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438 lines
11 KiB
438 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Common Ultravisor functions and initialization |
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* |
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* Copyright IBM Corp. 2019, 2020 |
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*/ |
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#define KMSG_COMPONENT "prot_virt" |
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
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#include <linux/kernel.h> |
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#include <linux/types.h> |
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#include <linux/sizes.h> |
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#include <linux/bitmap.h> |
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#include <linux/memblock.h> |
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#include <linux/pagemap.h> |
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#include <linux/swap.h> |
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#include <asm/facility.h> |
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#include <asm/sections.h> |
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#include <asm/uv.h> |
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/* the bootdata_preserved fields come from ones in arch/s390/boot/uv.c */ |
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#ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST |
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int __bootdata_preserved(prot_virt_guest); |
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#endif |
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struct uv_info __bootdata_preserved(uv_info); |
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#if IS_ENABLED(CONFIG_KVM) |
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int __bootdata_preserved(prot_virt_host); |
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EXPORT_SYMBOL(prot_virt_host); |
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EXPORT_SYMBOL(uv_info); |
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static int __init uv_init(unsigned long stor_base, unsigned long stor_len) |
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{ |
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struct uv_cb_init uvcb = { |
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.header.cmd = UVC_CMD_INIT_UV, |
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.header.len = sizeof(uvcb), |
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.stor_origin = stor_base, |
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.stor_len = stor_len, |
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}; |
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if (uv_call(0, (uint64_t)&uvcb)) { |
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pr_err("Ultravisor init failed with rc: 0x%x rrc: 0%x\n", |
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uvcb.header.rc, uvcb.header.rrc); |
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return -1; |
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} |
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return 0; |
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} |
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void __init setup_uv(void) |
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{ |
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unsigned long uv_stor_base; |
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/* |
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* keep these conditions in line with kasan init code has_uv_sec_stor_limit() |
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*/ |
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if (!is_prot_virt_host()) |
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return; |
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if (is_prot_virt_guest()) { |
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prot_virt_host = 0; |
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pr_warn("Protected virtualization not available in protected guests."); |
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return; |
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} |
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if (!test_facility(158)) { |
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prot_virt_host = 0; |
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pr_warn("Protected virtualization not supported by the hardware."); |
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return; |
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} |
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uv_stor_base = (unsigned long)memblock_alloc_try_nid( |
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uv_info.uv_base_stor_len, SZ_1M, SZ_2G, |
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MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE); |
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if (!uv_stor_base) { |
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pr_warn("Failed to reserve %lu bytes for ultravisor base storage\n", |
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uv_info.uv_base_stor_len); |
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goto fail; |
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} |
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if (uv_init(uv_stor_base, uv_info.uv_base_stor_len)) { |
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memblock_free(uv_stor_base, uv_info.uv_base_stor_len); |
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goto fail; |
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} |
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pr_info("Reserving %luMB as ultravisor base storage\n", |
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uv_info.uv_base_stor_len >> 20); |
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return; |
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fail: |
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pr_info("Disabling support for protected virtualization"); |
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prot_virt_host = 0; |
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} |
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void adjust_to_uv_max(unsigned long *vmax) |
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{ |
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if (uv_info.max_sec_stor_addr) |
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*vmax = min_t(unsigned long, *vmax, uv_info.max_sec_stor_addr); |
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} |
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/* |
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* Requests the Ultravisor to pin the page in the shared state. This will |
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* cause an intercept when the guest attempts to unshare the pinned page. |
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*/ |
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static int uv_pin_shared(unsigned long paddr) |
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{ |
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struct uv_cb_cfs uvcb = { |
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.header.cmd = UVC_CMD_PIN_PAGE_SHARED, |
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.header.len = sizeof(uvcb), |
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.paddr = paddr, |
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}; |
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if (uv_call(0, (u64)&uvcb)) |
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return -EINVAL; |
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return 0; |
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} |
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/* |
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* Requests the Ultravisor to destroy a guest page and make it |
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* accessible to the host. The destroy clears the page instead of |
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* exporting. |
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* |
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* @paddr: Absolute host address of page to be destroyed |
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*/ |
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int uv_destroy_page(unsigned long paddr) |
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{ |
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struct uv_cb_cfs uvcb = { |
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.header.cmd = UVC_CMD_DESTR_SEC_STOR, |
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.header.len = sizeof(uvcb), |
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.paddr = paddr |
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}; |
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if (uv_call(0, (u64)&uvcb)) { |
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/* |
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* Older firmware uses 107/d as an indication of a non secure |
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* page. Let us emulate the newer variant (no-op). |
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*/ |
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if (uvcb.header.rc == 0x107 && uvcb.header.rrc == 0xd) |
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return 0; |
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return -EINVAL; |
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} |
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return 0; |
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} |
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/* |
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* Requests the Ultravisor to encrypt a guest page and make it |
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* accessible to the host for paging (export). |
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* |
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* @paddr: Absolute host address of page to be exported |
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*/ |
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int uv_convert_from_secure(unsigned long paddr) |
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{ |
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struct uv_cb_cfs uvcb = { |
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.header.cmd = UVC_CMD_CONV_FROM_SEC_STOR, |
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.header.len = sizeof(uvcb), |
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.paddr = paddr |
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}; |
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if (uv_call(0, (u64)&uvcb)) |
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return -EINVAL; |
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return 0; |
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} |
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/* |
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* Calculate the expected ref_count for a page that would otherwise have no |
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* further pins. This was cribbed from similar functions in other places in |
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* the kernel, but with some slight modifications. We know that a secure |
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* page can not be a huge page for example. |
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*/ |
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static int expected_page_refs(struct page *page) |
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{ |
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int res; |
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res = page_mapcount(page); |
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if (PageSwapCache(page)) { |
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res++; |
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} else if (page_mapping(page)) { |
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res++; |
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if (page_has_private(page)) |
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res++; |
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} |
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return res; |
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} |
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static int make_secure_pte(pte_t *ptep, unsigned long addr, |
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struct page *exp_page, struct uv_cb_header *uvcb) |
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{ |
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pte_t entry = READ_ONCE(*ptep); |
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struct page *page; |
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int expected, rc = 0; |
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if (!pte_present(entry)) |
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return -ENXIO; |
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if (pte_val(entry) & _PAGE_INVALID) |
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return -ENXIO; |
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page = pte_page(entry); |
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if (page != exp_page) |
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return -ENXIO; |
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if (PageWriteback(page)) |
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return -EAGAIN; |
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expected = expected_page_refs(page); |
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if (!page_ref_freeze(page, expected)) |
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return -EBUSY; |
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set_bit(PG_arch_1, &page->flags); |
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rc = uv_call(0, (u64)uvcb); |
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page_ref_unfreeze(page, expected); |
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/* Return -ENXIO if the page was not mapped, -EINVAL otherwise */ |
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if (rc) |
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rc = uvcb->rc == 0x10a ? -ENXIO : -EINVAL; |
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return rc; |
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} |
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/* |
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* Requests the Ultravisor to make a page accessible to a guest. |
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* If it's brought in the first time, it will be cleared. If |
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* it has been exported before, it will be decrypted and integrity |
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* checked. |
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*/ |
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int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) |
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{ |
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struct vm_area_struct *vma; |
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bool local_drain = false; |
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spinlock_t *ptelock; |
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unsigned long uaddr; |
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struct page *page; |
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pte_t *ptep; |
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int rc; |
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again: |
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rc = -EFAULT; |
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mmap_read_lock(gmap->mm); |
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uaddr = __gmap_translate(gmap, gaddr); |
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if (IS_ERR_VALUE(uaddr)) |
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goto out; |
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vma = find_vma(gmap->mm, uaddr); |
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if (!vma) |
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goto out; |
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/* |
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* Secure pages cannot be huge and userspace should not combine both. |
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* In case userspace does it anyway this will result in an -EFAULT for |
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* the unpack. The guest is thus never reaching secure mode. If |
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* userspace is playing dirty tricky with mapping huge pages later |
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* on this will result in a segmentation fault. |
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*/ |
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if (is_vm_hugetlb_page(vma)) |
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goto out; |
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rc = -ENXIO; |
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page = follow_page(vma, uaddr, FOLL_WRITE); |
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if (IS_ERR_OR_NULL(page)) |
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goto out; |
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lock_page(page); |
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ptep = get_locked_pte(gmap->mm, uaddr, &ptelock); |
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rc = make_secure_pte(ptep, uaddr, page, uvcb); |
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pte_unmap_unlock(ptep, ptelock); |
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unlock_page(page); |
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out: |
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mmap_read_unlock(gmap->mm); |
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if (rc == -EAGAIN) { |
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wait_on_page_writeback(page); |
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} else if (rc == -EBUSY) { |
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/* |
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* If we have tried a local drain and the page refcount |
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* still does not match our expected safe value, try with a |
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* system wide drain. This is needed if the pagevecs holding |
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* the page are on a different CPU. |
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*/ |
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if (local_drain) { |
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lru_add_drain_all(); |
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/* We give up here, and let the caller try again */ |
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return -EAGAIN; |
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} |
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/* |
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* We are here if the page refcount does not match the |
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* expected safe value. The main culprits are usually |
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* pagevecs. With lru_add_drain() we drain the pagevecs |
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* on the local CPU so that hopefully the refcount will |
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* reach the expected safe value. |
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*/ |
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lru_add_drain(); |
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local_drain = true; |
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/* And now we try again immediately after draining */ |
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goto again; |
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} else if (rc == -ENXIO) { |
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if (gmap_fault(gmap, gaddr, FAULT_FLAG_WRITE)) |
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return -EFAULT; |
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return -EAGAIN; |
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} |
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return rc; |
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} |
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EXPORT_SYMBOL_GPL(gmap_make_secure); |
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int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr) |
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{ |
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struct uv_cb_cts uvcb = { |
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.header.cmd = UVC_CMD_CONV_TO_SEC_STOR, |
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.header.len = sizeof(uvcb), |
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.guest_handle = gmap->guest_handle, |
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.gaddr = gaddr, |
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}; |
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return gmap_make_secure(gmap, gaddr, &uvcb); |
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} |
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EXPORT_SYMBOL_GPL(gmap_convert_to_secure); |
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/* |
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* To be called with the page locked or with an extra reference! This will |
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* prevent gmap_make_secure from touching the page concurrently. Having 2 |
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* parallel make_page_accessible is fine, as the UV calls will become a |
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* no-op if the page is already exported. |
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*/ |
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int arch_make_page_accessible(struct page *page) |
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{ |
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int rc = 0; |
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/* Hugepage cannot be protected, so nothing to do */ |
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if (PageHuge(page)) |
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return 0; |
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/* |
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* PG_arch_1 is used in 3 places: |
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* 1. for kernel page tables during early boot |
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* 2. for storage keys of huge pages and KVM |
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* 3. As an indication that this page might be secure. This can |
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* overindicate, e.g. we set the bit before calling |
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* convert_to_secure. |
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* As secure pages are never huge, all 3 variants can co-exists. |
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*/ |
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if (!test_bit(PG_arch_1, &page->flags)) |
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return 0; |
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rc = uv_pin_shared(page_to_phys(page)); |
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if (!rc) { |
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clear_bit(PG_arch_1, &page->flags); |
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return 0; |
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} |
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rc = uv_convert_from_secure(page_to_phys(page)); |
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if (!rc) { |
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clear_bit(PG_arch_1, &page->flags); |
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return 0; |
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} |
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return rc; |
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} |
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EXPORT_SYMBOL_GPL(arch_make_page_accessible); |
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#endif |
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#if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM) |
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static ssize_t uv_query_facilities(struct kobject *kobj, |
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struct kobj_attribute *attr, char *page) |
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{ |
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return scnprintf(page, PAGE_SIZE, "%lx\n%lx\n%lx\n%lx\n", |
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uv_info.inst_calls_list[0], |
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uv_info.inst_calls_list[1], |
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uv_info.inst_calls_list[2], |
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uv_info.inst_calls_list[3]); |
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} |
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static struct kobj_attribute uv_query_facilities_attr = |
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__ATTR(facilities, 0444, uv_query_facilities, NULL); |
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static ssize_t uv_query_max_guest_cpus(struct kobject *kobj, |
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struct kobj_attribute *attr, char *page) |
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{ |
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return scnprintf(page, PAGE_SIZE, "%d\n", |
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uv_info.max_guest_cpu_id + 1); |
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} |
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static struct kobj_attribute uv_query_max_guest_cpus_attr = |
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__ATTR(max_cpus, 0444, uv_query_max_guest_cpus, NULL); |
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static ssize_t uv_query_max_guest_vms(struct kobject *kobj, |
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struct kobj_attribute *attr, char *page) |
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{ |
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return scnprintf(page, PAGE_SIZE, "%d\n", |
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uv_info.max_num_sec_conf); |
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} |
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static struct kobj_attribute uv_query_max_guest_vms_attr = |
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__ATTR(max_guests, 0444, uv_query_max_guest_vms, NULL); |
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static ssize_t uv_query_max_guest_addr(struct kobject *kobj, |
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struct kobj_attribute *attr, char *page) |
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{ |
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return scnprintf(page, PAGE_SIZE, "%lx\n", |
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uv_info.max_sec_stor_addr); |
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} |
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static struct kobj_attribute uv_query_max_guest_addr_attr = |
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__ATTR(max_address, 0444, uv_query_max_guest_addr, NULL); |
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static struct attribute *uv_query_attrs[] = { |
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&uv_query_facilities_attr.attr, |
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&uv_query_max_guest_cpus_attr.attr, |
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&uv_query_max_guest_vms_attr.attr, |
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&uv_query_max_guest_addr_attr.attr, |
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NULL, |
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}; |
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static struct attribute_group uv_query_attr_group = { |
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.attrs = uv_query_attrs, |
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}; |
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static struct kset *uv_query_kset; |
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static struct kobject *uv_kobj; |
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static int __init uv_info_init(void) |
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{ |
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int rc = -ENOMEM; |
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if (!test_facility(158)) |
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return 0; |
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uv_kobj = kobject_create_and_add("uv", firmware_kobj); |
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if (!uv_kobj) |
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return -ENOMEM; |
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uv_query_kset = kset_create_and_add("query", NULL, uv_kobj); |
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if (!uv_query_kset) |
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goto out_kobj; |
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rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group); |
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if (!rc) |
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return 0; |
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kset_unregister(uv_query_kset); |
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out_kobj: |
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kobject_del(uv_kobj); |
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kobject_put(uv_kobj); |
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return rc; |
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} |
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device_initcall(uv_info_init); |
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#endif
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