From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Michael Roth <michael.roth@amd.com>,
Binbin Wu <binbin.wu@linux.intel.com>
Subject: [PATCH 04/13] KVM: WARN if there are danging MMU invalidations at VM destruction
Date: Thu, 21 Sep 2023 13:33:21 -0700 [thread overview]
Message-ID: <20230921203331.3746712-5-seanjc@google.com> (raw)
In-Reply-To: <20230921203331.3746712-1-seanjc@google.com>
Add an assertion that there are no in-progress MMU invalidations when a
VM is being destroyed, with the exception of the scenario where KVM
unregisters its MMU notifier between an .invalidate_range_start() call and
the corresponding .invalidate_range_end().
KVM can't detect unpaired calls from the mmu_notifier due to the above
exception waiver, but the assertion can detect KVM bugs, e.g. such as the
bug that *almost* escaped initial guest_memfd development.
Link: https://lore.kernel.org/all/e397d30c-c6af-e68f-d18e-b4e3739c5389@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
virt/kvm/kvm_main.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 54480655bcce..277afeedd670 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1381,9 +1381,16 @@ static void kvm_destroy_vm(struct kvm *kvm)
* No threads can be waiting in kvm_swap_active_memslots() as the
* last reference on KVM has been dropped, but freeing
* memslots would deadlock without this manual intervention.
+ *
+ * If the count isn't unbalanced, i.e. KVM did NOT unregister between
+ * a start() and end(), then there shouldn't be any in-progress
+ * invalidations.
*/
WARN_ON(rcuwait_active(&kvm->mn_memslots_update_rcuwait));
- kvm->mn_active_invalidate_count = 0;
+ if (kvm->mn_active_invalidate_count)
+ kvm->mn_active_invalidate_count = 0;
+ else
+ WARN_ON(kvm->mmu_invalidate_in_progress);
#else
kvm_flush_shadow_all(kvm);
#endif
--
2.42.0.515.g380fc7ccd1-goog
next prev parent reply other threads:[~2023-09-21 21:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-21 20:33 [PATCH 00/13] KVM: guest_memfd fixes Sean Christopherson
2023-09-21 20:33 ` [PATCH 01/13] KVM: Assert that mmu_invalidate_in_progress *never* goes negative Sean Christopherson
2023-09-21 20:33 ` [PATCH 02/13] KVM: Actually truncate the inode when doing PUNCH_HOLE for guest_memfd Sean Christopherson
2023-09-21 20:33 ` [PATCH 03/13] KVM: WARN if *any* MMU invalidation sequence doesn't add a range Sean Christopherson
2023-09-21 20:33 ` Sean Christopherson [this message]
2023-09-27 3:16 ` [PATCH 04/13] KVM: WARN if there are danging MMU invalidations at VM destruction Binbin Wu
2023-09-28 18:11 ` Sean Christopherson
2023-09-21 20:33 ` [PATCH 05/13] KVM: Fix MMU invalidation bookkeeping in guest_memfd Sean Christopherson
2023-09-21 20:33 ` [PATCH 06/13] KVM: Disallow hugepages for incompatible gmem bindings, but let 'em succeed Sean Christopherson
2023-09-22 22:42 ` Michael Roth
2023-09-28 18:31 ` Sean Christopherson
2023-10-02 15:53 ` Michael Roth
2023-10-02 16:49 ` Sean Christopherson
2023-09-21 20:33 ` [PATCH 07/13] KVM: x86/mmu: Track PRIVATE impact on hugepage mappings for all memslots Sean Christopherson
2023-09-27 6:01 ` Binbin Wu
2023-09-27 14:25 ` Sean Christopherson
2023-09-21 20:33 ` [PATCH 08/13] KVM: x86/mmu: Zap shared-only memslots when private attribute changes Sean Christopherson
2023-09-21 20:33 ` [PATCH 09/13] KVM: Always add relevant ranges to invalidation set when changing attributes Sean Christopherson
2023-09-21 20:33 ` [PATCH 10/13] KVM: x86/mmu: Drop repeated add() of to-be-invalidated range Sean Christopherson
2023-09-21 20:33 ` [PATCH 11/13] KVM: selftests: Refactor private mem conversions to prep for punch_hole test Sean Christopherson
2023-09-21 20:33 ` [PATCH 12/13] KVM: selftests: Add a "pure" PUNCH_HOLE on guest_memfd testcase Sean Christopherson
2023-09-21 20:33 ` [PATCH 13/13] KVM: Rename guest_mem.c to guest_memfd.c Sean Christopherson
2023-09-29 2:22 ` [PATCH 00/13] KVM: guest_memfd fixes Sean Christopherson
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