From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paul Mackerras <paulus@ozlabs.org>
Date: Tue, 22 Oct 2019 00:43:35 +0000
Subject: Re: [PATCH 2/3] powerpc/kvm/book3e: Replace current->mm by kvm->mm
Message-Id: <20191022004335.GA30981@oak.ozlabs.ibm.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <20190923212409.7153-1-leonardo@linux.ibm.com>
 <20190923212409.7153-3-leonardo@linux.ibm.com>
In-Reply-To: <20190923212409.7153-3-leonardo@linux.ibm.com>
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To: Leonardo Bras <leonardo@linux.ibm.com>
Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Michael Ellerman <mpe@ellerman.id.au>

On Mon, Sep 23, 2019 at 06:24:08PM -0300, Leonardo Bras wrote:
> Given that in kvm_create_vm() there is:
> kvm->mm = current->mm;
> 
> And that on every kvm_*_ioctl we have:
> if (kvm->mm != current->mm)
> 	return -EIO;
> 
> I see no reason to keep using current->mm instead of kvm->mm.
> 
> By doing so, we would reduce the use of 'global' variables on code, relying
> more in the contents of kvm struct.
> 
> Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
> ---
>  arch/powerpc/kvm/booke.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index be9a45874194..383108263af5 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -775,7 +775,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
>  	debug = current->thread.debug;
>  	current->thread.debug = vcpu->arch.dbg_reg;
>  
> -	vcpu->arch.pgdir = current->mm->pgd;
> +	vcpu->arch.pgdir = kvm->mm->pgd;
>  	kvmppc_fix_ee_before_entry();
>  
>  	ret = __kvmppc_vcpu_run(kvm_run, vcpu);

With this patch, I get compile errors for Book E configs:

  CC      arch/powerpc/kvm/booke.o
/home/paulus/kernel/kvm/arch/powerpc/kvm/booke.c: In function ‘kvmppc_vcpu_run’:
/home/paulus/kernel/kvm/arch/powerpc/kvm/booke.c:778:21: error: ‘kvm’ undeclared (first use in this function)
  vcpu->arch.pgdir = kvm->mm->pgd;
                     ^
/home/paulus/kernel/kvm/arch/powerpc/kvm/booke.c:778:21: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [/home/paulus/kernel/kvm/scripts/Makefile.build:266: arch/powerpc/kvm/booke.o] Error 1
make[2]: *** [/home/paulus/kernel/kvm/scripts/Makefile.build:509: arch/powerpc/kvm] Error 2
make[1]: *** [/home/paulus/kernel/kvm/Makefile:1649: arch/powerpc] Error 2
make: *** [/home/paulus/kernel/kvm/Makefile:179: sub-make] Error 2

It seems that you didn't compile-test this patch.

Paul.