Commit ce6234b5 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Andi Kleen

[PATCH] i386: PARAVIRT: add kmap_atomic_pte for mapping highpte pages

Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space.  These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.

Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.

This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings.  Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.

[ Zach - vmi.c will need some attention after this patch.  It wasn't
  immediately obvious to me what needs to be done. ]
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
parent a27fe809
......@@ -20,6 +20,7 @@
#include <linux/efi.h>
#include <linux/bcd.h>
#include <linux/start_kernel.h>
#include <linux/highmem.h>
#include <asm/bug.h>
#include <asm/paravirt.h>
......@@ -316,6 +317,10 @@ struct paravirt_ops paravirt_ops = {
.ptep_get_and_clear = native_ptep_get_and_clear,
#ifdef CONFIG_HIGHPTE
.kmap_atomic_pte = kmap_atomic,
#endif
#ifdef CONFIG_X86_PAE
.set_pte_atomic = native_set_pte_atomic,
.set_pte_present = native_set_pte_present,
......
......@@ -26,7 +26,7 @@ void kunmap(struct page *page)
* However when holding an atomic kmap is is not legal to sleep, so atomic
* kmaps are appropriate for short, tight code paths only.
*/
void *kmap_atomic(struct page *page, enum km_type type)
void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
{
enum fixed_addresses idx;
unsigned long vaddr;
......@@ -41,12 +41,17 @@ void *kmap_atomic(struct page *page, enum km_type type)
return page_address(page);
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
set_pte(kmap_pte-idx, mk_pte(page, prot));
arch_flush_lazy_mmu_mode();
return (void*) vaddr;
}
void *kmap_atomic(struct page *page, enum km_type type)
{
return kmap_atomic_prot(page, type, kmap_prot);
}
void kunmap_atomic(void *kvaddr, enum km_type type)
{
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
......
......@@ -24,6 +24,7 @@
#include <linux/threads.h>
#include <asm/kmap_types.h>
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;
......@@ -67,11 +68,16 @@ extern void FASTCALL(kunmap_high(struct page *page));
void *kmap(struct page *page);
void kunmap(struct page *page);
void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot);
void *kmap_atomic(struct page *page, enum km_type type);
void kunmap_atomic(void *kvaddr, enum km_type type);
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
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)
#endif /* __KERNEL__ */
......
......@@ -16,7 +16,9 @@
#ifndef __ASSEMBLY__
#include <linux/types.h>
#include <linux/cpumask.h>
#include <asm/kmap_types.h>
struct page;
struct thread_struct;
struct Xgt_desc_struct;
struct tss_struct;
......@@ -187,6 +189,10 @@ struct paravirt_ops
pte_t (*ptep_get_and_clear)(pte_t *ptep);
#ifdef CONFIG_HIGHPTE
void *(*kmap_atomic_pte)(struct page *page, enum km_type type);
#endif
#ifdef CONFIG_X86_PAE
void (*set_pte_atomic)(pte_t *ptep, pte_t pteval);
void (*set_pte_present)(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte);
......@@ -884,6 +890,15 @@ static inline void paravirt_release_pd(unsigned pfn)
PVOP_VCALL1(release_pd, 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, kmap_atomic_pte, page, type);
return (void *)ret;
}
#endif
static inline void pte_update(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
......
......@@ -476,9 +476,9 @@ extern pte_t *lookup_address(unsigned long address);
#if defined(CONFIG_HIGHPTE)
#define pte_offset_map(dir, address) \
((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE0) + pte_index(address))
((pte_t *)kmap_atomic_pte(pmd_page(*(dir)),KM_PTE0) + pte_index(address))
#define pte_offset_map_nested(dir, address) \
((pte_t *)kmap_atomic(pmd_page(*(dir)),KM_PTE1) + pte_index(address))
((pte_t *)kmap_atomic_pte(pmd_page(*(dir)),KM_PTE1) + pte_index(address))
#define pte_unmap(pte) kunmap_atomic(pte, KM_PTE0)
#define pte_unmap_nested(pte) kunmap_atomic(pte, KM_PTE1)
#else
......
......@@ -27,6 +27,8 @@ static inline void flush_kernel_dcache_page(struct page *page)
unsigned int nr_free_highpages(void);
extern unsigned long totalhigh_pages;
void kmap_flush_unused(void);
#else /* CONFIG_HIGHMEM */
static inline unsigned int nr_free_highpages(void) { return 0; }
......@@ -44,9 +46,13 @@ static inline void *kmap(struct page *page)
#define kmap_atomic(page, idx) \
({ pagefault_disable(); page_address(page); })
#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx)
#define kunmap_atomic(addr, idx) do { pagefault_enable(); } while (0)
#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
#define kmap_flush_unused() do {} while(0)
#endif
#endif /* CONFIG_HIGHMEM */
......
......@@ -99,6 +99,15 @@ static void flush_all_zero_pkmaps(void)
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
}
/* Flush all unused kmap mappings in order to remove stray
mappings. */
void kmap_flush_unused(void)
{
spin_lock(&kmap_lock);
flush_all_zero_pkmaps();
spin_unlock(&kmap_lock);
}
static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
......
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