Messages in this thread | | | Subject | Re: [PATCH] KVM: VMX: drop I/O permission bitmaps | From | Quan Xu <> | Date | Tue, 12 Dec 2017 16:39:30 +0800 |
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On 2017/12/12 02:08, Jim Mattson wrote: > Removing these two lines from the initialization of > field_to_offset_table[] means that vmcs_field_to_offset() will return > -ENOENT for IO_BITMAP_A or IO_BITMAP_B. Hence, handle_vmread and > handle_vmwrite will incorrectly report these fields as unsupported > VMCS components if an L1 hypervisor tries to access them.
I will fix in v2.
Quan Alibaba Cloud
> On Sun, Dec 10, 2017 at 9:37 PM, Quan Xu <quan.xu0@gmail.com> wrote: >> >> On 2017/12/09 01:31, Jim Mattson wrote: >>> On Fri, Dec 8, 2017 at 2:22 AM, Quan Xu <quan.xu0@gmail.com> wrote: >>>> From: Quan Xu <quan.xu0@gmail.com> >>>> >>>> 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@google.com> >>>> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> >>>> Signed-off-by: Quan Xu <quan.xu0@gmail.com> >>>> --- >>>> 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. >> Jim, could you explain why these two lines should stay? >> >> >> IIUC, the main concern is from nested virtualization, which still uses >> io_bitmap_a/io_bitmap_b.. >> if so, we really need to further clean up these code, as >> >> CPU_BASED_USE_IO_BITMAPS is clear, and CPU_BASED_UNCOND_IO_EXITING is set >> for both L0/L2. after new patches which I mentioned >> in this thread. >> >> right? >> >> Alibaba Cloud >> Quan >> >> >>
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