Commit e18c5429 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Assert that correct locks are held for page write-tracking 



When adding/removing gfns to/from write-tracking, assert that mmu_lock
is held for write, and that either slots_lock or kvm->srcu is held.
mmu_lock must be held for write to protect gfn_write_track's refcount,
and SRCU or slots_lock must be held to protect the memslot itself.

Tested-by: default avatarYan Zhao <yan.y.zhao@intel.com>
Tested-by: default avatarYongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-26-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 7b574863

arch/x86/kvm/mmu/page_track.c

+11 −6
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/lockdep.h>

#include <linux/kvm_host.h>

#include <linux/rculist.h>
@@ -77,9 +78,6 @@ static void update_gfn_write_track(struct kvm_memory_slot *slot, gfn_t gfn, 
 * add guest page to the tracking pool so that corresponding access on that

 * page will be intercepted.

 *

 * It should be called under the protection both of mmu-lock and kvm->srcu

 * or kvm->slots_lock.

 *

 * @kvm: the guest instance we are interested in.

 * @slot: the @gfn belongs to.

 * @gfn: the guest page.
@@ -87,6 +85,11 @@ static void update_gfn_write_track(struct kvm_memory_slot *slot, gfn_t gfn, 
void kvm_write_track_add_gfn(struct kvm *kvm, struct kvm_memory_slot *slot,

			     gfn_t gfn)

{

	lockdep_assert_held_write(&kvm->mmu_lock);



	lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||

			    srcu_read_lock_held(&kvm->srcu));



	if (WARN_ON_ONCE(!kvm_page_track_write_tracking_enabled(kvm)))

		return;
@@ -107,9 +110,6 @@ EXPORT_SYMBOL_GPL(kvm_write_track_add_gfn); 
 * remove the guest page from the tracking pool which stops the interception

 * of corresponding access on that page.

 *

 * It should be called under the protection both of mmu-lock and kvm->srcu

 * or kvm->slots_lock.

 *

 * @kvm: the guest instance we are interested in.

 * @slot: the @gfn belongs to.

 * @gfn: the guest page.
@@ -117,6 +117,11 @@ EXPORT_SYMBOL_GPL(kvm_write_track_add_gfn); 
void kvm_write_track_remove_gfn(struct kvm *kvm,

				struct kvm_memory_slot *slot, gfn_t gfn)

{

	lockdep_assert_held_write(&kvm->mmu_lock);



	lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||

			    srcu_read_lock_held(&kvm->srcu));



	if (WARN_ON_ONCE(!kvm_page_track_write_tracking_enabled(kvm)))

		return;