On 02/10/2018 12:26 AM, Jim Mattson wrote:
On Thu, Feb 8, 2018 at 2:53 PM, KarimAllah Ahmed <karah...@amazon.de> wrote:
... otherwise we will just be running with the L1 MSR BITMAP!

It does not seem that we ever update the MSR_BITMAP when the nested guest
is running. The only place where we update the MSR_BITMAP field in VMCS is
for the L1 guest!

Signed-off-by: KarimAllah Ahmed <karah...@amazon.de>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Cc: k...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
  arch/x86/kvm/vmx.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 91e3539..f40be10 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10589,6 +10589,9 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct 
vmcs12 *vmcs12,
         vmcs_writel(GUEST_GDTR_BASE, vmcs12->guest_gdtr_base);
         vmcs_writel(GUEST_IDTR_BASE, vmcs12->guest_idtr_base);

+       if (cpu_has_vmx_msr_bitmap())
+               vmcs_write64(MSR_BITMAP, __pa(vmx->nested.vmcs02.msr_bitmap));

This is already in David's "[PATCH 5/9] KVM: VMX: make MSR bitmaps
per-VCPU," isn't it?

I assume you are referring to this:


.. which is now:

commit 904e14fb7cb9 ("KVM: VMX: make MSR bitmaps per-VCPU")


If this is the case, then I do not see where the MSR_BITMAP is being
updated here. In fact, would not this be the commit that actually broke

Now MSR_BITMAP is only set in vmx_vcpu_setup:

        if (cpu_has_vmx_msr_bitmap())
                vmcs_write64(MSR_BITMAP, __pa(vmx->vmcs01.msr_bitmap));

         if (from_vmentry &&
             (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) {
                 kvm_set_dr(vcpu, 7, vmcs12->guest_dr7);

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