linux-kernel - Re: [PATCH] KVM: s390: rename PROT_NONE to PROT_TYPE

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Message-ID: <ac567448-0dd1-48dd-ad54-d71215629c96@os.amperecomputing.com>
Date: Wed, 14 May 2025 10:46:04 -0700
From: Yang Shi <yang@...amperecomputing.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@...a.com>,
 linux-mm@...ck.org, Janosch Frank <frankja@...ux.ibm.com>,
 David Hildenbrand <david@...hat.com>, Heiko Carstens <hca@...ux.ibm.com>,
 Vasily Gorbik <gor@...ux.ibm.com>, Alexander Gordeev
 <agordeev@...ux.ibm.com>, Sven Schnelle <svens@...ux.ibm.com>,
 kvm@...r.kernel.org, linux-s390@...r.kernel.org,
 linux-kernel@...r.kernel.org, pbonzini@...hat.com
Subject: Re: [PATCH] KVM: s390: rename PROT_NONE to PROT_TYPE_DUMMY



On 5/14/25 9:35 AM, Lorenzo Stoakes wrote:
> The enum type prot_type declared in arch/s390/kvm/gaccess.c declares an
> unfortunate identifier within it - PROT_NONE.
>
> This clashes with the protection bit define from the uapi for mmap()
> declared in include/uapi/asm-generic/mman-common.h, which is indeed what
> those casually reading this code would assume this to refer to.
>
> This means that any changes which subsequently alter headers in any way
> which results in the uapi header being imported here will cause build
> errors.
>
> Resolve the issue by renaming PROT_NONE to PROT_TYPE_DUMMY.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Suggested-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@...a.com>
> Fixes: b3cefd6bf16e ("KVM: s390: Pass initialized arg even if unused")
> Cc: stable@...r.kernel.org
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202505140943.IgHDa9s7-lkp@intel.com/
> ---
>
> Andrew - sorry to be a pain - this needs to land before
> https://lore.kernel.org/all/20250508-madvise-nohugepage-noop-without-thp-v1-1-e7ceffb197f3@kuka.com/
>
> I can resend this as a series with it if that makes it easier for you? Let
> me know if there's anything I can do to make it easier to get the ordering right here.
>
> Thanks!
>
>   arch/s390/kvm/gaccess.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)

Acked-by: Yang Shi <yang@...amperecomputing.com>

>
> diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
> index f6fded15633a..4e5654ad1604 100644
> --- a/arch/s390/kvm/gaccess.c
> +++ b/arch/s390/kvm/gaccess.c
> @@ -318,7 +318,7 @@ enum prot_type {
>   	PROT_TYPE_DAT  = 3,
>   	PROT_TYPE_IEP  = 4,
>   	/* Dummy value for passing an initialized value when code != PGM_PROTECTION */
> -	PROT_NONE,
> +	PROT_TYPE_DUMMY,
>   };
>
>   static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva, u8 ar,
> @@ -334,7 +334,7 @@ static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva,
>   	switch (code) {
>   	case PGM_PROTECTION:
>   		switch (prot) {
> -		case PROT_NONE:
> +		case PROT_TYPE_DUMMY:
>   			/* We should never get here, acts like termination */
>   			WARN_ON_ONCE(1);
>   			break;
> @@ -804,7 +804,7 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
>   			gpa = kvm_s390_real_to_abs(vcpu, ga);
>   			if (!kvm_is_gpa_in_memslot(vcpu->kvm, gpa)) {
>   				rc = PGM_ADDRESSING;
> -				prot = PROT_NONE;
> +				prot = PROT_TYPE_DUMMY;
>   			}
>   		}
>   		if (rc)
> @@ -962,7 +962,7 @@ int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
>   		if (rc == PGM_PROTECTION)
>   			prot = PROT_TYPE_KEYC;
>   		else
> -			prot = PROT_NONE;
> +			prot = PROT_TYPE_DUMMY;
>   		rc = trans_exc_ending(vcpu, rc, ga, ar, mode, prot, terminate);
>   	}
>   out_unlock:
> --
> 2.49.0