linux-kernel - Re: [PATCH v2 26/50] KVM: PPC: Move processor compatibility check to module init

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Date:   Thu, 01 Dec 2022 16:21:31 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Paul Durrant <paul@....org>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Atish Patra <atishp@...shpatra.org>,
        David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yuan Yao <yuan.yao@...el.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        Philippe Mathieu-Daudé <philmd@...aro.org>,
        Fabiano Rosas <farosas@...ux.ibm.com>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 26/50] KVM: PPC: Move processor compatibility check
 to module init

Sean Christopherson <seanjc@...gle.com> writes:
> Move KVM PPC's compatibility checks to their respective module_init()
> hooks, there's no need to wait until KVM's common compat check, nor is
> there a need to perform the check on every CPU (provided by common KVM's
> hook), as the compatibility checks operate on global data.
>
>   arch/powerpc/include/asm/cputable.h: extern struct cpu_spec *cur_cpu_spec;
>   arch/powerpc/kvm/book3s.c: return 0
>   arch/powerpc/kvm/e500.c: strcmp(cur_cpu_spec->cpu_name, "e500v2")
>   arch/powerpc/kvm/e500mc.c: strcmp(cur_cpu_spec->cpu_name, "e500mc")
>                              strcmp(cur_cpu_spec->cpu_name, "e5500")
>                              strcmp(cur_cpu_spec->cpu_name, "e6500")

I'm not sure that output is really useful in the change log unless you
explain more about what it is.

> diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
> index 57e0ad6a2ca3..795667f7ebf0 100644
> --- a/arch/powerpc/kvm/e500mc.c
> +++ b/arch/powerpc/kvm/e500mc.c
> @@ -388,6 +388,10 @@ static int __init kvmppc_e500mc_init(void)
>  {
>  	int r;
>  
> +	r = kvmppc_e500mc_check_processor_compat();
> +	if (r)
> +		return kvmppc_e500mc;
 
This doesn't build:

linux/arch/powerpc/kvm/e500mc.c: In function ‘kvmppc_e500mc_init’:
linux/arch/powerpc/kvm/e500mc.c:391:13: error: implicit declaration of function ‘kvmppc_e500mc_check_processor_compat’; did you mean ‘kvmppc_core_check_processor_compat’? [-Werror=implicit-function-declaration]
  391 |         r = kvmppc_e500mc_check_processor_compat();
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |             kvmppc_core_check_processor_compat
linux/arch/powerpc/kvm/e500mc.c:393:24: error: ‘kvmppc_e500mc’ undeclared (first use in this function); did you mean ‘kvm_ops_e500mc’?
  393 |                 return kvmppc_e500mc;
      |                        ^~~~~~~~~~~~~
      |                        kvm_ops_e500mc
linux/arch/powerpc/kvm/e500mc.c:393:24: note: each undeclared identifier is reported only once for each function it appears in


It needs the delta below to compile.

With that:

Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)

cheers


diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 795667f7ebf0..4564aa27edcf 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/arch/powerpc/kvm/e500mc.c
@@ -168,7 +168,7 @@ static void kvmppc_core_vcpu_put_e500mc(struct kvm_vcpu *vcpu)
 	kvmppc_booke_vcpu_put(vcpu);
 }
 
-int kvmppc_core_check_processor_compat(void)
+int kvmppc_e500mc_check_processor_compat(void)
 {
 	int r;
 
@@ -390,7 +390,7 @@ static int __init kvmppc_e500mc_init(void)
 
 	r = kvmppc_e500mc_check_processor_compat();
 	if (r)
-		return kvmppc_e500mc;
+		goto err_out;
 
 	r = kvmppc_booke_init();
 	if (r)