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Subject[PATCH] [1/58] x86: Always flush pages in change_page_attr
Date

Fix a bug introduced with the CLFLUSH changes: we must always flush pages
changed in cpa(), not just when they are reverted.

Reenable CLFLUSH usage with that now (it was temporarily disabled
for .22)

Add some BUG_ONs

Contains fixes from Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Signed-off-by: Andi Kleen <ak@suse.de>

---
arch/i386/mm/pageattr.c | 20 +++++++++++++++++---
arch/x86_64/mm/pageattr.c | 23 ++++++++++++++---------
2 files changed, 31 insertions(+), 12 deletions(-)
Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86_64/mm/pageattr.c
+++ linux/arch/x86_64/mm/pageattr.c
@@ -74,14 +74,12 @@ static void flush_kernel_map(void *arg)
struct page *pg;

/* When clflush is available always use it because it is
- much cheaper than WBINVD. Disable clflush for now because
- the high level code is not ready yet */
- if (1 || !cpu_has_clflush)
+ much cheaper than WBINVD. */
+ if (!cpu_has_clflush)
asm volatile("wbinvd" ::: "memory");
else list_for_each_entry(pg, l, lru) {
void *adr = page_address(pg);
- if (cpu_has_clflush)
- cache_flush_page(adr);
+ cache_flush_page(adr);
}
__flush_tlb_all();
}
@@ -95,7 +93,8 @@ static LIST_HEAD(deferred_pages); /* pro

static inline void save_page(struct page *fpage)
{
- list_add(&fpage->lru, &deferred_pages);
+ if (!test_and_set_bit(PG_arch_1, &fpage->flags))
+ list_add(&fpage->lru, &deferred_pages);
}

/*
@@ -129,9 +128,12 @@ __change_page_attr(unsigned long address
pte_t *kpte;
struct page *kpte_page;
pgprot_t ref_prot2;
+
kpte = lookup_address(address);
if (!kpte) return 0;
kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+ BUG_ON(PageLRU(kpte_page));
+ BUG_ON(PageCompound(kpte_page));
if (pgprot_val(prot) != pgprot_val(ref_prot)) {
if (!pte_huge(*kpte)) {
set_pte(kpte, pfn_pte(pfn, prot));
@@ -159,10 +161,9 @@ __change_page_attr(unsigned long address
/* on x86-64 the direct mapping set at boot is not using 4k pages */
BUG_ON(PageReserved(kpte_page));

- if (page_private(kpte_page) == 0) {
- save_page(kpte_page);
+ save_page(kpte_page);
+ if (page_private(kpte_page) == 0)
revert_page(address, ref_prot);
- }
return 0;
}

@@ -234,6 +235,10 @@ void global_flush_tlb(void)
flush_map(&l);

list_for_each_entry_safe(pg, next, &l, lru) {
+ list_del(&pg->lru);
+ clear_bit(PG_arch_1, &pg->flags);
+ if (page_private(pg) != 0)
+ continue;
ClearPagePrivate(pg);
__free_page(pg);
}
Index: linux/arch/i386/mm/pageattr.c
===================================================================
--- linux.orig/arch/i386/mm/pageattr.c
+++ linux/arch/i386/mm/pageattr.c
@@ -82,7 +82,7 @@ static void flush_kernel_map(void *arg)
struct page *p;

/* High level code is not ready for clflush yet */
- if (0 && cpu_has_clflush) {
+ if (cpu_has_clflush) {
list_for_each_entry (p, lh, lru)
cache_flush_page(p);
} else if (boot_cpu_data.x86_model >= 4)
@@ -136,6 +136,12 @@ static inline void revert_page(struct pa
ref_prot));
}

+static inline void save_page(struct page *kpte_page)
+{
+ if (!test_and_set_bit(PG_arch_1, &kpte_page->flags))
+ list_add(&kpte_page->lru, &df_list);
+}
+
static int
__change_page_attr(struct page *page, pgprot_t prot)
{
@@ -150,6 +156,9 @@ __change_page_attr(struct page *page, pg
if (!kpte)
return -EINVAL;
kpte_page = virt_to_page(kpte);
+ BUG_ON(PageLRU(kpte_page));
+ BUG_ON(PageCompound(kpte_page));
+
if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
if (!pte_huge(*kpte)) {
set_pte_atomic(kpte, mk_pte(page, prot));
@@ -179,11 +188,11 @@ __change_page_attr(struct page *page, pg
* time (not via split_large_page) and in turn we must not
* replace it with a largepage.
*/
+
+ save_page(kpte_page);
if (!PageReserved(kpte_page)) {
if (cpu_has_pse && (page_private(kpte_page) == 0)) {
- ClearPagePrivate(kpte_page);
paravirt_release_pt(page_to_pfn(kpte_page));
- list_add(&kpte_page->lru, &df_list);
revert_page(kpte_page, address);
}
}
@@ -236,6 +245,11 @@ void global_flush_tlb(void)
spin_unlock_irq(&cpa_lock);
flush_map(&l);
list_for_each_entry_safe(pg, next, &l, lru) {
+ list_del(&pg->lru);
+ clear_bit(PG_arch_1, &pg->flags);
+ if (PageReserved(pg) || !cpu_has_pse || page_private(pg) != 0)
+ continue;
+ ClearPagePrivate(pg);
__free_page(pg);
}
}
-
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