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KVM: nVMX: WARN once and fail VM-Enter if eVMCS sees VMFUNC[63:32] != 0

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WARN and reject nested VM-Enter if KVM is using eVMCS and manages to
allow a non-zero value in the upper 32 bits of VM-function controls.  The
eVMCS code assumes all inputs are 32-bit values and subtly drops the
upper bits.  WARN instead of adding proper "support", it's unlikely the
upper bits will be defined/used in the next decade.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220830133737.1539624-15-vkuznets@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-08-30 15:37:18 +02:00 committed by Paolo Bonzini
parent 8174193163
commit 3ff8a13d41
1 changed files with 8 additions and 0 deletions
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8
arch/x86/kvm/vmx/evmcs.c
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@ -469,6 +469,14 @@ int nested_evmcs_check_controls(struct vmcs12 *vmcs12)
vmcs12->vm_entry_controls)))
return -EINVAL;
/*
* VM-Func controls are 64-bit, but KVM currently doesn't support any
* controls in bits 63:32, i.e. dropping those bits on the consistency
* check is intentional.
*/
if (WARN_ON_ONCE(vmcs12->vm_function_control >> 32))
return -EINVAL;
if (CC(!nested_evmcs_is_valid_controls(EVMCS_VMFUNC,
vmcs12->vm_function_control)))
return -EINVAL;