Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-09 14:50:19 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

KVM: s390: pv: properly handle page flags for protected guests

Browse Source 
Introduce variants of the convert and destroy page functions that also
clear the PG_arch_1 bit used to mark them as secure pages.

The PG_arch_1 flag is always allowed to overindicate; using the new
functions introduced here allows to reduce the extent of overindication
and thus improve performance.

These new functions can only be called on pages for which a reference
is already being held.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: https://lore.kernel.org/r/20210920132502.36111-7-imbrenda@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Claudio Imbrenda 2021-09-20 15:24:54 +02:00 committed by Christian Borntraeger
parent 85f517b294
commit 380d97bd02
4 changed files with 50 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/s390/include/asm/pgtable.h
View File

@ -1074,8 +1074,9 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
pte_t res; pte_t res;
res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID)); res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));
/* At this point the reference through the mapping is still present */
if (mm_is_protected(mm) && pte_present(res)) if (mm_is_protected(mm) && pte_present(res))
uv_convert_from_secure(pte_val(res) & PAGE_MASK); uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res; return res;
} }
@ -1091,8 +1092,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
pte_t res; pte_t res;
res = ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID)); res = ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID));
/* At this point the reference through the mapping is still present */
if (mm_is_protected(vma->vm_mm) && pte_present(res)) if (mm_is_protected(vma->vm_mm) && pte_present(res))
uv_convert_from_secure(pte_val(res) & PAGE_MASK); uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res; return res;
} }
@ -1116,8 +1118,9 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
} else { } else {
res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID)); res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));
} }
/* At this point the reference through the mapping is still present */
if (mm_is_protected(mm) && pte_present(res)) if (mm_is_protected(mm) && pte_present(res))
uv_convert_from_secure(pte_val(res) & PAGE_MASK); uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
return res; return res;
} }

10
arch/s390/include/asm/uv.h
View File

@ -356,8 +356,9 @@ static inline int is_prot_virt_host(void)
} }
int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb); int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb);
int uv_destroy_page(unsigned long paddr); int uv_destroy_owned_page(unsigned long paddr);
int uv_convert_from_secure(unsigned long paddr); int uv_convert_from_secure(unsigned long paddr);
int uv_convert_owned_from_secure(unsigned long paddr);
int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr); int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);
void setup_uv(void); void setup_uv(void);
@ -365,7 +366,7 @@ void setup_uv(void);
#define is_prot_virt_host() 0 #define is_prot_virt_host() 0
static inline void setup_uv(void) {} static inline void setup_uv(void) {}
static inline int uv_destroy_page(unsigned long paddr) static inline int uv_destroy_owned_page(unsigned long paddr)
{ {
return 0; return 0;
} }
@ -374,6 +375,11 @@ static inline int uv_convert_from_secure(unsigned long paddr)
{ {
return 0; return 0;
} }
static inline int uv_convert_owned_from_secure(unsigned long paddr)
{
return 0;
}
#endif #endif
#endif /* _ASM_S390_UV_H */ #endif /* _ASM_S390_UV_H */

34
arch/s390/kernel/uv.c
View File

@ -100,7 +100,7 @@ static int uv_pin_shared(unsigned long paddr)
* *
* @paddr: Absolute host address of page to be destroyed * @paddr: Absolute host address of page to be destroyed
*/ */
int uv_destroy_page(unsigned long paddr) static int uv_destroy_page(unsigned long paddr)
{ {
struct uv_cb_cfs uvcb = { struct uv_cb_cfs uvcb = {
.header.cmd = UVC_CMD_DESTR_SEC_STOR, .header.cmd = UVC_CMD_DESTR_SEC_STOR,
@ -120,6 +120,22 @@ int uv_destroy_page(unsigned long paddr)
return 0; return 0;
} }
/*
* The caller must already hold a reference to the page
*/
int uv_destroy_owned_page(unsigned long paddr)
{
struct page *page = phys_to_page(paddr);
int rc;
get_page(page);
rc = uv_destroy_page(paddr);
if (!rc)
clear_bit(PG_arch_1, &page->flags);
put_page(page);
return rc;
}
/* /*
* Requests the Ultravisor to encrypt a guest page and make it * Requests the Ultravisor to encrypt a guest page and make it
* accessible to the host for paging (export). * accessible to the host for paging (export).
@ -139,6 +155,22 @@ int uv_convert_from_secure(unsigned long paddr)
return 0; return 0;
} }
/*
* The caller must already hold a reference to the page
*/
int uv_convert_owned_from_secure(unsigned long paddr)
{
struct page *page = phys_to_page(paddr);
int rc;
get_page(page);
rc = uv_convert_from_secure(paddr);
if (!rc)
clear_bit(PG_arch_1, &page->flags);
put_page(page);
return rc;
}
/* /*
* Calculate the expected ref_count for a page that would otherwise have no * Calculate the expected ref_count for a page that would otherwise have no
* further pins. This was cribbed from similar functions in other places in * further pins. This was cribbed from similar functions in other places in

4
arch/s390/mm/gmap.c
View File

@ -2684,8 +2684,10 @@ static int __s390_reset_acc(pte_t *ptep, unsigned long addr,
{ {
pte_t pte = READ_ONCE(*ptep); pte_t pte = READ_ONCE(*ptep);
/* There is a reference through the mapping */
if (pte_present(pte)) if (pte_present(pte))
WARN_ON_ONCE(uv_destroy_page(pte_val(pte) & PAGE_MASK)); WARN_ON_ONCE(uv_destroy_owned_page(pte_val(pte) & PAGE_MASK));
return 0; return 0;
} }