The patch titled
paravirt: kpte flush
has been added to the -mm tree. Its filename is
paravirt-kpte-flush.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: paravirt: kpte flush
From: Zachary Amsden <zach@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/i386/mm/highmem.c | 18 +++++++-----------
include/asm-i386/pgtable.h | 7 +++++++
2 files changed, 14 insertions(+), 11 deletions(-)
diff -puN arch/i386/mm/highmem.c~paravirt-kpte-flush arch/i386/mm/highmem.c
--- a/arch/i386/mm/highmem.c~paravirt-kpte-flush
+++ a/arch/i386/mm/highmem.c
@@ -38,22 +38,19 @@ void *kmap_atomic(struct page *page, enu
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
-#ifdef CONFIG_DEBUG_HIGHMEM
if (!pte_none(*(kmap_pte-idx)))
BUG();
-#endif
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
- __flush_tlb_one(vaddr);
return (void*) vaddr;
}
void kunmap_atomic(void *kvaddr, enum km_type type)
{
-#ifdef CONFIG_DEBUG_HIGHMEM
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
+#ifdef CONFIG_DEBUG_HIGHMEM
if (vaddr >= PAGE_OFFSET && vaddr < (unsigned long)high_memory) {
dec_preempt_count();
preempt_check_resched();
@@ -62,14 +59,14 @@ void kunmap_atomic(void *kvaddr, enum km
if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
BUG();
-
+#endif
/*
- * force other mappings to Oops if they'll try to access
- * this pte without first remap it
+ * Force other mappings to Oops if they'll try to access this pte
+ * without first remap it. Keeping stale mappings around is a bad idea
+ * also, in case the page changes cacheability attributes or becomes
+ * a protected page in a hypervisor.
*/
- pte_clear(&init_mm, vaddr, kmap_pte-idx);
- __flush_tlb_one(vaddr);
-#endif
+ kpte_clear_flush(kmap_pte-idx, vaddr);
dec_preempt_count();
preempt_check_resched();
@@ -88,7 +85,6 @@ void *kmap_atomic_pfn(unsigned long pfn,
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
- __flush_tlb_one(vaddr);
return (void*) vaddr;
}
diff -puN include/asm-i386/pgtable.h~paravirt-kpte-flush include/asm-i386/pgtable.h
--- a/include/asm-i386/pgtable.h~paravirt-kpte-flush
+++ a/include/asm-i386/pgtable.h
@@ -441,6 +441,13 @@ extern pte_t *lookup_address(unsigned lo
#define pte_unmap_nested(pte) do { } while (0)
#endif
+/* Clear a kernel PTE and flush it from the TLB */
+#define kpte_clear_flush(ptep, vaddr) \
+do { \
+ pte_clear(&init_mm, vaddr, ptep); \
+ __flush_tlb_one(vaddr); \
+} while (0)
+
/*
* The i386 doesn't have any external MMU info: the kernel page
* tables contain all the necessary information.
_
Patches currently in -mm which might be from zach@xxxxxxxxxx are
split-i386-and-x86_64-ptraceh.patch
uml-use-ptrace-abih-instead-of-ptraceh.patch
x86-allow-a-kernel-to-not-be-in-ring-0.patch
x86-allow-a-kernel-to-not-be-in-ring-0-tidy.patch
x86-add-a-bootparameter-to-reserve-high-linear-address-space.patch
x86-trivial-pgtableh-__assembly__-move.patch
x86-trivial-move-of-__have-macros-in-i386-pagetable-headers.patch
x86-trivial-move-of-ptep_set_access_flags.patch
x86-remove-unused-include-from-efi_stubs.patch
paravirt-remove-read-hazard-from-cow.patch
paravirt-pte-clear-not-present.patch
paravirt-lazy-mmu-mode-hooks.patch
paravirt-combine-flush-accessed-dirty.patch
paravirt-kpte-flush.patch
paravirt-optimize-ptep-establish-for-pae.patch
paravirt-remove-set-pte-atomic.patch
paravirt-pae-compile-fix.patch
paravirt-update-pte-hook.patch
-
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