xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: nVMX: Open a window for pending nested VMX preemption timer

Browse Source 
Add a kvm_x86_ops hook to detect a nested pending "hypervisor timer" and
use it to effectively open a window for servicing the expired timer.
Like pending SMIs on VMX, opening a window simply means requesting an
immediate exit.

This fixes a bug where an expired VMX preemption timer (for L2) will be
delayed and/or lost if a pending exception is injected into L2.  The
pending exception is rightly prioritized by vmx_check_nested_events()
and injected into L2, with the preemption timer left pending.  Because
no window opened, L2 is free to run uninterrupted.

Fixes: f4124500c2 ("KVM: nVMX: Fully emulate preemption timer")
Reported-by: Jim Mattson <jmattson@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Peter Shier <pshier@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200423022550.15113-3-sean.j.christopherson@intel.com>
[Check it in kvm_vcpu_has_events too, to ensure that the preemption
 timer is serviced promptly even if the vCPU is halted and L1 is not
 intercepting HLT. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2020-04-22 19:25:39 -07:00
committed by Paolo Bonzini
parent 6ce347af14
commit d2060bd42e
3 changed files with 18 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/kvm/x86.c
View File

@@ -8355,6 +8355,10 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_x86_ops.enable_nmi_window(vcpu);
if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
kvm_x86_ops.enable_irq_window(vcpu);
if (is_guest_mode(vcpu) &&
kvm_x86_ops.nested_ops->hv_timer_pending &&
kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
req_immediate_exit = true;
WARN_ON(vcpu->arch.exception.pending);
}
@@ -10211,6 +10215,11 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
if (kvm_hv_has_stimer_pending(vcpu))
return true;
if (is_guest_mode(vcpu) &&
kvm_x86_ops.nested_ops->hv_timer_pending &&
kvm_x86_ops.nested_ops->hv_timer_pending(vcpu))
return true;
return false;
}