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1a71581012
Revert back to refreshing vmcs.HOST_CR3 immediately prior to VM-Enter. The PCID (ASID) part of CR3 can be bumped without KVM being scheduled out, as the kernel will switch CR3 during __text_poke(), e.g. in response to a static key toggling. If switch_mm_irqs_off() chooses a new ASID for the mm associate with KVM, KVM will do VM-Enter => VM-Exit with a stale vmcs.HOST_CR3. Add a comment to explain why KVM must wait until VM-Enter is imminent to refresh vmcs.HOST_CR3. The following splat was captured by stashing vmcs.HOST_CR3 in kvm_vcpu and adding a WARN in load_new_mm_cr3() to fire if a new ASID is being loaded for the KVM-associated mm while KVM has a "running" vCPU: static void load_new_mm_cr3(pgd_t *pgdir, u16 new_asid, bool need_flush) { struct kvm_vcpu *vcpu = kvm_get_running_vcpu(); ... WARN(vcpu && (vcpu->cr3 & GENMASK(11, 0)) != (new_mm_cr3 & GENMASK(11, 0)) && (vcpu->cr3 & PHYSICAL_PAGE_MASK) == (new_mm_cr3 & PHYSICAL_PAGE_MASK), "KVM is hosed, loading CR3 = %lx, vmcs.HOST_CR3 = %lx", new_mm_cr3, vcpu->cr3); } ------------[ cut here ]------------ KVM is hosed, loading CR3 = 8000000105393004, vmcs.HOST_CR3 = 105393003 WARNING: CPU: 4 PID: 20717 at arch/x86/mm/tlb.c:291 load_new_mm_cr3+0x82/0xe0 Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel CPU: 4 PID: 20717 Comm: stable Tainted: G W 5.17.0-rc3+ #747 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:load_new_mm_cr3+0x82/0xe0 RSP: 0018:ffffc9000489fa98 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 8000000105393004 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff888277d1b788 RBP: 0000000000000004 R08: ffff888277d1b780 R09: ffffc9000489f8b8 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: ffff88810678a800 R14: 0000000000000004 R15: 0000000000000c33 FS: 00007fa9f0e72700(0000) GS:ffff888277d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001001b5003 CR4: 0000000000172ea0 Call Trace: <TASK> switch_mm_irqs_off+0x1cb/0x460 __text_poke+0x308/0x3e0 text_poke_bp_batch+0x168/0x220 text_poke_finish+0x1b/0x30 arch_jump_label_transform_apply+0x18/0x30 static_key_slow_inc_cpuslocked+0x7c/0x90 static_key_slow_inc+0x16/0x20 kvm_lapic_set_base+0x116/0x190 kvm_set_apic_base+0xa5/0xe0 kvm_set_msr_common+0x2f4/0xf60 vmx_set_msr+0x355/0xe70 [kvm_intel] kvm_set_msr_ignored_check+0x91/0x230 kvm_emulate_wrmsr+0x36/0x120 vmx_handle_exit+0x609/0x6c0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x146f/0x1b80 kvm_vcpu_ioctl+0x279/0x690 __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae </TASK> ---[ end trace 0000000000000000 ]--- This reverts commit |
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.. | ||
boot | ||
configs | ||
crypto | ||
entry | ||
events | ||
hyperv | ||
ia32 | ||
include | ||
kernel | ||
kvm | ||
lib | ||
math-emu | ||
mm | ||
net | ||
pci | ||
platform | ||
power | ||
purgatory | ||
ras | ||
realmode | ||
tools | ||
um | ||
video | ||
xen | ||
.gitignore | ||
Kbuild | ||
Kconfig | ||
Kconfig.assembler | ||
Kconfig.cpu | ||
Kconfig.debug | ||
Makefile | ||
Makefile.um | ||
Makefile_32.cpu |