Re: [PATCH v3] KVM: nVMX: Fix setting of CR0 and CR4 in guest mode

[Marcelo Tosatti <mtosatti@redhat.com>]

On Thu, Mar 07, 2013 at 03:32:14PM +0200, Gleb Natapov wrote:
> On Thu, Mar 07, 2013 at 02:08:07PM +0100, Jan Kiszka wrote:
> > The logic for calculating the value with which we call kvm_set_cr0/4 was
> > broken (will definitely be visible with nested unrestricted guest mode
> > support). Also, we performed the check regarding CR0_ALWAYSON too early
> > when in guest mode.
> > 
> > What really needs to be done on both CR0 and CR4 is to mask out L1-owned
> > bits and merge them in from L1's guest_cr0/4. In contrast, arch.cr0/4
> > and arch.cr0/4_guest_owned_bits contain the mangled L0+L1 state and,
> > thus, are not suited as input.
> > 
> > For both CRs, we can then apply the check against VMXON_CRx_ALWAYSON and
> > refuse the update if it fails. To be fully consistent, we implement this
> > check now also for CR4. For CR4, we move the check into vmx_set_cr4
> > while we keep it in handle_set_cr0. This is because the CR0 checks for
> > vmxon vs. guest mode will diverge soon when adding unrestricted guest
> > mode support.
> > 
> > Finally, we have to set the shadow to the value L2 wanted to write
> > originally.
> > 
> > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> Reviewed-by: Gleb Natapov <gleb@redhat.com>

Applied, thanks.