The VMI backend uses explicit page type notification to track shadow
page tables. The allocation of page table roots is especially tricky.
We want to clone the root for non-PAE mode while it is protected under
the pgd lock.
Signed-off-by: Zachary Amsden <zach@vmware.com>
==================================================================---
a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -545,6 +545,12 @@ struct paravirt_ops paravirt_ops = {
.flush_tlb_kernel = native_flush_tlb_global,
.flush_tlb_single = native_flush_tlb_single,
+ .alloc_pt = (void *)native_nop,
+ .alloc_pd = (void *)native_nop,
+ .alloc_pd_clone = (void *)native_nop,
+ .release_pt = (void *)native_nop,
+ .release_pd = (void *)native_nop,
+
.set_pte = native_set_pte,
.set_pte_at = native_set_pte_at,
.set_pmd = native_set_pmd,
==================================================================---
a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -62,6 +62,7 @@ static pmd_t * __init one_md_table_init(
#ifdef CONFIG_X86_PAE
pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+ paravirt_alloc_pd(__pa(pmd_table) >> PAGE_SHIFT);
set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
pud = pud_offset(pgd, 0);
if (pmd_table != pmd_offset(pud, 0))
@@ -82,6 +83,7 @@ static pte_t * __init one_page_table_ini
{
if (pmd_none(*pmd)) {
pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+ paravirt_alloc_pt(__pa(page_table) >> PAGE_SHIFT);
set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
if (page_table != pte_offset_kernel(pmd, 0))
BUG();
@@ -347,6 +349,8 @@ static void __init pagetable_init (void)
/* Init entries of the first-level page table to the zero page */
for (i = 0; i < PTRS_PER_PGD; i++)
set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
+#else
+ paravirt_alloc_pd(__pa(swapper_pg_dir) >> PAGE_SHIFT);
#endif
/* Enable PSE if available */
==================================================================---
a/arch/i386/mm/pageattr.c
+++ b/arch/i386/mm/pageattr.c
@@ -60,6 +60,7 @@ static struct page *split_large_page(uns
address = __pa(address);
addr = address & LARGE_PAGE_MASK;
pbase = (pte_t *)page_address(base);
+ paravirt_alloc_pt(page_to_pfn(base));
for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
addr == address ? prot : ref_prot));
@@ -166,6 +167,7 @@ __change_page_attr(struct page *page, pg
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);
}
==================================================================---
a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -245,8 +245,14 @@ void pgd_ctor(void *pgd, kmem_cache_t *c
clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
KERNEL_PGD_PTRS);
+
if (PTRS_PER_PMD > 1)
return;
+
+ /* must happen under lock */
+ paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
+ __pa(swapper_pg_dir) >> PAGE_SHIFT,
+ USER_PTRS_PER_PGD, PTRS_PER_PGD - USER_PTRS_PER_PGD);
pgd_list_add(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
@@ -257,6 +263,7 @@ void pgd_dtor(void *pgd, kmem_cache_t *c
{
unsigned long flags; /* can be called from interrupt context */
+ paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
spin_lock_irqsave(&pgd_lock, flags);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
@@ -274,13 +281,18 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
if (!pmd)
goto out_oom;
+ paravirt_alloc_pd(__pa(pmd) >> PAGE_SHIFT);
set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
}
return pgd;
out_oom:
- for (i--; i >= 0; i--)
- kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1));
+ for (i--; i >= 0; i--) {
+ pgd_t pgdent = pgd[i];
+ void* pmd = (void *)__va(pgd_val(pgdent)-1);
+ paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
+ kmem_cache_free(pmd_cache, pmd);
+ }
kmem_cache_free(pgd_cache, pgd);
return NULL;
}
@@ -291,8 +303,12 @@ void pgd_free(pgd_t *pgd)
/* in the PAE case user pgd entries are overwritten before usage */
if (PTRS_PER_PMD > 1)
- for (i = 0; i < USER_PTRS_PER_PGD; ++i)
- kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1));
+ for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
+ pgd_t pgdent = pgd[i];
+ void* pmd = (void *)__va(pgd_val(pgdent)-1);
+ paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
+ kmem_cache_free(pmd_cache, pmd);
+ }
/* in the non-PAE case, free_pgtables() clears user pgd entries */
kmem_cache_free(pgd_cache, pgd);
}
==================================================================---
a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -126,6 +126,12 @@ struct paravirt_ops
void (fastcall *flush_tlb_user)(void);
void (fastcall *flush_tlb_kernel)(void);
void (fastcall *flush_tlb_single)(u32 addr);
+
+ void (fastcall *alloc_pt)(u32 pfn);
+ void (fastcall *alloc_pd)(u32 pfn);
+ void (fastcall *alloc_pd_clone)(u32 pfn, u32 clonepfn, u32 start, u32 count);
+ void (fastcall *release_pt)(u32 pfn);
+ void (fastcall *release_pd)(u32 pfn);
void (fastcall *set_pte)(pte_t *ptep, pte_t pteval);
void (fastcall *set_pte_at)(struct mm_struct *mm, u32 addr, pte_t *ptep, pte_t
pteval);
@@ -325,6 +331,14 @@ static __inline unsigned long apic_read(
#define __flush_tlb_global() paravirt_ops.flush_tlb_kernel()
#define __flush_tlb_single(addr) paravirt_ops.flush_tlb_single(addr)
+#define paravirt_alloc_pt(pfn) paravirt_ops.alloc_pt(pfn)
+#define paravirt_release_pt(pfn) paravirt_ops.release_pt(pfn)
+
+#define paravirt_alloc_pd(pfn) paravirt_ops.alloc_pd(pfn)
+#define paravirt_alloc_pd_clone(pfn, clonepfn, start, count) \
+ paravirt_ops.alloc_pd_clone(pfn, clonepfn, start, count)
+#define paravirt_release_pd(pfn) paravirt_ops.release_pd(pfn)
+
static inline void set_pte(pte_t *ptep, pte_t pteval)
{
paravirt_ops.set_pte(ptep, pteval);
==================================================================---
a/include/asm-i386/pgalloc.h
+++ b/include/asm-i386/pgalloc.h
@@ -5,13 +5,31 @@
#include <linux/threads.h>
#include <linux/mm.h> /* for struct page */
-#define pmd_populate_kernel(mm, pmd, pte) \
- set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)))
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
+#define paravirt_alloc_pt(pfn) do { } while (0)
+#define paravirt_alloc_pd(pfn) do { } while (0)
+#define paravirt_alloc_pd(pfn) do { } while (0)
+#define paravirt_alloc_pd_clone(pfn, clonepfn, start, count) do { } while (0)
+#define paravirt_release_pt(pfn) do { } while (0)
+#define paravirt_release_pd(pfn) do { } while (0)
+#endif
+
+#define pmd_populate_kernel(mm, pmd, pte) \
+do { \
+ paravirt_alloc_pt(__pa(pte) >> PAGE_SHIFT); \
+ set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte))); \
+} while (0)
#define pmd_populate(mm, pmd, pte) \
+do { \
+ paravirt_alloc_pt(page_to_pfn(pte)); \
set_pmd(pmd, __pmd(_PAGE_TABLE + \
((unsigned long long)page_to_pfn(pte) << \
- (unsigned long long) PAGE_SHIFT)))
+ (unsigned long long) PAGE_SHIFT))); \
+} while (0)
+
/*
* Allocate and free page tables.
*/
@@ -32,7 +50,11 @@ static inline void pte_free(struct page
}
-#define __pte_free_tlb(tlb,pte) tlb_remove_page((tlb),(pte))
+#define __pte_free_tlb(tlb,pte) \
+do { \
+ paravirt_release_pt(page_to_pfn(pte)); \
+ tlb_remove_page((tlb),(pte)); \
+} while (0)
#ifdef CONFIG_X86_PAE
/*
