]> git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blame - releases/3.19.7/arm64-kvm-fix-stage-2-pgd-allocation-to-have-per-page-refcounting.patch
projects / thirdparty / kernel / stable-queue.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
4.9-stable patches
[thirdparty/kernel/stable-queue.git] / releases / 3.19.7 / arm64-kvm-fix-stage-2-pgd-allocation-to-have-per-page-refcounting.patch
CommitLineData
c9c77b0b
GKH		 1From a987370f8e7a1677ae385042644326d9cd145a20 Mon Sep 17 00:00:00 2001
2From: Marc Zyngier <marc.zyngier@arm.com>
3Date: Tue, 10 Mar 2015 19:06:59 +0000
4Subject: arm64: KVM: Fix stage-2 PGD allocation to have per-page refcounting
5
6From: Marc Zyngier <marc.zyngier@arm.com>
7
8commit a987370f8e7a1677ae385042644326d9cd145a20 upstream.
9
10We're using __get_free_pages with to allocate the guest's stage-2
11PGD. The standard behaviour of this function is to return a set of
12pages where only the head page has a valid refcount.
13
14This behaviour gets us into trouble when we're trying to increment
15the refcount on a non-head page:
16
17page:ffff7c00cfb693c0 count:0 mapcount:0 mapping: (null) index:0x0
18flags: 0x4000000000000000()
19page dumped because: VM_BUG_ON_PAGE((*({ __attribute__((unused)) typeof((&page->_count)->counter) __var = ( typeof((&page->_count)->counter)) 0; (volatile typeof((&page->_count)->counter) *)&((&page->_count)->counter); })) <= 0)
20BUG: failure at include/linux/mm.h:548/get_page()!
21Kernel panic - not syncing: BUG!
22CPU: 1 PID: 1695 Comm: kvm-vcpu-0 Not tainted 4.0.0-rc1+ #3825
23Hardware name: APM X-Gene Mustang board (DT)
24Call trace:
25[<ffff80000008a09c>] dump_backtrace+0x0/0x13c
26[<ffff80000008a1e8>] show_stack+0x10/0x1c
27[<ffff800000691da8>] dump_stack+0x74/0x94
28[<ffff800000690d78>] panic+0x100/0x240
29[<ffff8000000a0bc4>] stage2_get_pmd+0x17c/0x2bc
30[<ffff8000000a1dc4>] kvm_handle_guest_abort+0x4b4/0x6b0
31[<ffff8000000a420c>] handle_exit+0x58/0x180
32[<ffff80000009e7a4>] kvm_arch_vcpu_ioctl_run+0x114/0x45c
33[<ffff800000099df4>] kvm_vcpu_ioctl+0x2e0/0x754
34[<ffff8000001c0a18>] do_vfs_ioctl+0x424/0x5c8
35[<ffff8000001c0bfc>] SyS_ioctl+0x40/0x78
36CPU0: stopping
37
38A possible approach for this is to split the compound page using
39split_page() at allocation time, and change the teardown path to
40free one page at a time. It turns out that alloc_pages_exact() and
41free_pages_exact() does exactly that.
42
43While we're at it, the PGD allocation code is reworked to reduce
44duplication.
45
46This has been tested on an X-Gene platform with a 4kB/48bit-VA host
47kernel, and kvmtool hacked to place memory in the second page of
48the hardware PGD (PUD for the host kernel). Also regression-tested
49on a Cubietruck (Cortex-A7).
50
51 [ Reworked to use alloc_pages_exact() and free_pages_exact() and to
52 return pointers directly instead of by reference as arguments
53 - Christoffer ]
54
55Reported-by: Mark Rutland <mark.rutland@arm.com>
56Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
57Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
58Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
59Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
60
61---
62 arch/arm/include/asm/kvm_mmu.h | 10 ++---
63 arch/arm/kvm/mmu.c | 67 ++++++++++++++++++++++++++++-----------
64 arch/arm64/include/asm/kvm_mmu.h | 46 ++------------------------
65 3 files changed, 57 insertions(+), 66 deletions(-)
66
67--- a/arch/arm/include/asm/kvm_mmu.h
68+++ b/arch/arm/include/asm/kvm_mmu.h
69@@ -141,16 +141,14 @@ static inline bool kvm_page_empty(void *
70
71 #define KVM_PREALLOC_LEVEL 0
72
73-static inline int kvm_prealloc_hwpgd(struct kvm *kvm, pgd_t *pgd)
74+static inline void *kvm_get_hwpgd(struct kvm *kvm)
75 {
76- return 0;
77+ return kvm->arch.pgd;
78 }
79
80-static inline void kvm_free_hwpgd(struct kvm *kvm) { }
81-
82-static inline void *kvm_get_hwpgd(struct kvm *kvm)
83+static inline unsigned int kvm_get_hwpgd_size(void)
84 {
85- return kvm->arch.pgd;
86+ return PTRS_PER_S2_PGD * sizeof(pgd_t);
87 }
88
89 struct kvm;
90--- a/arch/arm/kvm/mmu.c
91+++ b/arch/arm/kvm/mmu.c
92@@ -593,6 +593,20 @@ int create_hyp_io_mappings(void *from, v
93 __phys_to_pfn(phys_addr), PAGE_HYP_DEVICE);
94 }
95
96+/* Free the HW pgd, one page at a time */
97+static void kvm_free_hwpgd(void *hwpgd)
98+{
99+ free_pages_exact(hwpgd, kvm_get_hwpgd_size());
100+}
101+
102+/* Allocate the HW PGD, making sure that each page gets its own refcount */
103+static void *kvm_alloc_hwpgd(void)
104+{
105+ unsigned int size = kvm_get_hwpgd_size();
106+
107+ return alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
108+}
109+
110 /**
111 * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
112 * @kvm: The KVM struct pointer for the VM.
113@@ -606,15 +620,31 @@ int create_hyp_io_mappings(void *from, v
114 */
115 int kvm_alloc_stage2_pgd(struct kvm *kvm)
116 {
117- int ret;
118 pgd_t *pgd;
119+ void *hwpgd;
120
121 if (kvm->arch.pgd != NULL) {
122 kvm_err("kvm_arch already initialized?\n");
123 return -EINVAL;
124 }
125
126+ hwpgd = kvm_alloc_hwpgd();
127+ if (!hwpgd)
128+ return -ENOMEM;
129+
130+ /* When the kernel uses more levels of page tables than the
131+ * guest, we allocate a fake PGD and pre-populate it to point
132+ * to the next-level page table, which will be the real
133+ * initial page table pointed to by the VTTBR.
134+ *
135+ * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
136+ * the PMD and the kernel will use folded pud.
137+ * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
138+ * pages.
139+ */
140 if (KVM_PREALLOC_LEVEL > 0) {
141+ int i;
142+
143 /*
144 * Allocate fake pgd for the page table manipulation macros to
145 * work. This is not used by the hardware and we have no
146@@ -622,30 +652,32 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm
147 */
148 pgd = (pgd_t *)kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
149 GFP_KERNEL | __GFP_ZERO);
150+
151+ if (!pgd) {
152+ kvm_free_hwpgd(hwpgd);
153+ return -ENOMEM;
154+ }
155+
156+ /* Plug the HW PGD into the fake one. */
157+ for (i = 0; i < PTRS_PER_S2_PGD; i++) {
158+ if (KVM_PREALLOC_LEVEL == 1)
159+ pgd_populate(NULL, pgd + i,
160+ (pud_t *)hwpgd + i * PTRS_PER_PUD);
161+ else if (KVM_PREALLOC_LEVEL == 2)
162+ pud_populate(NULL, pud_offset(pgd, 0) + i,
163+ (pmd_t *)hwpgd + i * PTRS_PER_PMD);
164+ }
165 } else {
166 /*
167 * Allocate actual first-level Stage-2 page table used by the
168 * hardware for Stage-2 page table walks.
169 */
170- pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, S2_PGD_ORDER);
171+ pgd = (pgd_t *)hwpgd;
172 }
173
174- if (!pgd)
175- return -ENOMEM;
176-
177- ret = kvm_prealloc_hwpgd(kvm, pgd);
178- if (ret)
179- goto out_err;
180-
181 kvm_clean_pgd(pgd);
182 kvm->arch.pgd = pgd;
183 return 0;
184-out_err:
185- if (KVM_PREALLOC_LEVEL > 0)
186- kfree(pgd);
187- else
188- free_pages((unsigned long)pgd, S2_PGD_ORDER);
189- return ret;
190 }
191
192 /**
193@@ -746,11 +778,10 @@ void kvm_free_stage2_pgd(struct kvm *kvm
194 return;
195
196 unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
197- kvm_free_hwpgd(kvm);
198+ kvm_free_hwpgd(kvm_get_hwpgd(kvm));
199 if (KVM_PREALLOC_LEVEL > 0)
200 kfree(kvm->arch.pgd);
201- else
202- free_pages((unsigned long)kvm->arch.pgd, S2_PGD_ORDER);
203+
204 kvm->arch.pgd = NULL;
205 }
206
207--- a/arch/arm64/include/asm/kvm_mmu.h
208+++ b/arch/arm64/include/asm/kvm_mmu.h
209@@ -150,43 +150,6 @@ static inline void kvm_set_s2pmd_writabl
210 #define KVM_PREALLOC_LEVEL (0)
211 #endif
212
213-/**
214- * kvm_prealloc_hwpgd - allocate inital table for VTTBR
215- * @kvm: The KVM struct pointer for the VM.
216- * @pgd: The kernel pseudo pgd
217- *
218- * When the kernel uses more levels of page tables than the guest, we allocate
219- * a fake PGD and pre-populate it to point to the next-level page table, which
220- * will be the real initial page table pointed to by the VTTBR.
221- *
222- * When KVM_PREALLOC_LEVEL==2, we allocate a single page for the PMD and
223- * the kernel will use folded pud. When KVM_PREALLOC_LEVEL==1, we
224- * allocate 2 consecutive PUD pages.
225- */
226-static inline int kvm_prealloc_hwpgd(struct kvm *kvm, pgd_t *pgd)
227-{
228- unsigned int i;
229- unsigned long hwpgd;
230-
231- if (KVM_PREALLOC_LEVEL == 0)
232- return 0;
233-
234- hwpgd = __get_free_pages(GFP_KERNEL | __GFP_ZERO, PTRS_PER_S2_PGD_SHIFT);
235- if (!hwpgd)
236- return -ENOMEM;
237-
238- for (i = 0; i < PTRS_PER_S2_PGD; i++) {
239- if (KVM_PREALLOC_LEVEL == 1)
240- pgd_populate(NULL, pgd + i,
241- (pud_t *)hwpgd + i * PTRS_PER_PUD);
242- else if (KVM_PREALLOC_LEVEL == 2)
243- pud_populate(NULL, pud_offset(pgd, 0) + i,
244- (pmd_t *)hwpgd + i * PTRS_PER_PMD);
245- }
246-
247- return 0;
248-}
249-
250 static inline void *kvm_get_hwpgd(struct kvm *kvm)
251 {
252 pgd_t *pgd = kvm->arch.pgd;
253@@ -203,12 +166,11 @@ static inline void *kvm_get_hwpgd(struct
254 return pmd_offset(pud, 0);
255 }
256
257-static inline void kvm_free_hwpgd(struct kvm *kvm)
258+static inline unsigned int kvm_get_hwpgd_size(void)
259 {
260- if (KVM_PREALLOC_LEVEL > 0) {
261- unsigned long hwpgd = (unsigned long)kvm_get_hwpgd(kvm);
262- free_pages(hwpgd, PTRS_PER_S2_PGD_SHIFT);
263- }
264+ if (KVM_PREALLOC_LEVEL > 0)
265+ return PTRS_PER_S2_PGD * PAGE_SIZE;
266+ return PTRS_PER_S2_PGD * sizeof(pgd_t);
267 }
268
269 static inline bool kvm_page_empty(void *ptr)
Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git