Now that make_folio_secure() may only set PG_arch_1 for small folios,
let's convert relevant remaining UV code to only work on (small) folios
and simply reject large folios early. This way, we'll never end up
touching PG_arch_1 on tail pages of a large folio in UV code.
The folio_get()/folio_put() for functions that are documented to already
hold a folio reference look weird and it should probably be removed.
Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure()
should really consume a folio reference instead. But these are cleanups for
another day.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/include/asm/page.h | 1 +
arch/s390/kernel/uv.c | 39 +++++++++++++++++++++---------------
2 files changed, 24 insertions(+), 16 deletions(-)
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 54d015bcd8e3..b64384872c0f 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -214,6 +214,7 @@ static inline unsigned long __phys_addr(unsigned long x, bool is_31bit)
#define pfn_to_phys(pfn) ((pfn) << PAGE_SHIFT)
#define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
+#define phys_to_folio(phys) page_folio(phys_to_page(phys))
#define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
#define folio_to_phys(page) pfn_to_phys(folio_pfn(folio))
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index adcbd4b13035..9c0113b26735 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -134,14 +134,17 @@ static int uv_destroy_page(unsigned long paddr)
*/
int uv_destroy_owned_page(unsigned long paddr)
{
- struct page *page = phys_to_page(paddr);
+ struct folio *folio = phys_to_folio(paddr);
int rc;
- get_page(page);
+ if (unlikely(folio_test_large(folio)))
+ return 0;
+
+ folio_get(folio);
rc = uv_destroy_page(paddr);
if (!rc)
- clear_bit(PG_arch_1, &page->flags);
- put_page(page);
+ clear_bit(PG_arch_1, &folio->flags);
+ folio_put(folio);
return rc;
}
@@ -169,14 +172,17 @@ int uv_convert_from_secure(unsigned long paddr)
*/
int uv_convert_owned_from_secure(unsigned long paddr)
{
- struct page *page = phys_to_page(paddr);
+ struct folio *folio = phys_to_folio(paddr);
int rc;
- get_page(page);
+ if (unlikely(folio_test_large(folio)))
+ return 0;
+
+ folio_get(folio);
rc = uv_convert_from_secure(paddr);
if (!rc)
- clear_bit(PG_arch_1, &page->flags);
- put_page(page);
+ clear_bit(PG_arch_1, &folio->flags);
+ folio_put(folio);
return rc;
}
@@ -457,33 +463,34 @@ EXPORT_SYMBOL_GPL(gmap_destroy_page);
*/
int arch_make_page_accessible(struct page *page)
{
+ struct folio *folio = page_folio(page);
int rc = 0;
- /* Hugepage cannot be protected, so nothing to do */
- if (PageHuge(page))
+ /* Large folios cannot be protected, so nothing to do */
+ if (unlikely(folio_test_large(folio)))
return 0;
/*
* PG_arch_1 is used in 3 places:
* 1. for kernel page tables during early boot
* 2. for storage keys of huge pages and KVM
- * 3. As an indication that this page might be secure. This can
+ * 3. As an indication that this small folio might be secure. This can
* overindicate, e.g. we set the bit before calling
* convert_to_secure.
* As secure pages are never huge, all 3 variants can co-exists.
*/
- if (!test_bit(PG_arch_1, &page->flags))
+ if (!test_bit(PG_arch_1, &folio->flags))
return 0;
- rc = uv_pin_shared(page_to_phys(page));
+ rc = uv_pin_shared(folio_to_phys(folio));
if (!rc) {
- clear_bit(PG_arch_1, &page->flags);
+ clear_bit(PG_arch_1, &folio->flags);
return 0;
}
- rc = uv_convert_from_secure(page_to_phys(page));
+ rc = uv_convert_from_secure(folio_to_phys(folio));
if (!rc) {
- clear_bit(PG_arch_1, &page->flags);
+ clear_bit(PG_arch_1, &folio->flags);
return 0;
}
--
2.44.0On Thu, 4 Apr 2024 18:36:40 +0200
David Hildenbrand <david@redhat.com> wrote:
> Now that make_folio_secure() may only set PG_arch_1 for small folios,
> let's convert relevant remaining UV code to only work on (small) folios
> and simply reject large folios early. This way, we'll never end up
> touching PG_arch_1 on tail pages of a large folio in UV code.
>
> The folio_get()/folio_put() for functions that are documented to already
> hold a folio reference look weird and it should probably be removed.
> Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure()
> should really consume a folio reference instead. But these are cleanups for
> another day.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> arch/s390/include/asm/page.h | 1 +
> arch/s390/kernel/uv.c | 39 +++++++++++++++++++++---------------
> 2 files changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
> index 54d015bcd8e3..b64384872c0f 100644
> --- a/arch/s390/include/asm/page.h
> +++ b/arch/s390/include/asm/page.h
> @@ -214,6 +214,7 @@ static inline unsigned long __phys_addr(unsigned long x, bool is_31bit)
> #define pfn_to_phys(pfn) ((pfn) << PAGE_SHIFT)
>
> #define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
> +#define phys_to_folio(phys) page_folio(phys_to_page(phys))
> #define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
> #define folio_to_phys(page) pfn_to_phys(folio_pfn(folio))
>
> diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
> index adcbd4b13035..9c0113b26735 100644
> --- a/arch/s390/kernel/uv.c
> +++ b/arch/s390/kernel/uv.c
> @@ -134,14 +134,17 @@ static int uv_destroy_page(unsigned long paddr)
> */
> int uv_destroy_owned_page(unsigned long paddr)
> {
> - struct page *page = phys_to_page(paddr);
> + struct folio *folio = phys_to_folio(paddr);
> int rc;
>
> - get_page(page);
> + if (unlikely(folio_test_large(folio)))
> + return 0;
please add a comment here to explain why it's ok to just return 0
here...
> +
> + folio_get(folio);
> rc = uv_destroy_page(paddr);
> if (!rc)
> - clear_bit(PG_arch_1, &page->flags);
> - put_page(page);
> + clear_bit(PG_arch_1, &folio->flags);
> + folio_put(folio);
> return rc;
> }
>
> @@ -169,14 +172,17 @@ int uv_convert_from_secure(unsigned long paddr)
> */
> int uv_convert_owned_from_secure(unsigned long paddr)
> {
> - struct page *page = phys_to_page(paddr);
> + struct folio *folio = phys_to_folio(paddr);
> int rc;
>
> - get_page(page);
> + if (unlikely(folio_test_large(folio)))
> + return 0;
... and here
> +
> + folio_get(folio);
> rc = uv_convert_from_secure(paddr);
> if (!rc)
> - clear_bit(PG_arch_1, &page->flags);
> - put_page(page);
> + clear_bit(PG_arch_1, &folio->flags);
> + folio_put(folio);
> return rc;
> }
>
> @@ -457,33 +463,34 @@ EXPORT_SYMBOL_GPL(gmap_destroy_page);
> */
> int arch_make_page_accessible(struct page *page)
> {
> + struct folio *folio = page_folio(page);
> int rc = 0;
>
> - /* Hugepage cannot be protected, so nothing to do */
> - if (PageHuge(page))
> + /* Large folios cannot be protected, so nothing to do */
> + if (unlikely(folio_test_large(folio)))
> return 0;
>
> /*
> * PG_arch_1 is used in 3 places:
> * 1. for kernel page tables during early boot
> * 2. for storage keys of huge pages and KVM
> - * 3. As an indication that this page might be secure. This can
> + * 3. As an indication that this small folio might be secure. This can
> * overindicate, e.g. we set the bit before calling
> * convert_to_secure.
> * As secure pages are never huge, all 3 variants can co-exists.
> */
> - if (!test_bit(PG_arch_1, &page->flags))
> + if (!test_bit(PG_arch_1, &folio->flags))
> return 0;
>
> - rc = uv_pin_shared(page_to_phys(page));
> + rc = uv_pin_shared(folio_to_phys(folio));
> if (!rc) {
> - clear_bit(PG_arch_1, &page->flags);
> + clear_bit(PG_arch_1, &folio->flags);
> return 0;
> }
>
> - rc = uv_convert_from_secure(page_to_phys(page));
> + rc = uv_convert_from_secure(folio_to_phys(folio));
> if (!rc) {
> - clear_bit(PG_arch_1, &page->flags);
> + clear_bit(PG_arch_1, &folio->flags);
> return 0;
> }
>
On 10.04.24 19:42, Claudio Imbrenda wrote:
> On Thu, 4 Apr 2024 18:36:40 +0200
> David Hildenbrand <david@redhat.com> wrote:
>
>> Now that make_folio_secure() may only set PG_arch_1 for small folios,
>> let's convert relevant remaining UV code to only work on (small) folios
>> and simply reject large folios early. This way, we'll never end up
>> touching PG_arch_1 on tail pages of a large folio in UV code.
>>
>> The folio_get()/folio_put() for functions that are documented to already
>> hold a folio reference look weird and it should probably be removed.
>> Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure()
>> should really consume a folio reference instead. But these are cleanups for
>> another day.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>> arch/s390/include/asm/page.h | 1 +
>> arch/s390/kernel/uv.c | 39 +++++++++++++++++++++---------------
>> 2 files changed, 24 insertions(+), 16 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
>> index 54d015bcd8e3..b64384872c0f 100644
>> --- a/arch/s390/include/asm/page.h
>> +++ b/arch/s390/include/asm/page.h
>> @@ -214,6 +214,7 @@ static inline unsigned long __phys_addr(unsigned long x, bool is_31bit)
>> #define pfn_to_phys(pfn) ((pfn) << PAGE_SHIFT)
>>
>> #define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
>> +#define phys_to_folio(phys) page_folio(phys_to_page(phys))
>> #define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
>> #define folio_to_phys(page) pfn_to_phys(folio_pfn(folio))
>>
>> diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
>> index adcbd4b13035..9c0113b26735 100644
>> --- a/arch/s390/kernel/uv.c
>> +++ b/arch/s390/kernel/uv.c
>> @@ -134,14 +134,17 @@ static int uv_destroy_page(unsigned long paddr)
>> */
>> int uv_destroy_owned_page(unsigned long paddr)
>> {
>> - struct page *page = phys_to_page(paddr);
>> + struct folio *folio = phys_to_folio(paddr);
>> int rc;
>>
>> - get_page(page);
>> + if (unlikely(folio_test_large(folio)))
>> + return 0;
>
> please add a comment here to explain why it's ok to just return 0
> here...
Will use
"/* See gmap_make_secure(): large folios cannot be protected */"
>
>> +
>> + folio_get(folio);
>> rc = uv_destroy_page(paddr);
>> if (!rc)
>> - clear_bit(PG_arch_1, &page->flags);
>> - put_page(page);
>> + clear_bit(PG_arch_1, &folio->flags);
>> + folio_put(folio);
>> return rc;
>> }
>>
>> @@ -169,14 +172,17 @@ int uv_convert_from_secure(unsigned long paddr)
>> */
>> int uv_convert_owned_from_secure(unsigned long paddr)
>> {
>> - struct page *page = phys_to_page(paddr);
>> + struct folio *folio = phys_to_folio(paddr);
>> int rc;
>>
>> - get_page(page);
>> + if (unlikely(folio_test_large(folio)))
>> + return 0;
>
> ... and here
here as well and ...
>
>> +
>> + folio_get(folio);
>> rc = uv_convert_from_secure(paddr);
>> if (!rc)
>> - clear_bit(PG_arch_1, &page->flags);
>> - put_page(page);
>> + clear_bit(PG_arch_1, &folio->flags);
>> + folio_put(folio);
>> return rc;
>> }
>>
>> @@ -457,33 +463,34 @@ EXPORT_SYMBOL_GPL(gmap_destroy_page);
>> */
>> int arch_make_page_accessible(struct page *page)
>> {
>> + struct folio *folio = page_folio(page);
>> int rc = 0;
>>
>> - /* Hugepage cannot be protected, so nothing to do */
>> - if (PageHuge(page))
>> + /* Large folios cannot be protected, so nothing to do */
^ here as well.
>> + if (unlikely(folio_test_large(folio)))
>> return 0;
>>
--
Cheers,
David / dhildenb
On Thu, Apr 04, 2024 at 06:36:40PM +0200, David Hildenbrand wrote: > Now that make_folio_secure() may only set PG_arch_1 for small folios, > let's convert relevant remaining UV code to only work on (small) folios > and simply reject large folios early. This way, we'll never end up > touching PG_arch_1 on tail pages of a large folio in UV code. > > The folio_get()/folio_put() for functions that are documented to already > hold a folio reference look weird and it should probably be removed. > Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure() > should really consume a folio reference instead. But these are cleanups for > another day. Yes, and we should convert arch_make_page_accessible() to arch_make_folio_accessible() ... one of the two callers already has the folio (and page-writeback already calls arch_make_folio_accessible()
On 05.04.24 05:36, Matthew Wilcox wrote: > On Thu, Apr 04, 2024 at 06:36:40PM +0200, David Hildenbrand wrote: >> Now that make_folio_secure() may only set PG_arch_1 for small folios, >> let's convert relevant remaining UV code to only work on (small) folios >> and simply reject large folios early. This way, we'll never end up >> touching PG_arch_1 on tail pages of a large folio in UV code. >> >> The folio_get()/folio_put() for functions that are documented to already >> hold a folio reference look weird and it should probably be removed. >> Similarly, uv_destroy_owned_page() and uv_convert_owned_from_secure() >> should really consume a folio reference instead. But these are cleanups for >> another day. > > Yes, and we should convert arch_make_page_accessible() to > arch_make_folio_accessible() ... one of the two callers already has the > folio (and page-writeback already calls arch_make_folio_accessible() > Yes. We should then get rid of the arch_make_folio_accessible() loop over pages. Arch code can handle that, if required. Will include that in this series. -- Cheers, David / dhildenb
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