Vitaly Kuznetsov ee68154163 x86/hyperv: Restore VP assist page after cpu offlining/onlining ... Commit e5d9b714fe ("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: e5d9b714fe ("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>		2022-11-11 23:33:30 +00:00
..
hv_apic.c	KVM: x86: lapic: Rename [GET/SET]_APIC_DEST_FIELD to [GET/SET]_XAPIC_DEST_FIELD	2022-06-24 12:44:34 -04:00
hv_init.c	x86/hyperv: Restore VP assist page after cpu offlining/onlining	2022-11-11 23:33:30 +00:00
hv_proc.c	drivers: hv: Create a consistent pattern for checking Hyper-V hypercall status	2021-04-21 09:49:19 +00:00
hv_spinlock.c	x86/hyperv: Fix unused variable 'msr_val' warning in hv_qlock_wait	2021-03-24 11:31:04 +00:00
irqdomain.c	genirq: Return a const cpumask from irq_data_get_affinity_mask	2022-07-07 09:38:04 +01:00
ivm.c	x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM	2022-06-15 18:27:40 +00:00
Makefile	x86/hyperv: Add new hvcall guest address host visibility support	2021-10-28 11:21:33 +00:00
mmu.c	x86/hyperv: Properly deal with empty cpumasks in hyperv_flush_tlb_multi()	2022-01-10 11:50:20 +00:00
nested.c	drivers: hv: Create a consistent pattern for checking Hyper-V hypercall status	2021-04-21 09:49:19 +00:00