if any bit of a given bitmap is set. It's better to use bitmap_empty() in that case because bitmap_empty() stops traversing the bitmap as soon as it finds first set bit, while bitmap_weight() counts all bits unconditionally. Signed-off-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2022-04-11KVM: x86: hyper-v: Avoid writing to TSC page without an active vCPUVitaly Kuznetsov1-32/+8
The following WARN is triggered from kvm_vm_ioctl_set_clock(): WARNING: CPU: 10 PID: 579353 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:3161 mark_page_dirty_in_slot+0x6c/0x80 [kvm] ... CPU: 10 PID: 579353 Comm: qemu-system-x86 Tainted: G W O 5.16.0.stable #20 Hardware name: LENOVO 20UF001CUS/20UF001CUS, BIOS R1CET65W(1.34 ) 06/17/2021 RIP: 0010:mark_page_dirty_in_slot+0x6c/0x80 [kvm] ... Call Trace: <TASK> ? kvm_write_guest+0x114/0x120 [kvm] kvm_hv_invalidate_tsc_page+0x9e/0xf0 [kvm] kvm_arch_vm_ioctl+0xa26/0xc50 [kvm] ? schedule+0x4e/0xc0 ? __cond_resched+0x1a/0x50 ? futex_wait+0x166/0x250 ? __send_signal+0x1f1/0x3d0 kvm_vm_ioctl+0x747/0xda0 [kvm] ... The WARN was introduced by commit 03c0304a86bc ("KVM: Warn if mark_page_dirty() is called without an active vCPU") but the change seems to be correct (unlike Hyper-V TSC page update mechanism). In fact, there's no real need to actually write to guest memory to invalidate TSC page, this can be done by the first vCPU which goes through kvm_guest_time_update(). Reported-by: Maxim Levitsky <mlevitsk@redhat.com> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220407201013.963226-1-vkuznets@redhat.com>
2022-04-02KVM: x86: Add wrappers for setting/clearing APICv inhibitsSean Christopherson1-3/+7
Add set/clear wrappers for toggling APICv inhibits to make the call sites more readable, and opportunistically rename the inner helpers to align with the new wrappers and to make them more readable as well. Invert the flag from "activate" to "set"; activate is painfully ambiguous as it's not obvious if the inhibit is being activated, or if APICv is being activated, in which case the inhibit is being deactivated. For the functions that take @set, swap the order of the inhibit reason and @set so that the call sites are visually similar to those that bounce through the wrapper. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220311043517.17027-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-29KVM: x86: Forbid VMM to set SYNIC/STIMER MSRs when SynIC wasn't activatedVitaly Kuznetsov1-3/+6
Setting non-zero values to SYNIC/STIMER MSRs activates certain features, this should not happen when KVM_CAP_HYPERV_SYNIC{,2} was not activated. Note, it would've been better to forbid writing anything to SYNIC/STIMER MSRs, including zeroes, however, at least QEMU tries clearing HV_X64_MSR_STIMER0_CONFIG without SynIC. HV_X64_MSR_EOM MSR is somewhat 'special' as writing zero there triggers an action, this also should not happen when SynIC wasn't activated. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220325132140.25650-4-vkuznets@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-29KVM: x86: Check lapic_in_kernel() before attempting to set a SynIC irqVitaly Kuznetsov1-0/+3
When KVM_CAP_HYPERV_SYNIC{,2} is activated, KVM already checks for irqchip_in_kernel() so normally SynIC irqs should never be set. It is, however, possible for a misbehaving VMM to write to SYNIC/STIMER MSRs causing erroneous behavior. The immediate issue being fixed is that kvm_irq_delivery_to_apic() (kvm_irq_delivery_to_apic_fast()) crashes when called with 'irq.shorthand = APIC_DEST_SELF' and 'src == NULL'. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220325132140.25650-2-vkuznets@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-25Merge branch 'kvm-hv-xmm-hypercall-fixes' into HEADPaolo Bonzini1-36/+49
The fixes for 5.17 conflict with cleanups made in the same area earlier in the 5.18 development cycle.
2022-02-25KVM: x86: hyper-v: HVCALL_SEND_IPI_EX is an XMM fast hypercallVitaly Kuznetsov1-18/+34
It has been proven on practice that at least Windows Server 2019 tries using HVCALL_SEND_IPI_EX in 'XMM fast' mode when it has more than 64 vCPUs and it needs to send an IPI to a vCPU > 63. Similarly to other XMM Fast hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}{,_EX}), this information is missing in TLFS as of 6.0b. Currently, KVM returns an error (HV_STATUS_INVALID_HYPERCALL_INPUT) and Windows crashes. Note, HVCALL_SEND_IPI is a 'standard' fast hypercall (not 'XMM fast') as all its parameters fit into RDX:R8 and this is handled by KVM correctly. Cc: stable@vger.kernel.org # 5.14.x: 3244867af8c0: KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req Cc: stable@vger.kernel.org # 5.14.x Fixes: d8f5537a8816 ("KVM: hyper-v: Advertise support for fast XMM hypercalls") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220222154642.684285-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-25KVM: x86: hyper-v: Fix the maximum number of sparse banks for XMM fast TLB ↵Vitaly Kuznetsov1-1/+2
flush hypercalls When TLB flush hypercalls (HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE}_EX are issued in 'XMM fast' mode, the maximum number of allowed sparse_banks is not 'HV_HYPERCALL_MAX_XMM_REGISTERS - 1' (5) but twice as many (10) as each XMM register is 128 bit long and can hold two 64 bit long banks. Cc: stable@vger.kernel.org # 5.14.x Fixes: 5974565bc26d ("KVM: x86: kvm_hv_flush_tlb use inputs from XMM registers") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220222154642.684285-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-25KVM: x86: hyper-v: Drop redundant 'ex' parameter from kvm_hv_flush_tlb()Vitaly Kuznetsov1-17/+6
'struct kvm_hv_hcall' has all the required information already, there's no need to pass 'ex' additionally. No functional change intended. Cc: stable@vger.kernel.org # 5.14.x Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220222154642.684285-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-25KVM: x86: hyper-v: Drop redundant 'ex' parameter from kvm_hv_send_ipi()Vitaly Kuznetsov1-4/+4
'struct kvm_hv_hcall' has all the required information already, there's no need to pass 'ex' additionally. No functional change intended. Cc: stable@vger.kernel.org # 5.14.x Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220222154642.684285-2-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: nSVM: Implement Enlightened MSR-Bitmap featureVitaly Kuznetsov1-6/+1
Similar to nVMX commit 502d2bf5f2fd ("KVM: nVMX: Implement Enlightened MSR Bitmap feature"), add support for the feature for nSVM (Hyper-V on KVM). Notable differences from nVMX implementation: - As the feature uses SW reserved fields in VMCB control, KVM needs to make sure it's dealing with a Hyper-V guest (kvm_hv_hypercall_enabled()). - 'msrpm_base_pa' needs to be always be overwritten in nested_svm_vmrun_msrpm(), even when the update is skipped. As an optimization, nested_vmcb02_prepare_control() copies it from VMCB01 so when MSR-Bitmap feature for L2 is disabled nothing needs to be done. - 'struct vmcb_ctrl_area_cached' needs to be extended with clean fields/sw reserved data and __nested_copy_vmcb_control_to_cache() needs to copy it so nested_svm_vmrun_msrpm() can use it later. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220202095100.129834-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Make kvm_hv_hypercall_enabled() static inlineVitaly Kuznetsov1-5/+0
In preparation for using kvm_hv_hypercall_enabled() from SVM code, make it static inline to avoid the need to export it. The function is a simple check with only two call sites currently. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20220202095100.129834-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Add checks for reserved-to-zero Hyper-V hypercall fieldsSean Christopherson1-0/+5
Add checks for the three fields in Hyper-V's hypercall params that must be zero. Per the TLFS, HV_STATUS_INVALID_HYPERCALL_INPUT is returned if "A reserved bit in the specified hypercall input value is non-zero." Note, some versions of the TLFS have an off-by-one bug for the last reserved field, and define it as being bits 64:60. See https://github.com/MicrosoftDocs/Virtualization-Documentation/pull/1682. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-9-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Reject fixeds-size Hyper-V hypercalls with non-zero "var_cnt"Sean Christopherson1-6/+6
Reject Hyper-V hypercalls if the guest specifies a non-zero variable size header (var_cnt in KVM) for a hypercall that has a fixed header size. Per the TLFS: It is illegal to specify a non-zero variable header size for a hypercall that is not explicitly documented as accepting variable sized input headers. In such a case the hypercall will result in a return code of HV_STATUS_INVALID_HYPERCALL_INPUT. Note, at least some of the various DEBUG commands likely aren't allowed to use variable size headers, but the TLFS documentation doesn't clearly state what is/isn't allowed. Omit them for now to avoid unnecessary breakage. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Shove vp_bitmap handling down into sparse_set_to_vcpu_mask()Sean Christopherson1-27/+38
Move the vp_bitmap "allocation" that's needed to handle mismatched vp_index values down into sparse_set_to_vcpu_mask() and drop __always_inline from said helper. The need for an intermediate vp_bitmap is a detail that's specific to the sparse translation with mismatched VP<=>vCPU indexes and does not need to be exposed to the caller. Regarding the __always_inline, prior to commit f21dd494506a ("KVM: x86: hyperv: optimize sparse VP set processing") the helper, then named hv_vcpu_in_sparse_set(), was a tiny bit of code that effectively boiled down to a handful of bit ops. The __always_inline was understandable, if not justifiable. Since the aforementioned change, sparse_set_to_vcpu_mask() is a chunky 350-450+ bytes of code without KASAN=y, and balloons to 1100+ with KASAN=y. In other words, it has no business being forcefully inlined. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-7-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Don't bother reading sparse banks that end up being ignoredSean Christopherson1-3/+16
When handling "sparse" VP_SET requests, don't read sparse banks that can't possibly contain a legal VP index instead of ignoring such banks later on in sparse_set_to_vcpu_mask(). This allows KVM to cap the size of its sparse_banks arrays for VP_SET at KVM_HV_MAX_SPARSE_VCPU_SET_BITS. Add a compile time assert that KVM_HV_MAX_SPARSE_VCPU_SET_BITS<=64, i.e. that KVM_MAX_VCPUS<=4096, as the TLFS allows for at most 64 sparse banks, and KVM will need to do _something_ to play nice with Hyper-V. Reducing the size of sparse_banks fudges around a compilation warning (that becomes error with KVM_WERROR=y) when CONFIG_KASAN_STACK=y, which is selected (and can't be unselected) by CONFIG_KASAN=y when using gcc (clang/LLVM is a stack hog in some cases so it's opt-in for clang). KASAN_STACK adds a redzone around every stack variable, which pushes the Hyper-V functions over the default limit of 1024. Ideally, KVM would flat out reject such impossibilities, but the TLFS explicitly allows providing empty banks, even if a bank can't possibly contain a valid VP index due to its position exceeding KVM's max. Furthermore, for a bit 1 in ValidBankMask, it is valid state for the corresponding element in BanksContents can be all 0s, meaning no processors are specified in this bank. Arguably KVM should reject and not ignore the "extra" banks, but that can be done independently and without bloating sparse_banks, e.g. by reading each "extra" 8-byte chunk individually. Reported-by: Ajay Garg <ajaygargnsit@gmail.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-6-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Add a helper to get the sparse VP_SET for IPIs and TLB flushesSean Christopherson1-16/+16
Add a helper, kvm_get_sparse_vp_set(), to handle sanity checks related to the VARHEAD field and reading the sparse banks of a VP_SET. A future commit to reduce the memory footprint of sparse_banks will introduce more common code to the sparse bank retrieval. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-5-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Refactor kvm_hv_flush_tlb() to reduce indentationSean Christopherson1-19/+21
Refactor the "extended" path of kvm_hv_flush_tlb() to reduce the nesting depth for the non-fast sparse path, and to make the code more similar to the extended path in kvm_hv_send_ipi(). No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-02-10KVM: x86: Get the number of Hyper-V sparse banks from the VARHEAD fieldSean Christopherson1-14/+21
Get the number of sparse banks from the VARHEAD field, which the guest is required to provide as "The size of a variable header, in QWORDS.", where the variable header is: Variable Header Bytes = {Total Header Bytes - sizeof(Fixed Header)} rounded up to nearest multiple of 8 Variable HeaderSize = Variable Header Bytes / 8 In other words, the VARHEAD should match the number of sparse banks. Keep the manual count as a sanity check, but otherwise rely on the field so as to more closely align with the logic defined in the TLFS and to allow for future cleanups. Tweak the tracepoint output to use "rep_cnt" instead of simply "cnt" now that there is also "var_cnt". Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20211207220926.718794-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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