On Tue, Sep 03, 2013 at 10:51:31AM +0200, Jan Kiszka wrote:
> On 2013-09-03 10:39, Gleb Natapov wrote:
> > On Thu, Aug 08, 2013 at 04:26:32PM +0200, Jan Kiszka wrote:
> >> This job is normally performed by the architectural EFER set service
> >> which we cannot use as it prevents transitions that are valid when
> >> switching between L1 and L2. So open-code the update of base_role.nxe
> >> after changing EFER on VM-entry and exit.
> >>
> >> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> >> ---
> >> arch/x86/kvm/vmx.c | 4 ++++
> >> 1 files changed, 4 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> >> index 9b0510b..7cc208a 100644
> >> --- a/arch/x86/kvm/vmx.c
> >> +++ b/arch/x86/kvm/vmx.c
> >> @@ -7735,6 +7735,8 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> >> vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
> >> /* Note: modifies VM_ENTRY/EXIT_CONTROLS and GUEST/HOST_IA32_EFER */
> >> vmx_set_efer(vcpu, vcpu->arch.efer);
> >> + vcpu->arch.mmu.base_role.nxe =
> >> + (vcpu->arch.efer & EFER_NX) && !enable_ept;
> >>
> > kvm_mmu_reset_context() called later in this function does that.
>
> For all relevant scenarios? The code is pretty convoluted, so this is
> non-obvious for me: kvm_mmu_reset_context calls init_kvm_mmu which may
> call init_kvm_softmmu that does kvm_init_shadow_mmu with nxe
> initialization. But is that path always taken?
>
What scenarios are relevant here? kvm_mmu_reset_context() is what
kvm_set_efer() would have called anyway. Since you use !enable_ept
here I assume that relevant scenario is shadow on shadow and in this
case it is easy to see that kvm_mmu_reset_context() will call
kvm_init_shadow_mmu() eventually. For all other scenarios guest nx
setting is irrelevant.
> Jan
>
> >
> >> if (nested_cpu_has_ept(vmcs12)) {
> >> kvm_mmu_unload(vcpu);
> >> @@ -8179,6 +8181,8 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
> >> else
> >> vcpu->arch.efer &= ~(EFER_LMA | EFER_LME);
> >> vmx_set_efer(vcpu, vcpu->arch.efer);
> >> + vcpu->arch.mmu.base_role.nxe =
> >> + (vcpu->arch.efer & EFER_NX) && !enable_ept;
> >>
> > Same here.
> >
> >> kvm_register_write(vcpu, VCPU_REGS_RSP, vmcs12->host_rsp);
> >> kvm_register_write(vcpu, VCPU_REGS_RIP, vmcs12->host_rip);
> >> --
> >> 1.7.3.4
> >
> > --
> > Gleb.
> >
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SES-DE
> Corporate Competence Center Embedded Linux
--
Gleb.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
