From aba963cb98c6d9d42490262a39c3d383cfebc6a9 Mon Sep 17 00:00:00 2001 From: Alexandru Elisei Date: Tue, 16 Dec 2025 10:30:51 +0000 Subject: [PATCH] KVM: arm64: Inject UNDEF for a register trap without accessor Configuring a register trap without specifying an accessor function is abviously a bug. Instead of calling die() when that happens, let's be a bit more helpful and print the register encoding. Also inject an undefined instruction exception in the guest, similar to other unhandled register accesses. Signed-off-by: Alexandru Elisei Reviewed-by: Marc Zyngier Tested-by: Fuad Tabba Reviewed-by: Fuad Tabba Link: https://msgid.link/20251216103053.47224-3-alexandru.elisei@arm.com Signed-off-by: Oliver Upton --- arch/arm64/kvm/sys_regs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index c8fd7c6a12a1..88a57ca36d96 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -4668,7 +4668,10 @@ static void perform_access(struct kvm_vcpu *vcpu, * that we don't know how to handle. This certainly qualifies * as a gross bug that should be fixed right away. */ - BUG_ON(!r->access); + if (!r->access) { + bad_trap(vcpu, params, r, "register access"); + return; + } /* Skip instruction if instructed so */ if (likely(r->access(vcpu, params, r))) -- 2.47.3