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KVM: nVMX: Truncate bits 63:32 of VMCS field on nested check in !64-bit

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Drop bits 63:32 of the VMCS field encoding when checking for a nested
VM-Exit on VMREAD/VMWRITE in !64-bit mode.  VMREAD and VMWRITE always
use 32-bit operands outside of 64-bit mode.

The actual emulation of VMREAD/VMWRITE does the right thing, this bug is
purely limited to incorrectly causing a nested VM-Exit if a GPR happens
to have bits 63:32 set outside of 64-bit mode.

Fixes: a7cde481b6 ("KVM: nVMX: Do not forward VMREAD/VMWRITE VMExits to L1 if required so by vmcs12 vmread/vmwrite bitmaps")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-04-21 19:21:24 -07:00 • committed by Paolo Bonzini
commit ee050a5775
1 changed files with 1 additions and 1 deletions
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arch/x86/kvm/vmx/nested.c
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@ -5745,7 +5745,7 @@ static bool nested_vmx_exit_handled_vmcs_access(struct kvm_vcpu *vcpu,
/* Decode instruction info and find the field to access */
vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
field = kvm_register_read(vcpu, (((vmx_instruction_info) >> 28) & 0xf));
field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28) & 0xf));
/* Out-of-range fields always cause a VM exit from L2 to L1 */
if (field >> 15)