From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: mlevitsk@redhat.com, seanjc@google.com
Subject: [PATCH v3 5/7] KVM: x86: never write to memory from kvm_vcpu_check_block
Date: Mon, 22 Aug 2022 13:06:57 -0400 [thread overview]
Message-ID: <20220822170659.2527086-6-pbonzini@redhat.com> (raw)
In-Reply-To: <20220822170659.2527086-1-pbonzini@redhat.com>
kvm_vcpu_check_block() is called while not in TASK_RUNNING, and therefore
it cannot sleep. Writing to guest memory is therefore forbidden, but it
can happen on AMD processors if kvm_check_nested_events() causes a vmexit.
Fortunately, all events that are caught by kvm_check_nested_events() are
also recognized by kvm_vcpu_has_events() through vendor callbacks such as
kvm_x86_interrupt_allowed() or kvm_x86_ops.nested_ops->has_events(), so
remove the call and postpone the actual processing to vcpu_block().
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5c5341110876..f901cd872b6d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10637,6 +10637,15 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
return 1;
}
+ /*
+ * Evaluate nested events before exiting the halted state. This allows
+ * the halt state to be recorded properly in the VMCS12's activity
+ * state field (AMD does not have a similar field and a VM-Exit always
+ * causes a spurious wakeup from HLT).
+ */
+ if (is_guest_mode(vcpu))
+ kvm_check_nested_events(vcpu);
+
if (kvm_apic_accept_events(vcpu) < 0)
return 0;
switch(vcpu->arch.mp_state) {
@@ -10660,9 +10669,6 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
static inline bool kvm_vcpu_running(struct kvm_vcpu *vcpu)
{
- if (is_guest_mode(vcpu))
- kvm_check_nested_events(vcpu);
-
return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
!vcpu->arch.apf.halted);
}
--
2.31.1
next prev parent reply other threads:[~2022-08-22 17:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-22 17:06 [PATCH v3 0/7] KVM: x86: never write to memory from kvm_vcpu_check_block Paolo Bonzini
2022-08-22 17:06 ` [PATCH v3 1/7] KVM: x86: check validity of argument to KVM_SET_MP_STATE Paolo Bonzini
2022-08-22 17:06 ` [PATCH v3 2/7] KVM: x86: make vendor code check for all nested events Paolo Bonzini
2022-08-22 17:06 ` [PATCH v3 3/7] KVM: nVMX: Make an event request when pending an MTF nested VM-Exit Paolo Bonzini
2022-08-22 17:52 ` Jim Mattson
2022-08-22 19:40 ` Paolo Bonzini
2022-08-22 17:06 ` [PATCH v3 4/7] KVM: x86: lapic does not have to process INIT if it is blocked Paolo Bonzini
2022-08-22 17:06 ` Paolo Bonzini [this message]
2022-08-22 17:06 ` [PATCH v3 6/7] KVM: mips, x86: do not rely on KVM_REQ_UNHALT Paolo Bonzini
2022-08-22 17:06 ` [PATCH v3 7/7] KVM: remove KVM_REQ_UNHALT Paolo Bonzini
2022-09-08 15:36 ` [PATCH v3 0/7] KVM: x86: never write to memory from kvm_vcpu_check_block Sean Christopherson
2022-09-17 1:02 ` Sean Christopherson
2022-09-20 1:15 ` Sean Christopherson
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