[PATCH AUTOSEL 5.12 039/116] KVM: arm64: Use BUG and BUG_ON in nVHE hyp

[PATCH AUTOSEL 5.12 039/116] KVM: arm64: Use BUG and BUG_ON in nVHE hyp

[Sasha Levin]

From: Andrew Scull <ascull@google.com>

[ Upstream commit f79e616f27ab6cd74deb0995a8eead3d1c9d65af ]

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 an
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@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210318143311.839894-5-ascull@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 32ae676236b6..fe5fc814f228 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -100,7 +100,6 @@ 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 936328207bde..821a69601dd9 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -178,6 +178,6 @@ 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 879559057dee..9f54833af400 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 *)&kvm_arm_hyp_percpu_base;
 	this_cpu_base = kern_hyp_va(cpu_base_array[cpu]);
-- 
2.30.2

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Re: [PATCH AUTOSEL 5.12 039/116] KVM: arm64: Use BUG and BUG_ON in nVHE hyp

[Marc Zyngier]

On Wed, 05 May 2021 17:30:07 +0100,
Sasha Levin <sashal@kernel.org> wrote:
> 
> From: Andrew Scull <ascull@google.com>
> 
> [ Upstream commit f79e616f27ab6cd74deb0995a8eead3d1c9d65af ]
> 
> 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 an
> 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@google.com>
> Acked-by: Will Deacon <will@kernel.org>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Link: https://lore.kernel.org/r/20210318143311.839894-5-ascull@google.com
> Signed-off-by: Sasha Levin <sashal@kernel.org>

Same this for this patch.

	M.

-- 
Without deviation from the norm, progress is not possible.
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