From patchwork Fri Nov 29 12:39:28 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nikita Kalyazin X-Patchwork-Id: 846390 Received: from smtp-fw-6002.amazon.com (smtp-fw-6002.amazon.com [52.95.49.90]) (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 A0637155352; Fri, 29 Nov 2024 12:39:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.95.49.90 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732883994; cv=none; b=ZMW/6k/IV3gVqoUy3LOtAa2HYlvpHBsiXDyaLwYO8pDVFZ9zZB2JCf+VPDjleWZsyavyJnIK6JIjqduv2JiZ18ZPVjOG78XA84cndy7ICDzUyXgCZcbNzCdvwfJrstKFeYa41ucE6xd2tmpHfij9v6oW2sMp351+5JxobWZdbtc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732883994; c=relaxed/simple; bh=WJvGNlSDsguJ2lBq0cA4zbQZCWHT3NXIF2YwIi55AOY=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gWtkHwUCU3mOHYxDF/UvdGIJzzqz/+p+CnI8DTlfJg+HwfydhLz3JuDoFbe178qS8r8c6gc/+F+qJ3YVZ1vyefQAWUixyf3COWWh2Anytl0iQ6xcgLqiQvrKLebGBgAeTklwaIlOZLjbnhWpRhe6FOqW2PfxEOqnGFczKdFxeP0= 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=mJVBKR0v; arc=none smtp.client-ip=52.95.49.90 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="mJVBKR0v" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1732883993; x=1764419993; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=pruxSJBO+jg2vTrKWukJWri3CAYz3t7ISP8fRBBPjl8=; b=mJVBKR0vws3zANPD2VVYcF7J+adO0l7dNiq+SC26Uawswttn5bBO5k7+ sN5qTFGeNR1a8eyEIslFhETd6RSK1zKT643MMvfvELI8hEvXOTSZw8eFF FUYLmrpSHGOvO1yi/kc9hgWmiidXXZyaSsiRqh4u3W33NsfpjnNMJt3Ww 4=; X-IronPort-AV: E=Sophos;i="6.12,195,1728950400"; d="scan'208";a="452145714" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.124.125.6]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2024 12:39:49 +0000 Received: from EX19MTAUWB001.ant.amazon.com [10.0.7.35:13724] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.32.230:2525] with esmtp (Farcaster) id cf81e0c5-4a2e-4985-891e-674da5678ac5; Fri, 29 Nov 2024 12:39:48 +0000 (UTC) X-Farcaster-Flow-ID: cf81e0c5-4a2e-4985-891e-674da5678ac5 Received: from EX19D003UWB001.ant.amazon.com (10.13.138.92) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34; Fri, 29 Nov 2024 12:39:47 +0000 Received: from EX19MTAUWA001.ant.amazon.com (10.250.64.204) by EX19D003UWB001.ant.amazon.com (10.13.138.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.35; Fri, 29 Nov 2024 12:39:47 +0000 Received: from email-imr-corp-prod-pdx-all-2c-8a67eb17.us-west-2.amazon.com (10.25.36.214) by mail-relay.amazon.com (10.250.64.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.34 via Frontend Transport; Fri, 29 Nov 2024 12:39:47 +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-8a67eb17.us-west-2.amazon.com (Postfix) with ESMTPS id B78B0406EB; Fri, 29 Nov 2024 12:39:44 +0000 (UTC) From: Nikita Kalyazin To: , , , , CC: , , , , , , , , , , , , , Subject: [RFC PATCH v2 1/2] KVM: guest_memfd: add generic population via write Date: Fri, 29 Nov 2024 12:39:28 +0000 Message-ID: <20241129123929.64790-2-kalyazin@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20241129123929.64790-1-kalyazin@amazon.com> References: <20241129123929.64790-1-kalyazin@amazon.com> Precedence: bulk X-Mailing-List: linux-kselftest@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 | 79 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 47a9f68f7b24..e80566ef56e9 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -102,6 +102,80 @@ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index) return filemap_grab_folio(inode->i_mapping, index); } +#if defined(CONFIG_KVM_GENERIC_PRIVATE_MEM) && !defined(CONFIG_KVM_AMD_SEV) +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(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; + } + + 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); + if (ret) + ret = -EINVAL; + kunmap_local(vaddr); + + kvm_gmem_mark_prepared(folio); + folio_put(folio); + + index = folio_next_index(folio); + *offset += PAGE_SIZE; + } + +out: + filemap_invalidate_unlock(file->f_mapping); + + return ret && start == (*offset >> PAGE_SHIFT) ? + ret : *offset - (start << PAGE_SHIFT); +} +#endif + static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, pgoff_t end) { @@ -308,6 +382,10 @@ static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) } static struct file_operations kvm_gmem_fops = { +#if defined(CONFIG_KVM_GENERIC_PRIVATE_MEM) && !defined(CONFIG_KVM_AMD_SEV) + .llseek = default_llseek, + .write = kvm_kmem_gmem_write, +#endif .open = generic_file_open, .release = kvm_gmem_release, .fallocate = kvm_gmem_fallocate, @@ -423,6 +501,7 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) } file->f_flags |= O_LARGEFILE; + file->f_mode |= FMODE_LSEEK | FMODE_PWRITE; inode = file->f_inode; WARN_ON(file->f_mapping != inode->i_mapping);