diff options
| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2020-04-15 17:07:39 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-04-21 09:13:09 -0400 |
| commit | b8d295f96b6c9745d7eebee622690e0e835c63af (patch) | |
| tree | 1ea185121d41d5ec121422bf758397870f05b554 /Documentation/virt | |
| parent | c36b71503a2268206ebeda6697094ffb4e7e94c2 (diff) | |
KVM: nVMX: Remove non-functional "support" for CR3 target values
Remove all references to cr3_target_value[0-3] and replace the fields
in vmcs12 with "dead_space" to preserve the vmcs12 layout. KVM doesn't
support emulating CR3-target values, despite a variety of code that
implies otherwise, as KVM unconditionally reports '0' for the number of
supported CR3-target values.
This technically fixes a bug where KVM would incorrectly allow VMREAD
and VMWRITE to nonexistent fields, i.e. cr3_target_value[0-3]. Per
Intel's SDM, the number of supported CR3-target values reported in
VMX_MISC also enumerates the existence of the associated VMCS fields:
If a future implementation supports more than 4 CR3-target values, they
will be encoded consecutively following the 4 encodings given here.
Alternatively, the "bug" could be fixed by actually advertisting support
for 4 CR3-target values, but that'd likely just enable kvm-unit-tests
given that no one has complained about lack of support for going on ten
years, e.g. KVM, Xen and HyperV don't use CR3-target values.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200416000739.9012-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virt')
| -rw-r--r-- | Documentation/virt/kvm/nested-vmx.rst | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/nested-vmx.rst b/Documentation/virt/kvm/nested-vmx.rst index 592b0ab6970b..89851cbb7df9 100644 --- a/Documentation/virt/kvm/nested-vmx.rst +++ b/Documentation/virt/kvm/nested-vmx.rst @@ -116,10 +116,7 @@ struct shadow_vmcs is ever changed. natural_width cr4_guest_host_mask; natural_width cr0_read_shadow; natural_width cr4_read_shadow; - natural_width cr3_target_value0; - natural_width cr3_target_value1; - natural_width cr3_target_value2; - natural_width cr3_target_value3; + natural_width dead_space[4]; /* Last remnants of cr3_target_value[0-3]. */ natural_width exit_qualification; natural_width guest_linear_address; natural_width guest_cr0; |