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Only page missing event is currently supported. Signed-off-by: Nikita Kalyazin --- virt/kvm/guest_memfd.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index af825f7494ea..358c3776ed66 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -4,6 +4,9 @@ #include #include #include +#ifdef CONFIG_KVM_PRIVATE_MEM +#include +#endif /* CONFIG_KVM_PRIVATE_MEM */ #include "kvm_mm.h" @@ -332,9 +335,16 @@ static vm_fault_t kvm_gmem_fault(struct vm_fault *vmf) struct folio *folio; vm_fault_t ret = VM_FAULT_LOCKED; + folio = filemap_get_entry(inode->i_mapping, vmf->pgoff); + if (!folio && userfaultfd_missing(vmf->vma)) + return handle_userfault(vmf, VM_UFFD_MISSING); + if (folio) + folio_lock(folio); + filemap_invalidate_lock_shared(inode->i_mapping); - folio = kvm_gmem_get_folio(inode, vmf->pgoff); + if (!folio) + folio = kvm_gmem_get_folio(inode, vmf->pgoff); if (IS_ERR(folio)) { switch (PTR_ERR(folio)) { case -EAGAIN: From patchwork Mon Mar 3 13:30:10 2025 Content-Type: text/plain; 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Mon, 3 Mar 2025 13:31:08 +0000 Received: from EX19MTAUWC002.ant.amazon.com (10.250.64.143) by EX19D003UWB004.ant.amazon.com (10.13.138.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14; Mon, 3 Mar 2025 13:31:07 +0000 Received: from email-imr-corp-prod-pdx-all-2c-785684ef.us-west-2.amazon.com (10.25.36.210) by mail-relay.amazon.com (10.250.64.149) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14 via Frontend Transport; Mon, 3 Mar 2025 13:31:07 +0000 Received: from dev-dsk-kalyazin-1a-a12e27e2.eu-west-1.amazon.com (dev-dsk-kalyazin-1a-a12e27e2.eu-west-1.amazon.com [172.19.103.116]) by email-imr-corp-prod-pdx-all-2c-785684ef.us-west-2.amazon.com (Postfix) with ESMTPS id 27701A1025; Mon, 3 Mar 2025 13:31:05 +0000 (UTC) From: Nikita Kalyazin To: , , CC: , , , , , , , , , , , , , , , , Subject: [RFC PATCH 4/5] mm: userfaultfd: support continue for guest_memfd Date: Mon, 3 Mar 2025 13:30:10 +0000 Message-ID: <20250303133011.44095-5-kalyazin@amazon.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250303133011.44095-1-kalyazin@amazon.com> References: <20250303133011.44095-1-kalyazin@amazon.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 When userspace receives a page missing event, it is supposed to populate the missing page in guest_memfd pagecache via the write syscall and unblock the faulting process via UFFDIO_CONTINUE. Signed-off-by: Nikita Kalyazin --- mm/userfaultfd.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index af3dfc3633db..aaff66a7f15b 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -19,6 +19,10 @@ #include #include "internal.h" +#ifdef CONFIG_KVM_PRIVATE_MEM +bool kvm_gmem_vma_is_gmem(struct vm_area_struct *vma); +#endif + static __always_inline bool validate_dst_vma(struct vm_area_struct *dst_vma, unsigned long dst_end) { @@ -391,6 +395,16 @@ static int mfill_atomic_pte_continue(pmd_t *dst_pmd, struct page *page; int ret; +#ifdef CONFIG_KVM_PRIVATE_MEM + if (kvm_gmem_vma_is_gmem(dst_vma)) { + ret = 0; + folio = filemap_get_entry(inode->i_mapping, pgoff); + if (IS_ERR(folio)) + ret = PTR_ERR(folio); + else + folio_lock(folio); + } else +#endif ret = shmem_get_folio(inode, pgoff, 0, &folio, SGP_NOALLOC); /* Our caller expects us to return -EFAULT if we failed to find folio */ if (ret == -ENOENT) @@ -769,9 +783,16 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, return mfill_atomic_hugetlb(ctx, dst_vma, dst_start, src_start, len, flags); - if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) + if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma) +#ifdef CONFIG_KVM_PRIVATE_MEM + && !kvm_gmem_vma_is_gmem(dst_vma) +#endif + ) goto out_unlock; if (!vma_is_shmem(dst_vma) && +#ifdef CONFIG_KVM_PRIVATE_MEM + !kvm_gmem_vma_is_gmem(dst_vma) && +#endif uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) goto out_unlock;