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authorZachary Amsden <zach@vmware.com>2006-10-01 02:29:35 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-01 03:39:34 -0400
commit23002d88be309a7c78db69363c9d933a29a3b0bb (patch)
treeecd99ef70c0f38ff81bf2e3c6d7caeed2b88b41e
parent25e4df5bae333a06cd2c9b88baf14432652dc9f7 (diff)
[PATCH] paravirt: kpte flush
Create a new PTE function which combines clearing a kernel PTE with the subsequent flush. This allows the two to be easily combined into a single hypercall or paravirt-op. More subtly, reverse the order of the flush for kmap_atomic. Instead of flushing on establishing a mapping, flush on clearing a mapping. This eliminates the possibility of leaving stale kmap entries which may still have valid TLB mappings. This is required for direct mode hypervisors, which need to reprotect all mappings of a given page when changing the page type from a normal page to a protected page (such as a page table or descriptor table page). But it also provides some nicer semantics for real hardware, by providing extra debug-proofing against using stale mappings, as well as ensuring that no stale mappings exist when changing the cacheability attributes of a page, which could lead to cache conflicts when two different types of mappings exist for the same page. Signed-off-by: Zachary Amsden <zach@vmware.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/mm/highmem.c18
-rw-r--r--include/asm-i386/pgtable.h7
2 files changed, 14 insertions, 11 deletions
diff --git a/arch/i386/mm/highmem.c b/arch/i386/mm/highmem.c
index ba44000b9069..f9f647cdbc7b 100644
--- a/arch/i386/mm/highmem.c
+++ b/arch/i386/mm/highmem.c
@@ -38,22 +38,19 @@ void *kmap_atomic(struct page *page, enum km_type type)
38 38
39 idx = type + KM_TYPE_NR*smp_processor_id(); 39 idx = type + KM_TYPE_NR*smp_processor_id();
40 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 40 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
41#ifdef CONFIG_DEBUG_HIGHMEM
42 if (!pte_none(*(kmap_pte-idx))) 41 if (!pte_none(*(kmap_pte-idx)))
43 BUG(); 42 BUG();
44#endif
45 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); 43 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
46 __flush_tlb_one(vaddr);
47 44
48 return (void*) vaddr; 45 return (void*) vaddr;
49} 46}
50 47
51void kunmap_atomic(void *kvaddr, enum km_type type) 48void kunmap_atomic(void *kvaddr, enum km_type type)
52{ 49{
53#ifdef CONFIG_DEBUG_HIGHMEM
54 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; 50 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
55 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); 51 enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
56 52
53#ifdef CONFIG_DEBUG_HIGHMEM
57 if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) { 54 if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
58 dec_preempt_count(); 55 dec_preempt_count();
59 preempt_check_resched(); 56 preempt_check_resched();
@@ -62,14 +59,14 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
62 59
63 if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)) 60 if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
64 BUG(); 61 BUG();
65 62#endif
66 /* 63 /*
67 * force other mappings to Oops if they'll try to access 64 * Force other mappings to Oops if they'll try to access this pte
68 * this pte without first remap it 65 * without first remap it. Keeping stale mappings around is a bad idea
66 * also, in case the page changes cacheability attributes or becomes
67 * a protected page in a hypervisor.
69 */ 68 */
70 pte_clear(&init_mm, vaddr, kmap_pte-idx); 69 kpte_clear_flush(kmap_pte-idx, vaddr);
71 __flush_tlb_one(vaddr);
72#endif
73 70
74 dec_preempt_count(); 71 dec_preempt_count();
75 preempt_check_resched(); 72 preempt_check_resched();
@@ -88,7 +85,6 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
88 idx = type + KM_TYPE_NR*smp_processor_id(); 85 idx = type + KM_TYPE_NR*smp_processor_id();
89 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); 86 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
90 set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot)); 87 set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
91 __flush_tlb_one(vaddr);
92 88
93 return (void*) vaddr; 89 return (void*) vaddr;
94} 90}
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index 94c87ff4b5ac..ee9696d2f67f 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -441,6 +441,13 @@ extern pte_t *lookup_address(unsigned long address);
441#define pte_unmap_nested(pte) do { } while (0) 441#define pte_unmap_nested(pte) do { } while (0)
442#endif 442#endif
443 443
444/* Clear a kernel PTE and flush it from the TLB */
445#define kpte_clear_flush(ptep, vaddr) \
446do { \
447 pte_clear(&init_mm, vaddr, ptep); \
448 __flush_tlb_one(vaddr); \
449} while (0)
450
444/* 451/*
445 * The i386 doesn't have any external MMU info: the kernel page 452 * The i386 doesn't have any external MMU info: the kernel page
446 * tables contain all the necessary information. 453 * tables contain all the necessary information.