diff options
author | Carsten Otte <cotte@de.ibm.com> | 2008-03-25 18:47:10 +0100 |
---|---|---|
committer | Avi Kivity <avi@qumranet.com> | 2008-04-27 11:00:40 +0200 |
commit | 402b08622d9ac6e32e25289573272e0f21bb58a7 (patch) | |
tree | 40d7386154cef85c9bfd2bd862db025933820776 /arch/s390/mm | |
parent | KVM: x86: hardware task switching support (diff) | |
download | linux-402b08622d9ac6e32e25289573272e0f21bb58a7.tar.xz linux-402b08622d9ac6e32e25289573272e0f21bb58a7.zip |
s390: KVM preparation: provide hook to enable pgstes in user pagetable
The SIE instruction on s390 uses the 2nd half of the page table page to
virtualize the storage keys of a guest. This patch offers the s390_enable_sie
function, which reorganizes the page tables of a single-threaded process to
reserve space in the page table:
s390_enable_sie makes sure that the process is single threaded and then uses
dup_mm to create a new mm with reorganized page tables. The old mm is freed
and the process has now a page status extended field after every page table.
Code that wants to exploit pgstes should SELECT CONFIG_PGSTE.
This patch has a small common code hit, namely making dup_mm non-static.
Edit (Carsten): I've modified Martin's patch, following Jeremy Fitzhardinge's
review feedback. Now we do have the prototype for dup_mm in
include/linux/sched.h. Following Martin's suggestion, s390_enable_sie() does now
call task_lock() to prevent race against ptrace modification of mm_users.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch/s390/mm')
-rw-r--r-- | arch/s390/mm/pgtable.c | 65 |
1 files changed, 62 insertions, 3 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index fd072013f88c..5c1aea97cd12 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -30,11 +30,27 @@ #define TABLES_PER_PAGE 4 #define FRAG_MASK 15UL #define SECOND_HALVES 10UL + +void clear_table_pgstes(unsigned long *table) +{ + clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/4); + memset(table + 256, 0, PAGE_SIZE/4); + clear_table(table + 512, _PAGE_TYPE_EMPTY, PAGE_SIZE/4); + memset(table + 768, 0, PAGE_SIZE/4); +} + #else #define ALLOC_ORDER 2 #define TABLES_PER_PAGE 2 #define FRAG_MASK 3UL #define SECOND_HALVES 2UL + +void clear_table_pgstes(unsigned long *table) +{ + clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2); + memset(table + 256, 0, PAGE_SIZE/2); +} + #endif unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec) @@ -153,7 +169,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm) unsigned long *table; unsigned long bits; - bits = mm->context.noexec ? 3UL : 1UL; + bits = (mm->context.noexec || mm->context.pgstes) ? 3UL : 1UL; spin_lock(&mm->page_table_lock); page = NULL; if (!list_empty(&mm->context.pgtable_list)) { @@ -170,7 +186,10 @@ unsigned long *page_table_alloc(struct mm_struct *mm) pgtable_page_ctor(page); page->flags &= ~FRAG_MASK; table = (unsigned long *) page_to_phys(page); - clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE); + if (mm->context.pgstes) + clear_table_pgstes(table); + else + clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE); spin_lock(&mm->page_table_lock); list_add(&page->lru, &mm->context.pgtable_list); } @@ -191,7 +210,7 @@ void page_table_free(struct mm_struct *mm, unsigned long *table) struct page *page; unsigned long bits; - bits = mm->context.noexec ? 3UL : 1UL; + bits = (mm->context.noexec || mm->context.pgstes) ? 3UL : 1UL; bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long); page = pfn_to_page(__pa(table) >> PAGE_SHIFT); spin_lock(&mm->page_table_lock); @@ -228,3 +247,43 @@ void disable_noexec(struct mm_struct *mm, struct task_struct *tsk) mm->context.noexec = 0; update_mm(mm, tsk); } + +/* + * switch on pgstes for its userspace process (for kvm) + */ +int s390_enable_sie(void) +{ + struct task_struct *tsk = current; + struct mm_struct *mm; + int rc; + + task_lock(tsk); + + rc = 0; + if (tsk->mm->context.pgstes) + goto unlock; + + rc = -EINVAL; + if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 || + tsk->mm != tsk->active_mm || tsk->mm->ioctx_list) + goto unlock; + + tsk->mm->context.pgstes = 1; /* dirty little tricks .. */ + mm = dup_mm(tsk); + tsk->mm->context.pgstes = 0; + + rc = -ENOMEM; + if (!mm) + goto unlock; + mmput(tsk->mm); + tsk->mm = tsk->active_mm = mm; + preempt_disable(); + update_mm(mm, tsk); + cpu_set(smp_processor_id(), mm->cpu_vm_mask); + preempt_enable(); + rc = 0; +unlock: + task_unlock(tsk); + return rc; +} +EXPORT_SYMBOL_GPL(s390_enable_sie); |