From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5255CA5FA2 for ; Tue, 20 Jan 2026 16:09:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iIZ7bzfOU+32o456dducA6V77xDpYZ8q7ZzTpg2VDtM=; b=frx1CfBlpjk0nQM6s3FT/Z3B/u cTVjpLVCAOaWo/h9ai5m5QCb6gogGqP6Gsnd2gNZjgffzWlEqOZihnYdC8jxUl5PpaOJLx9I+bT3I xZgCdKsjeaxIZcmRQM39CM0JI7psanggRCjNhcRuqyxIVM8+ufV9lZpVeNHaRSCqSKHR/ta72R5Ie ikEaHHkWn5wl+tkH+ub5OZPY4CrT2mkO4GCRIs9nG/BlCvG6S2oo8ljy+56NviFbYnG52Y8letbmt G4S9gMHSEuBF0L2xH3L7JeFFOP1SIoVLhNDkDCmEkFDH6BXcl8QEbWe2Kocv5ik76NtG1Okv2AFOU xiiQJuHA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1viEHy-000000048Er-2mbh; Tue, 20 Jan 2026 16:09:06 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1viEHv-000000048Dt-3Bl7 for linux-arm-kernel@lists.infradead.org; Tue, 20 Jan 2026 16:09:04 +0000 Received: from skinsburskii.localdomain (unknown [20.236.11.102]) by linux.microsoft.com (Postfix) with ESMTPSA id 2544020B7167; Tue, 20 Jan 2026 08:09:02 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 2544020B7167 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1768925342; bh=iIZ7bzfOU+32o456dducA6V77xDpYZ8q7ZzTpg2VDtM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KDJga7K0N+4P68lcEAZIkzvNWr/d4a4erZoM6A9oDmUjDtDW8qpeY2QlJaVLNMMho AjVJWrCGPrMN01TJa64q6v0vAEqXHMR6+xcTbpJMwqsm9W/h3tQqNtNaYNf0kDWpBb Npz5ZO5vyjcIirlciM5xur4auzAEdCskgnwCgqtk= Date: Tue, 20 Jan 2026 08:09:02 -0800 From: Stanislav Kinsburskii To: Mukesh R 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 Subject: Re: [PATCH v0 06/15] mshv: Implement mshv bridge device for VFIO Message-ID: References: <20260120064230.3602565-1-mrathor@linux.microsoft.com> <20260120064230.3602565-7-mrathor@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260120064230.3602565-7-mrathor@linux.microsoft.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260120_080903_856740_D790F867 X-CRM114-Status: GOOD ( 28.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. This was explicitly mentioned in the patch originated this code. Please fix, add a comment and credits to the commit message. 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 >