From 817a824b75b1475f1b067c8cee318c7b4d66fcde Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@citrix.com>
Date: Fri, 26 Feb 2010 17:16:00 +0000
Subject: x86, xen: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y
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There's a path in the pagefault code where the kernel deliberately
breaks its own locking rules by kmapping a high pte page without
holding the pagetable lock (in at least page_check_address). This
breaks Xen's ability to track the pinned/unpinned state of the
page. There does not appear to be a viable workaround for this
behaviour so simply disable HIGHPTE for all Xen guests.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-1-git-send-email-ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pasi Kärkkäinen <pasik@iki.fi>
Cc: <stable@kernel.org> # .32.x: 14315592: Allow highmem user page tables to be disabled at boot time
Cc: <stable@kernel.org> # .32.x
Cc: <xen-devel@lists.xensource.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/xen/enlighten.c |  7 +++++++
 arch/x86/xen/mmu.c       | 11 ++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

(limited to 'arch')

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 36daccb68642..b607239c1ba8 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -50,6 +50,7 @@
 #include <asm/traps.h>
 #include <asm/setup.h>
 #include <asm/desc.h>
+#include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/reboot.h>
@@ -1094,6 +1095,12 @@ asmlinkage void __init xen_start_kernel(void)
 
 	__supported_pte_mask |= _PAGE_IOMAP;
 
+	/*
+	 * Prevent page tables from being allocated in highmem, even
+	 * if CONFIG_HIGHPTE is enabled.
+	 */
+	__userpte_alloc_gfp &= ~__GFP_HIGHMEM;
+
 	/* Work out if we support NX */
 	x86_configure_nx();
 
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index bf4cd6bfe959..350a3deedf25 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1432,14 +1432,15 @@ static void *xen_kmap_atomic_pte(struct page *page, enum km_type type)
 {
 	pgprot_t prot = PAGE_KERNEL;
 
+	/*
+	 * We disable highmem allocations for page tables so we should never
+	 * see any calls to kmap_atomic_pte on a highmem page.
+	 */
+	BUG_ON(PageHighMem(page));
+
 	if (PagePinned(page))
 		prot = PAGE_KERNEL_RO;
 
-	if (0 && PageHighMem(page))
-		printk("mapping highpte %lx type %d prot %s\n",
-		       page_to_pfn(page), type,
-		       (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" : "READ");
-
 	return kmap_atomic_prot(page, type, prot);
 }
 #endif
-- 
cgit v1.2.3


From 3249b7e1df6380e9d7bb3238f64f445bf614f787 Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@citrix.com>
Date: Fri, 26 Feb 2010 17:16:01 +0000
Subject: x86, vmi: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y

Preventing HIGHPTE allocations under VMI will allow us to remove the
kmap_atomic_pte paravirt op.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-2-git-send-email-ian.campbell@citrix.com>
Acked-by: Alok Kataria <akataria@vmware.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/kernel/vmi_32.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

(limited to 'arch')

diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index d430e4c30193..58aca86193e5 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -33,6 +33,7 @@
 #include <asm/fixmap.h>
 #include <asm/apicdef.h>
 #include <asm/apic.h>
+#include <asm/pgalloc.h>
 #include <asm/processor.h>
 #include <asm/timer.h>
 #include <asm/vmi_time.h>
@@ -272,19 +273,11 @@ static void *vmi_kmap_atomic_pte(struct page *page, enum km_type type)
 	void *va = kmap_atomic(page, type);
 
 	/*
-	 * Internally, the VMI ROM must map virtual addresses to physical
-	 * addresses for processing MMU updates.  By the time MMU updates
-	 * are issued, this information is typically already lost.
-	 * Fortunately, the VMI provides a cache of mapping slots for active
-	 * page tables.
-	 *
-	 * We use slot zero for the linear mapping of physical memory, and
-	 * in HIGHPTE kernels, slot 1 and 2 for KM_PTE0 and KM_PTE1.
-	 *
-	 *  args:                 SLOT                 VA    COUNT PFN
+	 * We disable highmem allocations for page tables so we should never
+	 * see any calls to kmap_atomic_pte on a highmem page.
 	 */
-	BUG_ON(type != KM_PTE0 && type != KM_PTE1);
-	vmi_ops.set_linear_mapping((type - KM_PTE0)+1, va, 1, page_to_pfn(page));
+
+	BUG_ON(PageHighmem(page));
 
 	return va;
 }
@@ -640,6 +633,12 @@ static inline int __init activate_vmi(void)
 	u64 reloc;
 	const struct vmi_relocation_info *rel = (struct vmi_relocation_info *)&reloc;
 
+	/*
+	 * Prevent page tables from being allocated in highmem, even if
+	 * CONFIG_HIGHPTE is enabled.
+	 */
+	__userpte_alloc_gfp &= ~__GFP_HIGHMEM;
+
 	if (call_vrom_func(vmi_rom, vmi_init) != 0) {
 		printk(KERN_ERR "VMI ROM failed to initialize!");
 		return 0;
-- 
cgit v1.2.3


From dad52fc01161afcb8798c609e009aed4d104927f Mon Sep 17 00:00:00 2001
From: Ian Campbell <ian.campbell@citrix.com>
Date: Fri, 26 Feb 2010 17:16:02 +0000
Subject: x86, paravirt: Remove kmap_atomic_pte paravirt op.

Now that both Xen and VMI disable allocations of PTE pages from high
memory this paravirt op serves no further purpose.

This effectively reverts ce6234b5 "add kmap_atomic_pte for mapping
highpte pages".

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-3-git-send-email-ian.campbell@citrix.com>
Acked-by: Alok Kataria <akataria@vmware.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/include/asm/highmem.h        |  4 ----
 arch/x86/include/asm/paravirt.h       |  9 ---------
 arch/x86/include/asm/paravirt_types.h |  4 ----
 arch/x86/include/asm/pgtable_32.h     |  4 ++--
 arch/x86/kernel/paravirt.c            |  4 ----
 arch/x86/kernel/vmi_32.c              | 20 --------------------
 arch/x86/xen/mmu.c                    | 22 ----------------------
 7 files changed, 2 insertions(+), 65 deletions(-)

(limited to 'arch')

diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h
index 014c2b85ae45..a726650fc80f 100644
--- a/arch/x86/include/asm/highmem.h
+++ b/arch/x86/include/asm/highmem.h
@@ -66,10 +66,6 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
 void *kmap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot);
 struct page *kmap_atomic_to_page(void *ptr);
 
-#ifndef CONFIG_PARAVIRT
-#define kmap_atomic_pte(page, type)	kmap_atomic(page, type)
-#endif
-
 #define flush_cache_kmaps()	do { } while (0)
 
 extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn,
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index dd59a85a918f..5653f43d90e5 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -435,15 +435,6 @@ static inline void paravirt_release_pud(unsigned long pfn)
 	PVOP_VCALL1(pv_mmu_ops.release_pud, pfn);
 }
 
-#ifdef CONFIG_HIGHPTE
-static inline void *kmap_atomic_pte(struct page *page, enum km_type type)
-{
-	unsigned long ret;
-	ret = PVOP_CALL2(unsigned long, pv_mmu_ops.kmap_atomic_pte, page, type);
-	return (void *)ret;
-}
-#endif
-
 static inline void pte_update(struct mm_struct *mm, unsigned long addr,
 			      pte_t *ptep)
 {
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index b1e70d51e40c..db9ef5532341 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -304,10 +304,6 @@ struct pv_mmu_ops {
 #endif	/* PAGETABLE_LEVELS == 4 */
 #endif	/* PAGETABLE_LEVELS >= 3 */
 
-#ifdef CONFIG_HIGHPTE
-	void *(*kmap_atomic_pte)(struct page *page, enum km_type type);
-#endif
-
 	struct pv_lazy_ops lazy_mode;
 
 	/* dom0 ops */
diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pgtable_32.h
index 01fd9461d323..b422d2201af3 100644
--- a/arch/x86/include/asm/pgtable_32.h
+++ b/arch/x86/include/asm/pgtable_32.h
@@ -54,10 +54,10 @@ extern void set_pmd_pfn(unsigned long, unsigned long, pgprot_t);
 	 in_irq() ? KM_IRQ_PTE :	\
 	 KM_PTE0)
 #define pte_offset_map(dir, address)					\
-	((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), __KM_PTE) +		\
+	((pte_t *)kmap_atomic(pmd_page(*(dir)), __KM_PTE) +		\
 	 pte_index((address)))
 #define pte_offset_map_nested(dir, address)				\
-	((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), KM_PTE1) +		\
+	((pte_t *)kmap_atomic(pmd_page(*(dir)), KM_PTE1) +		\
 	 pte_index((address)))
 #define pte_unmap(pte) kunmap_atomic((pte), __KM_PTE)
 #define pte_unmap_nested(pte) kunmap_atomic((pte), KM_PTE1)
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 1b1739d16310..1db183ed7c01 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -428,10 +428,6 @@ struct pv_mmu_ops pv_mmu_ops = {
 	.ptep_modify_prot_start = __ptep_modify_prot_start,
 	.ptep_modify_prot_commit = __ptep_modify_prot_commit,
 
-#ifdef CONFIG_HIGHPTE
-	.kmap_atomic_pte = kmap_atomic,
-#endif
-
 #if PAGETABLE_LEVELS >= 3
 #ifdef CONFIG_X86_PAE
 	.set_pte_atomic = native_set_pte_atomic,
diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index 58aca86193e5..7dd599deca4a 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -267,22 +267,6 @@ static void vmi_nop(void)
 {
 }
 
-#ifdef CONFIG_HIGHPTE
-static void *vmi_kmap_atomic_pte(struct page *page, enum km_type type)
-{
-	void *va = kmap_atomic(page, type);
-
-	/*
-	 * We disable highmem allocations for page tables so we should never
-	 * see any calls to kmap_atomic_pte on a highmem page.
-	 */
-
-	BUG_ON(PageHighmem(page));
-
-	return va;
-}
-#endif
-
 static void vmi_allocate_pte(struct mm_struct *mm, unsigned long pfn)
 {
 	vmi_ops.allocate_page(pfn, VMI_PAGE_L1, 0, 0, 0);
@@ -777,10 +761,6 @@ static inline int __init activate_vmi(void)
 
 	/* Set linear is needed in all cases */
 	vmi_ops.set_linear_mapping = vmi_get_function(VMI_CALL_SetLinearMapping);
-#ifdef CONFIG_HIGHPTE
-	if (vmi_ops.set_linear_mapping)
-		pv_mmu_ops.kmap_atomic_pte = vmi_kmap_atomic_pte;
-#endif
 
 	/*
 	 * These MUST always be patched.  Don't support indirect jumps
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 350a3deedf25..f9eb7de74f42 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1427,24 +1427,6 @@ static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
 #endif
 }
 
-#ifdef CONFIG_HIGHPTE
-static void *xen_kmap_atomic_pte(struct page *page, enum km_type type)
-{
-	pgprot_t prot = PAGE_KERNEL;
-
-	/*
-	 * We disable highmem allocations for page tables so we should never
-	 * see any calls to kmap_atomic_pte on a highmem page.
-	 */
-	BUG_ON(PageHighMem(page));
-
-	if (PagePinned(page))
-		prot = PAGE_KERNEL_RO;
-
-	return kmap_atomic_prot(page, type, prot);
-}
-#endif
-
 #ifdef CONFIG_X86_32
 static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
 {
@@ -1903,10 +1885,6 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
 	.alloc_pmd_clone = paravirt_nop,
 	.release_pmd = xen_release_pmd_init,
 
-#ifdef CONFIG_HIGHPTE
-	.kmap_atomic_pte = xen_kmap_atomic_pte,
-#endif
-
 #ifdef CONFIG_X86_64
 	.set_pte = xen_set_pte,
 #else
-- 
cgit v1.2.3