diff options
Diffstat (limited to 'include/linux/hmm.h')
| -rw-r--r-- | include/linux/hmm.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index ed89fbc525d2..66f9ebbb1df3 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -69,6 +69,7 @@ #define LINUX_HMM_H #include <linux/kconfig.h> +#include <asm/pgtable.h> #if IS_ENABLED(CONFIG_HMM) @@ -486,6 +487,7 @@ struct hmm_devmem_ops { * @device: device to bind resource to * @ops: memory operations callback * @ref: per CPU refcount + * @page_fault: callback when CPU fault on an unaddressable device page * * This an helper structure for device drivers that do not wish to implement * the gory details related to hotplugging new memoy and allocating struct @@ -493,7 +495,28 @@ struct hmm_devmem_ops { * * Device drivers can directly use ZONE_DEVICE memory on their own if they * wish to do so. + * + * The page_fault() callback must migrate page back, from device memory to + * system memory, so that the CPU can access it. This might fail for various + * reasons (device issues, device have been unplugged, ...). When such error + * conditions happen, the page_fault() callback must return VM_FAULT_SIGBUS and + * set the CPU page table entry to "poisoned". + * + * Note that because memory cgroup charges are transferred to the device memory, + * this should never fail due to memory restrictions. However, allocation + * of a regular system page might still fail because we are out of memory. If + * that happens, the page_fault() callback must return VM_FAULT_OOM. + * + * The page_fault() callback can also try to migrate back multiple pages in one + * chunk, as an optimization. It must, however, prioritize the faulting address + * over all the others. */ +typedef int (*dev_page_fault_t)(struct vm_area_struct *vma, + unsigned long addr, + const struct page *page, + unsigned int flags, + pmd_t *pmdp); + struct hmm_devmem { struct completion completion; unsigned long pfn_first; @@ -503,6 +526,7 @@ struct hmm_devmem { struct dev_pagemap pagemap; const struct hmm_devmem_ops *ops; struct percpu_ref ref; + dev_page_fault_t page_fault; }; /* |