From ceb90fa0a8008059ecbbf9114cb89dc71a730bb6 Mon Sep 17 00:00:00 2001 From: Andres Lagar-Cavilla Date: Fri, 31 Aug 2012 09:59:30 -0400 Subject: [PATCH] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl PRIVCMD_MMAPBATCH_V2 extends PRIVCMD_MMAPBATCH with an additional field for reporting the error code for every frame that could not be mapped. libxc prefers PRIVCMD_MMAPBATCH_V2 over PRIVCMD_MMAPBATCH. Also expand PRIVCMD_MMAPBATCH to return appropriate error-encoding top nibble in the mfn array. Signed-off-by: David Vrabel Signed-off-by: Andres Lagar-Cavilla Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/privcmd.c | 130 ++++++++++++++++++++++++++++++++---------- include/xen/privcmd.h | 24 +++++++- 2 files changed, 123 insertions(+), 31 deletions(-) diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 85226cbeca2..92a285b1b96 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -76,7 +76,7 @@ static void free_page_list(struct list_head *pages) */ static int gather_array(struct list_head *pagelist, unsigned nelem, size_t size, - void __user *data) + const void __user *data) { unsigned pageidx; void *pagedata; @@ -246,61 +246,117 @@ struct mmap_batch_state { domid_t domain; unsigned long va; struct vm_area_struct *vma; - int err; - - xen_pfn_t __user *user; + /* A tristate: + * 0 for no errors + * 1 if at least one error has happened (and no + * -ENOENT errors have happened) + * -ENOENT if at least 1 -ENOENT has happened. + */ + int global_error; + /* An array for individual errors */ + int *err; + + /* User-space mfn array to store errors in the second pass for V1. */ + xen_pfn_t __user *user_mfn; }; static int mmap_batch_fn(void *data, void *state) { xen_pfn_t *mfnp = data; struct mmap_batch_state *st = state; + int ret; - if (xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1, - st->vma->vm_page_prot, st->domain) < 0) { - *mfnp |= 0xf0000000U; - st->err++; + ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1, + st->vma->vm_page_prot, st->domain); + + /* Store error code for second pass. */ + *(st->err++) = ret; + + /* And see if it affects the global_error. */ + if (ret < 0) { + if (ret == -ENOENT) + st->global_error = -ENOENT; + else { + /* Record that at least one error has happened. */ + if (st->global_error == 0) + st->global_error = 1; + } } st->va += PAGE_SIZE; return 0; } -static int mmap_return_errors(void *data, void *state) +static int mmap_return_errors_v1(void *data, void *state) { xen_pfn_t *mfnp = data; struct mmap_batch_state *st = state; - - return put_user(*mfnp, st->user++); + int err = *(st->err++); + + /* + * V1 encodes the error codes in the 32bit top nibble of the + * mfn (with its known limitations vis-a-vis 64 bit callers). + */ + *mfnp |= (err == -ENOENT) ? + PRIVCMD_MMAPBATCH_PAGED_ERROR : + PRIVCMD_MMAPBATCH_MFN_ERROR; + return __put_user(*mfnp, st->user_mfn++); } static struct vm_operations_struct privcmd_vm_ops; -static long privcmd_ioctl_mmap_batch(void __user *udata) +static long privcmd_ioctl_mmap_batch(void __user *udata, int version) { int ret; - struct privcmd_mmapbatch m; + struct privcmd_mmapbatch_v2 m; struct mm_struct *mm = current->mm; struct vm_area_struct *vma; unsigned long nr_pages; LIST_HEAD(pagelist); + int *err_array = NULL; struct mmap_batch_state state; if (!xen_initial_domain()) return -EPERM; - if (copy_from_user(&m, udata, sizeof(m))) - return -EFAULT; + switch (version) { + case 1: + if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch))) + return -EFAULT; + /* Returns per-frame error in m.arr. */ + m.err = NULL; + if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr))) + return -EFAULT; + break; + case 2: + if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2))) + return -EFAULT; + /* Returns per-frame error code in m.err. */ + if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err)))) + return -EFAULT; + break; + default: + return -EINVAL; + } nr_pages = m.num; if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT))) return -EINVAL; - ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), - m.arr); + ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr); + + if (ret) + goto out; + if (list_empty(&pagelist)) { + ret = -EINVAL; + goto out; + } - if (ret || list_empty(&pagelist)) + err_array = kcalloc(m.num, sizeof(int), GFP_KERNEL); + if (err_array == NULL) { + ret = -ENOMEM; goto out; + } down_write(&mm->mmap_sem); @@ -315,24 +371,34 @@ static long privcmd_ioctl_mmap_batch(void __user *udata) goto out; } - state.domain = m.dom; - state.vma = vma; - state.va = m.addr; - state.err = 0; + state.domain = m.dom; + state.vma = vma; + state.va = m.addr; + state.global_error = 0; + state.err = err_array; - ret = traverse_pages(m.num, sizeof(xen_pfn_t), - &pagelist, mmap_batch_fn, &state); + /* mmap_batch_fn guarantees ret == 0 */ + BUG_ON(traverse_pages(m.num, sizeof(xen_pfn_t), + &pagelist, mmap_batch_fn, &state)); up_write(&mm->mmap_sem); - if (state.err > 0) { - state.user = m.arr; + if (state.global_error && (version == 1)) { + /* Write back errors in second pass. */ + state.user_mfn = (xen_pfn_t *)m.arr; + state.err = err_array; ret = traverse_pages(m.num, sizeof(xen_pfn_t), - &pagelist, - mmap_return_errors, &state); - } + &pagelist, mmap_return_errors_v1, &state); + } else + ret = __copy_to_user(m.err, err_array, m.num * sizeof(int)); + + /* If we have not had any EFAULT-like global errors then set the global + * error to -ENOENT if necessary. */ + if ((ret == 0) && (state.global_error == -ENOENT)) + ret = -ENOENT; out: + kfree(err_array); free_page_list(&pagelist); return ret; @@ -354,7 +420,11 @@ static long privcmd_ioctl(struct file *file, break; case IOCTL_PRIVCMD_MMAPBATCH: - ret = privcmd_ioctl_mmap_batch(udata); + ret = privcmd_ioctl_mmap_batch(udata, 1); + break; + + case IOCTL_PRIVCMD_MMAPBATCH_V2: + ret = privcmd_ioctl_mmap_batch(udata, 2); break; default: diff --git a/include/xen/privcmd.h b/include/xen/privcmd.h index 45c1aa14b83..a85316811d7 100644 --- a/include/xen/privcmd.h +++ b/include/xen/privcmd.h @@ -58,13 +58,33 @@ struct privcmd_mmapbatch { int num; /* number of pages to populate */ domid_t dom; /* target domain */ __u64 addr; /* virtual address */ - xen_pfn_t __user *arr; /* array of mfns - top nibble set on err */ + xen_pfn_t __user *arr; /* array of mfns - or'd with + PRIVCMD_MMAPBATCH_*_ERROR on err */ +}; + +#define PRIVCMD_MMAPBATCH_MFN_ERROR 0xf0000000U +#define PRIVCMD_MMAPBATCH_PAGED_ERROR 0x80000000U + +struct privcmd_mmapbatch_v2 { + unsigned int num; /* number of pages to populate */ + domid_t dom; /* target domain */ + __u64 addr; /* virtual address */ + const xen_pfn_t __user *arr; /* array of mfns */ + int __user *err; /* array of error codes */ }; /* * @cmd: IOCTL_PRIVCMD_HYPERCALL * @arg: &privcmd_hypercall_t * Return: Value returned from execution of the specified hypercall. + * + * @cmd: IOCTL_PRIVCMD_MMAPBATCH_V2 + * @arg: &struct privcmd_mmapbatch_v2 + * Return: 0 on success (i.e., arg->err contains valid error codes for + * each frame). On an error other than a failed frame remap, -1 is + * returned and errno is set to EINVAL, EFAULT etc. As an exception, + * if the operation was otherwise successful but any frame failed with + * -ENOENT, then -1 is returned and errno is set to ENOENT. */ #define IOCTL_PRIVCMD_HYPERCALL \ _IOC(_IOC_NONE, 'P', 0, sizeof(struct privcmd_hypercall)) @@ -72,5 +92,7 @@ struct privcmd_mmapbatch { _IOC(_IOC_NONE, 'P', 2, sizeof(struct privcmd_mmap)) #define IOCTL_PRIVCMD_MMAPBATCH \ _IOC(_IOC_NONE, 'P', 3, sizeof(struct privcmd_mmapbatch)) +#define IOCTL_PRIVCMD_MMAPBATCH_V2 \ + _IOC(_IOC_NONE, 'P', 4, sizeof(struct privcmd_mmapbatch_v2)) #endif /* __LINUX_PUBLIC_PRIVCMD_H__ */ -- 2.20.1