Hyper-V cleanup code comes under panic path where preemption and irq
is already disabled. So calling of unregister_syscore_ops might schedule
out the thread even for the case where mutex lock is free.
hyperv_cleanup
	unregister_syscore_ops
			mutex_lock(&syscore_ops_lock)
				might_sleep
Here might_sleep might schedule out this thread, where voluntary preemption
config is on and this thread will never comes back. And also this was added
earlier to maintain the symmetry which is not required as this can comes
during crash shutdown path only.

To prevent the same, removing unregister_syscore_ops function call.

Signed-off-by: Gaurav Kohli <gauravkohli@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

Microsoft Hypervisor root partition has to map the TSC page specified
by the hypervisor, instead of providing the page to the hypervisor like
it's done in the guest partitions.

However, it's too early to map the page when the clock is initialized, so, the
actual mapping is happening later.

Signed-off-by: Stanislav Kinsburskiy <stanislav.kinsburskiy@gmail.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: Wei Liu <wei.liu@kernel.org>
CC: Dexuan Cui <decui@microsoft.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: Borislav Petkov <bp@alien8.de>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: x86@kernel.org
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: linux-hyperv@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Link: https://lore.kernel.org/r/166759443644.385891.15921594265843430260.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net
Signed-off-by: Wei Liu <wei.liu@kernel.org>

Commit e5d9b714fe40 ("x86/hyperv: fix root partition faults when writing
to VP assist page MSR") moved 'wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE)' under
'if (*hvp)' condition. This works for root partition as hv_cpu_die()
does memunmap() and sets 'hv_vp_assist_page[cpu]' to NULL but breaks
non-root partitions as hv_cpu_die() doesn't free 'hv_vp_assist_page[cpu]'
for them. This causes VP assist page to remain unset after CPU
offline/online cycle:

$ rdmsr -p 24 0x40000073
  10212f001
$ echo 0 > /sys/devices/system/cpu/cpu24/online
$ echo 1 > /sys/devices/system/cpu/cpu24/online
$ rdmsr -p 24 0x40000073
  0

Fix the issue by always writing to HV_X64_MSR_VP_ASSIST_PAGE in
hv_cpu_init(). Note, checking 'if (!*hvp)', for root partition is
pointless as hv_cpu_die() always sets 'hv_vp_assist_page[cpu]' to
NULL (and it's also NULL initially).

Note: the fact that 'hv_vp_assist_page[cpu]' is reset to NULL may
present a (potential) issue for KVM. While Hyper-V uses
CPUHP_AP_ONLINE_DYN stage in CPU hotplug, KVM uses CPUHP_AP_KVM_STARTING
which comes earlier in CPU teardown sequence. It is theoretically
possible that Enlightened VMCS is still in use. It is unclear if the
issue is real and if using KVM with Hyper-V root partition is even
possible.

While on it, drop the unneeded smp_processor_id() call from hv_cpu_init().

Fixes: e5d9b714fe40 ("x86/hyperv: fix root partition faults when writing to VP assist page MSR")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20221103190601.399343-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

hyperv_cleanup resets the hypercall page by setting the MSR to 0. However,
the root partition is not allowed to write to the GPA bits of the MSR.
Instead, it uses the hypercall page provided by the MSR. Similar is the
case with the reference TSC MSR.

Clear only the enable bit instead of zeroing the entire MSR to make
the code valid for root partition too.

Signed-off-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20221027095729.1676394-3-anrayabh@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

The commit 154fb14df7a3c ("x86/hyperv: Replace kmap() with
kmap_local_page()") keeps the BUG_ON() to check if kmap_local_page()
fails.

But in fact, kmap_local_page() always returns a valid kernel address
and won't return NULL here. It will BUG on its own if it fails. [1]

So directly use memcpy_to_page() which creates local mapping to copy.

[1]: https://lore.kernel.org/lkml/YztFEyUA48et0yTt@iweiny-mobl/

Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20221020083820.2341088-1-zhao1.liu@linux.intel.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

kmap() is being deprecated in favor of kmap_local_page()[1].

There are two main problems with kmap(): (1) It comes with an overhead as
mapping space is restricted and protected by a global lock for
synchronization and (2) it also requires global TLB invalidation when the
kmap's pool wraps and it might block when the mapping space is fully
utilized until a slot becomes available.

With kmap_local_page() the mappings are per thread, CPU local, can take
page faults, and can be called from any context (including interrupts).
It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore,
the tasks can be preempted and, when they are scheduled to run again, the
kernel virtual addresses are restored and are still valid.

In the fuction hyperv_init() of hyperv/hv_init.c, the mapping is used in a
single thread and is short live. So, in this case, it's safe to simply use
kmap_local_page() to create mapping, and this avoids the wasted cost of
kmap() for global synchronization.

In addtion, the fuction hyperv_init() checks if kmap() fails by BUG_ON().
From the original discussion[2], the BUG_ON() here is just used to
explicitly panic NULL pointer. So still keep the BUG_ON() in place to check
if kmap_local_page() fails. Based on this consideration, memcpy_to_page()
is not selected here but only kmap_local_page() is used.

Therefore, replace kmap() with kmap_local_page() in hyperv/hv_init.c.

[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com
[2]: https://lore.kernel.org/lkml/20200915103710.cqmdvzh5lys4wsqo@liuwe-devbox-debian-v2/

Suggested-by: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20220928095640.626350-1-zhao1.liu@linux.intel.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

The generate_guest_id function is more suitable for use after the
following modifications.

1. The return value of the function is modified to u64.
2. Remove the d_info1 and d_info2 parameters from the function, keep the
   u64 type kernel_version parameter.
3. Rename the function to make it clearly a Hyper-V related function,
   and modify it to hv_generate_guest_id.

Signed-off-by: Li kunyu <kunyu@nfschina.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220928064046.3545-1-kunyu@nfschina.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

Pull kvm updates from Paolo Bonzini:
 "Quite a large pull request due to a selftest API overhaul and some
  patches that had come in too late for 5.19.

  ARM:

   - Unwinder implementations for both nVHE modes (classic and
     protected), complete with an overflow stack

   - Rework of the sysreg access from userspace, with a complete rewrite
     of the vgic-v3 view to allign with the rest of the infrastructure

   - Disagregation of the vcpu flags in separate sets to better track
     their use model.

   - A fix for the GICv2-on-v3 selftest

   - A small set of cosmetic fixes

  RISC-V:

   - Track ISA extensions used by Guest using bitmap

   - Added system instruction emulation framework

   - Added CSR emulation framework

   - Added gfp_custom flag in struct kvm_mmu_memory_cache

   - Added G-stage ioremap() and iounmap() functions

   - Added support for Svpbmt inside Guest

  s390:

   - add an interface to provide a hypervisor dump for secure guests

   - improve selftests to use TAP interface

   - enable interpretive execution of zPCI instructions (for PCI
     passthrough)

   - First part of deferred teardown

   - CPU Topology

   - PV attestation

   - Minor fixes

  x86:

   - Permit guests to ignore single-bit ECC errors

   - Intel IPI virtualization

   - Allow getting/setting pending triple fault with
     KVM_GET/SET_VCPU_EVENTS

   - PEBS virtualization

   - Simplify PMU emulation by just using PERF_TYPE_RAW events

   - More accurate event reinjection on SVM (avoid retrying
     instructions)

   - Allow getting/setting the state of the speaker port data bit

   - Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls
     are inconsistent

   - "Notify" VM exit (detect microarchitectural hangs) for Intel

   - Use try_cmpxchg64 instead of cmpxchg64

   - Ignore benign host accesses to PMU MSRs when PMU is disabled

   - Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior

   - Allow NX huge page mitigation to be disabled on a per-vm basis

   - Port eager page splitting to shadow MMU as well

   - Enable CMCI capability by default and handle injected UCNA errors

   - Expose pid of vcpu threads in debugfs

   - x2AVIC support for AMD

   - cleanup PIO emulation

   - Fixes for LLDT/LTR emulation

   - Don't require refcounted "struct page" to create huge SPTEs

   - Miscellaneous cleanups:
      - MCE MSR emulation
      - Use separate namespaces for guest PTEs and shadow PTEs bitmasks
      - PIO emulation
      - Reorganize rmap API, mostly around rmap destruction
      - Do not workaround very old KVM bugs for L0 that runs with nesting enabled
      - new selftests API for CPUID

  Generic:

   - Fix races in gfn->pfn cache refresh; do not pin pages tracked by
     the cache

   - new selftests API using struct kvm_vcpu instead of a (vm, id)
     tuple"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (606 commits)
  selftests: kvm: set rax before vmcall
  selftests: KVM: Add exponent check for boolean stats
  selftests: KVM: Provide descriptive assertions in kvm_binary_stats_test
  selftests: KVM: Check stat name before other fields
  KVM: x86/mmu: remove unused variable
  RISC-V: KVM: Add support for Svpbmt inside Guest/VM
  RISC-V: KVM: Use PAGE_KERNEL_IO in kvm_riscv_gstage_ioremap()
  RISC-V: KVM: Add G-stage ioremap() and iounmap() functions
  KVM: Add gfp_custom flag in struct kvm_mmu_memory_cache
  RISC-V: KVM: Add extensible CSR emulation framework
  RISC-V: KVM: Add extensible system instruction emulation framework
  RISC-V: KVM: Factor-out instruction emulation into separate sources
  RISC-V: KVM: move preempt_disable() call in kvm_arch_vcpu_ioctl_run
  RISC-V: KVM: Make kvm_riscv_guest_timer_init a void function
  RISC-V: KVM: Fix variable spelling mistake
  RISC-V: KVM: Improve ISA extension by using a bitmap
  KVM, x86/mmu: Fix the comment around kvm_tdp_mmu_zap_leafs()
  KVM: SVM: Dump Virtual Machine Save Area (VMSA) to klog
  KVM: x86/mmu: Treat NX as a valid SPTE bit for NPT
  KVM: x86: Do not block APIC write for non ICR registers
  ...

KVM/s390, KVM/x86 and common infrastructure changes for 5.20

x86:

* Permit guests to ignore single-bit ECC errors

* Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache

* Intel IPI virtualization

* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS

* PEBS virtualization

* Simplify PMU emulation by just using PERF_TYPE_RAW events

* More accurate event reinjection on SVM (avoid retrying instructions)

* Allow getting/setting the state of the speaker port data bit

* Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent

* "Notify" VM exit (detect microarchitectural hangs) for Intel

* Cleanups for MCE MSR emulation

s390:

* add an interface to provide a hypervisor dump for secure guests

* improve selftests to use TAP interface

* enable interpretive execution of zPCI instructions (for PCI passthrough)

* First part of deferred teardown

* CPU Topology

* PV attestation

* Minor fixes

Generic:

* new selftests API using struct kvm_vcpu instead of a (vm, id) tuple

x86:

* Use try_cmpxchg64 instead of cmpxchg64

* Bugfixes

* Ignore benign host accesses to PMU MSRs when PMU is disabled

* Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior

* x86/MMU: Allow NX huge pages to be disabled on a per-vm basis

* Port eager page splitting to shadow MMU as well

* Enable CMCI capability by default and handle injected UCNA errors

* Expose pid of vcpu threads in debugfs

* x2AVIC support for AMD

* cleanup PIO emulation

* Fixes for LLDT/LTR emulation

* Don't require refcounted "struct page" to create huge SPTEs

x86 cleanups:

* Use separate namespaces for guest PTEs and shadow PTEs bitmasks

* PIO emulation

* Reorganize rmap API, mostly around rmap destruction

* Do not workaround very old KVM bugs for L0 that runs with nesting enabled

* new selftests API for CPUID

Now that the irq_data_update_affinity helper exists, enforce its use
by returning a a const cpumask from irq_data_get_affinity_mask.

Since the previous commit already updated places that needed to call
irq_data_update_affinity, this commit updates the remaining code that
either did not modify the cpumask or immediately passed the modified
mask to irq_set_affinity.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220701200056.46555-8-samuel@sholland.org