kvm: emulating exchange as write
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BUG: KCSAN: data-race in emulator_read_write_onepage / install_new_memslots

write to 0xffff8880a6480000 of 8 bytes by task 10220 on cpu 1:
 install_new_memslots+0xef/0x130 arch/x86/kvm/../../../virt/kvm/kvm_main.c:972
 __kvm_set_memory_region+0xeea/0x1380 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1131
 kvm_set_memory_region+0x36/0x60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1154
 kvm_vm_ioctl_set_memory_region arch/x86/kvm/../../../virt/kvm/kvm_main.c:1166 [inline]
 kvm_vm_ioctl+0x6d0/0x1190 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3293
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x991/0xc60 fs/ioctl.c:696
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:718
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a6480000 of 8 bytes by task 10226 on cpu 0:
 vcpu_match_mmio_gen arch/x86/kvm/x86.h:206 [inline]
 vcpu_match_mmio_gva arch/x86/kvm/x86.h:225 [inline]
 vcpu_mmio_gva_to_gpa arch/x86/kvm/x86.c:5517 [inline]
 emulator_read_write_onepage+0x1dc/0x750 arch/x86/kvm/x86.c:5643
 emulator_read_write+0x178/0x330 arch/x86/kvm/x86.c:5703
 emulator_write_emulated+0x45/0x60 arch/x86/kvm/x86.c:5740
 segmented_write+0xa2/0xe0 arch/x86/kvm/emulate.c:1462
 writeback arch/x86/kvm/emulate.c:1824 [inline]
 writeback+0x246/0x440 arch/x86/kvm/emulate.c:1810
 x86_emulate_insn+0x1429/0x28e0 arch/x86/kvm/emulate.c:5734
 x86_emulate_instruction+0x498/0x1110 arch/x86/kvm/x86.c:6718
 kvm_mmu_page_fault+0x233/0xbc0 arch/x86/kvm/mmu.c:5589
 handle_ept_violation+0x1e5/0x340 arch/x86/kvm/vmx/vmx.c:5199
 vmx_handle_exit+0x1c2/0xd60 arch/x86/kvm/vmx/vmx.c:5943
 vcpu_enter_guest+0xc1f/0x3830 arch/x86/kvm/x86.c:8255
 vcpu_run arch/x86/kvm/x86.c:8319 [inline]
 kvm_arch_vcpu_ioctl_run+0x2a2/0xdc0 arch/x86/kvm/x86.c:8526
 kvm_vcpu_ioctl+0x752/0xa30 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2834
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x991/0xc60 fs/ioctl.c:696
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:718
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10226 Comm: syz-executor.4 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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