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[x86] Fix booting as Xen dom0 

This patch is from the tip repo, and will show up in 4.19 later.
This commit is contained in:
Hans van Kranenburg 2018-12-12 00:10:19 +01:00
parent 17d52832bc
commit edc7c6ee64
3 changed files with 118 additions and 0 deletions
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3
debian/changelog vendored
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@ -59,6 +59,9 @@ linux (4.19.8-1) UNRELEASED; urgency=medium
* Add patches to build libbpf.so with SONAME, link against libelf
* Add versioned libbpf, libbpf-dev package (Closes: #914428)
[ Hans van Kranenburg ]
* [x86] Add patch to repair booting as Xen dom0 (Closes: #914951)
-- Uwe Kleine-König <ukleinek@debian.org> Wed, 28 Nov 2018 12:20:46 +0100
linux (4.19.5-1~exp1) experimental; urgency=medium

114
debian/patches/bugfix/x86/x86-mm-Fix-guard-hole-handling.patch vendored Normal file
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@ -0,0 +1,114 @@
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Fri, 30 Nov 2018 23:23:27 +0300
Subject: x86/mm: Fix guard hole handling
Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=16877a5570e0c5f4270d5b17f9bab427bcae9514
There is a guard hole at the beginning of the kernel address space, also
used by hypervisors. It occupies 16 PGD entries.
This reserved range is not defined explicitely, it is calculated relative
to other entities: direct mapping and user space ranges.
The calculation got broken by recent changes of the kernel memory layout:
LDT remap range is now mapped before direct mapping and makes the
calculation invalid.
The breakage leads to crash on Xen dom0 boot[1].
Define the reserved range explicitely. It's part of kernel ABI (hypervisors
expect it to be stable) and must not depend on changes in the rest of
kernel memory layout.
[1] https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03313.html
Fixes: d52888aa2753 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging")
Reported-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: peterz@infradead.org
Cc: boris.ostrovsky@oracle.com
Cc: bhe@redhat.com
Cc: linux-mm@kvack.org
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20181130202328.65359-2-kirill.shutemov@linux.intel.com
---
arch/x86/include/asm/pgtable_64_types.h | 5 +++++
arch/x86/mm/dump_pagetables.c | 8 ++++----
arch/x86/xen/mmu_pv.c | 11 ++++++-----
3 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 84bd9bdc1987..88bca456da99 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -111,6 +111,11 @@ extern unsigned int ptrs_per_p4d;
*/
#define MAXMEM (1UL << MAX_PHYSMEM_BITS)
+#define GUARD_HOLE_PGD_ENTRY -256UL
+#define GUARD_HOLE_SIZE (16UL << PGDIR_SHIFT)
+#define GUARD_HOLE_BASE_ADDR (GUARD_HOLE_PGD_ENTRY << PGDIR_SHIFT)
+#define GUARD_HOLE_END_ADDR (GUARD_HOLE_BASE_ADDR + GUARD_HOLE_SIZE)
+
#define LDT_PGD_ENTRY -240UL
#define LDT_BASE_ADDR (LDT_PGD_ENTRY << PGDIR_SHIFT)
#define LDT_END_ADDR (LDT_BASE_ADDR + PGDIR_SIZE)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index fc37bbd23eb8..dad153e5a427 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -512,11 +512,11 @@ static inline bool is_hypervisor_range(int idx)
{
#ifdef CONFIG_X86_64
/*
- * ffff800000000000 - ffff87ffffffffff is reserved for
- * the hypervisor.
+ * A hole in the beginning of kernel address space reserved
+ * for a hypervisor.
*/
- return (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
- (idx < pgd_index(__PAGE_OFFSET));
+ return (idx >= pgd_index(GUARD_HOLE_BASE_ADDR)) &&
+ (idx < pgd_index(GUARD_HOLE_END_ADDR));
#else
return false;
#endif
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index a5d7ed125337..0f4fe206dcc2 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -648,19 +648,20 @@ static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
unsigned long limit)
{
int i, nr, flush = 0;
- unsigned hole_low, hole_high;
+ unsigned hole_low = 0, hole_high = 0;
/* The limit is the last byte to be touched */
limit--;
BUG_ON(limit >= FIXADDR_TOP);
+#ifdef CONFIG_X86_64
/*
* 64-bit has a great big hole in the middle of the address
- * space, which contains the Xen mappings. On 32-bit these
- * will end up making a zero-sized hole and so is a no-op.
+ * space, which contains the Xen mappings.
*/
- hole_low = pgd_index(USER_LIMIT);
- hole_high = pgd_index(PAGE_OFFSET);
+ hole_low = pgd_index(GUARD_HOLE_BASE_ADDR);
+ hole_high = pgd_index(GUARD_HOLE_END_ADDR);
+#endif
nr = pgd_index(limit) + 1;
for (i = 0; i < nr; i++) {
--
2.19.2

1
debian/patches/series vendored
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@ -77,6 +77,7 @@ bugfix/arm/arm-mm-export-__sync_icache_dcache-for-xen-privcmd.patch
bugfix/powerpc/powerpc-boot-fix-missing-crc32poly.h-when-building-with-kernel_xz.patch
bugfix/arm64/arm64-acpi-Add-fixup-for-HPE-m400-quirks.patch
bugfix/x86/x86-32-disable-3dnow-in-generic-config.patch
bugfix/x86/x86-mm-Fix-guard-hole-handling.patch
# Arch features
features/mips/MIPS-increase-MAX-PHYSMEM-BITS-on-Loongson-3-only.patch