[PATCH 4.15 036/163] x86/kexec: Make kexec (mostly) work in 5-level paging mode

[PATCH 4.15 036/163] x86/kexec: Make kexec (mostly) work in 5-level paging mode

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

commit 5bf30316991d5bcda046343ee77d823cf16fdd03 upstream.

Currently kexec() will crash when switching into a 5-level paging
enabled kernel.

I missed that we need to change relocate_kernel() to set CR4.LA57
flag if the kernel has 5-level paging enabled.

I avoided using #ifdef CONFIG_X86_5LEVEL here and inferred if we need to
enable 5-level paging from previous CR4 value. This way the code is
ready for boot-time switching between paging modes.

With this patch applied, in addition to kexec 4-to-4 which always worked,
we can kexec 4-to-5 and 5-to-5 - while 5-to-4 will need more work.

Reported-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Baoquan He <bhe@redhat.com>
Cc: <stable@vger.kernel.org> # v4.14+
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Fixes: 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y")
Link: http://lkml.kernel.org/r/20180129110845.26633-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/relocate_kernel_64.S |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -68,6 +68,9 @@ relocate_kernel:
 	movq	%cr4, %rax
 	movq	%rax, CR4(%r11)
 
+	/* Save CR4. Required to enable the right paging mode later. */
+	movq	%rax, %r13
+
 	/* zero out flags, and disable interrupts */
 	pushq $0
 	popfq
@@ -126,8 +129,13 @@ identity_mapped:
 	/*
 	 * Set cr4 to a known state:
 	 *  - physical address extension enabled
+	 *  - 5-level paging, if it was enabled before
 	 */
 	movl	$X86_CR4_PAE, %eax
+	testq	$X86_CR4_LA57, %r13
+	jz	1f
+	orl	$X86_CR4_LA57, %eax
+1:
 	movq	%rax, %cr4
 
 	jmp 1f


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[PATCH 4.15 082/163] x86/mm: Rename flush_tlb_single() and flush_tlb_one() to __flush_tlb_one_[user|kernel]()

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@kernel.org>

commit 1299ef1d8870d2d9f09a5aadf2f8b2c887c2d033 upstream.

flush_tlb_single() and flush_tlb_one() sound almost identical, but
they really mean "flush one user translation" and "flush one kernel
translation".  Rename them to flush_tlb_one_user() and
flush_tlb_one_kernel() to make the semantics more obvious.

[ I was looking at some PTI-related code, and the flush-one-address code
  is unnecessarily hard to understand because the names of the helpers are
  uninformative.  This came up during PTI review, but no one got around to
  doing it. ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux-MM <linux-mm@kvack.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/3303b02e3c3d049dc5235d5651e0ae6d29a34354.1517414378.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/paravirt.h       |    4 ++--
 arch/x86/include/asm/paravirt_types.h |    2 +-
 arch/x86/include/asm/pgtable_32.h     |    2 +-
 arch/x86/include/asm/tlbflush.h       |   27 ++++++++++++++++++++-------
 arch/x86/kernel/paravirt.c            |    6 +++---
 arch/x86/mm/init_64.c                 |    2 +-
 arch/x86/mm/ioremap.c                 |    2 +-
 arch/x86/mm/kmmio.c                   |    2 +-
 arch/x86/mm/pgtable_32.c              |    2 +-
 arch/x86/mm/tlb.c                     |    6 +++---
 arch/x86/platform/uv/tlb_uv.c         |    2 +-
 arch/x86/xen/mmu_pv.c                 |    6 +++---
 include/trace/events/xen.h            |    2 +-
 13 files changed, 39 insertions(+), 26 deletions(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -297,9 +297,9 @@ static inline void __flush_tlb_global(vo
 {
 	PVOP_VCALL0(pv_mmu_ops.flush_tlb_kernel);
 }
-static inline void __flush_tlb_single(unsigned long addr)
+static inline void __flush_tlb_one_user(unsigned long addr)
 {
-	PVOP_VCALL1(pv_mmu_ops.flush_tlb_single, addr);
+	PVOP_VCALL1(pv_mmu_ops.flush_tlb_one_user, addr);
 }
 
 static inline void flush_tlb_others(const struct cpumask *cpumask,
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -217,7 +217,7 @@ struct pv_mmu_ops {
 	/* TLB operations */
 	void (*flush_tlb_user)(void);
 	void (*flush_tlb_kernel)(void);
-	void (*flush_tlb_single)(unsigned long addr);
+	void (*flush_tlb_one_user)(unsigned long addr);
 	void (*flush_tlb_others)(const struct cpumask *cpus,
 				 const struct flush_tlb_info *info);
 
--- a/arch/x86/include/asm/pgtable_32.h
+++ b/arch/x86/include/asm/pgtable_32.h
@@ -61,7 +61,7 @@ void paging_init(void);
 #define kpte_clear_flush(ptep, vaddr)		\
 do {						\
 	pte_clear(&init_mm, (vaddr), (ptep));	\
-	__flush_tlb_one((vaddr));		\
+	__flush_tlb_one_kernel((vaddr));		\
 } while (0)
 
 #endif /* !__ASSEMBLY__ */
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -140,7 +140,7 @@ static inline unsigned long build_cr3_no
 #else
 #define __flush_tlb() __native_flush_tlb()
 #define __flush_tlb_global() __native_flush_tlb_global()
-#define __flush_tlb_single(addr) __native_flush_tlb_single(addr)
+#define __flush_tlb_one_user(addr) __native_flush_tlb_one_user(addr)
 #endif
 
 static inline bool tlb_defer_switch_to_init_mm(void)
@@ -400,7 +400,7 @@ static inline void __native_flush_tlb_gl
 /*
  * flush one page in the user mapping
  */
-static inline void __native_flush_tlb_single(unsigned long addr)
+static inline void __native_flush_tlb_one_user(unsigned long addr)
 {
 	u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
 
@@ -437,18 +437,31 @@ static inline void __flush_tlb_all(void)
 /*
  * flush one page in the kernel mapping
  */
-static inline void __flush_tlb_one(unsigned long addr)
+static inline void __flush_tlb_one_kernel(unsigned long addr)
 {
 	count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
-	__flush_tlb_single(addr);
+
+	/*
+	 * If PTI is off, then __flush_tlb_one_user() is just INVLPG or its
+	 * paravirt equivalent.  Even with PCID, this is sufficient: we only
+	 * use PCID if we also use global PTEs for the kernel mapping, and
+	 * INVLPG flushes global translations across all address spaces.
+	 *
+	 * If PTI is on, then the kernel is mapped with non-global PTEs, and
+	 * __flush_tlb_one_user() will flush the given address for the current
+	 * kernel address space and for its usermode counterpart, but it does
+	 * not flush it for other address spaces.
+	 */
+	__flush_tlb_one_user(addr);
 
 	if (!static_cpu_has(X86_FEATURE_PTI))
 		return;
 
 	/*
-	 * __flush_tlb_single() will have cleared the TLB entry for this ASID,
-	 * but since kernel space is replicated across all, we must also
-	 * invalidate all others.
+	 * See above.  We need to propagate the flush to all other address
+	 * spaces.  In principle, we only need to propagate it to kernelmode
+	 * address spaces, but the extra bookkeeping we would need is not
+	 * worth it.
 	 */
 	invalidate_other_asid();
 }
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -200,9 +200,9 @@ static void native_flush_tlb_global(void
 	__native_flush_tlb_global();
 }
 
-static void native_flush_tlb_single(unsigned long addr)
+static void native_flush_tlb_one_user(unsigned long addr)
 {
-	__native_flush_tlb_single(addr);
+	__native_flush_tlb_one_user(addr);
 }
 
 struct static_key paravirt_steal_enabled;
@@ -401,7 +401,7 @@ struct pv_mmu_ops pv_mmu_ops __ro_after_
 
 	.flush_tlb_user = native_flush_tlb,
 	.flush_tlb_kernel = native_flush_tlb_global,
-	.flush_tlb_single = native_flush_tlb_single,
+	.flush_tlb_one_user = native_flush_tlb_one_user,
 	.flush_tlb_others = native_flush_tlb_others,
 
 	.pgd_alloc = __paravirt_pgd_alloc,
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -256,7 +256,7 @@ static void __set_pte_vaddr(pud_t *pud,
 	 * It's enough to flush this one mapping.
 	 * (PGE mappings get flushed as well)
 	 */
-	__flush_tlb_one(vaddr);
+	__flush_tlb_one_kernel(vaddr);
 }
 
 void set_pte_vaddr_p4d(p4d_t *p4d_page, unsigned long vaddr, pte_t new_pte)
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -820,5 +820,5 @@ void __init __early_set_fixmap(enum fixe
 		set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
 	else
 		pte_clear(&init_mm, addr, pte);
-	__flush_tlb_one(addr);
+	__flush_tlb_one_kernel(addr);
 }
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -168,7 +168,7 @@ static int clear_page_presence(struct km
 		return -1;
 	}
 
-	__flush_tlb_one(f->addr);
+	__flush_tlb_one_kernel(f->addr);
 	return 0;
 }
 
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -63,7 +63,7 @@ void set_pte_vaddr(unsigned long vaddr,
 	 * It's enough to flush this one mapping.
 	 * (PGE mappings get flushed as well)
 	 */
-	__flush_tlb_one(vaddr);
+	__flush_tlb_one_kernel(vaddr);
 }
 
 unsigned long __FIXADDR_TOP = 0xfffff000;
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -492,7 +492,7 @@ static void flush_tlb_func_common(const
 	 *    flush that changes context.tlb_gen from 2 to 3.  If they get
 	 *    processed on this CPU in reverse order, we'll see
 	 *     local_tlb_gen == 1, mm_tlb_gen == 3, and end != TLB_FLUSH_ALL.
-	 *    If we were to use __flush_tlb_single() and set local_tlb_gen to
+	 *    If we were to use __flush_tlb_one_user() and set local_tlb_gen to
 	 *    3, we'd be break the invariant: we'd update local_tlb_gen above
 	 *    1 without the full flush that's needed for tlb_gen 2.
 	 *
@@ -513,7 +513,7 @@ static void flush_tlb_func_common(const
 
 		addr = f->start;
 		while (addr < f->end) {
-			__flush_tlb_single(addr);
+			__flush_tlb_one_user(addr);
 			addr += PAGE_SIZE;
 		}
 		if (local)
@@ -660,7 +660,7 @@ static void do_kernel_range_flush(void *
 
 	/* flush range by one by one 'invlpg' */
 	for (addr = f->start; addr < f->end; addr += PAGE_SIZE)
-		__flush_tlb_one(addr);
+		__flush_tlb_one_kernel(addr);
 }
 
 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -299,7 +299,7 @@ static void bau_process_message(struct m
 		local_flush_tlb();
 		stat->d_alltlb++;
 	} else {
-		__flush_tlb_single(msg->address);
+		__flush_tlb_one_user(msg->address);
 		stat->d_onetlb++;
 	}
 	stat->d_requestee++;
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1300,12 +1300,12 @@ static void xen_flush_tlb(void)
 	preempt_enable();
 }
 
-static void xen_flush_tlb_single(unsigned long addr)
+static void xen_flush_tlb_one_user(unsigned long addr)
 {
 	struct mmuext_op *op;
 	struct multicall_space mcs;
 
-	trace_xen_mmu_flush_tlb_single(addr);
+	trace_xen_mmu_flush_tlb_one_user(addr);
 
 	preempt_disable();
 
@@ -2370,7 +2370,7 @@ static const struct pv_mmu_ops xen_mmu_o
 
 	.flush_tlb_user = xen_flush_tlb,
 	.flush_tlb_kernel = xen_flush_tlb,
-	.flush_tlb_single = xen_flush_tlb_single,
+	.flush_tlb_one_user = xen_flush_tlb_one_user,
 	.flush_tlb_others = xen_flush_tlb_others,
 
 	.pgd_alloc = xen_pgd_alloc,
--- a/include/trace/events/xen.h
+++ b/include/trace/events/xen.h
@@ -368,7 +368,7 @@ TRACE_EVENT(xen_mmu_flush_tlb,
 	    TP_printk("%s", "")
 	);
 
-TRACE_EVENT(xen_mmu_flush_tlb_single,
+TRACE_EVENT(xen_mmu_flush_tlb_one_user,
 	    TP_PROTO(unsigned long addr),
 	    TP_ARGS(addr),
 	    TP_STRUCT__entry(


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[PATCH 4.15 153/163] x86/mm, mm/hwpoison: Dont unconditionally unmap kernel 1:1 pages

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tony Luck <tony.luck@intel.com>

commit fd0e786d9d09024f67bd71ec094b110237dc3840 upstream.

In the following commit:

  ce0fa3e56ad2 ("x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages")

... we added code to memory_failure() to unmap the page from the
kernel 1:1 virtual address space to avoid speculative access to the
page logging additional errors.

But memory_failure() may not always succeed in taking the page offline,
especially if the page belongs to the kernel.  This can happen if
there are too many corrected errors on a page and either mcelog(8)
or drivers/ras/cec.c asks to take a page offline.

Since we remove the 1:1 mapping early in memory_failure(), we can
end up with the page unmapped, but still in use. On the next access
the kernel crashes :-(

There are also various debug paths that call memory_failure() to simulate
occurrence of an error. Since there is no actual error in memory, we
don't need to map out the page for those cases.

Revert most of the previous attempt and keep the solution local to
arch/x86/kernel/cpu/mcheck/mce.c. Unmap the page only when:

	1) there is a real error
	2) memory_failure() succeeds.

All of this only applies to 64-bit systems. 32-bit kernel doesn't map
all of memory into kernel space. It isn't worth adding the code to unmap
the piece that is mapped because nobody would run a 32-bit kernel on a
machine that has recoverable machine checks.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert (Persistent Memory) <elliott@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: stable@vger.kernel.org #v4.14
Fixes: ce0fa3e56ad2 ("x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/page_64.h            |    4 ----
 arch/x86/kernel/cpu/mcheck/mce-internal.h |   15 +++++++++++++++
 arch/x86/kernel/cpu/mcheck/mce.c          |   17 +++++++++++------
 include/linux/mm_inline.h                 |    6 ------
 mm/memory-failure.c                       |    2 --
 5 files changed, 26 insertions(+), 18 deletions(-)

--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -52,10 +52,6 @@ static inline void clear_page(void *page
 
 void copy_page(void *to, void *from);
 
-#ifdef CONFIG_X86_MCE
-#define arch_unmap_kpfn arch_unmap_kpfn
-#endif
-
 #endif	/* !__ASSEMBLY__ */
 
 #ifdef CONFIG_X86_VSYSCALL_EMULATION
--- a/arch/x86/kernel/cpu/mcheck/mce-internal.h
+++ b/arch/x86/kernel/cpu/mcheck/mce-internal.h
@@ -115,4 +115,19 @@ static inline void mce_unregister_inject
 
 extern struct mca_config mca_cfg;
 
+#ifndef CONFIG_X86_64
+/*
+ * On 32-bit systems it would be difficult to safely unmap a poison page
+ * from the kernel 1:1 map because there are no non-canonical addresses that
+ * we can use to refer to the address without risking a speculative access.
+ * However, this isn't much of an issue because:
+ * 1) Few unmappable pages are in the 1:1 map. Most are in HIGHMEM which
+ *    are only mapped into the kernel as needed
+ * 2) Few people would run a 32-bit kernel on a machine that supports
+ *    recoverable errors because they have too much memory to boot 32-bit.
+ */
+static inline void mce_unmap_kpfn(unsigned long pfn) {}
+#define mce_unmap_kpfn mce_unmap_kpfn
+#endif
+
 #endif /* __X86_MCE_INTERNAL_H__ */
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -106,6 +106,10 @@ static struct irq_work mce_irq_work;
 
 static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs);
 
+#ifndef mce_unmap_kpfn
+static void mce_unmap_kpfn(unsigned long pfn);
+#endif
+
 /*
  * CPU/chipset specific EDAC code can register a notifier call here to print
  * MCE errors in a human-readable form.
@@ -582,7 +586,8 @@ static int srao_decode_notifier(struct n
 
 	if (mce_usable_address(mce) && (mce->severity == MCE_AO_SEVERITY)) {
 		pfn = mce->addr >> PAGE_SHIFT;
-		memory_failure(pfn, MCE_VECTOR, 0);
+		if (memory_failure(pfn, MCE_VECTOR, 0))
+			mce_unmap_kpfn(pfn);
 	}
 
 	return NOTIFY_OK;
@@ -1049,12 +1054,13 @@ static int do_memory_failure(struct mce
 	ret = memory_failure(m->addr >> PAGE_SHIFT, MCE_VECTOR, flags);
 	if (ret)
 		pr_err("Memory error not recovered");
+	else
+		mce_unmap_kpfn(m->addr >> PAGE_SHIFT);
 	return ret;
 }
 
-#if defined(arch_unmap_kpfn) && defined(CONFIG_MEMORY_FAILURE)
-
-void arch_unmap_kpfn(unsigned long pfn)
+#ifndef mce_unmap_kpfn
+static void mce_unmap_kpfn(unsigned long pfn)
 {
 	unsigned long decoy_addr;
 
@@ -1065,7 +1071,7 @@ void arch_unmap_kpfn(unsigned long pfn)
 	 * We would like to just call:
 	 *	set_memory_np((unsigned long)pfn_to_kaddr(pfn), 1);
 	 * but doing that would radically increase the odds of a
-	 * speculative access to the posion page because we'd have
+	 * speculative access to the poison page because we'd have
 	 * the virtual address of the kernel 1:1 mapping sitting
 	 * around in registers.
 	 * Instead we get tricky.  We create a non-canonical address
@@ -1090,7 +1096,6 @@ void arch_unmap_kpfn(unsigned long pfn)
 
 	if (set_memory_np(decoy_addr, 1))
 		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn);
-
 }
 #endif
 
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -127,10 +127,4 @@ static __always_inline enum lru_list pag
 
 #define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
 
-#ifdef arch_unmap_kpfn
-extern void arch_unmap_kpfn(unsigned long pfn);
-#else
-static __always_inline void arch_unmap_kpfn(unsigned long pfn) { }
-#endif
-
 #endif
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1146,8 +1146,6 @@ int memory_failure(unsigned long pfn, in
 		return 0;
 	}
 
-	arch_unmap_kpfn(pfn);
-
 	orig_head = hpage = compound_head(p);
 	num_poisoned_pages_inc();
 


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