Patch "KVM: nVMX: initialize PML fields in vmcs02" has been added to the 4.4-stable tree

Patch "KVM: nVMX: initialize PML fields in vmcs02" has been added to the 4.4-stable tree

[gregkh]

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 4.4-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-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1fb883bb827ee8efc1cc9ea0154f953f8a219d38 Mon Sep 17 00:00:00 2001
From: Ladi Prosek <lprosek@redhat.com>
Date: Tue, 4 Apr 2017 14:18:53 +0200
Subject: KVM: nVMX: initialize PML fields in vmcs02
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ladi Prosek <lprosek@redhat.com>

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.

Fixes: 843e4330573c ("KVM: VMX: Add PML support in VMX")
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9757,6 +9757,18 @@ 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 lprosek@redhat.com are

queue-4.4/kvm-nvmx-do-not-leak-pml-full-vmexit-to-l1.patch
queue-4.4/kvm-nvmx-initialize-pml-fields-in-vmcs02.patch