On 04.04.2017 14:18, Ladi Prosek wrote:
> 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@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2ee00db..f47d701 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -10267,6 +10267,18 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
>
> }
>
> + 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
we == KVM running in g2?
If so, other hypervisors might handle this differently.
> + * 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);
>
--
Thanks,
David
