From: Nina Schoetterl-Glausch Date: Fri, 12 Jun 2026 12:23:01 +0000 (+0200) Subject: KVM: s390: Minor refactor of base/ext facility lists X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=20dcfaf2d3261ef84631114ae37213f5ebd3eb37;p=thirdparty%2Flinux.git KVM: s390: Minor refactor of base/ext facility lists Directly use the size of the arrays instead of going through the indirection of kvm_s390_fac_size(). 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 Reviewed-by: Janosch Frank Reviewed-by: Claudio Imbrenda Signed-off-by: Claudio Imbrenda Message-ID: <20260612-vsie-alter-stfle-fac-v4-1-74f0e1559929@linux.ibm.com> --- diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index d503e4d0072a..7334c160d019 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -237,33 +237,25 @@ static int async_destroy = 1; module_param(async_destroy, int, 0444); MODULE_PARM_DESC(async_destroy, "Asynchronous destroy for protected guests"); -/* - * 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 beyond - * 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] = { FACILITIES_KVM }; +static unsigned long kvm_s390_fac_base[HMFAI_DWORDS] = { FACILITIES_KVM }; +static_assert(ARRAY_SIZE(((long[]){ FACILITIES_KVM })) <= HMFAI_DWORDS); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <= S390_ARCH_FAC_MASK_SIZE_U64); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <= S390_ARCH_FAC_LIST_SIZE_U64); +static_assert(ARRAY_SIZE(kvm_s390_fac_base) <= ARRAY_SIZE(stfle_fac_list)); + /* * Extended feature mask. Consists of the defines in FACILITIES_KVM_CPUMODEL * and defines the facilities that can be enabled via a cpu model. */ -static unsigned long kvm_s390_fac_ext[SIZE_INTERNAL] = { 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[] = { FACILITIES_KVM_CPUMODEL }; +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <= S390_ARCH_FAC_MASK_SIZE_U64); +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <= S390_ARCH_FAC_LIST_SIZE_U64); +static_assert(ARRAY_SIZE(kvm_s390_fac_ext) <= ARRAY_SIZE(stfle_fac_list)); /* available cpu features supported by kvm */ static DECLARE_BITMAP(kvm_s390_available_cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS); @@ -3249,13 +3241,16 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.sie_page2->kvm = kvm; kvm->arch.model.fac_list = kvm->arch.sie_page2->fac_list; - for (i = 0; i < kvm_s390_fac_size(); i++) { + for (i = 0; i < ARRAY_SIZE(kvm_s390_fac_base); i++) { kvm->arch.model.fac_mask[i] = 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] = stfle_fac_list[i] & kvm_s390_fac_base[i]; } + for (i = 0; i < ARRAY_SIZE(kvm_s390_fac_ext); i++) { + kvm->arch.model.fac_mask[i] |= stfle_fac_list[i] & + kvm_s390_fac_ext[i]; + } kvm->arch.model.subfuncs = kvm_s390_available_subfunc; /* we are always in czam mode - even on pre z14 machines */ @@ -5878,9 +5873,8 @@ static int __init kvm_s390_init(void) pr_info("Disabling 2G hugepage support, since 1M hugepage support is not enabled.\n"); } - for (i = 0; i < 16; i++) - kvm_s390_fac_base[i] |= - stfle_fac_list[i] & nonhyp_mask(i); + for (i = 0; i < HMFAI_DWORDS; i++) + kvm_s390_fac_base[i] |= nonhyp_mask(i); r = __kvm_s390_init(); if (r)