[PATCH v4 07/12] KVM: nVMX: Make an event request if INIT or SIPI is pending on VM-Enter

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 07/12] KVM: nVMX: Make an event request if INIT or SIPI is pending on VM-Enter
Date: Wed, 21 Sep 2022 00:31:56 +0000	[thread overview]
Message-ID: <20220921003201.1441511-8-seanjc@google.com> (raw)
In-Reply-To: <20220921003201.1441511-1-seanjc@google.com>

Evaluate interrupts, i.e. set KVM_REQ_EVENT, if INIT or SIPI is pending
when emulating nested VM-Enter.  INIT is blocked while the CPU is in VMX
root mode, but not in VMX non-root, i.e. becomes unblocked on VM-Enter.
This bug has been masked by KVM calling ->check_nested_events() in the
core run loop, but that hack will be fixed in the near future.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/nested.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3a080051a4ec..5922531f6c52 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3377,6 +3377,8 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
 		(CPU_BASED_INTR_WINDOW_EXITING | CPU_BASED_NMI_WINDOW_EXITING);
 	if (likely(!evaluate_pending_interrupts) && kvm_vcpu_apicv_active(vcpu))
 		evaluate_pending_interrupts |= vmx_has_apicv_interrupt(vcpu);
+	if (!evaluate_pending_interrupts)
+		evaluate_pending_interrupts |= kvm_apic_has_pending_init_or_sipi(vcpu);
 
 	if (!vmx->nested.nested_run_pending ||
 	    !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS))
@@ -3457,18 +3459,10 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
 	}
 
 	/*
-	 * If L1 had a pending IRQ/NMI until it executed
-	 * VMLAUNCH/VMRESUME which wasn't delivered because it was
-	 * disallowed (e.g. interrupts disabled), L0 needs to
-	 * evaluate if this pending event should cause an exit from L2
-	 * to L1 or delivered directly to L2 (e.g. In case L1 don't
-	 * intercept EXTERNAL_INTERRUPT).
-	 *
-	 * Usually this would be handled by the processor noticing an
-	 * IRQ/NMI window request, or checking RVI during evaluation of
-	 * pending virtual interrupts.  However, this setting was done
-	 * on VMCS01 and now VMCS02 is active instead. Thus, we force L0
-	 * to perform pending event evaluation by requesting a KVM_REQ_EVENT.
+	 * Re-evaluate pending events if L1 had a pending IRQ/NMI/INIT/SIPI
+	 * when it executed VMLAUNCH/VMRESUME, as entering non-root mode can
+	 * effectively unblock various events, e.g. INIT/SIPI cause VM-Exit
+	 * unconditionally.
 	 */
 	if (unlikely(evaluate_pending_interrupts))
 		kvm_make_request(KVM_REQ_EVENT, vcpu);
-- 
2.37.3.968.ga6b4b080e4-goog

