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Peter Anvin" , x86@kernel.org, Liran Alon , Nikita Leshenko , Barret Rhoden , Boris Ostrovsky , Matthew Wilcox , Konrad Rzeszutek Wilk Subject: [PATCH RFC 07/10] device-dax: Add support for PFN_SPECIAL flags Date: Fri, 10 Jan 2020 19:03:10 +0000 Message-Id: <20200110190313.17144-8-joao.m.martins@oracle.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20200110190313.17144-1-joao.m.martins@oracle.com> References: <20200110190313.17144-1-joao.m.martins@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9496 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001100154 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9496 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001100154 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Right now we assume there's gonna be a PFN_DEV|PFN_MAP which means it will have a struct page backing the PFN but that is not placed in normal system RAM zones. Add support for PFN_DEV|PFN_SPECIAL only and therefore the underlying vma won't have a struct page. For device dax, this means not assuming callers will pass a dev_pagemap, and avoid returning SIGBUS for the lack of PFN_MAP region pfn flag and finally not setting struct page index/mapping on fault. Signed-off-by: Joao Martins --- drivers/dax/bus.c | 3 ++- drivers/dax/device.c | 40 ++++++++++++++++++++++------------------ 2 files changed, 24 insertions(+), 19 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 46e46047a1f7..96ca3ac85278 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -414,7 +414,8 @@ struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id, if (!dev_dax) return ERR_PTR(-ENOMEM); - memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap)); + if (pgmap) + memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap)); /* * No 'host' or dax_operations since there is no access to this diff --git a/drivers/dax/device.c b/drivers/dax/device.c index 113a554de3ee..aa38f5ff180a 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -14,6 +14,12 @@ #include "dax-private.h" #include "bus.h" +static int dax_is_pfn_special(struct dev_dax *dev_dax) +{ + return (dev_dax->region->pfn_flags & + (PFN_DEV|PFN_SPECIAL)) == (PFN_DEV|PFN_SPECIAL); +} + static int dax_is_pfn_dev(struct dev_dax *dev_dax) { return (dev_dax->region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV; @@ -104,6 +110,7 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax, struct dax_region *dax_region; phys_addr_t phys; unsigned int fault_size = PAGE_SIZE; + int rc; if (check_vma(dev_dax, vmf->vma, __func__)) return VM_FAULT_SIGBUS; @@ -126,7 +133,12 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax, *pfn = phys_to_pfn_t(phys, dax_region->pfn_flags); - return vmf_insert_mixed(vmf->vma, vmf->address, *pfn); + if (dax_is_pfn_special(dev_dax)) + rc = vmf_insert_pfn(vmf->vma, vmf->address, pfn_t_to_pfn(*pfn)); + else + rc = vmf_insert_mixed(vmf->vma, vmf->address, *pfn); + + return rc; } static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax, @@ -149,12 +161,6 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax, return VM_FAULT_SIGBUS; } - /* dax pmd mappings require pfn_t_devmap() */ - if (!dax_is_pfn_map(dev_dax)) { - dev_dbg(dev, "region lacks devmap flags\n"); - return VM_FAULT_SIGBUS; - } - if (fault_size < dax_region->align) return VM_FAULT_SIGBUS; else if (fault_size > dax_region->align) @@ -199,12 +205,6 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax, return VM_FAULT_SIGBUS; } - /* dax pud mappings require pfn_t_devmap() */ - if (!dax_is_pfn_map(dev_dax)) { - dev_dbg(dev, "region lacks devmap flags\n"); - return VM_FAULT_SIGBUS; - } - if (fault_size < dax_region->align) return VM_FAULT_SIGBUS; else if (fault_size > dax_region->align) @@ -266,7 +266,7 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf, rc = VM_FAULT_SIGBUS; } - if (rc == VM_FAULT_NOPAGE) { + if (dax_is_pfn_map(dev_dax) && (rc == VM_FAULT_NOPAGE)) { unsigned long i; pgoff_t pgoff; @@ -344,6 +344,8 @@ static int dax_mmap(struct file *filp, struct vm_area_struct *vma) vma->vm_ops = &dax_vm_ops; vma->vm_flags |= VM_HUGEPAGE; + if (dax_is_pfn_special(dev_dax)) + vma->vm_flags |= VM_PFNMAP; return 0; } @@ -450,10 +452,12 @@ int dev_dax_probe(struct device *dev) return -EBUSY; } - dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX; - addr = devm_memremap_pages(dev, &dev_dax->pgmap); - if (IS_ERR(addr)) - return PTR_ERR(addr); + if (dax_is_pfn_map(dev_dax)) { + dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX; + addr = devm_memremap_pages(dev, &dev_dax->pgmap); + if (IS_ERR(addr)) + return PTR_ERR(addr); + } inode = dax_inode(dax_dev); cdev = inode->i_cdev; -- 2.17.1