On Wed, Apr 17, 2013 at 02:55:40PM +0300, Abel Gordon wrote:
> Once L1 loads VMCS12 we enable shadow-vmcs capability and copy all the VMCS12
> shadowed fields to the shadow vmcs. When we release the VMCS12, we also
> disable shadow-vmcs capability.
>
> Signed-off-by: Abel Gordon <abelg@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> --- .before/arch/x86/kvm/vmx.c 2013-04-17 14:20:51.000000000 +0300
> +++ .after/arch/x86/kvm/vmx.c 2013-04-17 14:20:51.000000000 +0300
> @@ -5590,12 +5590,17 @@ static int nested_vmx_check_permission(s
>
> static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
> {
> + u32 exec_control;
> if (enable_shadow_vmcs) {
> if (vmx->nested.current_vmcs12 != NULL) {
> /* copy to memory all shadowed fields in case
> they were modified */
> copy_shadow_to_vmcs12(vmx);
> vmx->nested.sync_shadow_vmcs = false;
> + exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> + exec_control &= ~SECONDARY_EXEC_SHADOW_VMCS;
> + vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
> + vmcs_write64(VMCS_LINK_POINTER, -1ull);
> free_vmcs(vmx->nested.current_shadow_vmcs);
> }
> }
> @@ -6084,6 +6089,7 @@ static int handle_vmptrld(struct kvm_vcp
> gpa_t vmptr;
> struct x86_exception e;
> struct vmcs *shadow_vmcs;
> + u32 exec_control;
>
> if (!nested_vmx_check_permission(vcpu))
> return 1;
> @@ -6140,6 +6146,11 @@ static int handle_vmptrld(struct kvm_vcp
> /* init shadow vmcs */
> vmcs_clear(shadow_vmcs);
> vmx->nested.current_shadow_vmcs = shadow_vmcs;
> + exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
> + exec_control |= SECONDARY_EXEC_SHADOW_VMCS;
> + vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);
> + vmcs_write64(VMCS_LINK_POINTER,
> + __pa(shadow_vmcs));
How hard would it be to disable shadowing for individual vmcs if shadow
vmcs allocation fails? It bothers me a little that we can fail perfectly
valid vmptrld() because of failed allocation.
> vmx->nested.sync_shadow_vmcs = true;
> }
> }
>
> --
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--
Gleb.
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