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Thu, 26 Feb 2026 12:49:32 +0000 (GMT) From: Christoph Schlameuss Date: Thu, 26 Feb 2026 13:49:04 +0100 Subject: [PATCH v2 1/4] KVM: s390: Minor refactor of base/ext facility lists Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260226-vsie-alter-stfle-fac-v2-1-914974cb922c@linux.ibm.com> References: <20260226-vsie-alter-stfle-fac-v2-0-914974cb922c@linux.ibm.com> In-Reply-To: <20260226-vsie-alter-stfle-fac-v2-0-914974cb922c@linux.ibm.com> To: linux-s390@vger.kernel.org Cc: David Hildenbrand , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Hendrik Brueckner , Nina Schoetterl-Glausch , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Schlameuss X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4114; i=schlameuss@linux.ibm.com; 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Don't use magic number for the number of entries in the non hypervisor managed facility bit mask list. Make the constraint of that number on kvm_s390_fac_base obvious. Get rid of implicit double anding of stfle_fac_list. Signed-off-by: Nina Schoetterl-Glausch Co-developed-by: Christoph Schlameuss Signed-off-by: Christoph Schlameuss --- arch/s390/kvm/kvm-s390.c | 44 +++++++++++++++++++------------------------- 1 file changed, 19 insertions(+), 25 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 7a175d86cef0359ec71b6b631b5808e9f626fb9e..1a4abac697a40079c4dd6566581= aaed321871a1f 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -232,33 +232,25 @@ static int async_destroy =3D 1; module_param(async_destroy, int, 0444); MODULE_PARM_DESC(async_destroy, "Asynchronous destroy for protected guests= "); =20 -/* - * For now we handle at most 16 double words as this is what the s390 base - * kernel handles and stores in the prefix page. If we ever need to go bey= ond - * this, this requires changes to code, but the external uapi can stay. - */ -#define SIZE_INTERNAL 16 - +#define HMFAI_DWORDS 16 /* * Base feature mask that defines default mask for facilities. Consists of= the * defines in FACILITIES_KVM and the non-hypervisor managed bits. */ -static unsigned long kvm_s390_fac_base[SIZE_INTERNAL] =3D { FACILITIES_KVM= }; +static unsigned long kvm_s390_fac_base[HMFAI_DWORDS] =3D { FACILITIES_KVM = }; +static_assert(ARRAY_SIZE(((long[]){ FACILITIES_KVM })) <=3D HMFAI_DWORDS); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <=3D S390_ARCH_FAC_MASK_SIZE_U= 64); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <=3D S390_ARCH_FAC_LIST_SIZE_U= 64); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <=3D ARRAY_SIZE(stfle_fac_list= )); + /* * Extended feature mask. Consists of the defines in FACILITIES_KVM_CPUMOD= EL * and defines the facilities that can be enabled via a cpu model. */ -static unsigned long kvm_s390_fac_ext[SIZE_INTERNAL] =3D { FACILITIES_KVM_= CPUMODEL }; - -static unsigned long kvm_s390_fac_size(void) -{ - BUILD_BUG_ON(SIZE_INTERNAL > S390_ARCH_FAC_MASK_SIZE_U64); - BUILD_BUG_ON(SIZE_INTERNAL > S390_ARCH_FAC_LIST_SIZE_U64); - BUILD_BUG_ON(SIZE_INTERNAL * sizeof(unsigned long) > - sizeof(stfle_fac_list)); - - return SIZE_INTERNAL; -} +static const unsigned long kvm_s390_fac_ext[] =3D { FACILITIES_KVM_CPUMODE= L }; +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <=3D S390_ARCH_FAC_MASK_SIZE_U6= 4); +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <=3D S390_ARCH_FAC_LIST_SIZE_U6= 4); +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <=3D ARRAY_SIZE(stfle_fac_list)= ); =20 /* available cpu features supported by kvm */ static DECLARE_BITMAP(kvm_s390_available_cpu_feat, KVM_S390_VM_CPU_FEAT_NR= _BITS); @@ -3212,13 +3204,16 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long= type) kvm->arch.sie_page2->kvm =3D kvm; kvm->arch.model.fac_list =3D kvm->arch.sie_page2->fac_list; =20 - for (i =3D 0; i < kvm_s390_fac_size(); i++) { + for (i =3D 0; i < ARRAY_SIZE(kvm_s390_fac_base); i++) { kvm->arch.model.fac_mask[i] =3D stfle_fac_list[i] & - (kvm_s390_fac_base[i] | - kvm_s390_fac_ext[i]); + kvm_s390_fac_base[i]; kvm->arch.model.fac_list[i] =3D stfle_fac_list[i] & kvm_s390_fac_base[i]; } + for (i =3D 0; i < ARRAY_SIZE(kvm_s390_fac_ext); i++) { + kvm->arch.model.fac_mask[i] |=3D stfle_fac_list[i] & + kvm_s390_fac_ext[i]; + } kvm->arch.model.subfuncs =3D kvm_s390_available_subfunc; =20 /* we are always in czam mode - even on pre z14 machines */ @@ -5788,9 +5783,8 @@ static int __init kvm_s390_init(void) return -ENODEV; } =20 - for (i =3D 0; i < 16; i++) - kvm_s390_fac_base[i] |=3D - stfle_fac_list[i] & nonhyp_mask(i); + for (i =3D 0; i < HMFAI_DWORDS; i++) + kvm_s390_fac_base[i] |=3D nonhyp_mask(i); =20 r =3D __kvm_s390_init(); if (r) --=20 2.53.0