From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f180.google.com (mail-pl1-f180.google.com [209.85.214.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B09FE390987 for ; Mon, 27 Jul 2026 15:27:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785166045; cv=none; b=PyD6I8233p2rY1ePaVzCDDDf/ymOQ2eH6xHaOKvoTqab0LpOklj5W76q2rkrxs6KhrIfYlmnHXgrVvnRORNO6F/6FwEONlZAM9bUpiBR1OJQ8yAqW2HCJBSMZdS5B0kwN9KiDIU8iwlta7Pn/o6Gl+rn1Ac5Z1Nlz2hUKTSY+uM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785166045; c=relaxed/simple; bh=Swgn6s2kY7p2tvnBeuVFL1zLewFRMddlqXIih/LU3m0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=pfPi4HWSKrxguwL8knH9dhTk2qXR6w3JuiUdiBqACIcXkuxIoa451CyM6/ERf491tsMVlqW21y5aJcGA+0FlB7jhhRV11q6+8wlL9+S8TZVP+LsFyoP6PhSocXf2K3UfjuUMH0P7OV42Ca74IZMC/xWMwZQRdYb1FRMVmKWvmKY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=MKMtK+cV; arc=none smtp.client-ip=209.85.214.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MKMtK+cV" Received: by mail-pl1-f180.google.com with SMTP id d9443c01a7336-2ceae1ed204so30370025ad.0 for ; Mon, 27 Jul 2026 08:27:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785166043; x=1785770843; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=KqISqetJ0Hj8Ab0QVlJRkGNZyqybFdl4vH7c2gdR6nQ=; b=MKMtK+cVoR3eXlrUZwE0zlSWXmlltG1t88urSbXYLfmKz1mmx5ZUhit7ihR8bkfnYe MNo2KP+yu7dusMxriGwAXeRtT5nmDiVr7rk0rjw4VUlo7yiP+GNJnUqleG7rtCtB38l9 LDgW8LGYwufanI1D0DP/js+5qetpdzbS/JK7T/41OBvtxyt6mzIJ74HpuGVNvFwlccgq d8Nm7P5ThoZBNI/CmR0/WIP6QZSBnDrIX9BSyixk91zf9GSBnRJe6BnaFpf2zyAyZE/O bOnv3EbHLwyABzEVQY/Oa0I3THBKqgFIZqVYKbSGdrxOwSDgX+38fzuEnutM+MxU5y6/ vESA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785166043; x=1785770843; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=KqISqetJ0Hj8Ab0QVlJRkGNZyqybFdl4vH7c2gdR6nQ=; b=n/EDBnhOzP40uOcivtLMNmvqLqV8zWxfKp5PDNAXySGXTJIF0UqyULjLjGmKFx2k0r rOhAN5zFKgK4U++y86pI9ekZGHEc5/dF/XQ/+CoyQ2O1cjUoaOAuDFaHrE1u0TXKtG82 41YH+k3wfYJ8sdIm3OyNM54jnbzSCRBwI3Y+/FU5XkVTGS/uOP2NcHLBdvkd+y/XVc7U TzcxhMe4QWS9+n/8VoyybsxtpqnsoiKYLu+9VVBacdcnGWJLxBvedXauz2x2Vkg9oB1S rOkNuZmyJwPOAIkhL5IhNajMiB3aqYdzyGcdqnPdEXEmUOoVpgUu3DFzbdpi48GfngXL azGQ== X-Forwarded-Encrypted: i=1; AHgh+RpStaelzMN9e3fPuQVlBwGv06wMmwIRS1kgJWeqclgL6XcjyPBBncjcxKaxjK9osOM8jxvHdajTEKwr@vger.kernel.org X-Gm-Message-State: AOJu0YyY5RRdyx0Ozb6rI7l1H9g/n/c0vxjxdcfZqEbDHZNSkLkW7iB+ Rjt8S1I62BC2S2b+WsKvxsOv0f6LvidlwTEjoaMDfY28j3lXr32V201k X-Gm-Gg: AR+sD12tiQQ7yYE18/z6SoClVZhLreysf6wNkxmbAgAROdWGXPpL4fCvSoKFuQUw6Jo KoxcSYGnrPgm9liy69T81GnrifWwX3qH/4uEAfYU5GI3NQQVqc0B81fXarIMnOuHGi/grBfHOW0 Uka77cUBaTpHRhEBtwnP/RY3G1jgNAmMIqvqshO79hU75sgxvvtNFnJ6wymjVhrvqVwYP9w9kUz 5sCAhuMvhxODPcZZs7y+H4eJSNoWfbHFKDPq0e9KbDZNV5M11ASVjDEQlnxZjH0WDUGULwmxx4/ wIT/yx51FxCNzjTzfEXujLvS2cCCEOhTysshCUPOVbXYbHCHXofGBWa4n080bbhIcdOS4uXf9pC 7f7Vsb8CEgtfBrEvz6hMDvPVyFmwo80ED/sDXWIGbWYISQhU5Wht2vNW9WD82JRnxkibi0cP7h7 SmHeL8+hiTmE/PhZ/n+9d2ieZNSA== X-Received: by 2002:a05:6a21:6005:b0:3c3:b57b:645e with SMTP id adf61e73a8af0-3c67d9b3e93mr8509256637.5.1785166042810; Mon, 27 Jul 2026 08:27:22 -0700 (PDT) Received: from ubuntu-Virtual-Machine.mshome.net ([104.43.2.12]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cbbb660f4d8sm3389724a12.5.2026.07.27.08.27.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jul 2026 08:27:22 -0700 (PDT) From: Tianyu Lan X-Google-Original-From: Tianyu Lan To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, James.Bottomley@HansenPartnership.com, martin.petersen@oracle.com Cc: Tianyu Lan , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, hch@infradead.org, robin.murphy@arm.com, vdso@hexbites.dev, mhklinux@outlook.com Subject: [PATCH V2 1/1] x86/VMBus: Confidential VMBus for dynamic DMA transfers Date: Mon, 27 Jul 2026 11:27:11 -0400 Message-Id: <20260727152711.2045-1-tiala@microsoft.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hyper-V provides Confidential VMBus to communicate between device model and device guest driver via encrypted/private memory in Confidential VM. The device model is in OpenHCL (https://openvmm.dev/guide/user_guide/openhcl.html) that plays the paravisor role. For a VMBus device, there are two communication methods to talk with Host/Hypervisor. 1) VMBUS Ring buffer 2) Dynamic DMA transfer. The Confidential VMBus Ring buffer has been upstreamed by Roman Kisel(commit 6802d8af47d1). The dynamic DMA transition of VMBus device normally goes through DMA core and it uses SWIOTLB as bounce buffer in a CoCo VM. The Confidential VMBus device can do DMA directly to private/encrypted memory. Because the swiotlb is decrypted memory, the DMA transfer must not be bounced through the swiotlb, so as to preserve confidentiality. This is different from the default for Linux CoCo VMs, so not use DMA(SWIOTLB) API in VMBus driver when confidential dynamic DMA transfers capability is present. Signed-off-by: Tianyu Lan --- Change since v1: * Fix code style issue * Use co_external_memory flag in struct vmbus_channel directly instead of adding new flag in the struct hv_device. --- drivers/scsi/storvsc_drv.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 6977ca8a0658..a3b22cba3421 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1326,7 +1326,8 @@ static void storvsc_on_channel_callback(void *context) continue; } request = (struct storvsc_cmd_request *)scsi_cmd_priv(scmnd); - scsi_dma_unmap(scmnd); + if (!device->channel->co_external_memory) + scsi_dma_unmap(scmnd); } storvsc_on_receive(stor_device, packet, request); @@ -1815,7 +1816,7 @@ static enum scsi_qc_status storvsc_queuecommand(struct Scsi_Host *host, unsigned long offset_in_hvpg = offset_in_hvpage(sgl->offset); unsigned int hvpg_count = HVPFN_UP(offset_in_hvpg + length); struct scatterlist *sg; - unsigned long hvpfn, hvpfns_to_add; + unsigned long hvpfn, hvpfns_to_add, hvpgoff; int j, i = 0, sg_count; payload_sz = (hvpg_count * sizeof(u64) + @@ -1831,10 +1832,14 @@ static enum scsi_qc_status storvsc_queuecommand(struct Scsi_Host *host, payload->range.len = length; payload->range.offset = offset_in_hvpg; - sg_count = scsi_dma_map(scmnd); - if (sg_count < 0) { - ret = SCSI_MLQUEUE_DEVICE_BUSY; - goto err_free_payload; + if (dev->channel->co_external_memory) { + sg_count = scsi_sg_count(scmnd); + } else { + sg_count = scsi_dma_map(scmnd); + if (sg_count < 0) { + ret = SCSI_MLQUEUE_DEVICE_BUSY; + goto err_free_payload; + } } for_each_sg(sgl, sg, sg_count, j) { @@ -1846,9 +1851,16 @@ static enum scsi_qc_status storvsc_queuecommand(struct Scsi_Host *host, * Such offsets are handled even on other than the first * sgl entry, provided they are a multiple of PAGE_SIZE. */ - hvpfn = HVPFN_DOWN(sg_dma_address(sg)); - hvpfns_to_add = HVPFN_UP(sg_dma_address(sg) + - sg_dma_len(sg)) - hvpfn; + if (dev->channel->co_external_memory) { + hvpgoff = HVPFN_DOWN(sg->offset); + hvpfn = page_to_hvpfn(sg_page(sg)) + hvpgoff; + hvpfns_to_add = HVPFN_UP(sg->offset + sg->length) - + hvpgoff; + } else { + hvpfn = HVPFN_DOWN(sg_dma_address(sg)); + hvpfns_to_add = HVPFN_UP(sg_dma_address(sg) + + sg_dma_len(sg)) - hvpfn; + } /* * Fill the next portion of the PFN array with @@ -1870,7 +1882,7 @@ static enum scsi_qc_status storvsc_queuecommand(struct Scsi_Host *host, ret = storvsc_do_io(dev, cmd_request, smp_processor_id()); migrate_enable(); - if (ret) + if (ret && (!dev->channel->co_external_memory)) scsi_dma_unmap(scmnd); if (ret == -EAGAIN) { -- 2.50.1