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From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	<kvmarm@lists.cs.columbia.edu>, <kvmarm@lists.linux.dev>,
	kvm@vger.kernel.org
Cc: D Scott Phillips <scott@os.amperecomputing.com>,
	Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH 3/3] KVM: arm64: timers: Don't BUG() on unhandled timer trap
Date: Thu, 12 Jan 2023 12:38:29 +0000	[thread overview]
Message-ID: <20230112123829.458912-4-maz@kernel.org> (raw)
In-Reply-To: <20230112123829.458912-1-maz@kernel.org>

Although not handling a trap is a pretty bad situation to be in,
panicing the kernel isn't useful and provides no valuable
information to help debugging the situation.

Instead, dump the encoding of the unhandled sysreg, and inject
an UNDEF in the guest. At least, this gives a user an opportunity
to report the issue with some information to help debugging it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/sys_regs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d5ee52d6bf73..32f4e424b9a5 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1049,7 +1049,9 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
 		treg = TIMER_REG_CVAL;
 		break;
 	default:
-		BUG();
+		print_sys_reg_msg(p, "%s", "Unhandled trapped timer register");
+		kvm_inject_undefined(vcpu);
+		return false;
 	}
 
 	if (p->is_write)
-- 
2.34.1


WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	<kvmarm@lists.cs.columbia.edu>, <kvmarm@lists.linux.dev>,
	kvm@vger.kernel.org
Cc: D Scott Phillips <scott@os.amperecomputing.com>,
	Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH 3/3] KVM: arm64: timers: Don't BUG() on unhandled timer trap
Date: Thu, 12 Jan 2023 12:38:29 +0000	[thread overview]
Message-ID: <20230112123829.458912-4-maz@kernel.org> (raw)
In-Reply-To: <20230112123829.458912-1-maz@kernel.org>

Although not handling a trap is a pretty bad situation to be in,
panicing the kernel isn't useful and provides no valuable
information to help debugging the situation.

Instead, dump the encoding of the unhandled sysreg, and inject
an UNDEF in the guest. At least, this gives a user an opportunity
to report the issue with some information to help debugging it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/sys_regs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d5ee52d6bf73..32f4e424b9a5 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1049,7 +1049,9 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
 		treg = TIMER_REG_CVAL;
 		break;
 	default:
-		BUG();
+		print_sys_reg_msg(p, "%s", "Unhandled trapped timer register");
+		kvm_inject_undefined(vcpu);
+		return false;
 	}
 
 	if (p->is_write)
-- 
2.34.1


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  parent reply	other threads:[~2023-01-12 12:38 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-12 12:38 [PATCH 0/3] KVM: arm64: timer fixes and optimisations Marc Zyngier
2023-01-12 12:38 ` Marc Zyngier
2023-01-12 12:38 ` [PATCH 1/3] KVM: arm64: Don't arm a hrtimer for an already pending timer Marc Zyngier
2023-01-12 12:38   ` Marc Zyngier
2023-01-12 12:38 ` [PATCH 2/3] KVM: arm64: Reduce overhead of trapped timer sysreg accesses Marc Zyngier
2023-01-12 12:38   ` Marc Zyngier
2023-01-12 12:38 ` Marc Zyngier [this message]
2023-01-12 12:38   ` [PATCH 3/3] KVM: arm64: timers: Don't BUG() on unhandled timer trap Marc Zyngier
2023-01-30 18:30 ` [PATCH 0/3] KVM: arm64: timer fixes and optimisations Oliver Upton
2023-01-30 18:30   ` Oliver Upton

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