From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A40043A5E6C; Tue, 7 Apr 2026 17:41:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775583680; cv=none; b=bQdbpz5IpevUHns4YFX8kSnr+Vuv8hX/F5MrotPPhFGFbN/rgRyX+7zYkxcqAOOzPV9QxQK5Dtn2scZNuxTE6/9G06CEF7tqLJcO4PtTiXwrXyVmImgCBcoqVVlbNvwlcFAimJQDB2Onv3IKHIXJ7MEO2rPAY4vau9mzjjdbdt8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775583680; c=relaxed/simple; bh=fW7dVnyNZbMQpfKnAv9leZAgrwCzzp1rw3DQkL9t5zQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aZlJO6HexteWfmQwEOUj5+Qvu7O/oh2gSs74aOZtI3XFIXwXRH5vbYBmFhEQtxpwNXUSa19I4hXl+VsDZUikTIJLSEMjFf2xAAGNuBryTCaTOnsV4QoOM6m0bfR8YmcFboIEOcDAHtGyiP5PICzoarb/J0JBiNtSgGKgirQyBv8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=rNvVRUuq; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="rNvVRUuq" Received: from [192.168.0.88] (192-184-212-33.fiber.dynamic.sonic.net [192.184.212.33]) by linux.microsoft.com (Postfix) with ESMTPSA id 670E720B710C; Tue, 7 Apr 2026 10:41:13 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 670E720B710C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775583674; bh=1Tp92fEIAGHRC4zj4SLEj5o26KziJ4vsTcxFPPrAedI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=rNvVRUuqwPHom7yczpPG4UTHQmqi/e8QocA4gchgWOaUaGPrnn021pC6/wGBukoTB juoBUdNvjAT8xg7WXdvzgITKomhuwHRDrHOx3Sz+gEgSRtMxJsb1M/SLGXq4sL1Mkp pWktucBD5k1IIfSPbUI1ZVck8Kh27iP2ezBiiIas= Message-ID: Date: Tue, 7 Apr 2026 10:41:12 -0700 Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH v0 06/15] mshv: Implement mshv bridge device for VFIO Content-Language: en-US To: Stanislav Kinsburskii Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, joro@8bytes.org, lpieralisi@kernel.org, kwilczynski@kernel.org, mani@kernel.org, robh@kernel.org, bhelgaas@google.com, arnd@arndb.de, nunodasneves@linux.microsoft.com, mhklinux@outlook.com, romank@linux.microsoft.com References: <20260120064230.3602565-1-mrathor@linux.microsoft.com> <20260120064230.3602565-7-mrathor@linux.microsoft.com> From: Mukesh R In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/20/26 08:09, Stanislav Kinsburskii wrote: > On Mon, Jan 19, 2026 at 10:42:21PM -0800, Mukesh R wrote: >> From: Mukesh Rathor >> >> Add a new file to implement VFIO-MSHV bridge pseudo device. These >> functions are called in the VFIO framework, and credits to kvm/vfio.c >> as this file was adapted from it. >> >> Original author: Wei Liu >> (Slightly modified from the original version). >> > > There is a Linux standard for giving credits when code is adapted from. > This doesn't follow that standard. Please fix. > >> Signed-off-by: Mukesh Rathor >> --- >> drivers/hv/Makefile | 3 +- >> drivers/hv/mshv_vfio.c | 210 +++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 212 insertions(+), 1 deletion(-) >> create mode 100644 drivers/hv/mshv_vfio.c >> >> diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile >> index a49f93c2d245..eae003c4cb8f 100644 >> --- a/drivers/hv/Makefile >> +++ b/drivers/hv/Makefile >> @@ -14,7 +14,8 @@ hv_vmbus-y := vmbus_drv.o \ >> hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o >> hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o >> mshv_root-y := mshv_root_main.o mshv_synic.o mshv_eventfd.o mshv_irq.o \ >> - mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o >> + mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o \ >> + mshv_vfio.o >> mshv_vtl-y := mshv_vtl_main.o >> >> # Code that must be built-in >> diff --git a/drivers/hv/mshv_vfio.c b/drivers/hv/mshv_vfio.c >> new file mode 100644 >> index 000000000000..6ea4d99a3bd2 >> --- /dev/null >> +++ b/drivers/hv/mshv_vfio.c >> @@ -0,0 +1,210 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * VFIO-MSHV bridge pseudo device >> + * >> + * Heavily inspired by the VFIO-KVM bridge pseudo device. >> + */ >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +#include "mshv.h" >> +#include "mshv_root.h" >> + >> +struct mshv_vfio_file { >> + struct list_head node; >> + struct file *file; /* list of struct mshv_vfio_file */ >> +}; >> + >> +struct mshv_vfio { >> + struct list_head file_list; >> + struct mutex lock; >> +}; >> + >> +static bool mshv_vfio_file_is_valid(struct file *file) >> +{ >> + bool (*fn)(struct file *file); >> + bool ret; >> + >> + fn = symbol_get(vfio_file_is_valid); >> + if (!fn) >> + return false; >> + >> + ret = fn(file); >> + >> + symbol_put(vfio_file_is_valid); >> + >> + return ret; >> +} >> + >> +static long mshv_vfio_file_add(struct mshv_device *mshvdev, unsigned int fd) >> +{ >> + struct mshv_vfio *mshv_vfio = mshvdev->device_private; >> + struct mshv_vfio_file *mvf; >> + struct file *filp; >> + long ret = 0; >> + >> + filp = fget(fd); >> + if (!filp) >> + return -EBADF; >> + >> + /* Ensure the FD is a vfio FD. */ >> + if (!mshv_vfio_file_is_valid(filp)) { >> + ret = -EINVAL; >> + goto out_fput; >> + } >> + >> + mutex_lock(&mshv_vfio->lock); >> + >> + list_for_each_entry(mvf, &mshv_vfio->file_list, node) { >> + if (mvf->file == filp) { >> + ret = -EEXIST; >> + goto out_unlock; >> + } >> + } >> + >> + mvf = kzalloc(sizeof(*mvf), GFP_KERNEL_ACCOUNT); >> + if (!mvf) { >> + ret = -ENOMEM; >> + goto out_unlock; >> + } >> + >> + mvf->file = get_file(filp); >> + list_add_tail(&mvf->node, &mshv_vfio->file_list); >> + >> +out_unlock: >> + mutex_unlock(&mshv_vfio->lock); >> +out_fput: >> + fput(filp); >> + return ret; >> +} >> + >> +static long mshv_vfio_file_del(struct mshv_device *mshvdev, unsigned int fd) >> +{ >> + struct mshv_vfio *mshv_vfio = mshvdev->device_private; >> + struct mshv_vfio_file *mvf; >> + long ret; >> + >> + CLASS(fd, f)(fd); >> + >> + if (fd_empty(f)) >> + return -EBADF; >> + >> + ret = -ENOENT; >> + mutex_lock(&mshv_vfio->lock); >> + >> + list_for_each_entry(mvf, &mshv_vfio->file_list, node) { >> + if (mvf->file != fd_file(f)) >> + continue; >> + >> + list_del(&mvf->node); >> + fput(mvf->file); >> + kfree(mvf); >> + ret = 0; >> + break; >> + } >> + >> + mutex_unlock(&mshv_vfio->lock); >> + return ret; >> +} >> + >> +static long mshv_vfio_set_file(struct mshv_device *mshvdev, long attr, >> + void __user *arg) >> +{ >> + int32_t __user *argp = arg; >> + int32_t fd; >> + >> + switch (attr) { >> + case MSHV_DEV_VFIO_FILE_ADD: >> + if (get_user(fd, argp)) >> + return -EFAULT; >> + return mshv_vfio_file_add(mshvdev, fd); >> + >> + case MSHV_DEV_VFIO_FILE_DEL: >> + if (get_user(fd, argp)) >> + return -EFAULT; >> + return mshv_vfio_file_del(mshvdev, fd); >> + } >> + >> + return -ENXIO; >> +} >> + >> +static long mshv_vfio_set_attr(struct mshv_device *mshvdev, >> + struct mshv_device_attr *attr) >> +{ >> + switch (attr->group) { >> + case MSHV_DEV_VFIO_FILE: >> + return mshv_vfio_set_file(mshvdev, attr->attr, >> + u64_to_user_ptr(attr->addr)); >> + } >> + >> + return -ENXIO; >> +} >> + >> +static long mshv_vfio_has_attr(struct mshv_device *mshvdev, >> + struct mshv_device_attr *attr) >> +{ >> + switch (attr->group) { >> + case MSHV_DEV_VFIO_FILE: >> + switch (attr->attr) { >> + case MSHV_DEV_VFIO_FILE_ADD: >> + case MSHV_DEV_VFIO_FILE_DEL: >> + return 0; >> + } >> + >> + break; >> + } >> + >> + return -ENXIO; >> +} >> + >> +static long mshv_vfio_create_device(struct mshv_device *mshvdev, u32 type) >> +{ >> + struct mshv_device *tmp; >> + struct mshv_vfio *mshv_vfio; >> + >> + /* Only one VFIO "device" per VM */ >> + hlist_for_each_entry(tmp, &mshvdev->device_pt->pt_devices, >> + device_ptnode) >> + if (tmp->device_ops == &mshv_vfio_device_ops) >> + return -EBUSY; >> + >> + mshv_vfio = kzalloc(sizeof(*mshv_vfio), GFP_KERNEL_ACCOUNT); >> + if (mshv_vfio == NULL) >> + return -ENOMEM; >> + >> + INIT_LIST_HEAD(&mshv_vfio->file_list); >> + mutex_init(&mshv_vfio->lock); >> + >> + mshvdev->device_private = mshv_vfio; >> + >> + return 0; >> +} >> + >> +/* This is called from mshv_device_fop_release() */ >> +static void mshv_vfio_release_device(struct mshv_device *mshvdev) >> +{ >> + struct mshv_vfio *mv = mshvdev->device_private; >> + struct mshv_vfio_file *mvf, *tmp; >> + >> + list_for_each_entry_safe(mvf, tmp, &mv->file_list, node) { >> + fput(mvf->file); > > This put must be sync as device must be detached from domain before > attempting partition destruction. Like I said in 6.6 PR, this does not attach or detach devices. > This was explicitly mentioned in the patch originated this code. > Please fix, add a comment and credits to the commit message. That was ".detstroy" hook which is gone. Thanks, -Mukesh > Thanks, > Stanislav > > >> + list_del(&mvf->node); >> + kfree(mvf); >> + } >> + >> + kfree(mv); >> + kfree(mshvdev); >> +} >> + >> +struct mshv_device_ops mshv_vfio_device_ops = { >> + .device_name = "mshv-vfio", >> + .device_create = mshv_vfio_create_device, >> + .device_release = mshv_vfio_release_device, >> + .device_set_attr = mshv_vfio_set_attr, >> + .device_has_attr = mshv_vfio_has_attr, >> +}; >> -- >> 2.51.2.vfs.0.1 >>