Patch "KVM: nVMX: initialize PML fields in vmcs02" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

KVM: nVMX: initialize PML fields in vmcs02

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-nvmx-initialize-pml-fields-in-vmcs02.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ladi Prosek <[email protected]>
Date: Tue, 4 Apr 2017 14:18:53 +0200
Subject: KVM: nVMX: initialize PML fields in vmcs02
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From: Ladi Prosek <[email protected]>

commit 1fb883bb827ee8efc1cc9ea0154f953f8a219d38 upstream.

L2 was running with uninitialized PML fields which led to incomplete dirty bitmap logging. This manifested as all kinds of subtle erratic behavior of the nested guest.

---
 arch/x86/kvm/vmx.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

@@ -10071,6 +10071,18 @@ static void prepare_vmcs02(struct kvm_vc
 
 	}
 
+	if (enable_pml) {
+		/*
+		 * Conceptually we want to copy the PML address and index from
+		 * vmcs01 here, and then back to vmcs01 on nested vmexit. But,
+		 * since we always flush the log on each vmexit, this happens
+		 * to be equivalent to simply resetting the fields in vmcs02.
+		 */
+		ASSERT(vmx->pml_pg);
+		vmcs_write64(PML_ADDRESS, page_to_phys(vmx->pml_pg));
+		vmcs_write16(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
+	}
+
 	if (nested_cpu_has_ept(vmcs12)) {
 		kvm_mmu_unload(vcpu);
 		nested_ept_init_mmu_context(vcpu);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/kvm-nvmx-do-not-leak-pml-full-vmexit-to-l1.patch queue-4.9/kvm-nvmx-initialize-pml-fields-in-vmcs02.patch