Commit 8234b22e authored by Avi Kivity's avatar Avi Kivity Committed by Marcelo Tosatti
Browse files

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



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

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 054cfaac

arch/x86/kvm/mmu.c

+8 −4
Original line number Diff line number Diff line
@@ -3538,15 +3538,19 @@ 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);

}

virt/kvm/kvm_main.c

+1 −6
Original line number Diff line number Diff line
@@ -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 @@ int __kvm_set_memory_region(struct kvm *kvm, 
		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 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	kvm_free_physmem_slot(&old, &new);

	kfree(old_memslots);



	if (flush_shadow)

		kvm_arch_flush_shadow(kvm);



	return 0;



out_free: