L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
=====================================================
BUG: KMSAN: uninit-value in x86_emulate_instruction+0x2846/0x59e0 arch/x86/kvm/x86.c:7638
 x86_emulate_instruction+0x2846/0x59e0 arch/x86/kvm/x86.c:7638
 kvm_mmu_page_fault+0xb9a/0xc30 arch/x86/kvm/mmu/mmu.c:5127
 handle_ept_violation+0x5b2/0x7b0 arch/x86/kvm/vmx/vmx.c:5401
 __vmx_handle_exit+0xe15/0x1700 arch/x86/kvm/vmx/vmx.c:6105
 vmx_handle_exit+0x6d/0x270 arch/x86/kvm/vmx/vmx.c:6122
 vcpu_enter_guest+0x5f14/0x7860 arch/x86/kvm/x86.c:9447
 vcpu_run+0x7a5/0x1610 arch/x86/kvm/x86.c:9513
 kvm_arch_vcpu_ioctl_run+0xefd/0x13d0 arch/x86/kvm/x86.c:9741
 kvm_vcpu_ioctl+0x1109/0x1f40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3475
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0x311/0x4d0 fs/ioctl.c:1055
 __x64_sys_ioctl+0xd8/0x110 fs/ioctl.c:1055
 do_syscall_64+0xb3/0x180 arch/x86/entry/common.c:53
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/core.c:78 [inline]
 kmsan_internal_chain_origin+0xa0/0x110 mm/kmsan/core.c:213
 kmsan_memmove_metadata+0x203/0x270 mm/kmsan/core.c:162
 __msan_memcpy+0x5e/0x90 mm/kmsan/instrumentation.c:111
 paging64_gva_to_gpa+0x22a/0x290 arch/x86/kvm/mmu/paging_tmpl.h:987
 kvm_fetch_guest_virt+0x1ca/0x460 arch/x86/kvm/x86.c:6220
 __do_insn_fetch_bytes+0xb8a/0xdc0 arch/x86/kvm/emulate.c:918
 x86_decode_insn+0x3cd/0x9bc0 arch/x86/kvm/emulate.c:5135
 x86_decode_emulated_instruction+0x2e3/0x1be0 arch/x86/kvm/x86.c:7589
 x86_emulate_instruction+0x31a/0x59e0 arch/x86/kvm/x86.c:7621
 kvm_mmu_page_fault+0xb9a/0xc30 arch/x86/kvm/mmu/mmu.c:5127
 handle_ept_violation+0x5b2/0x7b0 arch/x86/kvm/vmx/vmx.c:5401
 __vmx_handle_exit+0xe15/0x1700 arch/x86/kvm/vmx/vmx.c:6105
 vmx_handle_exit+0x6d/0x270 arch/x86/kvm/vmx/vmx.c:6122
 vcpu_enter_guest+0x5f14/0x7860 arch/x86/kvm/x86.c:9447
 vcpu_run+0x7a5/0x1610 arch/x86/kvm/x86.c:9513
 kvm_arch_vcpu_ioctl_run+0xefd/0x13d0 arch/x86/kvm/x86.c:9741
 kvm_vcpu_ioctl+0x1109/0x1f40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3475
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0x311/0x4d0 fs/ioctl.c:1055
 __x64_sys_ioctl+0xd8/0x110 fs/ioctl.c:1055
 do_syscall_64+0xb3/0x180 arch/x86/entry/common.c:53
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/core.c:78 [inline]
 kmsan_internal_chain_origin+0xa0/0x110 mm/kmsan/core.c:213
 __msan_chain_origin+0xcb/0x140 mm/kmsan/instrumentation.c:148
 translate_gpa+0x194/0x1a0 arch/x86/kvm/mmu/mmu.c:260
 paging64_walk_addr_generic+0x808/0x2390 arch/x86/kvm/mmu/paging_tmpl.h:377
 paging64_walk_addr arch/x86/kvm/mmu/paging_tmpl.h:518 [inline]
 paging64_gva_to_gpa+0x154/0x290 arch/x86/kvm/mmu/paging_tmpl.h:981
 kvm_fetch_guest_virt+0x1ca/0x460 arch/x86/kvm/x86.c:6220
 __do_insn_fetch_bytes+0xb8a/0xdc0 arch/x86/kvm/emulate.c:918
 x86_decode_insn+0x3cd/0x9bc0 arch/x86/kvm/emulate.c:5135
 x86_decode_emulated_instruction+0x2e3/0x1be0 arch/x86/kvm/x86.c:7589
 x86_emulate_instruction+0x31a/0x59e0 arch/x86/kvm/x86.c:7621
 kvm_mmu_page_fault+0xb9a/0xc30 arch/x86/kvm/mmu/mmu.c:5127
 handle_ept_violation+0x5b2/0x7b0 arch/x86/kvm/vmx/vmx.c:5401
 __vmx_handle_exit+0xe15/0x1700 arch/x86/kvm/vmx/vmx.c:6105
 vmx_handle_exit+0x6d/0x270 arch/x86/kvm/vmx/vmx.c:6122
 vcpu_enter_guest+0x5f14/0x7860 arch/x86/kvm/x86.c:9447
 vcpu_run+0x7a5/0x1610 arch/x86/kvm/x86.c:9513
 kvm_arch_vcpu_ioctl_run+0xefd/0x13d0 arch/x86/kvm/x86.c:9741
 kvm_vcpu_ioctl+0x1109/0x1f40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3475
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0x311/0x4d0 fs/ioctl.c:1055
 __x64_sys_ioctl+0xd8/0x110 fs/ioctl.c:1055
 do_syscall_64+0xb3/0x180 arch/x86/entry/common.c:53
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Local variable ----walker@paging64_gva_to_gpa created at:
 paging64_gva_to_gpa+0xaa/0x290 arch/x86/kvm/mmu/paging_tmpl.h:977
 kvm_fetch_guest_virt+0x1ca/0x460 arch/x86/kvm/x86.c:6220
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