From patchwork Mon Mar 3 13:08:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nikita Kalyazin X-Patchwork-Id: 13998822 Received: from smtp-fw-80007.amazon.com (smtp-fw-80007.amazon.com [99.78.197.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 181CA21129F; Mon, 3 Mar 2025 13:08:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=99.78.197.218 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741007337; cv=none; b=pECj3u8HVlYM/1jGdnbmLyk/Kzo7Lq8ndBAc9X+hJMMsyOX5Jd5dEi6l787IURpjufX3gmorCzHpemNuZw58Fbog61SDH2Le5GYgObjK0rs6km5uB3EBfztpeasPraHP2cxo8M6KYxDzqVmv97KcKvH4lkL6/WGSD5sP/GhF+7Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741007337; c=relaxed/simple; bh=O+1kyzMjMuVSclP/dGDX7WvTQ3qb9jZg68fPpc8T+yE=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=qGYKEEMFbZ9bXK5xECkZE0nf2Qe3QLrO++zzfxBFtX8Ric7qoSsFvRutGRLHrNxvri31lIuVC7iPq130xJE7djxXGd+N09nWEt5b/6q35SkGImk796xFdLzWg9nmHF6TYAtxhaEesfwm2SZh2qE774WgOqPGTcY0EI7KJoNLnIw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.uk; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=I2IDkUtl; arc=none smtp.client-ip=99.78.197.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="I2IDkUtl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1741007337; x=1772543337; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=fo0RfFhjOlaWjyHUEezlWZqA9yMhjyUNGY8gIayRQKY=; b=I2IDkUtliTSdICOOZOja+o2KRv/R5z5Ky+EeWO9Y9O4GRF/gbY69iM7k TWLuitm4OcSoflrJ5CngkN27xEKPjLSQqnLfuOe72oFsE1Ma2nBy1J+S1 xEEMGj053E6Gw+dKiCB8KR92kcTU6drBRrM7O2/yzOONZNphwzDI1u6JE s=; X-IronPort-AV: E=Sophos;i="6.13,329,1732579200"; d="scan'208";a="382575134" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-80007.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Mar 2025 13:08:55 +0000 Received: from EX19MTAEUA001.ant.amazon.com [10.0.10.100:44365] by smtpin.naws.eu-west-1.prod.farcaster.email.amazon.dev [10.0.12.5:2525] with esmtp (Farcaster) id a3ca6071-d059-430d-be89-565f65c948ae; Mon, 3 Mar 2025 13:08:53 +0000 (UTC) X-Farcaster-Flow-ID: a3ca6071-d059-430d-be89-565f65c948ae Received: from EX19D015EUA002.ant.amazon.com (10.252.50.219) by EX19MTAEUA001.ant.amazon.com (10.252.50.192) 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 13:08:53 +0000 Received: from EX19MTAUEB002.ant.amazon.com (10.252.135.47) by EX19D015EUA002.ant.amazon.com (10.252.50.219) 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 13:08:52 +0000 Received: from email-imr-corp-prod-iad-all-1b-3ae3de11.us-east-1.amazon.com (10.43.8.2) by mail-relay.amazon.com (10.252.135.97) 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 13:08:52 +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-iad-all-1b-3ae3de11.us-east-1.amazon.com (Postfix) with ESMTPS id 0E275A0686; Mon, 3 Mar 2025 13:08:50 +0000 (UTC) From: Nikita Kalyazin To: , CC: , , , , , , , , , , , , , , , Subject: [v3 PATCH 1/2] KVM: guest_memfd: add generic population via write Date: Mon, 3 Mar 2025 13:08:37 +0000 Message-ID: <20250303130838.28812-2-kalyazin@amazon.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250303130838.28812-1-kalyazin@amazon.com> References: <20250303130838.28812-1-kalyazin@amazon.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 write syscall populates guest_memfd with user-supplied data in a generic way, ie no vendor-specific preparation is performed. This is supposed to be used in non-CoCo setups where guest memory is not hardware-encrypted. The following behaviour is implemented: - only page-aligned count and offset are allowed - if the memory is already allocated, the call will successfully populate it - if the memory is not allocated, the call will both allocate and populate - if the memory is already populated, the call will not repopulate it Signed-off-by: Nikita Kalyazin --- virt/kvm/guest_memfd.c | 94 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 91 insertions(+), 3 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 30b47ff0e6d2..f93fe5835173 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -417,12 +417,97 @@ static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma) return 0; } -#else -#define kvm_gmem_mmap NULL + +static ssize_t kvm_kmem_gmem_write(struct file *file, const char __user *buf, + size_t count, loff_t *offset) +{ + pgoff_t start, end, index; + ssize_t ret = 0; + + if (!PAGE_ALIGNED(*offset) || !PAGE_ALIGNED(count)) + return -EINVAL; + + if (*offset + count > i_size_read(file_inode(file))) + return -EINVAL; + + if (!buf) + return -EINVAL; + + start = *offset >> PAGE_SHIFT; + end = (*offset + count) >> PAGE_SHIFT; + + filemap_invalidate_lock_shared(file->f_mapping); + + for (index = start; index < end; ) { + struct folio *folio; + void *vaddr; + pgoff_t buf_offset = (index - start) << PAGE_SHIFT; + + if (signal_pending(current)) { + ret = -EINTR; + goto out; + } + + folio = kvm_gmem_get_folio(file_inode(file), index); + if (IS_ERR(folio)) { + ret = -EFAULT; + goto out; + } + + if (folio_test_hwpoison(folio)) { + folio_unlock(folio); + folio_put(folio); + ret = -EFAULT; + goto out; + } + + /* No support for huge pages. */ + if (WARN_ON_ONCE(folio_test_large(folio))) { + folio_unlock(folio); + folio_put(folio); + ret = -EFAULT; + goto out; + } + + if (folio_test_uptodate(folio)) { + folio_unlock(folio); + folio_put(folio); + ret = -ENOSPC; + goto out; + } + + folio_unlock(folio); + + vaddr = kmap_local_folio(folio, 0); + ret = copy_from_user(vaddr, buf + buf_offset, PAGE_SIZE); + kunmap_local(vaddr); + if (ret) { + ret = -EINVAL; + folio_put(folio); + goto out; + } + + kvm_gmem_mark_prepared(folio); + folio_put(folio); + + index = folio_next_index(folio); + *offset += PAGE_SIZE; + } + +out: + filemap_invalidate_unlock_shared(file->f_mapping); + + return ret && start == (*offset >> PAGE_SHIFT) ? + ret : *offset - (start << PAGE_SHIFT); +} #endif /* CONFIG_KVM_GMEM_SHARED_MEM */ static struct file_operations kvm_gmem_fops = { - .mmap = kvm_gmem_mmap, +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + .mmap = kvm_gmem_mmap, + .llseek = default_llseek, + .write = kvm_kmem_gmem_write, +#endif /* CONFIG_KVM_GMEM_SHARED_MEM */ .open = generic_file_open, .release = kvm_gmem_release, .fallocate = kvm_gmem_fallocate, @@ -538,6 +623,9 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) } file->f_flags |= O_LARGEFILE; +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + file->f_mode |= FMODE_LSEEK | FMODE_PWRITE; +#endif /* CONFIG_KVM_GMEM_SHARED_MEM */ inode = file->f_inode; WARN_ON(file->f_mapping != inode->i_mapping);