kernel/linux.git/arch/x86/hyperv, branch v5.10.257

x86/hyperv: Remove unregister syscore call from Hyper-V cleanup

2023-01-14T09:16:13+00:00

[ Upstream commit 32c97d980e2eef25465d453f2956a9ca68926a3c ] 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 Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@linux.microsoft.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails

2021-11-26T09:39:19+00:00

commit daf972118c517b91f74ff1731417feb4270625a4 upstream. Check for a valid hv_vp_index array prior to derefencing hv_vp_index when setting Hyper-V's TSC change callback. If Hyper-V setup failed in hyperv_init(), the kernel will still report that it's running under Hyper-V, but will have silently disabled nearly all functionality. BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:set_hv_tscchange_cb+0x15/0xa0 Code: <8b> 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08 ... Call Trace: kvm_arch_init+0x17c/0x280 kvm_init+0x31/0x330 vmx_init+0xba/0x13a do_one_initcall+0x41/0x1c0 kernel_init_freeable+0x1f2/0x23b kernel_init+0x16/0x120 ret_from_fork+0x22/0x30 Fixes: 93286261de1b ("x86/hyperv: Reenlightenment notifications support") Cc: stable@vger.kernel.org Cc: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Reviewed-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20211104182239.1302956-2-seanjc@google.com Signed-off-by: Wei Liu Signed-off-by: Greg Kroah-Hartman

x86/hyperv: Protect set_hv_tscchange_cb() against getting preempted

2021-11-18T13:04:00+00:00

[ Upstream commit 285f68afa8b20f752b0b7194d54980b5e0e27b75 ] The following issue is observed with CONFIG_DEBUG_PREEMPT when KVM loads: KVM: vmx: using Hyper-V Enlightened VMCS BUG: using smp_processor_id() in preemptible [00000000] code: systemd-udevd/488 caller is set_hv_tscchange_cb+0x16/0x80 CPU: 1 PID: 488 Comm: systemd-udevd Not tainted 5.15.0-rc5+ #396 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.0 12/17/2019 Call Trace: dump_stack_lvl+0x6a/0x9a check_preemption_disabled+0xde/0xe0 ? kvm_gen_update_masterclock+0xd0/0xd0 [kvm] set_hv_tscchange_cb+0x16/0x80 kvm_arch_init+0x23f/0x290 [kvm] kvm_init+0x30/0x310 [kvm] vmx_init+0xaf/0x134 [kvm_intel] ... set_hv_tscchange_cb() can get preempted in between acquiring smp_processor_id() and writing to HV_X64_MSR_REENLIGHTENMENT_CONTROL. This is not an issue by itself: HV_X64_MSR_REENLIGHTENMENT_CONTROL is a partition-wide MSR and it doesn't matter which particular CPU will be used to receive reenlightenment notifications. The only real problem can (in theory) be observed if the CPU whose id was acquired with smp_processor_id() goes offline before we manage to write to the MSR, the logic in hv_cpu_die() won't be able to reassign it correctly. Reported-by: Michael Kelley Signed-off-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20211012155005.1613352-1-vkuznets@redhat.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

x86/hyperv: Fix kexec panic/hang issues

2021-01-27T10:54:57+00:00

[ Upstream commit dfe94d4086e40e92b1926bddcefa629b791e9b28 ] Currently the kexec kernel can panic or hang due to 2 causes: 1) hv_cpu_die() is not called upon kexec, so the hypervisor corrupts the old VP Assist Pages when the kexec kernel runs. The same issue is fixed for hibernation in commit 421f090c819d ("x86/hyperv: Suspend/resume the VP assist page for hibernation"). Now fix it for kexec. 2) hyperv_cleanup() is called too early. In the kexec path, the other CPUs are stopped in hv_machine_shutdown() -> native_machine_shutdown(), so between hv_kexec_handler() and native_machine_shutdown(), the other CPUs can still try to access the hypercall page and cause panic. The workaround "hv_hypercall_pg = NULL;" in hyperv_cleanup() is unreliabe. Move hyperv_cleanup() to a better place. Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20201222065541.24312-1-decui@microsoft.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

x86/hyperv: Initialize clockevents after LAPIC is initialized

2021-01-23T15:03:57+00:00

[ Upstream commit fff7b5e6ee63c5d20406a131b260c619cdd24fd1 ] With commit 4df4cb9e99f8, the Hyper-V direct-mode STIMER is actually initialized before LAPIC is initialized: see apic_intr_mode_init() x86_platform.apic_post_init() hyperv_init() hv_stimer_alloc() apic_bsp_setup() setup_local_APIC() setup_local_APIC() temporarily disables LAPIC, initializes it and re-eanble it. The direct-mode STIMER depends on LAPIC, and when it's registered, it can be programmed immediately and the timer can fire very soon: hv_stimer_init clockevents_config_and_register clockevents_register_device tick_check_new_device tick_setup_device tick_setup_periodic(), tick_setup_oneshot() clockevents_program_event When the timer fires in the hypervisor, if the LAPIC is in the disabled state, new versions of Hyper-V ignore the event and don't inject the timer interrupt into the VM, and hence the VM hangs when it boots. Note: when the VM starts/reboots, the LAPIC is pre-enabled by the firmware, so the window of LAPIC being temporarily disabled is pretty small, and the issue can only happen once out of 100~200 reboots for a 40-vCPU VM on one dev host, and on another host the issue doesn't reproduce after 2000 reboots. The issue is more noticeable for kdump/kexec, because the LAPIC is disabled by the first kernel, and stays disabled until the kdump/kexec kernel enables it. This is especially an issue to a Generation-2 VM (for which Hyper-V doesn't emulate the PIT timer) when CONFIG_HZ=1000 (rather than CONFIG_HZ=250) is used. Fix the issue by moving hv_stimer_alloc() to a later place where the LAPIC timer is initialized. Fixes: 4df4cb9e99f8 ("x86/hyperv: Initialize clockevents earlier in CPU onlining") Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20210116223136.13892-1-decui@microsoft.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

x86/hyperv: check cpu mask after interrupt has been disabled

2021-01-19T17:27:18+00:00

commit ad0a6bad44758afa3b440c254a24999a0c7e35d5 upstream. We've observed crashes due to an empty cpu mask in hyperv_flush_tlb_others. Obviously the cpu mask in question is changed between the cpumask_empty call at the beginning of the function and when it is actually used later. One theory is that an interrupt comes in between and a code path ends up changing the mask. Move the check after interrupt has been disabled to see if it fixes the issue. Signed-off-by: Wei Liu Cc: stable@kernel.org Link: https://lore.kernel.org/r/20210105175043.28325-1-wei.liu@kernel.org Reviewed-by: Michael Kelley Signed-off-by: Greg Kroah-Hartman

Merge tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2020-11-05T19:32:03+00:00

Pull hyperv fixes from Wei Liu: - clarify a comment (Michael Kelley) - change a pr_warn() to pr_info() (Olaf Hering) * tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: x86/hyperv: Clarify comment on x2apic mode hv_balloon: disable warning when floor reached

x86/hyperv: Clarify comment on x2apic mode

2020-10-26T16:28:06+00:00

The comment about Hyper-V accessors is unclear regarding their potential use in x2apic mode, as is the associated commit message in e211288b72f1. Clarify that while the architectural and synthetic MSRs are equivalent in x2apic mode, the full set of xapic accessors cannot be used because of register layout differences. Fixes: e211288b72f1 ("x86/hyperv: Make vapic support x2apic mode") Signed-off-by: Michael Kelley Link: https://lore.kernel.org/r/1603723972-81303-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu

x86/hyperv: Remove aliases with X64 in their name

2020-09-27T09:34:54+00:00

In the architecture independent version of hyperv-tlfs.h, commit c55a844f46f958b removed the "X64" in the symbol names so they would make sense for both x86 and ARM64. That commit added aliases with the "X64" in the x86 version of hyperv-tlfs.h so that existing x86 code would continue to compile. As a cleanup, update the x86 code to use the symbols without the "X64", then remove the aliases. There's no functional change. Signed-off-by: Joseph Salisbury Signed-off-by: Thomas Gleixner Reviewed-by: Michael Kelley Acked-by: Paolo Bonzini Link: https://lore.kernel.org/r/1601130386-11111-1-git-send-email-jsalisbury@linux.microsoft.com

vmalloc: fix the owner argument for the new __vmalloc_node_range callers

2020-07-03T23:15:25+00:00

Fix the recently added new __vmalloc_node_range callers to pass the correct values as the owner for display in /proc/vmallocinfo. Fixes: 800e26b81311 ("x86/hyperv: allocate the hypercall page with only read and execute bits") Fixes: 10d5e97c1bf8 ("arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page") Fixes: 7a0e27b2a0ce ("mm: remove vmalloc_exec") Reported-by: Ard Biesheuvel Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200627075649.2455097-1-hch@lst.de Signed-off-by: Linus Torvalds