Re: [PATCH] KVM: VMX: drop I/O permission bitmaps

[Jim Mattson]

On Fri, Dec 8, 2017 at 2:22 AM, Quan Xu <quan.xu0@xxxxxxxxx> wrote:
> From: Quan Xu <quan.xu0@xxxxxxxxx>
>
> Since KVM removes the only I/O port 0x80 bypass on Intel hosts,
> clear CPU_BASED_USE_IO_BITMAPS and set CPU_BASED_UNCOND_IO_EXITING
> bit. Then these I/O permission bitmaps are not used at all, so
> drop I/O permission bitmaps.
>
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> Signed-off-by: Quan Xu <quan.xu0@xxxxxxxxx>
> ---
>  arch/x86/kvm/vmx.c |   17 +----------------
>  1 files changed, 1 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2fd9a8c..3e4f760 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -771,8 +771,6 @@ enum segment_cache_field {
>         FIELD(HOST_FS_SELECTOR, host_fs_selector),
>         FIELD(HOST_GS_SELECTOR, host_gs_selector),
>         FIELD(HOST_TR_SELECTOR, host_tr_selector),
> -       FIELD64(IO_BITMAP_A, io_bitmap_a),
> -       FIELD64(IO_BITMAP_B, io_bitmap_b),
These two lines should stay.
>         FIELD64(MSR_BITMAP, msr_bitmap),
>         FIELD64(VM_EXIT_MSR_STORE_ADDR, vm_exit_msr_store_addr),
>         FIELD64(VM_EXIT_MSR_LOAD_ADDR, vm_exit_msr_load_addr),
> @@ -943,8 +941,6 @@ static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12,
>  static DEFINE_PER_CPU(spinlock_t, blocked_vcpu_on_cpu_lock);
>
>  enum {
> -       VMX_IO_BITMAP_A,
> -       VMX_IO_BITMAP_B,
>         VMX_MSR_BITMAP_LEGACY,
>         VMX_MSR_BITMAP_LONGMODE,
>         VMX_MSR_BITMAP_LEGACY_X2APIC_APICV,
> @@ -958,8 +954,6 @@ enum {
>
>  static unsigned long *vmx_bitmap[VMX_BITMAP_NR];
>
> -#define vmx_io_bitmap_a                      (vmx_bitmap[VMX_IO_BITMAP_A])
> -#define vmx_io_bitmap_b                      (vmx_bitmap[VMX_IO_BITMAP_B])
>  #define vmx_msr_bitmap_legacy                (vmx_bitmap[VMX_MSR_BITMAP_LEGACY])
>  #define vmx_msr_bitmap_longmode              (vmx_bitmap[VMX_MSR_BITMAP_LONGMODE])
>  #define vmx_msr_bitmap_legacy_x2apic_apicv   (vmx_bitmap[VMX_MSR_BITMAP_LEGACY_X2APIC_APICV])
> @@ -3632,7 +3626,7 @@ 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 |
> @@ -5445,10 +5439,6 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
>  #endif
>         int i;
>
> -       /* I/O */
> -       vmcs_write64(IO_BITMAP_A, __pa(vmx_io_bitmap_a));
> -       vmcs_write64(IO_BITMAP_B, __pa(vmx_io_bitmap_b));
> -
>         if (enable_shadow_vmcs) {
>                 vmcs_write64(VMREAD_BITMAP, __pa(vmx_vmread_bitmap));
>                 vmcs_write64(VMWRITE_BITMAP, __pa(vmx_vmwrite_bitmap));
> @@ -6751,14 +6741,9 @@ static __init int hardware_setup(void)
>                         goto out;
>         }
>
> -       vmx_io_bitmap_b = (unsigned long *)__get_free_page(GFP_KERNEL);
>         memset(vmx_vmread_bitmap, 0xff, PAGE_SIZE);
>         memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE);
>
> -       memset(vmx_io_bitmap_a, 0xff, PAGE_SIZE);
> -
> -       memset(vmx_io_bitmap_b, 0xff, PAGE_SIZE);
> -
>         memset(vmx_msr_bitmap_legacy, 0xff, PAGE_SIZE);
>         memset(vmx_msr_bitmap_longmode, 0xff, PAGE_SIZE);
>
> --
> 1.7.1
>