linux-kernel - [PATCH v2 3/4] KVM: arm64: Use BUG and BUG

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Date:   Tue, 23 Feb 2021 15:57:58 +0000
From:   Andrew Scull <ascull@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-kernel@...r.kernel.org, maz@...nel.org, james.morse@....com,
        suzuki.poulose@....com, julien.thierry.kdev@...il.com,
        will@...nel.org, catalin.marinas@....com, kernel-team@...roid.com,
        Andrew Scull <ascull@...gle.com>
Subject: [PATCH v2 3/4] KVM: arm64: Use BUG and BUG_ON in nVHE hyp

hyp_panic() reports the address of the panic by using ELR_EL2, but this
isn't a useful address when hyp_panic() is called directly. Replace such
direct calls with BUG() and BUG_ON() which use BRK to trigger and
exception that then goes to hyp_panic() with the correct address. Also
remove the hyp_panic() declaration from the header file to avoid
accidental misuse.

Signed-off-by: Andrew Scull <ascull@...gle.com>
---
 arch/arm64/include/asm/kvm_hyp.h   | 1 -
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +-
 arch/arm64/kvm/hyp/nvhe/hyp-smp.c  | 6 ++----
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index fb8404fefd1f..746eb9a2891b 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -95,7 +95,6 @@ u64 __guest_enter(struct kvm_vcpu *vcpu);
 
 bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt);
 
-void __noreturn hyp_panic(void);
 #ifdef __KVM_NVHE_HYPERVISOR__
 void __noreturn __hyp_do_panic(struct kvm_cpu_context *host_ctxt, u64 spsr,
 			       u64 elr, u64 par);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index a906f9e2ff34..9f37a4240562 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -181,6 +181,6 @@ void handle_trap(struct kvm_cpu_context *host_ctxt)
 		handle_host_smc(host_ctxt);
 		break;
 	default:
-		hyp_panic();
+		BUG();
 	}
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
index 2997aa156d8e..4495aed04240 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
@@ -18,8 +18,7 @@ u64 __ro_after_init hyp_cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID
 
 u64 cpu_logical_map(unsigned int cpu)
 {
-	if (cpu >= ARRAY_SIZE(hyp_cpu_logical_map))
-		hyp_panic();
+	BUG_ON(cpu >= ARRAY_SIZE(hyp_cpu_logical_map));
 
 	return hyp_cpu_logical_map[cpu];
 }
@@ -30,8 +29,7 @@ unsigned long __hyp_per_cpu_offset(unsigned int cpu)
 	unsigned long this_cpu_base;
 	unsigned long elf_base;
 
-	if (cpu >= ARRAY_SIZE(kvm_arm_hyp_percpu_base))
-		hyp_panic();
+	BUG_ON(cpu >= ARRAY_SIZE(kvm_arm_hyp_percpu_base));
 
 	cpu_base_array = (unsigned long *)hyp_symbol_addr(kvm_arm_hyp_percpu_base);
 	this_cpu_base = kern_hyp_va(cpu_base_array[cpu]);
-- 
2.30.0.617.g56c4b15f3c-goog