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KVM: VMX: Refresh available regs and IDT vectoring info before NMI handling

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Reset the mask of available "registers" and refresh the IDT vectoring
info snapshot in vmx_vcpu_enter_exit(), before KVM potentially handles a
an NMI VM-Exit.  One of the "registers" that KVM VMX lazily loads is the
vmcs.VM_EXIT_INTR_INFO field, which is holds the vector+type on "exception
or NMI" VM-Exits, i.e. is needed to identify NMIs.  Clearing the available
registers bitmask after handling NMIs results in KVM querying info from
the last VM-Exit that read vmcs.VM_EXIT_INTR_INFO, and leads to both
missed NMIs and spurious NMIs in the host.

Opportunistically grab vmcs.IDT_VECTORING_INFO_FIELD early in the VM-Exit
path too, e.g. to guard against similar consumption of stale data.  The
field is read on every "normal" VM-Exit, and there's no point in delaying
the inevitable.

Reported-by: Like Xu <like.xu.linux@gmail.com>
Fixes: 11df586d774f ("KVM: VMX: Handle NMI VM-Exits in noinstr region")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230825014532.2846714-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-08-24 18:45:32 -07:00
parent 9ca0c1a126
commit 50011c2a24
1 changed files with 11 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
arch/x86/kvm/vmx/vmx.c
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@ -7209,13 +7209,20 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
flags);
vcpu->arch.cr2 = native_read_cr2();
vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;
vmx->idt_vectoring_info = 0;
vmx_enable_fb_clear(vmx);
if (unlikely(vmx->fail))
if (unlikely(vmx->fail)) {
vmx->exit_reason.full = 0xdead;
else
vmx->exit_reason.full = vmcs_read32(VM_EXIT_REASON);
goto out;
}
vmx->exit_reason.full = vmcs_read32(VM_EXIT_REASON);
if (likely(!vmx->exit_reason.failed_vmentry))
vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
if ((u16)vmx->exit_reason.basic == EXIT_REASON_EXCEPTION_NMI &&
is_nmi(vmx_get_intr_info(vcpu))) {
@ -7224,6 +7231,7 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
kvm_after_interrupt(vcpu);
}
out:
guest_state_exit_irqoff();
}
@ -7345,8 +7353,6 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
loadsegment(es, __USER_DS);
#endif
vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;
pt_guest_exit(vmx);
kvm_load_host_xsave_state(vcpu);
@ -7363,17 +7369,12 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmx->nested.nested_run_pending = 0;
}
vmx->idt_vectoring_info = 0;
if (unlikely(vmx->fail))
return EXIT_FASTPATH_NONE;
if (unlikely((u16)vmx->exit_reason.basic == EXIT_REASON_MCE_DURING_VMENTRY))
kvm_machine_check();
if (likely(!vmx->exit_reason.failed_vmentry))
vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
trace_kvm_exit(vcpu, KVM_ISA_VMX);
if (unlikely(vmx->exit_reason.failed_vmentry))