From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Anup Patel <anup@brainfault.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>
Cc: James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Oliver Upton <oliver.upton@linux.dev>,
Atish Patra <atishp@atishpatra.org>,
David Hildenbrand <david@redhat.com>,
kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH v4 10/12] KVM: x86: never write to memory from kvm_vcpu_check_block()
Date: Wed, 21 Sep 2022 00:31:59 +0000 [thread overview]
Message-ID: <20220921003201.1441511-11-seanjc@google.com> (raw)
In-Reply-To: <20220921003201.1441511-1-seanjc@google.com>
From: Paolo Bonzini <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().
Opportunistically honor the return of kvm_check_nested_events(). KVM
punted on the check in kvm_vcpu_running() because the only error path is
if vmx_complete_nested_posted_interrupt() fails, in which case KVM exits
to userspace with "internal error" i.e. the VM is likely dead anyways so
it wasn't worth overloading the return of kvm_vcpu_running().
Add the check mostly so that KVM is consistent with itself; the return of
the call via kvm_apic_accept_events()=>kvm_check_nested_events() that
immediately follows _is_ checked.
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[sean: check and handle return of kvm_check_nested_events()]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/x86.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dcc675d4e44b..8aeacbc2bff9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10815,6 +10815,17 @@ 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)) {
+ if (kvm_check_nested_events(vcpu) < 0)
+ return 0;
+ }
+
if (kvm_apic_accept_events(vcpu) < 0)
return 0;
switch(vcpu->arch.mp_state) {
@@ -10837,9 +10848,6 @@ 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);
}
--
2.37.3.968.ga6b4b080e4-goog
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next prev parent reply other threads:[~2022-09-21 0:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 0:31 [PATCH v4 00/12] KVM: x86: never write to memory from kvm_vcpu_check_block Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 01/12] KVM: x86: make vendor code check for all nested events Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 02/12] KVM: nVMX: Make an event request when pending an MTF nested VM-Exit Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 03/12] KVM: x86: Rename and expose helper to detect if INIT/SIPI are allowed Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 04/12] KVM: x86: Rename kvm_apic_has_events() to make it INIT/SIPI specific Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 05/12] KVM: x86: lapic does not have to process INIT if it is blocked Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 06/12] KVM: SVM: Make an event request if INIT or SIPI is pending when GIF is set Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 07/12] KVM: nVMX: Make an event request if INIT or SIPI is pending on VM-Enter Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 08/12] KVM: nVMX: Make event request on VMXOFF iff INIT/SIPI is pending Sean Christopherson
2022-09-21 0:31 ` [PATCH v4 09/12] KVM: x86: Don't snapshot pending INIT/SIPI prior to checking nested events Sean Christopherson
2022-09-21 0:31 ` Sean Christopherson [this message]
2023-12-07 1:03 ` [PATCH v4 10/12] KVM: x86: never write to memory from kvm_vcpu_check_block() Jim Mattson
2023-12-07 16:21 ` Sean Christopherson
2023-12-10 22:52 ` Jim Mattson
2023-12-12 15:28 ` Sean Christopherson
2023-12-13 22:25 ` Maxim Levitsky
2023-12-13 22:31 ` Jim Mattson
2023-12-13 22:44 ` Maxim Levitsky
2023-12-13 22:59 ` Sean Christopherson
2022-09-21 0:32 ` [PATCH v4 11/12] KVM: mips, x86: do not rely on KVM_REQ_UNHALT Sean Christopherson
2022-09-22 13:17 ` Philippe Mathieu-Daudé
2022-09-21 0:32 ` [PATCH v4 12/12] KVM: remove KVM_REQ_UNHALT Sean Christopherson
2022-09-22 14:52 ` Marc Zyngier
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