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t=1788683257; bh=s9ZM75Oj1X5kSc3IVFNLWbiJNUqBfJ8HFbN3imH3XNM=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=LEaSjZJzcZh5DGcvXdyiiI5ZPI69KmLsiONdb27CcK2pOBlqgkoLV9ANAKT6N6QJt QVJooOn5NfL8Z8krU/IidkYMfWo7mwRRGt6q1jyMMgc8fnFqs+8HJS4beV3f7vui0t zDGgt1ejbZhXGLMlb0Xf0C6KPo2gj5gyKUid8F/0n33qu4cSi3mgKV2QPsM8C2k6ds L7cqss+5Ej9CDdnO6SxSHcK04CLzQ/KrPrOgvhy9KZlrt4uiAbSiYACkYWXMp5RaSu aly5fL+egIsPNx0EQ/fkGBZRXeUExX3kZyAOkBo7MmbvJIgHZWLCQmcz3dXghQD7VZ +IB2+fC92Tr5Q== From: "Mike Rapoport (Microsoft)" Date: Sun, 06 Sep 2026 11:27:12 +0300 Subject: [PATCH v2 4/4] KVM: s390: Replace get_zeroed_page() with kzalloc() for sie_page2 and CMMA MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260906-s390-kvm-v2-4-2cf6434e6646@kernel.org> References: <20260906-s390-kvm-v2-0-2cf6434e6646@kernel.org> In-Reply-To: <20260906-s390-kvm-v2-0-2cf6434e6646@kernel.org> To: Christian Borntraeger , Claudio Imbrenda , Janosch Frank Cc: Alexander Gordeev , David Hildenbrand , Heiko Carstens , Mike Rapoport , Sven Schnelle , Vasily Gorbik , Vlastimil Babka , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org X-Mailer: b4 0.17-dev X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2C54E1A0006 X-Stat-Signature: 6ysrkgorfrbeizr3by4he6jwzc7zrair X-HE-Tag: 1788683258-667765 X-HE-Meta: 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 oWbwySB1 SmYPx743UCTOhyA/C3UvTGKeOMAg+m0PnjTPeuRn7mmD6or+mDxcE52kAJ+CuNY4YQeiYnqZQkzKgPd/lPf+T47hst4LG7tAbsSP+8iwudwigWML6GgDT8XKXChP97opjvdcD5Cn2CSu83M2D4YSXaeRFPieMQ3YItt/NcYhGlil8YUoTUWoKKiLgGY41PnkapzLuUZeSas8gIxV1kdJzACnbJDUmo7FBRADp4lCHkmXQE9LRtu9YV38fy+5rN3ozaz59goTE3CRV/ltI4cO6CXJan3419RbAhcl/vjdVdsbsaBg9uwZ7keip3qh9x63cVaRU Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: kvm_arch_init_vm() allocates struct sie_page2 that holds the facility list and the crypto control block of a VM and kvm_s390_vcpu_setup_cmma() allocates the CMMA collaborative memory management block referenced by the SIE control block. Both are passed to the hardware as physical addresses and must be page aligned. kmalloc() guarantees that a power of two sized allocation is aligned to its size, so a PAGE_SIZE allocation is page aligned as well. These buffers can be allocated with kmalloc() as there's nothing special about them to go directly to the page allocator. kmalloc() provides a better API that does not require ugly casts and kfree() does not need to know the size of the freed object. Performance difference between kmalloc() and __get_free_pages() is not measurable as both allocators take an object/page from a per-CPU list for fast path allocations. For the slow path the performance is anyway determined by the amount of reclaim involved rather than by what allocator is used. The sie_page allocated in kvm_arch_vcpu_create() is left alone because it is mapped to userspace with virt_to_page() in kvm_arch_vcpu_fault() and therefore really needs a struct page. The SIE hardware stores the offset of the next CBR entry in the low bits of cbrlo, so mask them out before converting cbrlo back to a virtual address. free_page() did not care, kfree() needs the address kzalloc() returned. Replace use of get_zeroed_page() with kzalloc() and free_page() with kfree(). Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com Assisted-by: copilot:claude-opus Signed-off-by: Mike Rapoport (Microsoft) --- arch/s390/kvm/s390/s390.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/s390/kvm/s390/s390.c b/arch/s390/kvm/s390/s390.c index b0839e887221e..1d9eea64f3dbd 100644 --- a/arch/s390/kvm/s390/s390.c +++ b/arch/s390/kvm/s390/s390.c @@ -3273,8 +3273,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) goto out_err; BUILD_BUG_ON(sizeof(struct sie_page2) != 4096); - kvm->arch.sie_page2 = - (struct sie_page2 *) get_zeroed_page(GFP_KERNEL_ACCOUNT | GFP_DMA); + kvm->arch.sie_page2 = kzalloc_obj(*kvm->arch.sie_page2, + GFP_KERNEL_ACCOUNT | GFP_DMA); if (!kvm->arch.sie_page2) goto out_err; @@ -3369,7 +3369,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) return 0; out_err: - free_page((unsigned long)kvm->arch.sie_page2); + kfree(kvm->arch.sie_page2); debug_unregister(kvm->arch.dbf); sca_dispose(kvm); KVM_EVENT(3, "creation of vm failed: %d", rc); @@ -3427,7 +3427,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) mmu_notifier_unregister(&kvm->arch.pv.mmu_notifier, kvm->mm); debug_unregister(kvm->arch.dbf); - free_page((unsigned long)kvm->arch.sie_page2); + kfree(kvm->arch.sie_page2); kvm_s390_destroy_adapters(kvm); kvm_s390_clear_float_irqs(kvm); kvm_s390_vsie_destroy(kvm); @@ -3657,13 +3657,13 @@ static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu) void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu) { if (vcpu->arch.sie_block->cbrlo) - free_page((unsigned long)phys_to_virt(vcpu->arch.sie_block->cbrlo)); + kfree(phys_to_virt(vcpu->arch.sie_block->cbrlo & PAGE_MASK)); vcpu->arch.sie_block->cbrlo = 0; } int kvm_s390_vcpu_setup_cmma(struct kvm_vcpu *vcpu) { - void *cbrlo_page = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + void *cbrlo_page = kzalloc(PAGE_SIZE, GFP_KERNEL_ACCOUNT); if (!cbrlo_page) return -ENOMEM; -- 2.53.0