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KVM: MMU: Don't flush shadow when enabling dirty tracking 

Instead, drop large mappings, which were the reason we dropped shadow.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2010-12-27 12:08:45 +02:00 committed by Marcelo Tosatti
parent 054cfaacf8
commit 8234b22e1c
2 changed files with 9 additions and 10 deletions
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12
arch/x86/kvm/mmu.c
View File

@ -3538,14 +3538,18 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
if (!test_bit(slot, sp->slot_bitmap))
continue;
if (sp->role.level != PT_PAGE_TABLE_LEVEL)
continue;
pt = sp->spt;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
if (sp->role.level != PT_PAGE_TABLE_LEVEL
&& is_large_pte(pt[i])) {
drop_spte(kvm, &pt[i],
shadow_trap_nonpresent_pte);
--kvm->stat.lpages;
}
/* avoid RMW */
if (is_writable_pte(pt[i]))
update_spte(&pt[i], pt[i] & ~PT_WRITABLE_MASK);
}
}
kvm_flush_remote_tlbs(kvm);
}

7
virt/kvm/kvm_main.c
View File

@ -621,7 +621,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
int user_alloc)
{
int r, flush_shadow = 0;
int r;
gfn_t base_gfn;
unsigned long npages;
unsigned long i;
@ -741,8 +741,6 @@ skip_lpage:
if (kvm_create_dirty_bitmap(&new) < 0)
goto out_free;
/* destroy any largepage mappings for dirty tracking */
if (old.npages)
flush_shadow = 1;
}
#else /* not defined CONFIG_S390 */
new.user_alloc = user_alloc;
@ -813,9 +811,6 @@ skip_lpage:
kvm_free_physmem_slot(&old, &new);
kfree(old_memslots);
if (flush_shadow)
kvm_arch_flush_shadow(kvm);
return 0;
out_free: