linux-stable.git/arch/x86/kernel/cpu/mshyperv.c, branch linux-6.3.y Linux kernel stable tree x86/hyperv: Block root partition functionality in a Confidential VM 2023-03-17T10:57:35+00:00 Michael Kelley mikelley@microsoft.com 2023-03-15T15:34:13+00:00 f8acb24aaf89fc46cd953229462ea8abe31b395f Hyper-V should never specify a VM that is a Confidential VM and also running in the root partition. Nonetheless, explicitly block such a combination to guard against a compromised Hyper-V maliciously trying to exploit root partition functionality in a Confidential VM to expose Confidential VM secrets. No known bug is being fixed, but the attack surface for Confidential VMs on Hyper-V is reduced. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1678894453-95392-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
Hyper-V should never specify a VM that is a Confidential VM and also
running in the root partition.  Nonetheless, explicitly block such a
combination to guard against a compromised Hyper-V maliciously trying to
exploit root partition functionality in a Confidential VM to expose
Confidential VM secrets. No known bug is being fixed, but the attack
surface for Confidential VMs on Hyper-V is reduced.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1678894453-95392-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2023-02-25T19:30:21+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-02-25T19:30:21+00:00 49d575926890e6ada930bf6f06d62b2fde8fce95 Pull kvm updates from Paolo Bonzini: "ARM: - Provide a virtual cache topology to the guest to avoid inconsistencies with migration on heterogenous systems. Non secure software has no practical need to traverse the caches by set/way in the first place - Add support for taking stage-2 access faults in parallel. This was an accidental omission in the original parallel faults implementation, but should provide a marginal improvement to machines w/o FEAT_HAFDBS (such as hardware from the fruit company) - A preamble to adding support for nested virtualization to KVM, including vEL2 register state, rudimentary nested exception handling and masking unsupported features for nested guests - Fixes to the PSCI relay that avoid an unexpected host SVE trap when resuming a CPU when running pKVM - VGIC maintenance interrupt support for the AIC - Improvements to the arch timer emulation, primarily aimed at reducing the trap overhead of running nested - Add CONFIG_USERFAULTFD to the KVM selftests config fragment in the interest of CI systems - Avoid VM-wide stop-the-world operations when a vCPU accesses its own redistributor - Serialize when toggling CPACR_EL1.SMEN to avoid unexpected exceptions in the host - Aesthetic and comment/kerneldoc fixes - Drop the vestiges of the old Columbia mailing list and add [Oliver] as co-maintainer RISC-V: - Fix wrong usage of PGDIR_SIZE instead of PUD_SIZE - Correctly place the guest in S-mode after redirecting a trap to the guest - Redirect illegal instruction traps to guest - SBI PMU support for guest s390: - Sort out confusion between virtual and physical addresses, which currently are the same on s390 - A new ioctl that performs cmpxchg on guest memory - A few fixes x86: - Change tdp_mmu to a read-only parameter - Separate TDP and shadow MMU page fault paths - Enable Hyper-V invariant TSC control - Fix a variety of APICv and AVIC bugs, some of them real-world, some of them affecting architecurally legal but unlikely to happen in practice - Mark APIC timer as expired if its in one-shot mode and the count underflows while the vCPU task was being migrated - Advertise support for Intel's new fast REP string features - Fix a double-shootdown issue in the emergency reboot code - Ensure GIF=1 and disable SVM during an emergency reboot, i.e. give SVM similar treatment to VMX - Update Xen's TSC info CPUID sub-leaves as appropriate - Add support for Hyper-V's extended hypercalls, where "support" at this point is just forwarding the hypercalls to userspace - Clean up the kvm->lock vs. kvm->srcu sequences when updating the PMU and MSR filters - One-off fixes and cleanups - Fix and cleanup the range-based TLB flushing code, used when KVM is running on Hyper-V - Add support for filtering PMU events using a mask. If userspace wants to restrict heavily what events the guest can use, it can now do so without needing an absurd number of filter entries - Clean up KVM's handling of "PMU MSRs to save", especially when vPMU support is disabled - Add PEBS support for Intel Sapphire Rapids - Fix a mostly benign overflow bug in SEV's send|receive_update_data() - Move several SVM-specific flags into vcpu_svm x86 Intel: - Handle NMI VM-Exits before leaving the noinstr region - A few trivial cleanups in the VM-Enter flows - Stop enabling VMFUNC for L1 purely to document that KVM doesn't support EPTP switching (or any other VM function) for L1 - Fix a crash when using eVMCS's enlighted MSR bitmaps Generic: - Clean up the hardware enable and initialization flow, which was scattered around multiple arch-specific hooks. Instead, just let the arch code call into generic code. Both x86 and ARM should benefit from not having to fight common KVM code's notion of how to do initialization - Account allocations in generic kvm_arch_alloc_vm() - Fix a memory leak if coalesced MMIO unregistration fails selftests: - On x86, cache the CPU vendor (AMD vs. Intel) and use the info to emit the correct hypercall instruction instead of relying on KVM to patch in VMMCALL - Use TAP interface for kvm_binary_stats_test and tsc_msrs_test" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (325 commits) KVM: SVM: hyper-v: placate modpost section mismatch error KVM: x86/mmu: Make tdp_mmu_allowed static KVM: arm64: nv: Use reg_to_encoding() to get sysreg ID KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes KVM: arm64: nv: Filter out unsupported features from ID regs KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2 KVM: arm64: nv: Allow a sysreg to be hidden from userspace only KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor KVM: arm64: nv: Add accessors for SPSR_EL1, ELR_EL1 and VBAR_EL1 from virtual EL2 KVM: arm64: nv: Handle SMCs taken from virtual EL2 KVM: arm64: nv: Handle trapped ERET from virtual EL2 KVM: arm64: nv: Inject HVC exceptions to the virtual EL2 KVM: arm64: nv: Support virtual EL2 exceptions KVM: arm64: nv: Handle HCR_EL2.NV system register traps KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state KVM: arm64: nv: Add EL2 system registers to vcpu context KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set KVM: arm64: nv: Introduce nested virtualization VCPU feature KVM: arm64: Use the S2 MMU context to iterate over S2 table ... 
Pull kvm updates from Paolo Bonzini:
 "ARM:

   - Provide a virtual cache topology to the guest to avoid
     inconsistencies with migration on heterogenous systems. Non secure
     software has no practical need to traverse the caches by set/way in
     the first place

   - Add support for taking stage-2 access faults in parallel. This was
     an accidental omission in the original parallel faults
     implementation, but should provide a marginal improvement to
     machines w/o FEAT_HAFDBS (such as hardware from the fruit company)

   - A preamble to adding support for nested virtualization to KVM,
     including vEL2 register state, rudimentary nested exception
     handling and masking unsupported features for nested guests

   - Fixes to the PSCI relay that avoid an unexpected host SVE trap when
     resuming a CPU when running pKVM

   - VGIC maintenance interrupt support for the AIC

   - Improvements to the arch timer emulation, primarily aimed at
     reducing the trap overhead of running nested

   - Add CONFIG_USERFAULTFD to the KVM selftests config fragment in the
     interest of CI systems

   - Avoid VM-wide stop-the-world operations when a vCPU accesses its
     own redistributor

   - Serialize when toggling CPACR_EL1.SMEN to avoid unexpected
     exceptions in the host

   - Aesthetic and comment/kerneldoc fixes

   - Drop the vestiges of the old Columbia mailing list and add [Oliver]
     as co-maintainer

  RISC-V:

   - Fix wrong usage of PGDIR_SIZE instead of PUD_SIZE

   - Correctly place the guest in S-mode after redirecting a trap to the
     guest

   - Redirect illegal instruction traps to guest

   - SBI PMU support for guest

  s390:

   - Sort out confusion between virtual and physical addresses, which
     currently are the same on s390

   - A new ioctl that performs cmpxchg on guest memory

   - A few fixes

  x86:

   - Change tdp_mmu to a read-only parameter

   - Separate TDP and shadow MMU page fault paths

   - Enable Hyper-V invariant TSC control

   - Fix a variety of APICv and AVIC bugs, some of them real-world, some
     of them affecting architecurally legal but unlikely to happen in
     practice

   - Mark APIC timer as expired if its in one-shot mode and the count
     underflows while the vCPU task was being migrated

   - Advertise support for Intel's new fast REP string features

   - Fix a double-shootdown issue in the emergency reboot code

   - Ensure GIF=1 and disable SVM during an emergency reboot, i.e. give
     SVM similar treatment to VMX

   - Update Xen's TSC info CPUID sub-leaves as appropriate

   - Add support for Hyper-V's extended hypercalls, where "support" at
     this point is just forwarding the hypercalls to userspace

   - Clean up the kvm->lock vs. kvm->srcu sequences when updating the
     PMU and MSR filters

   - One-off fixes and cleanups

   - Fix and cleanup the range-based TLB flushing code, used when KVM is
     running on Hyper-V

   - Add support for filtering PMU events using a mask. If userspace
     wants to restrict heavily what events the guest can use, it can now
     do so without needing an absurd number of filter entries

   - Clean up KVM's handling of "PMU MSRs to save", especially when vPMU
     support is disabled

   - Add PEBS support for Intel Sapphire Rapids

   - Fix a mostly benign overflow bug in SEV's
     send|receive_update_data()

   - Move several SVM-specific flags into vcpu_svm

  x86 Intel:

   - Handle NMI VM-Exits before leaving the noinstr region

   - A few trivial cleanups in the VM-Enter flows

   - Stop enabling VMFUNC for L1 purely to document that KVM doesn't
     support EPTP switching (or any other VM function) for L1

   - Fix a crash when using eVMCS's enlighted MSR bitmaps

  Generic:

   - Clean up the hardware enable and initialization flow, which was
     scattered around multiple arch-specific hooks. Instead, just let
     the arch code call into generic code. Both x86 and ARM should
     benefit from not having to fight common KVM code's notion of how to
     do initialization

   - Account allocations in generic kvm_arch_alloc_vm()

   - Fix a memory leak if coalesced MMIO unregistration fails

  selftests:

   - On x86, cache the CPU vendor (AMD vs. Intel) and use the info to
     emit the correct hypercall instruction instead of relying on KVM to
     patch in VMMCALL

   - Use TAP interface for kvm_binary_stats_test and tsc_msrs_test"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (325 commits)
  KVM: SVM: hyper-v: placate modpost section mismatch error
  KVM: x86/mmu: Make tdp_mmu_allowed static
  KVM: arm64: nv: Use reg_to_encoding() to get sysreg ID
  KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes
  KVM: arm64: nv: Filter out unsupported features from ID regs
  KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2
  KVM: arm64: nv: Allow a sysreg to be hidden from userspace only
  KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor
  KVM: arm64: nv: Add accessors for SPSR_EL1, ELR_EL1 and VBAR_EL1 from virtual EL2
  KVM: arm64: nv: Handle SMCs taken from virtual EL2
  KVM: arm64: nv: Handle trapped ERET from virtual EL2
  KVM: arm64: nv: Inject HVC exceptions to the virtual EL2
  KVM: arm64: nv: Support virtual EL2 exceptions
  KVM: arm64: nv: Handle HCR_EL2.NV system register traps
  KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state
  KVM: arm64: nv: Add EL2 system registers to vcpu context
  KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x
  KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set
  KVM: arm64: nv: Introduce nested virtualization VCPU feature
  KVM: arm64: Use the S2 MMU context to iterate over S2 table
  ...
x86/hyperv: Fix hv_get/set_register for nested bringup 2023-02-16T14:32:37+00:00 Nuno Das Neves nunodasneves@linux.microsoft.com 2023-02-09T22:02:52+00:00 b14033a3e6ba73a5c68974a80b05cba55553ed5b hv_get_nested_reg only translates SINT0, resulting in the wrong sint being registered by nested vmbus. Fix the issue with new utility function hv_is_sint_reg. While at it, improve clarity of hv_set_non_nested_register and hv_is_synic_reg. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Jinank Jain <jinankjain@linux.microsoft.com> Link: https://lore.kernel.org/r/1675980172-6851-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
hv_get_nested_reg only translates SINT0, resulting in the wrong sint
being registered by nested vmbus.

Fix the issue with new utility function hv_is_sint_reg.

While at it, improve clarity of hv_set_non_nested_register and hv_is_synic_reg.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Jinank Jain <jinankjain@linux.microsoft.com>
Link: https://lore.kernel.org/r/1675980172-6851-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Drivers: hv: Setup synic registers in case of nested root partition 2023-01-17T13:36:43+00:00 Jinank Jain jinankjain@linux.microsoft.com 2023-01-02T07:12:52+00:00 7fec185a56f45b98d9547982370c2ab33f0f72b5 Child partitions are free to allocate SynIC message and event page but in case of root partition it must use the pages allocated by Microsoft Hypervisor (MSHV). Base address for these pages can be found using synthetic MSRs exposed by MSHV. There is a slight difference in those MSRs for nested vs non-nested root partition. Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com> Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/cb951fb1ad6814996fc54f4a255c5841a20a151f.1672639707.git.jinankjain@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
Child partitions are free to allocate SynIC message and event page but in
case of root partition it must use the pages allocated by Microsoft
Hypervisor (MSHV). Base address for these pages can be found using
synthetic MSRs exposed by MSHV. There is a slight difference in those MSRs
for nested vs non-nested root partition.

Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/cb951fb1ad6814996fc54f4a255c5841a20a151f.1672639707.git.jinankjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
x86/hyperv: Add support for detecting nested hypervisor 2023-01-12T15:23:26+00:00 Jinank Jain jinankjain@linux.microsoft.com 2023-01-02T07:12:51+00:00 c4bdf94f97c86bdee8bacc87f8f85dc67866c928 Detect if Linux is running as a nested hypervisor in the root partition for Microsoft Hypervisor, using flags provided by MSHV. Expose a new variable hv_nested that is used later for decisions specific to the nested use case. Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/8e3e7112806e81d2292a66a56fe547162754ecea.1672639707.git.jinankjain@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
Detect if Linux is running as a nested hypervisor in the root
partition for Microsoft Hypervisor, using flags provided by MSHV.
Expose a new variable hv_nested that is used later for decisions
specific to the nested use case.

Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/8e3e7112806e81d2292a66a56fe547162754ecea.1672639707.git.jinankjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Merge branch 'kvm-late-6.1' into HEAD 2022-12-29T20:36:47+00:00 Paolo Bonzini pbonzini@redhat.com 2022-12-29T20:35:48+00:00 fc471e831016c1741f3e8042997969ace0b5a013 x86: * Change tdp_mmu to a read-only parameter * Separate TDP and shadow MMU page fault paths * Enable Hyper-V invariant TSC control selftests: * Use TAP interface for kvm_binary_stats_test and tsc_msrs_test Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> 
x86:

* Change tdp_mmu to a read-only parameter

* Separate TDP and shadow MMU page fault paths

* Enable Hyper-V invariant TSC control

selftests:

* Use TAP interface for kvm_binary_stats_test and tsc_msrs_test

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x86/hyperv: Add HV_EXPOSE_INVARIANT_TSC define 2022-12-29T20:33:27+00:00 Vitaly Kuznetsov vkuznets@redhat.com 2022-10-13T09:58:43+00:00 b961aa757f940bebc608a412f66951e52a39a298 Avoid open coding BIT(0) of HV_X64_MSR_TSC_INVARIANT_CONTROL by adding a dedicated define. While there's only one user at this moment, the upcoming KVM implementation of Hyper-V Invariant TSC feature will need to use it as well. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221013095849.705943-2-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> 
Avoid open coding BIT(0) of HV_X64_MSR_TSC_INVARIANT_CONTROL by adding
a dedicated define. While there's only one user at this moment, the
upcoming KVM implementation of Hyper-V Invariant TSC feature will need
to use it as well.

Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013095849.705943-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
iommu/hyper-v: Allow hyperv irq remapping without x2apic 2022-11-28T16:48:20+00:00 Nuno Das Neves nunodasneves@linux.microsoft.com 2022-11-17T20:11:39+00:00 fea858dc5d901626e5d794037b5bff9f59b9ded7 If x2apic is not available, hyperv-iommu skips remapping irqs. This breaks root partition which always needs irqs remapped. Fix this by allowing irq remapping regardless of x2apic, and change hyperv_enable_irq_remapping() to return IRQ_REMAP_XAPIC_MODE in case x2apic is missing. Tested with root and non-root hyperv partitions. Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com> Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1668715899-8971-1-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
If x2apic is not available, hyperv-iommu skips remapping
irqs. This breaks root partition which always needs irqs
remapped.

Fix this by allowing irq remapping regardless of x2apic,
and change hyperv_enable_irq_remapping() to return
IRQ_REMAP_XAPIC_MODE in case x2apic is missing.

Tested with root and non-root hyperv partitions.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1668715899-8971-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Merge tag 'hyperv-next-signed-20220528' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux 2022-05-28T18:39:01+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-05-28T18:39:01+00:00 f56dbdda4322d33d485f3d30f3aabba71de9098c Pull hyperv updates from Wei Liu: - Harden hv_sock driver (Andrea Parri) - Harden Hyper-V PCI driver (Andrea Parri) - Fix multi-MSI for Hyper-V PCI driver (Jeffrey Hugo) - Fix Hyper-V PCI to reduce boot time (Dexuan Cui) - Remove code for long EOL'ed Hyper-V versions (Michael Kelley, Saurabh Sengar) - Fix balloon driver error handling (Shradha Gupta) - Fix a typo in vmbus driver (Julia Lawall) - Ignore vmbus IMC device (Michael Kelley) - Add a new error message to Hyper-V DRM driver (Saurabh Sengar) * tag 'hyperv-next-signed-20220528' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (28 commits) hv_balloon: Fix balloon_probe() and balloon_remove() error handling scsi: storvsc: Removing Pre Win8 related logic Drivers: hv: vmbus: fix typo in comment PCI: hv: Fix synchronization between channel callback and hv_pci_bus_exit() PCI: hv: Add validation for untrusted Hyper-V values PCI: hv: Fix interrupt mapping for multi-MSI PCI: hv: Reuse existing IRTE allocation in compose_msi_msg() drm/hyperv: Remove support for Hyper-V 2008 and 2008R2/Win7 video: hyperv_fb: Remove support for Hyper-V 2008 and 2008R2/Win7 scsi: storvsc: Remove support for Hyper-V 2008 and 2008R2/Win7 Drivers: hv: vmbus: Remove support for Hyper-V 2008 and Hyper-V 2008R2/Win7 x86/hyperv: Disable hardlockup detector by default in Hyper-V guests drm/hyperv: Add error message for fb size greater than allocated PCI: hv: Do not set PCI_COMMAND_MEMORY to reduce VM boot time PCI: hv: Fix hv_arch_irq_unmask() for multi-MSI Drivers: hv: vmbus: Refactor the ring-buffer iterator functions Drivers: hv: vmbus: Accept hv_sock offers in isolated guests hv_sock: Add validation for untrusted Hyper-V values hv_sock: Copy packets sent by Hyper-V out of the ring buffer hv_sock: Check hv_pkt_iter_first_raw()'s return value ... 
Pull hyperv updates from Wei Liu:

 - Harden hv_sock driver (Andrea Parri)

 - Harden Hyper-V PCI driver (Andrea Parri)

 - Fix multi-MSI for Hyper-V PCI driver (Jeffrey Hugo)

 - Fix Hyper-V PCI to reduce boot time (Dexuan Cui)

 - Remove code for long EOL'ed Hyper-V versions (Michael Kelley, Saurabh
   Sengar)

 - Fix balloon driver error handling (Shradha Gupta)

 - Fix a typo in vmbus driver (Julia Lawall)

 - Ignore vmbus IMC device (Michael Kelley)

 - Add a new error message to Hyper-V DRM driver (Saurabh Sengar)

* tag 'hyperv-next-signed-20220528' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (28 commits)
  hv_balloon: Fix balloon_probe() and balloon_remove() error handling
  scsi: storvsc: Removing Pre Win8 related logic
  Drivers: hv: vmbus: fix typo in comment
  PCI: hv: Fix synchronization between channel callback and hv_pci_bus_exit()
  PCI: hv: Add validation for untrusted Hyper-V values
  PCI: hv: Fix interrupt mapping for multi-MSI
  PCI: hv: Reuse existing IRTE allocation in compose_msi_msg()
  drm/hyperv: Remove support for Hyper-V 2008 and 2008R2/Win7
  video: hyperv_fb: Remove support for Hyper-V 2008 and 2008R2/Win7
  scsi: storvsc: Remove support for Hyper-V 2008 and 2008R2/Win7
  Drivers: hv: vmbus: Remove support for Hyper-V 2008 and Hyper-V 2008R2/Win7
  x86/hyperv: Disable hardlockup detector by default in Hyper-V guests
  drm/hyperv: Add error message for fb size greater than allocated
  PCI: hv: Do not set PCI_COMMAND_MEMORY to reduce VM boot time
  PCI: hv: Fix hv_arch_irq_unmask() for multi-MSI
  Drivers: hv: vmbus: Refactor the ring-buffer iterator functions
  Drivers: hv: vmbus: Accept hv_sock offers in isolated guests
  hv_sock: Add validation for untrusted Hyper-V values
  hv_sock: Copy packets sent by Hyper-V out of the ring buffer
  hv_sock: Check hv_pkt_iter_first_raw()'s return value
  ...
x86/hyperv: Disable hardlockup detector by default in Hyper-V guests 2022-05-11T14:36:46+00:00 Michael Kelley mikelley@microsoft.com 2022-05-09T15:44:23+00:00 f1f8288d19d03af9d03db219c23d07a6e8ecd51b In newer versions of Hyper-V, the x86/x64 PMU can be virtualized into guest VMs by explicitly enabling it. Linux kernels are typically built to automatically enable the hardlockup detector if the PMU is found. To prevent the possibility of false positives due to the vagaries of VM scheduling, disable the PMU-based hardlockup detector by default in a VM on Hyper-V. The hardlockup detector can still be enabled by overriding the default with the nmi_watchdog=1 option on the kernel boot line or via sysctl at runtime. This change mimics the approach taken with KVM guests in commit 692297d8f968 ("watchdog: introduce the hardlockup_detector_disable() function"). Linux on ARM64 does not provide a PMU-based hardlockup detector, so there's no corresponding disable in the Hyper-V init code on ARM64. Signed-off-by: Michael Kelley <mikelley@microsoft.com> Link: https://lore.kernel.org/r/1652111063-6535-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org> 
In newer versions of Hyper-V, the x86/x64 PMU can be virtualized
into guest VMs by explicitly enabling it. Linux kernels are typically
built to automatically enable the hardlockup detector if the PMU is
found. To prevent the possibility of false positives due to the
vagaries of VM scheduling, disable the PMU-based hardlockup detector
by default in a VM on Hyper-V.  The hardlockup detector can still be
enabled by overriding the default with the nmi_watchdog=1 option on
the kernel boot line or via sysctl at runtime.

This change mimics the approach taken with KVM guests in
commit 692297d8f968 ("watchdog: introduce the hardlockup_detector_disable()
function").

Linux on ARM64 does not provide a PMU-based hardlockup detector, so
there's no corresponding disable in the Hyper-V init code on ARM64.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1652111063-6535-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>