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author | 2021-09-20 15:24:54 +0200 | |
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committer | 2021-10-27 07:55:53 +0200 | |
commit | 380d97bd02fca7b9b41aec2d1c767874d602bc78 (patch) | |
tree | 8e9f822ec608744ebcb9f4e5ddb293936e59393a /arch/s390 | |
parent | KVM: s390: Fix handle_sske page fault handling (diff) | |
download | linux-380d97bd02fca7b9b41aec2d1c767874d602bc78.tar.gz linux-380d97bd02fca7b9b41aec2d1c767874d602bc78.tar.bz2 linux-380d97bd02fca7b9b41aec2d1c767874d602bc78.zip |
KVM: s390: pv: properly handle page flags for protected guests
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>
Diffstat (limited to 'arch/s390')
-rw-r--r-- | arch/s390/include/asm/pgtable.h | 9 | ||||
-rw-r--r-- | arch/s390/include/asm/uv.h | 10 | ||||
-rw-r--r-- | arch/s390/kernel/uv.c | 34 | ||||
-rw-r--r-- | arch/s390/mm/gmap.c | 4 |
4 files changed, 50 insertions, 7 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index b61426c9ef17..e43416950245 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1074,8 +1074,9 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, pte_t res; 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)) - uv_convert_from_secure(pte_val(res) & PAGE_MASK); + uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK); return res; } @@ -1091,8 +1092,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma, pte_t res; 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)) - uv_convert_from_secure(pte_val(res) & PAGE_MASK); + uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK); return res; } @@ -1116,8 +1118,9 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, } else { 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)) - uv_convert_from_secure(pte_val(res) & PAGE_MASK); + uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK); return res; } diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h index 9ab1914c5b95..72d3e49c2860 100644 --- a/arch/s390/include/asm/uv.h +++ b/arch/s390/include/asm/uv.h @@ -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 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_owned_from_secure(unsigned long paddr); int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr); void setup_uv(void); @@ -365,7 +366,7 @@ void setup_uv(void); #define is_prot_virt_host() 0 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; } @@ -374,6 +375,11 @@ static inline int uv_convert_from_secure(unsigned long paddr) { return 0; } + +static inline int uv_convert_owned_from_secure(unsigned long paddr) +{ + return 0; +} #endif #endif /* _ASM_S390_UV_H */ diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index 09b80d371409..8b0e62507d62 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -100,7 +100,7 @@ static int uv_pin_shared(unsigned long paddr) * * @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 = { .header.cmd = UVC_CMD_DESTR_SEC_STOR, @@ -121,6 +121,22 @@ int uv_destroy_page(unsigned long paddr) } /* + * 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 * accessible to the host for paging (export). * @@ -140,6 +156,22 @@ int uv_convert_from_secure(unsigned long paddr) } /* + * 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 * further pins. This was cribbed from similar functions in other places in * the kernel, but with some slight modifications. We know that a secure diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index d63c0ccc5ccd..dfee0ebb2fac 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -2684,8 +2684,10 @@ static int __s390_reset_acc(pte_t *ptep, unsigned long addr, { pte_t pte = READ_ONCE(*ptep); + /* There is a reference through the mapping */ 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; } |