| Message ID | 20231026024930.382898-5-baolu.lu@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | IOMMUFD: Deliver IO page faults to user space | expand |
On Thu, Oct 26, 2023 at 10:49:28AM +0800, Lu Baolu wrote: > +static ssize_t hwpt_fault_fops_write(struct file *filep, > + const char __user *buf, > + size_t count, loff_t *ppos) > +{ > + size_t response_size = sizeof(struct iommu_hwpt_page_response); > + struct hw_pgtable_fault *fault = filep->private_data; > + struct iommu_hwpt_page_response response; > + struct iommufd_hw_pagetable *hwpt; > + struct iopf_group *iter, *group; > + struct iommufd_device *idev; > + size_t done = 0; > + int rc = 0; > + > + if (*ppos || count % response_size) > + return -ESPIPE; > + > + mutex_lock(&fault->mutex); > + while (!list_empty(&fault->response) && count > done) { > + rc = copy_from_user(&response, buf + done, response_size); > + if (rc) > + break; > + > + /* Get the device that this response targets at. */ > + idev = container_of(iommufd_get_object(fault->ictx, > + response.dev_id, > + IOMMUFD_OBJ_DEVICE), > + struct iommufd_device, obj); > + if (IS_ERR(idev)) { > + rc = PTR_ERR(idev); > + break; > + } See here it might be better to have a per-fd list of outstanding faults per-fd and then the cookie would just index that list, then you get everything in one shot instead of having to do a xarray looking and then a linear list search > +static const struct file_operations hwpt_fault_fops = { > + .owner = THIS_MODULE, > + .read = hwpt_fault_fops_read, > + .write = hwpt_fault_fops_write, > +}; nonseekable_open() behavior should be integrated into this > +static int hw_pagetable_get_fault_fd(struct hw_pgtable_fault *fault) > +{ > + struct file *filep; > + int fdno; > + > + fdno = get_unused_fd_flags(O_CLOEXEC); > + if (fdno < 0) > + return fdno; > + > + filep = anon_inode_getfile("[iommufd-pgfault]", &hwpt_fault_fops, > + fault, O_RDWR); > + if (IS_ERR(filep)) { > + put_unused_fd(fdno); > + return PTR_ERR(filep); > + } > + > + fd_install(fdno, filep); > + fault->fault_file = filep; > + fault->fault_fd = fdno; fd_install must be the very last thing before returning success from a system call because we cannot undo it. There are other failure paths before here and the final return Jason
On 2023/12/1 23:24, Jason Gunthorpe wrote: > On Thu, Oct 26, 2023 at 10:49:28AM +0800, Lu Baolu wrote: > >> +static ssize_t hwpt_fault_fops_write(struct file *filep, >> + const char __user *buf, >> + size_t count, loff_t *ppos) >> +{ >> + size_t response_size = sizeof(struct iommu_hwpt_page_response); >> + struct hw_pgtable_fault *fault = filep->private_data; >> + struct iommu_hwpt_page_response response; >> + struct iommufd_hw_pagetable *hwpt; >> + struct iopf_group *iter, *group; >> + struct iommufd_device *idev; >> + size_t done = 0; >> + int rc = 0; >> + >> + if (*ppos || count % response_size) >> + return -ESPIPE; >> + >> + mutex_lock(&fault->mutex); >> + while (!list_empty(&fault->response) && count > done) { >> + rc = copy_from_user(&response, buf + done, response_size); >> + if (rc) >> + break; >> + >> + /* Get the device that this response targets at. */ >> + idev = container_of(iommufd_get_object(fault->ictx, >> + response.dev_id, >> + IOMMUFD_OBJ_DEVICE), >> + struct iommufd_device, obj); >> + if (IS_ERR(idev)) { >> + rc = PTR_ERR(idev); >> + break; >> + } > > See here it might be better to have a per-fd list of outstanding > faults per-fd and then the cookie would just index that list, then you > get everything in one shot instead of having to do a xarray looking > and then a linear list search Yours is more efficient. I will do it that way in the next version. > >> +static const struct file_operations hwpt_fault_fops = { >> + .owner = THIS_MODULE, >> + .read = hwpt_fault_fops_read, >> + .write = hwpt_fault_fops_write, >> +}; > > nonseekable_open() behavior should be integrated into this Sure. > >> +static int hw_pagetable_get_fault_fd(struct hw_pgtable_fault *fault) >> +{ >> + struct file *filep; >> + int fdno; >> + >> + fdno = get_unused_fd_flags(O_CLOEXEC); >> + if (fdno < 0) >> + return fdno; >> + >> + filep = anon_inode_getfile("[iommufd-pgfault]", &hwpt_fault_fops, >> + fault, O_RDWR); >> + if (IS_ERR(filep)) { >> + put_unused_fd(fdno); >> + return PTR_ERR(filep); >> + } >> + >> + fd_install(fdno, filep); >> + fault->fault_file = filep; >> + fault->fault_fd = fdno; > > fd_install must be the very last thing before returning success from a > system call because we cannot undo it. Yes. > > There are other failure paths before here and the final return > > Jason Best regards, baolu
> -----Original Message----- > From: Lu Baolu <baolu.lu@linux.intel.com> > Sent: Thursday, October 26, 2023 3:49 AM > To: Jason Gunthorpe <jgg@ziepe.ca>; Kevin Tian <kevin.tian@intel.com>; Joerg > Roedel <joro@8bytes.org>; Will Deacon <will@kernel.org>; Robin Murphy > <robin.murphy@arm.com>; Jean-Philippe Brucker <jean-philippe@linaro.org>; > Nicolin Chen <nicolinc@nvidia.com>; Yi Liu <yi.l.liu@intel.com>; Jacob Pan > <jacob.jun.pan@linux.intel.com> > Cc: iommu@lists.linux.dev; linux-kselftest@vger.kernel.org; > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org; Lu > Baolu <baolu.lu@linux.intel.com> > Subject: [PATCH v2 4/6] iommufd: Deliver fault messages to user space > [...] Hi, > +static ssize_t hwpt_fault_fops_write(struct file *filep, > + const char __user *buf, > + size_t count, loff_t *ppos) > +{ > + size_t response_size = sizeof(struct iommu_hwpt_page_response); > + struct hw_pgtable_fault *fault = filep->private_data; > + struct iommu_hwpt_page_response response; > + struct iommufd_hw_pagetable *hwpt; > + struct iopf_group *iter, *group; > + struct iommufd_device *idev; > + size_t done = 0; > + int rc = 0; > + > + if (*ppos || count % response_size) > + return -ESPIPE; > + > + mutex_lock(&fault->mutex); > + while (!list_empty(&fault->response) && count > done) { > + rc = copy_from_user(&response, buf + done, response_size); > + if (rc) > + break; > + > + /* Get the device that this response targets at. */ > + idev = container_of(iommufd_get_object(fault->ictx, > + response.dev_id, > + IOMMUFD_OBJ_DEVICE), > + struct iommufd_device, obj); > + if (IS_ERR(idev)) { > + rc = PTR_ERR(idev); > + break; > + } > + > + /* > + * Get the hw page table that this response was generated for. > + * It must match the one stored in the fault data. > + */ > + hwpt = container_of(iommufd_get_object(fault->ictx, > + response.hwpt_id, > + > IOMMUFD_OBJ_HW_PAGETABLE), > + struct iommufd_hw_pagetable, obj); > + if (IS_ERR(hwpt)) { > + iommufd_put_object(&idev->obj); > + rc = PTR_ERR(hwpt); > + break; > + } > + > + if (hwpt != fault->hwpt) { > + rc = -EINVAL; > + goto put_obj; > + } > + > + group = NULL; > + list_for_each_entry(iter, &fault->response, node) { > + if (response.grpid != iter->last_fault.fault.prm.grpid) > + continue; > + > + if (idev->dev != iter->dev) > + continue; > + > + if ((iter->last_fault.fault.prm.flags & > + IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) && > + response.pasid != iter->last_fault.fault.prm.pasid) > + continue; I am trying to get vSVA working with this series and got hit by the above check. On ARM platforms, page responses to stall events(CMD_RESUME) do not have an associated pasid. I think, either we need to check here using IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID or remove the check as it will be eventually done in iommu_page_response(). Thanks, Shameer
> -----Original Message----- > From: Jason Gunthorpe <jgg@ziepe.ca> > Sent: Monday, January 15, 2024 4:47 PM > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com> > Cc: Lu Baolu <baolu.lu@linux.intel.com>; Kevin Tian <kevin.tian@intel.com>; > Joerg Roedel <joro@8bytes.org>; Will Deacon <will@kernel.org>; Robin > Murphy <robin.murphy@arm.com>; Jean-Philippe Brucker <jean- > philippe@linaro.org>; Nicolin Chen <nicolinc@nvidia.com>; Yi Liu > <yi.l.liu@intel.com>; Jacob Pan <jacob.jun.pan@linux.intel.com>; > iommu@lists.linux.dev; linux-kselftest@vger.kernel.org; > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH v2 4/6] iommufd: Deliver fault messages to user space > > On Fri, Jan 12, 2024 at 05:46:13PM +0000, Shameerali Kolothum Thodi wrote: > > > > > > > -----Original Message----- > > > From: Lu Baolu <baolu.lu@linux.intel.com> > > > Sent: Thursday, October 26, 2023 3:49 AM > > > To: Jason Gunthorpe <jgg@ziepe.ca>; Kevin Tian <kevin.tian@intel.com>; > Joerg > > > Roedel <joro@8bytes.org>; Will Deacon <will@kernel.org>; Robin > Murphy > > > <robin.murphy@arm.com>; Jean-Philippe Brucker <jean- > philippe@linaro.org>; > > > Nicolin Chen <nicolinc@nvidia.com>; Yi Liu <yi.l.liu@intel.com>; Jacob > Pan > > > <jacob.jun.pan@linux.intel.com> > > > Cc: iommu@lists.linux.dev; linux-kselftest@vger.kernel.org; > > > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org; > Lu > > > Baolu <baolu.lu@linux.intel.com> > > > Subject: [PATCH v2 4/6] iommufd: Deliver fault messages to user space > > > > > [...] > > > > Hi, > > > > > +static ssize_t hwpt_fault_fops_write(struct file *filep, > > > + const char __user *buf, > > > + size_t count, loff_t *ppos) > > > +{ > > > + size_t response_size = sizeof(struct iommu_hwpt_page_response); > > > + struct hw_pgtable_fault *fault = filep->private_data; > > > + struct iommu_hwpt_page_response response; > > > + struct iommufd_hw_pagetable *hwpt; > > > + struct iopf_group *iter, *group; > > > + struct iommufd_device *idev; > > > + size_t done = 0; > > > + int rc = 0; > > > + > > > + if (*ppos || count % response_size) > > > + return -ESPIPE; > > > + > > > + mutex_lock(&fault->mutex); > > > + while (!list_empty(&fault->response) && count > done) { > > > + rc = copy_from_user(&response, buf + done, response_size); > > > + if (rc) > > > + break; > > > + > > > + /* Get the device that this response targets at. */ > > > + idev = container_of(iommufd_get_object(fault->ictx, > > > + response.dev_id, > > > + IOMMUFD_OBJ_DEVICE), > > > + struct iommufd_device, obj); > > > + if (IS_ERR(idev)) { > > > + rc = PTR_ERR(idev); > > > + break; > > > + } > > > + > > > + /* > > > + * Get the hw page table that this response was generated > for. > > > + * It must match the one stored in the fault data. > > > + */ > > > + hwpt = container_of(iommufd_get_object(fault->ictx, > > > + response.hwpt_id, > > > + > > > IOMMUFD_OBJ_HW_PAGETABLE), > > > + struct iommufd_hw_pagetable, obj); > > > + if (IS_ERR(hwpt)) { > > > + iommufd_put_object(&idev->obj); > > > + rc = PTR_ERR(hwpt); > > > + break; > > > + } > > > + > > > + if (hwpt != fault->hwpt) { > > > + rc = -EINVAL; > > > + goto put_obj; > > > + } > > > + > > > + group = NULL; > > > + list_for_each_entry(iter, &fault->response, node) { > > > + if (response.grpid != iter->last_fault.fault.prm.grpid) > > > + continue; > > > + > > > + if (idev->dev != iter->dev) > > > + continue; > > > + > > > + if ((iter->last_fault.fault.prm.flags & > > > + IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) > && > > > + response.pasid != iter->last_fault.fault.prm.pasid) > > > + continue; > > > > I am trying to get vSVA working with this series and got hit by the above > check. > > On ARM platforms, page responses to stall events(CMD_RESUME) do not > have > > an associated pasid. I think, either we need to check here using > > IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID or remove the check > > as it will be eventually done in iommu_page_response(). > > That doesn't sound right.. > > The PASID is the only information we have for userspace to identify > the domain that is being faulted. It cannot be optional on the request > side. > Yes, it is valid on the request side. But this is on the response side. > If it is valid when userspace does read() then it should be valid when > userspace does write() too. > > It is the only way the kernel can actually match request and response > here. The kernel currently checks the pasid only if IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID is set. https://lore.kernel.org/linux-iommu/20200616144712.748818-1-jean-philippe@linaro.org/ > So, I think you have a userspace issue to not provide the right > pasid?? This is not just ARM stall resume case, but for some PCI devices as well as per the above commit log. So do we really need to track this in userspace ? Thanks, Shameer
On Mon, Jan 15, 2024 at 05:44:13PM +0000, Shameerali Kolothum Thodi wrote: > > If it is valid when userspace does read() then it should be valid when > > userspace does write() too. > > > > It is the only way the kernel can actually match request and response > > here. > > The kernel currently checks the pasid only if IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID > is set. > > https://lore.kernel.org/linux-iommu/20200616144712.748818-1-jean-philippe@linaro.org/ > > > So, I think you have a userspace issue to not provide the right > > pasid?? > > This is not just ARM stall resume case, but for some PCI devices as well as per > the above commit log. So do we really need to track this in userspace ? Yes, these weird HW details should not leak into userspace. The PASID is required on the read() side, userspace should provide it on the write() side. It is trivial for it to do, there is no reason to accommodate anything else. Alternatively I'm wondering if we should supply a serial number to userspace so it can match the request/response instead of relying on guessing based on pasid/grpid? Jason
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 0dbaa2dc5b22..ff063bc48150 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -237,6 +237,8 @@ struct hw_pgtable_fault { struct mutex mutex; struct list_head deliver; struct list_head response; + struct file *fault_file; + int fault_fd; }; /* diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index 9f94c824cf86..f0aac1bb2d2d 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -3,6 +3,8 @@ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES */ #include <linux/iommu.h> +#include <linux/file.h> +#include <linux/anon_inodes.h> #include <uapi/linux/iommufd.h> #include "../iommu-priv.h" @@ -38,9 +40,198 @@ static void iommufd_kernel_managed_hwpt_destroy(struct iommufd_object *obj) refcount_dec(&hwpt->ioas->obj.users); } +static int iommufd_compose_fault_message(struct iommu_fault *fault, + struct iommu_hwpt_pgfault *hwpt_fault, + struct device *dev) +{ + struct iommufd_device *idev = iopf_pasid_cookie_get(dev, IOMMU_NO_PASID); + + if (!idev) + return -ENODEV; + + if (IS_ERR(idev)) + return PTR_ERR(idev); + + hwpt_fault->size = sizeof(*hwpt_fault); + hwpt_fault->flags = fault->prm.flags; + hwpt_fault->dev_id = idev->obj.id; + hwpt_fault->pasid = fault->prm.pasid; + hwpt_fault->grpid = fault->prm.grpid; + hwpt_fault->perm = fault->prm.perm; + hwpt_fault->addr = fault->prm.addr; + hwpt_fault->private_data[0] = fault->prm.private_data[0]; + hwpt_fault->private_data[1] = fault->prm.private_data[1]; + + return 0; +} + +static ssize_t hwpt_fault_fops_read(struct file *filep, char __user *buf, + size_t count, loff_t *ppos) +{ + size_t fault_size = sizeof(struct iommu_hwpt_pgfault); + struct hw_pgtable_fault *fault = filep->private_data; + struct iommu_hwpt_pgfault data; + struct iopf_group *group; + struct iopf_fault *iopf; + size_t done = 0; + int rc; + + if (*ppos || count % fault_size) + return -ESPIPE; + + mutex_lock(&fault->mutex); + while (!list_empty(&fault->deliver) && count > done) { + group = list_first_entry(&fault->deliver, + struct iopf_group, node); + + if (list_count_nodes(&group->faults) * fault_size > count - done) + break; + + list_for_each_entry(iopf, &group->faults, list) { + rc = iommufd_compose_fault_message(&iopf->fault, + &data, group->dev); + if (rc) + goto err_unlock; + rc = copy_to_user(buf + done, &data, fault_size); + if (rc) + goto err_unlock; + done += fault_size; + } + + list_move_tail(&group->node, &fault->response); + } + mutex_unlock(&fault->mutex); + + return done; +err_unlock: + mutex_unlock(&fault->mutex); + return rc; +} + +static ssize_t hwpt_fault_fops_write(struct file *filep, + const char __user *buf, + size_t count, loff_t *ppos) +{ + size_t response_size = sizeof(struct iommu_hwpt_page_response); + struct hw_pgtable_fault *fault = filep->private_data; + struct iommu_hwpt_page_response response; + struct iommufd_hw_pagetable *hwpt; + struct iopf_group *iter, *group; + struct iommufd_device *idev; + size_t done = 0; + int rc = 0; + + if (*ppos || count % response_size) + return -ESPIPE; + + mutex_lock(&fault->mutex); + while (!list_empty(&fault->response) && count > done) { + rc = copy_from_user(&response, buf + done, response_size); + if (rc) + break; + + /* Get the device that this response targets at. */ + idev = container_of(iommufd_get_object(fault->ictx, + response.dev_id, + IOMMUFD_OBJ_DEVICE), + struct iommufd_device, obj); + if (IS_ERR(idev)) { + rc = PTR_ERR(idev); + break; + } + + /* + * Get the hw page table that this response was generated for. + * It must match the one stored in the fault data. + */ + hwpt = container_of(iommufd_get_object(fault->ictx, + response.hwpt_id, + IOMMUFD_OBJ_HW_PAGETABLE), + struct iommufd_hw_pagetable, obj); + if (IS_ERR(hwpt)) { + iommufd_put_object(&idev->obj); + rc = PTR_ERR(hwpt); + break; + } + + if (hwpt != fault->hwpt) { + rc = -EINVAL; + goto put_obj; + } + + group = NULL; + list_for_each_entry(iter, &fault->response, node) { + if (response.grpid != iter->last_fault.fault.prm.grpid) + continue; + + if (idev->dev != iter->dev) + continue; + + if ((iter->last_fault.fault.prm.flags & + IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) && + response.pasid != iter->last_fault.fault.prm.pasid) + continue; + + group = iter; + break; + } + + if (!group) { + rc = -ENODEV; + goto put_obj; + } + + rc = iopf_group_response(group, response.code); + if (rc) + goto put_obj; + + list_del(&group->node); + iopf_free_group(group); + done += response_size; +put_obj: + iommufd_put_object(&hwpt->obj); + iommufd_put_object(&idev->obj); + if (rc) + break; + } + mutex_unlock(&fault->mutex); + + return (rc < 0) ? rc : done; +} + +static const struct file_operations hwpt_fault_fops = { + .owner = THIS_MODULE, + .read = hwpt_fault_fops_read, + .write = hwpt_fault_fops_write, +}; + +static int hw_pagetable_get_fault_fd(struct hw_pgtable_fault *fault) +{ + struct file *filep; + int fdno; + + fdno = get_unused_fd_flags(O_CLOEXEC); + if (fdno < 0) + return fdno; + + filep = anon_inode_getfile("[iommufd-pgfault]", &hwpt_fault_fops, + fault, O_RDWR); + if (IS_ERR(filep)) { + put_unused_fd(fdno); + return PTR_ERR(filep); + } + + fd_install(fdno, filep); + fault->fault_file = filep; + fault->fault_fd = fdno; + + return 0; +} + static struct hw_pgtable_fault *hw_pagetable_fault_alloc(void) { struct hw_pgtable_fault *fault; + int rc; fault = kzalloc(sizeof(*fault), GFP_KERNEL); if (!fault) @@ -50,6 +241,12 @@ static struct hw_pgtable_fault *hw_pagetable_fault_alloc(void) INIT_LIST_HEAD(&fault->response); mutex_init(&fault->mutex); + rc = hw_pagetable_get_fault_fd(fault); + if (rc) { + kfree(fault); + return ERR_PTR(rc); + } + return fault; } @@ -58,6 +255,8 @@ static void hw_pagetable_fault_free(struct hw_pgtable_fault *fault) WARN_ON(!list_empty(&fault->deliver)); WARN_ON(!list_empty(&fault->response)); + fput(fault->fault_file); + put_unused_fd(fault->fault_fd); kfree(fault); } @@ -347,7 +546,9 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd) struct mutex *mutex; int rc; - if (cmd->flags & ~IOMMU_HWPT_ALLOC_NEST_PARENT || cmd->__reserved) + if ((cmd->flags & ~(IOMMU_HWPT_ALLOC_NEST_PARENT | + IOMMU_HWPT_ALLOC_IOPF_CAPABLE)) || + cmd->__reserved) return -EOPNOTSUPP; if (!cmd->data_len && cmd->hwpt_type != IOMMU_HWPT_TYPE_DEFAULT) return -EINVAL; @@ -416,6 +617,7 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd) hwpt->fault->hwpt = hwpt; hwpt->domain->iopf_handler = iommufd_hw_pagetable_iopf_handler; hwpt->domain->fault_data = hwpt; + cmd->out_fault_fd = hwpt->fault->fault_fd; } cmd->out_hwpt_id = hwpt->obj.id;
Add the file interface that provides a simple and efficient way for userspace to handle page faults. The file interface allows userspace to read fault messages sequentially, and to respond to the handling result by writing to the same file. Userspace applications are recommended to use io_uring to speed up read and write efficiency. With this done, allow userspace application to allocate a hw page table with IOMMU_HWPT_ALLOC_IOPF_CAPABLE flag set. Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> --- drivers/iommu/iommufd/iommufd_private.h | 2 + drivers/iommu/iommufd/hw_pagetable.c | 204 +++++++++++++++++++++++- 2 files changed, 205 insertions(+), 1 deletion(-)