On 8/10/21 6:58 PM, Will Deacon wrote:

On Tue, Aug 10, 2021 at 12:32:39PM +0530, Anshuman Khandual wrote:

quoted

kvm_target_cpu() never returns a negative error code, so check_kvm_target()
would never have 'ret' filled with a negative error code. Hence the percpu
probe via check_kvm_target_cpu() does not make sense as its never going to
find an unsupported CPU, forcing kvm_arch_init() to exit early. Hence lets
just drop this percpu probe (and also check_kvm_target_cpu()) altogether.

Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Alexandru Elisei <redacted>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <redacted>
---
 arch/arm64/kvm/arm.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 19560e457c11..16f93678c17e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c

@@ -2010,11 +2010,6 @@ static int finalize_hyp_mode(void)
 	return 0;
 }
 
-static void check_kvm_target_cpu(void *ret)
-{
-	*(int *)ret = kvm_target_cpu();
-}
-
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
 {
 	struct kvm_vcpu *vcpu;

@@ -2074,7 +2069,6 @@ void kvm_arch_irq_bypass_start(struct irq_bypass_consumer *cons)
 int kvm_arch_init(void *opaque)
 {
 	int err;
-	int ret, cpu;
 	bool in_hyp_mode;
 
 	if (!is_hyp_mode_available()) {

@@ -2089,14 +2083,6 @@ int kvm_arch_init(void *opaque)
 		kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \
 			 "Only trusted guests should be used on this system.\n");
 
-	for_each_online_cpu(cpu) {
-		smp_call_function_single(cpu, check_kvm_target_cpu, &ret, 1);
-		if (ret < 0) {
-			kvm_err("Error, CPU %d not supported!\n", cpu);
-			return -ENODEV;
-		}
-	}

Looks like kvm_target_cpu() *could* return an error at one time of day (at
least on 32-bit), but agreed that this checking is no longer needed:

Acked-by: Will Deacon <will@kernel.org>

Perhaps it's worth making the return type of kvm_target_cpu() a u32 to
make it a bit more explicit that you shouldn't be returning an error code
there?

Sure, will change the return type to u32.

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