[PATCH 10/11] x86, cpa: Map in an arbitrary pgd

Borislav Petkov
2013-09-19T14:54:53Z

From: Borislav Petkov <bp@suse.de>

Add the ability to map pages in an arbitrary pgd. This wires in the
remaining stuff so that there's a new interface with which you can map a
region into an arbitrary PGD.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/mm/pageattr.c | 53 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 46 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index ca76481c09e8..991386bf3aad 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -453,7 +453,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
* Check for races, another CPU might have split this page
* up already:
*/
- tmp = lookup_address(address, &level);
+ tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte)
goto out_unlock;

@@ -559,7 +559,8 @@ out_unlock:
}

static int
-__split_large_page(pte_t *kpte, unsigned long address, struct page *base)
+__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
+ struct page *base)
{
pte_t *pbase = (pte_t *)page_address(base);
unsigned long pfn, pfninc = 1;
@@ -572,7 +573,7 @@ __split_large_page(pte_t *kpte, unsigned long address, struct page *base)
* Check for races, another CPU might have split this page
* up for us already:
*/
- tmp = lookup_address(address, &level);
+ tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte) {
spin_unlock(&pgd_lock);
return 1;
@@ -648,7 +649,8 @@ __split_large_page(pte_t *kpte, unsigned long address, struct page *base)
return 0;
}

-static int split_large_page(pte_t *kpte, unsigned long address)
+static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
+ unsigned long address)
{
struct page *base;

@@ -660,7 +662,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
if (!base)
return -ENOMEM;

- if (__split_large_page(kpte, address, base))
+ if (__split_large_page(cpa, kpte, address, base))
__free_page(base);

return 0;
@@ -1041,6 +1043,9 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
int primary)
{
+ if (cpa->pgd)
+ return populate_pgd(cpa, vaddr);
+
/*
* Ignore all non primary paths.
*/
@@ -1085,7 +1090,7 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
else
address = *cpa->vaddr;
repeat:
- kpte = lookup_address(address, &level);
+ kpte = _lookup_address_cpa(cpa, address, &level);
if (!kpte)
return __cpa_process_fault(cpa, address, primary);

@@ -1149,7 +1154,7 @@ repeat:
/*
* We have to split the large page:
*/
- err = split_large_page(kpte, address);
+ err = split_large_page(cpa, kpte, address);
if (!err) {
/*
* Do a global flush tlb after splitting the large page
@@ -1298,6 +1303,8 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages,
int ret, cache, checkalias;
unsigned long baddr = 0;

+ memset(&cpa, 0, sizeof(cpa));
+
/*
* Check, if we are requested to change a not supported
* feature:
@@ -1744,6 +1751,7 @@ static int __set_pages_p(struct page *page, int numpages)
{
unsigned long tempaddr = (unsigned long) page_address(page);
struct cpa_data cpa = { .vaddr = &tempaddr,
+ .pgd = 0,
.numpages = numpages,
.mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
.mask_clr = __pgprot(0),
@@ -1762,6 +1770,7 @@ static int __set_pages_np(struct page *page, int numpages)
{
unsigned long tempaddr = (unsigned long) page_address(page);
struct cpa_data cpa = { .vaddr = &tempaddr,
+ .pgd = 0,
.numpages = numpages,
.mask_set = __pgprot(0),
.mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW),
@@ -1822,6 +1831,36 @@ bool kernel_page_present(struct page *page)

#endif /* CONFIG_DEBUG_PAGEALLOC */

+int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
+ unsigned numpages, unsigned long page_flags)
+{
+ int retval = 0;
+
+ struct cpa_data cpa = {
+ .vaddr = &address,
+ .pfn = pfn,
+ .pgd = pgd,
+ .numpages = numpages,
+ .mask_set = __pgprot(0),
+ .mask_clr = __pgprot(0),
+ .flags = 0,
+ };
+
+ if (!(__supported_pte_mask & _PAGE_NX))
+ goto out;
+
+ if (!(page_flags & _PAGE_NX))
+ cpa.mask_clr = __pgprot(_PAGE_NX);
+
+ cpa.mask_set = __pgprot(_PAGE_PRESENT | page_flags);
+
+ retval = __change_page_attr_set_clr(&cpa, 0);
+ __flush_tlb_all();
+
+out:
+ return retval;
+}
+
/*
* The testcases use internal knowledge of the implementation that shouldn't
* be exposed to the rest of the kernel. Include these directly here.
--
1.8.4