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| author | Florian Funke <ffunke@de.ibm.com> | 2008-10-10 21:33:26 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-10-10 21:34:00 +0200 |
| commit | 15e86b0c752d50e910b2cca6e83ce74c4440d06c (patch) | |
| tree | c17e8e71362bb9432e215a01bbd671c76216d262 /arch/s390 | |
| parent | [S390] Add ioctl support for EMC Symmetrix Subsystem Control I/O (diff) | |
| download | linux-15e86b0c752d50e910b2cca6e83ce74c4440d06c.tar.xz linux-15e86b0c752d50e910b2cca6e83ce74c4440d06c.zip | |
[S390] introduce dirty bit for kvm live migration
This patch defines a dirty bit in the PGSTE that can be used to implement
dirty pages logging for KVM's live migration. The bit is set in the
ptep_rcp_copy function, which is called to save dirty and referenced information
from the storage key in the PGSTE. The bit can be tested and reset by KVM using
the kvm_s390_test_and_clear_page_dirty function that is introduced by this patch.
Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Florian Funke <ffunke@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/pgtable.h | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 0bdb704ae051..1a928f84afd6 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -281,6 +281,9 @@ extern char empty_zero_page[PAGE_SIZE]; #define RCP_GR_BIT 50 #define RCP_GC_BIT 49 +/* User dirty bit for KVM's migration feature */ +#define KVM_UD_BIT 47 + #ifndef __s390x__ /* Bits in the segment table address-space-control-element */ @@ -575,12 +578,16 @@ static inline void ptep_rcp_copy(pte_t *ptep) unsigned long *pgste = (unsigned long *) (ptep + PTRS_PER_PTE); skey = page_get_storage_key(page_to_phys(page)); - if (skey & _PAGE_CHANGED) + if (skey & _PAGE_CHANGED) { set_bit_simple(RCP_GC_BIT, pgste); + set_bit_simple(KVM_UD_BIT, pgste); + } if (skey & _PAGE_REFERENCED) set_bit_simple(RCP_GR_BIT, pgste); - if (test_and_clear_bit_simple(RCP_HC_BIT, pgste)) + if (test_and_clear_bit_simple(RCP_HC_BIT, pgste)) { SetPageDirty(page); + set_bit_simple(KVM_UD_BIT, pgste); + } if (test_and_clear_bit_simple(RCP_HR_BIT, pgste)) SetPageReferenced(page); #endif @@ -744,6 +751,40 @@ static inline pte_t pte_mkspecial(pte_t pte) return pte; } +#ifdef CONFIG_PGSTE +/* + * Get (and clear) the user dirty bit for a PTE. + */ +static inline int kvm_s390_test_and_clear_page_dirty(struct mm_struct *mm, + pte_t *ptep) +{ + int dirty; + unsigned long *pgste; + struct page *page; + unsigned int skey; + + if (!mm->context.pgstes) + return -EINVAL; + rcp_lock(ptep); + pgste = (unsigned long *) (ptep + PTRS_PER_PTE); + page = virt_to_page(pte_val(*ptep)); + skey = page_get_storage_key(page_to_phys(page)); + if (skey & _PAGE_CHANGED) { + set_bit_simple(RCP_GC_BIT, pgste); + set_bit_simple(KVM_UD_BIT, pgste); + } + if (test_and_clear_bit_simple(RCP_HC_BIT, pgste)) { + SetPageDirty(page); + set_bit_simple(KVM_UD_BIT, pgste); + } + dirty = test_and_clear_bit_simple(KVM_UD_BIT, pgste); + if (skey & _PAGE_CHANGED) + page_clear_dirty(page); + rcp_unlock(ptep); + return dirty; +} +#endif + #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) |