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Shutemov" X-Google-Original-From: "Kirill A. Shutemov" Received: by box.localdomain (Postfix, from userid 1000) id 3C9F0102F6F; Tue, 20 Oct 2020 09:19:02 +0300 (+03) To: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Cc: David Rientjes , Andrea Arcangeli , Kees Cook , Will Drewry , "Edgecombe, Rick P" , "Kleen, Andi" , Liran Alon , Mike Rapoport , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [RFCv2 16/16] mm: Do not use zero page for VM_KVM_PROTECTED VMAs Date: Tue, 20 Oct 2020 09:18:59 +0300 Message-Id: <20201020061859.18385-17-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> References: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Presence of zero pages in the mapping would disclose content of the mapping. Don't use them if KVM memory protection is enabled. Signed-off-by: Kirill A. Shutemov --- arch/s390/include/asm/pgtable.h | 2 +- include/linux/mm.h | 4 ++-- mm/huge_memory.c | 3 +-- mm/memory.c | 3 +-- 4 files changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index b55561cc8786..72ca3b3f04cb 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -543,7 +543,7 @@ static inline int mm_alloc_pgste(struct mm_struct *mm) * In the case that a guest uses storage keys * faults should no longer be backed by zero pages */ -#define mm_forbids_zeropage mm_has_pgste +#define vma_forbids_zeropage(vma) mm_has_pgste(vma->vm_mm) static inline int mm_uses_skeys(struct mm_struct *mm) { #ifdef CONFIG_PGSTE diff --git a/include/linux/mm.h b/include/linux/mm.h index 74efc51e63f0..ee713b7c2819 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -130,8 +130,8 @@ extern int mmap_rnd_compat_bits __read_mostly; * s390 does this to prevent multiplexing of hardware bits * related to the physical page in case of virtualization. */ -#ifndef mm_forbids_zeropage -#define mm_forbids_zeropage(X) (0) +#ifndef vma_forbids_zeropage +#define vma_forbids_zeropage(vma) vma_is_kvm_protected(vma) #endif /* diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 40974656cb43..383614b24c4f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -709,8 +709,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) return VM_FAULT_OOM; if (unlikely(khugepaged_enter(vma, vma->vm_flags))) return VM_FAULT_OOM; - if (!(vmf->flags & FAULT_FLAG_WRITE) && - !mm_forbids_zeropage(vma->vm_mm) && + if (!(vmf->flags & FAULT_FLAG_WRITE) && !vma_forbids_zeropage(vma) && transparent_hugepage_use_zero_page()) { pgtable_t pgtable; struct page *zero_page; diff --git a/mm/memory.c b/mm/memory.c index e28bd5f902a7..9907ffe00490 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3495,8 +3495,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) return 0; /* Use the zero-page for reads */ - if (!(vmf->flags & FAULT_FLAG_WRITE) && - !mm_forbids_zeropage(vma->vm_mm)) { + if (!(vmf->flags & FAULT_FLAG_WRITE) && !vma_forbids_zeropage(vma)) { entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), vma->vm_page_prot)); vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, -- 2.26.2