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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
|
||
|---|---|---|
| .. | ||
| mmu | ||
| svm | ||
| vmx | ||
| cpuid.c | ||
| cpuid.h | ||
| debugfs.c | ||
| emulate.c | ||
| fpu.h | ||
| hyperv.c | ||
| hyperv.h | ||
| i8254.c | ||
| i8254.h | ||
| i8259.c | ||
| ioapic.c | ||
| ioapic.h | ||
| irq_comm.c | ||
| irq.c | ||
| irq.h | ||
| Kconfig | ||
| kvm_cache_regs.h | ||
| kvm_emulate.h | ||
| kvm_onhyperv.c | ||
| kvm_onhyperv.h | ||
| lapic.c | ||
| lapic.h | ||
| Makefile | ||
| mmu.h | ||
| mtrr.c | ||
| pmu.c | ||
| pmu.h | ||
| reverse_cpuid.h | ||
| trace.h | ||
| tss.h | ||
| x86.c | ||
| x86.h | ||
| xen.c | ||
| xen.h | ||