To do dirty loging with huge pages, we protect huge pmds in the
gmap. When they are written to, we unprotect them and mark them dirty.
We introduce the function gmap_test_and_clear_dirty_segment which
handles dirty sync for huge pages.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
---
arch/s390/include/asm/gmap.h | 3 +
arch/s390/include/asm/pgtable.h | 3 +-
arch/s390/kvm/kvm-s390.c | 25 ++++++---
arch/s390/mm/gmap.c | 119 +++++++++++++++++++++++++++++++++++++++-
arch/s390/mm/pgtable.c | 34 +-----------
5 files changed, 143 insertions(+), 41 deletions(-)
diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index 276268b48aff..fcbd638fb9f4 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -15,6 +15,7 @@
/* Status bits only for huge segment entries */
#define _SEGMENT_ENTRY_GMAP_IN 0x8000 /* invalidation notify bit */
+#define _SEGMENT_ENTRY_GMAP_UC 0x4000 /* dirty (migration) */
/**
* struct gmap_struct - guest address space
@@ -139,4 +140,6 @@ void gmap_pte_notify(struct mm_struct *, unsigned long addr, pte_t *,
int gmap_mprotect_notify(struct gmap *, unsigned long start,
unsigned long len, int prot);
+void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4],
+ unsigned long gaddr, unsigned long vmaddr);
#endif /* _ASM_S390_GMAP_H */
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 087e0282f165..21378cb5a962 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1103,7 +1103,8 @@ int ptep_shadow_pte(struct mm_struct *mm, unsigned long saddr,
pte_t *sptep, pte_t *tptep, pte_t pte);
void ptep_unshadow_pte(struct mm_struct *mm, unsigned long saddr, pte_t *ptep);
-bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long address);
+bool test_and_clear_uc(struct mm_struct *mm, unsigned long address,
+ pte_t *ptep);
int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char key, bool nq);
int cond_set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3b7a5151b6a5..4cff5e31ca36 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -511,19 +511,30 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
}
static void kvm_s390_sync_dirty_log(struct kvm *kvm,
- struct kvm_memory_slot *memslot)
+ struct kvm_memory_slot *memslot)
{
+ int i;
gfn_t cur_gfn, last_gfn;
- unsigned long address;
+ unsigned long gaddr, vmaddr;
struct gmap *gmap = kvm->arch.gmap;
+ DECLARE_BITMAP(bitmap, _PAGE_ENTRIES);
- /* Loop over all guest pages */
+ /* Loop over all guest segments */
+ cur_gfn = memslot->base_gfn;
last_gfn = memslot->base_gfn + memslot->npages;
- for (cur_gfn = memslot->base_gfn; cur_gfn <= last_gfn; cur_gfn++) {
- address = gfn_to_hva_memslot(memslot, cur_gfn);
+ for (; cur_gfn <= last_gfn; cur_gfn += _PAGE_ENTRIES) {
+ gaddr = gfn_to_gpa(cur_gfn);
+ vmaddr = gfn_to_hva_memslot(memslot, cur_gfn);
+ if (kvm_is_error_hva(vmaddr))
+ continue;
+
+ bitmap_zero(bitmap, _PAGE_ENTRIES);
+ gmap_sync_dirty_log_pmd(gmap, bitmap, gaddr, vmaddr);
+ for (i = 0; i < _PAGE_ENTRIES; i++) {
+ if (test_bit(i, bitmap))
+ mark_page_dirty(kvm, cur_gfn + i);
+ }
- if (test_and_clear_guest_dirty(gmap->mm, address))
- mark_page_dirty(kvm, cur_gfn);
if (fatal_signal_pending(current))
return;
cond_resched();
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 3cdb088c20c2..eeca95203c5e 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -15,6 +15,7 @@
#include <linux/swapops.h>
#include <linux/ksm.h>
#include <linux/mman.h>
+#include <linux/hugetlb.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -521,6 +522,9 @@ void gmap_unlink(struct mm_struct *mm, unsigned long *table,
rcu_read_unlock();
}
+static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
+ unsigned long gaddr);
+
/**
* gmap_link - set up shadow page tables to connect a host to a guest address
* @gmap: pointer to guest mapping meta data structure
@@ -541,6 +545,7 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
+ u64 unprot;
int rc;
BUG_ON(gmap_is_shadow(gmap));
@@ -598,12 +603,19 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
vmaddr >> PMD_SHIFT, table);
if (!rc) {
if (pmd_large(*pmd)) {
- *table = pmd_val(*pmd) &
- _SEGMENT_ENTRY_HARDWARE_BITS_LARGE;
+ *table = (pmd_val(*pmd) &
+ _SEGMENT_ENTRY_HARDWARE_BITS_LARGE)
+ | _SEGMENT_ENTRY_GMAP_UC;
} else
*table = pmd_val(*pmd) &
_SEGMENT_ENTRY_HARDWARE_BITS;
}
+ } else if (*table & _SEGMENT_ENTRY_PROTECT &&
+ !(pmd_val(*pmd) & _SEGMENT_ENTRY_PROTECT)) {
+ unprot = (u64)*table;
+ unprot &= ~_SEGMENT_ENTRY_PROTECT;
+ unprot |= _SEGMENT_ENTRY_GMAP_UC;
+ gmap_pmdp_xchg(gmap, (pmd_t *)table, __pmd(unprot), gaddr);
}
spin_unlock(&gmap->guest_table_lock);
spin_unlock(ptl);
@@ -931,11 +943,23 @@ static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
{
int pmd_i = pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID;
int pmd_p = pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT;
+ pmd_t new = *pmdp;
/* Fixup needed */
if ((pmd_i && (prot != PROT_NONE)) || (pmd_p && (prot == PROT_WRITE)))
return -EAGAIN;
+ if (prot == PROT_NONE && !pmd_i) {
+ pmd_val(new) |= _SEGMENT_ENTRY_INVALID;
+ gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
+ }
+
+ if (prot == PROT_READ && !pmd_p) {
+ pmd_val(new) &= ~_SEGMENT_ENTRY_INVALID;
+ pmd_val(new) |= _SEGMENT_ENTRY_PROTECT;
+ gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
+ }
+
if (bits & GMAP_NOTIFY_MPROT)
pmd_val(*pmdp) |= _SEGMENT_ENTRY_GMAP_IN;
@@ -2229,6 +2253,32 @@ static void pmdp_notify_gmap(struct gmap *gmap, pmd_t *pmdp,
gmap_call_notifier(gmap, gaddr, gaddr + HPAGE_SIZE - 1);
}
+/**
+ * gmap_pmdp_xchg - exchange a gmap pmd with another
+ * @gmap: pointer to the guest address space structure
+ * @pmdp: pointer to the pmd entry
+ * @new: replacement entry
+ * @gaddr: the affected guest address
+ *
+ * This function is assumed to be called with the guest_table_lock
+ * held.
+ */
+static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
+ unsigned long gaddr)
+{
+ gaddr &= HPAGE_MASK;
+ pmdp_notify_gmap(gmap, pmdp, gaddr);
+ pmd_val(new) &= ~_SEGMENT_ENTRY_GMAP_IN;
+ if (MACHINE_HAS_TLB_GUEST)
+ __pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
+ IDTE_GLOBAL);
+ else if (MACHINE_HAS_IDTE)
+ __pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
+ else
+ __pmdp_csp(pmdp);
+ *pmdp = new;
+}
+
static void gmap_pmdp_clear(struct mm_struct *mm, unsigned long vmaddr,
int purge)
{
@@ -2350,6 +2400,71 @@ void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr)
}
EXPORT_SYMBOL_GPL(gmap_pmdp_idte_global);
+/**
+ * gmap_test_and_clear_dirty_pmd - test and reset segment dirty status
+ * @gmap: pointer to guest address space
+ * @pmdp: pointer to the pmd to be tested
+ * @gaddr: virtual address in the guest address space
+ *
+ * This function is assumed to be called with the guest_table_lock
+ * held.
+ */
+bool gmap_test_and_clear_dirty_pmd(struct gmap *gmap, pmd_t *pmdp,
+ unsigned long gaddr)
+{
+ if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
+ return false;
+
+ /* Already protected memory, which did not change is clean */
+ if (pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT &&
+ !(pmd_val(*pmdp) & _SEGMENT_ENTRY_GMAP_UC))
+ return false;
+
+ /* Clear UC indication and reset protection */
+ pmd_val(*pmdp) &= ~_SEGMENT_ENTRY_GMAP_UC;
+ gmap_protect_pmd(gmap, gaddr, pmdp, PROT_READ, 0);
+ return true;
+}
+
+/**
+ * gmap_sync_dirty_log_pmd - set bitmap based on dirty status of segment
+ * @gmap: pointer to guest address space
+ * @bitmap: dirty bitmap for this pmd
+ * @gaddr: virtual address in the guest address space
+ * @vmaddr: virtual address in the host address space
+ *
+ * This function is assumed to be called with the guest_table_lock
+ * held.
+ */
+void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long bitmap[4],
+ unsigned long gaddr, unsigned long vmaddr)
+{
+ int i;
+ pmd_t *pmdp;
+ pte_t *ptep;
+ spinlock_t *ptl;
+
+ pmdp = gmap_pmd_op_walk(gmap, gaddr);
+ if (!pmdp)
+ return;
+
+ if (pmd_large(*pmdp)) {
+ if (gmap_test_and_clear_dirty_pmd(gmap, pmdp, gaddr))
+ bitmap_fill(bitmap, _PAGE_ENTRIES);
+ } else {
+ for (i = 0; i < _PAGE_ENTRIES; i++, vmaddr += PAGE_SIZE) {
+ ptep = pte_alloc_map_lock(gmap->mm, pmdp, vmaddr, &ptl);
+ if (!ptep)
+ continue;
+ if (test_and_clear_uc(gmap->mm, vmaddr, ptep))
+ set_bit(i, bitmap);
+ spin_unlock(ptl);
+ }
+ }
+ gmap_pmd_op_end(gmap, pmdp);
+}
+EXPORT_SYMBOL_GPL(gmap_sync_dirty_log_pmd);
+
static inline void thp_split_mm(struct mm_struct *mm)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index fe84c0715395..09531f779271 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -704,40 +704,14 @@ void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
/*
* Test and reset if a guest page is dirty
*/
-bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr)
+bool test_and_clear_uc(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep)
{
- spinlock_t *ptl;
- pgd_t *pgd;
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
pgste_t pgste;
- pte_t *ptep;
pte_t pte;
bool dirty;
int nodat;
- pgd = pgd_offset(mm, addr);
- p4d = p4d_alloc(mm, pgd, addr);
- if (!p4d)
- return false;
- pud = pud_alloc(mm, p4d, addr);
- if (!pud)
- return false;
- pmd = pmd_alloc(mm, pud, addr);
- if (!pmd)
- return false;
- /* We can't run guests backed by huge pages, but userspace can
- * still set them up and then try to migrate them without any
- * migration support.
- */
- if (pmd_large(*pmd))
- return true;
-
- ptep = pte_alloc_map_lock(mm, pmd, addr, &ptl);
- if (unlikely(!ptep))
- return false;
-
pgste = pgste_get_lock(ptep);
dirty = !!(pgste_val(pgste) & PGSTE_UC_BIT);
pgste_val(pgste) &= ~PGSTE_UC_BIT;
@@ -753,11 +727,9 @@ bool test_and_clear_guest_dirty(struct mm_struct *mm, unsigned long addr)
*ptep = pte;
}
pgste_set_unlock(ptep, pgste);
-
- spin_unlock(ptl);
return dirty;
}
-EXPORT_SYMBOL_GPL(test_and_clear_guest_dirty);
+EXPORT_SYMBOL_GPL(test_and_clear_uc);
int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char key, bool nq)
--
2.14.3
