linux-kernel - [PATCH 13/15] KVM: selftests: Fall back to split IRQ chip if full in-kernel chip is unsupported

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Message-ID: <20250519232808.2745331-14-seanjc@google.com>
Date: Mon, 19 May 2025 16:28:06 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 13/15] KVM: selftests: Fall back to split IRQ chip if full
 in-kernel chip is unsupported

Now that KVM x86 allows compiling out support for in-kernel I/O APIC (and
PIC and PIT) emulation, i.e. allows disabling KVM_CREATE_IRQCHIP for all
intents and purposes, fall back to a split IRQ chip for x86 if creating
the full in-kernel version fails with ENOTTY.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 50edc59cc0ca..53116f4ffe97 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1713,7 +1713,18 @@ void *addr_gpa2alias(struct kvm_vm *vm, vm_paddr_t gpa)
 /* Create an interrupt controller chip for the specified VM. */
 void vm_create_irqchip(struct kvm_vm *vm)
 {
-	vm_ioctl(vm, KVM_CREATE_IRQCHIP, NULL);
+	int r;
+
+	/*
+	 * Allocate a fully in-kernel IRQ chip by default, but fall back to a
+	 * split model (x86 only) if that fails (KVM x86 allows compiling out
+	 * support for KVM_CREATE_IRQCHIP).
+	 */
+	r = __vm_ioctl(vm, KVM_CREATE_IRQCHIP, NULL);
+	if (r && errno == ENOTTY && kvm_has_cap(KVM_CAP_SPLIT_IRQCHIP))
+		vm_enable_cap(vm, KVM_CAP_SPLIT_IRQCHIP, 24);
+	else
+		TEST_ASSERT_VM_VCPU_IOCTL(!r, KVM_CREATE_IRQCHIP, r, vm);
 
 	vm->has_irqchip = true;
 }
-- 
2.49.0.1101.gccaa498523-goog