KVM: x86: Disallow EFER.LME and EFER.LMA if long mode is not supported

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Remove EFER.LME and EFER.LMA from EFER reserved bits only if long mode
is actually supported. KVM does check long-mode support before allowing
the bits for guest writes and userspace writes through KVM_SET_SREGS*
(in __kvm_valid_efer()), but userspace writes through KVM_SET_MSRS only
check reserved bits.

In practice, this doesn't really matter. The true motiviation is getting
rid of the #ifdeffery when initializing efer_reserved_bits.

Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260713181020.2735367-3-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

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Yosry Ahmed 2026-07-13 18:10:17 +00:00 • committed by Sean Christopherson

parent 6ccc19d4c1

commit e62392bf39

2 changed files with 4 additions and 9 deletions

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10

arch/x86/kvm/msrs.c

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3

arch/x86/kvm/x86.c

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