Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Fri, 23 Dec 2022 00:57:35 +0000
In-Reply-To: <20221223005739.1295925-1-seanjc@google.com>
Mime-Version: 1.0
References: <20221223005739.1295925-1-seanjc@google.com>
Message-ID: <20221223005739.1295925-24-seanjc@google.com>
Subject: [PATCH 23/27] KVM: x86/mmu: Bug the VM if write-tracking is used but
 not enabled
From:   Sean Christopherson <seanjc@google.com>
To:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>
Cc:     kvm@vger.kernel.org, intel-gvt-dev@lists.freedesktop.org,
        intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Yan Zhao <yan.y.zhao@intel.com>,
        Ben Gardon <bgardon@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Bug the VM if something attempts to write-track a gfn, but write-tracking
isn't enabled.  The VM is doomed (and KVM has an egregious bug) if KVM or
KVMGT wants to shadow guest page tables but can't because write-tracking
isn't enabled.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/page_track.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 209f6beba5ac..d4c3bd6642b3 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -89,7 +89,7 @@ void kvm_write_track_add_gfn(struct kvm *kvm, struct kvm_memory_slot *slot,
 	lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
 			    srcu_read_lock_held(&kvm->srcu));
 
-	if (WARN_ON(!kvm_page_track_write_tracking_enabled(kvm)))
+	if (KVM_BUG_ON(!kvm_page_track_write_tracking_enabled(kvm), kvm))
 		return;
 
 	update_gfn_write_track(slot, gfn, 1);
@@ -121,7 +121,7 @@ void kvm_write_track_remove_gfn(struct kvm *kvm,
 	lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
 			    srcu_read_lock_held(&kvm->srcu));
 
-	if (WARN_ON(!kvm_page_track_write_tracking_enabled(kvm)))
+	if (KVM_BUG_ON(!kvm_page_track_write_tracking_enabled(kvm), kvm))
 		return;
 
 	update_gfn_write_track(slot, gfn, -1);
-- 
2.39.0.314.g84b9a713c41-goog