[2/2] KVM: VMX: Use just one page for I/O permission bitmaps

Commit Message

Radim Krčmář Dec. 5, 2017, 9:26 p.m. UTC

2017-12-01 10:21-0800, Jim Mattson:
> Since we no longer allow any I/O ports to be passed through to the guest,
> we can use the same page for I/O bitmap A and I/O bitmap B.

I think we can disable the feature and save the second page as well:

Comments

Jim Mattson Dec. 6, 2017, 12:16 a.m. UTC | #1

Yes, of course.

Thanks!

On Tue, Dec 5, 2017 at 1:26 PM, Radim Krčmář <[e-mail]> wrote:
> 2017-12-01 10:21-0800, Jim Mattson:
>> Since we no longer allow any I/O ports to be passed through to the guest,
>> we can use the same page for I/O bitmap A and I/O bitmap B.
>
> I think we can disable the feature and save the second page as well:
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e25c55ea2eb7..80859a7cdf6d 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3624,7 +3624,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>  #endif
>               CPU_BASED_CR3_LOAD_EXITING |
>               CPU_BASED_CR3_STORE_EXITING |
> -             CPU_BASED_USE_IO_BITMAPS |
> +             CPU_BASED_UNCOND_IO_EXITING |
>               CPU_BASED_MOV_DR_EXITING |
>               CPU_BASED_USE_TSC_OFFSETING |
>               CPU_BASED_INVLPG_EXITING |

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e25c55ea2eb7..80859a7cdf6d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3624,7 +3624,7 @@  static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 #endif
 	      CPU_BASED_CR3_LOAD_EXITING |
 	      CPU_BASED_CR3_STORE_EXITING |
-	      CPU_BASED_USE_IO_BITMAPS |
+	      CPU_BASED_UNCOND_IO_EXITING |
 	      CPU_BASED_MOV_DR_EXITING |
 	      CPU_BASED_USE_TSC_OFFSETING |
 	      CPU_BASED_INVLPG_EXITING |