* [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW
@ 2018-10-09 6:43 Jan Beulich
2018-10-09 11:00 ` Andrew Cooper
2018-10-09 13:29 ` Wei Liu
0 siblings, 2 replies; 3+ messages in thread
From: Jan Beulich @ 2018-10-09 6:43 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper, Wei Liu
56fff3e5e9 ("x86: nuke PV superpage option and code") has introduced a
(luckily latent only) bug here, in that it didn't make reference
dropping dependent on whether the page was mapped writable. The only
current source of large page mappings for PV domains is the Dom0
builder, which only produces writeable ones.
Take the opportunity and also convert to bool both put_data_page()'s
respective parameter and the argument put_page_from_l3e() passes.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -663,8 +663,7 @@ static int get_page_and_type_from_mfn(
return rc;
}
-static void put_data_page(
- struct page_info *page, int writeable)
+static void put_data_page(struct page_info *page, bool writeable)
{
if ( writeable )
put_page_and_type(page);
@@ -1289,10 +1288,13 @@ static int put_page_from_l2e(l2_pgentry_
if ( l2e_get_flags(l2e) & _PAGE_PSE )
{
struct page_info *page = l2e_get_page(l2e);
+ bool writeable = l2e_get_flags(l2e) & _PAGE_RW;
unsigned int i;
+ ASSERT(!(mfn_x(page_to_mfn(page)) &
+ ((1UL << (L2_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1)));
for ( i = 0; i < (1u << PAGETABLE_ORDER); i++, page++ )
- put_page_and_type(page);
+ put_data_page(page, writeable);
}
else
{
@@ -1318,7 +1320,7 @@ static int put_page_from_l3e(l3_pgentry_
if ( unlikely(l3e_get_flags(l3e) & _PAGE_PSE) )
{
unsigned long mfn = l3e_get_pfn(l3e);
- int writeable = l3e_get_flags(l3e) & _PAGE_RW;
+ bool writeable = l3e_get_flags(l3e) & _PAGE_RW;
ASSERT(!(mfn & ((1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1)));
do {
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW
2018-10-09 6:43 [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW Jan Beulich
@ 2018-10-09 11:00 ` Andrew Cooper
2018-10-09 13:29 ` Wei Liu
1 sibling, 0 replies; 3+ messages in thread
From: Andrew Cooper @ 2018-10-09 11:00 UTC (permalink / raw)
To: Jan Beulich, xen-devel; +Cc: Wei Liu
On 09/10/18 07:43, Jan Beulich wrote:
> 56fff3e5e9 ("x86: nuke PV superpage option and code") has introduced a
> (luckily latent only) bug here, in that it didn't make reference
> dropping dependent on whether the page was mapped writable. The only
> current source of large page mappings for PV domains is the Dom0
> builder, which only produces writeable ones.
>
> Take the opportunity and also convert to bool both put_data_page()'s
> respective parameter and the argument put_page_from_l3e() passes.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW
2018-10-09 6:43 [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW Jan Beulich
2018-10-09 11:00 ` Andrew Cooper
@ 2018-10-09 13:29 ` Wei Liu
1 sibling, 0 replies; 3+ messages in thread
From: Wei Liu @ 2018-10-09 13:29 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel, Wei Liu, Andrew Cooper
On Tue, Oct 09, 2018 at 12:43:05AM -0600, Jan Beulich wrote:
> 56fff3e5e9 ("x86: nuke PV superpage option and code") has introduced a
> (luckily latent only) bug here, in that it didn't make reference
It seems that the bug was from the original superpage code -- see
put_spage_pages.
> dropping dependent on whether the page was mapped writable. The only
> current source of large page mappings for PV domains is the Dom0
> builder, which only produces writeable ones.
>
> Take the opportunity and also convert to bool both put_data_page()'s
> respective parameter and the argument put_page_from_l3e() passes.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
>
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -663,8 +663,7 @@ static int get_page_and_type_from_mfn(
> return rc;
> }
>
> -static void put_data_page(
> - struct page_info *page, int writeable)
> +static void put_data_page(struct page_info *page, bool writeable)
> {
> if ( writeable )
> put_page_and_type(page);
> @@ -1289,10 +1288,13 @@ static int put_page_from_l2e(l2_pgentry_
> if ( l2e_get_flags(l2e) & _PAGE_PSE )
> {
> struct page_info *page = l2e_get_page(l2e);
> + bool writeable = l2e_get_flags(l2e) & _PAGE_RW;
> unsigned int i;
>
> + ASSERT(!(mfn_x(page_to_mfn(page)) &
> + ((1UL << (L2_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1)));
> for ( i = 0; i < (1u << PAGETABLE_ORDER); i++, page++ )
> - put_page_and_type(page);
> + put_data_page(page, writeable);
> }
> else
> {
> @@ -1318,7 +1320,7 @@ static int put_page_from_l3e(l3_pgentry_
> if ( unlikely(l3e_get_flags(l3e) & _PAGE_PSE) )
> {
> unsigned long mfn = l3e_get_pfn(l3e);
> - int writeable = l3e_get_flags(l3e) & _PAGE_RW;
> + bool writeable = l3e_get_flags(l3e) & _PAGE_RW;
>
> ASSERT(!(mfn & ((1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1)));
> do {
>
>
>
>
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2018-10-09 6:43 [PATCH] x86: put_page_from_l2e() should honor _PAGE_RW Jan Beulich
2018-10-09 11:00 ` Andrew Cooper
2018-10-09 13:29 ` Wei Liu
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