KVM: x86: Always initialize EFER reserved bits on vendor initialization

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EFER reserved bits are statically initialized, and do not reset if a
vendor module is re-loaded. For example, loading kvm_amd with nested=1
removes EFER.SVME (and potentially EFER.LMSLE) from the reserved bits.
Reloading kvm_amd with nested=0 does not add them back, allowing
userspace to set EFER.SVME with nested=0.

Re-initializing EFER reserved bits before configuring them on vendor
initialization.

Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260713181020.2735367-4-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

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

parent e62392bf39

commit a4b8acd428

3 changed files with 11 additions and 2 deletions

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10

arch/x86/kvm/msrs.c

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1

arch/x86/kvm/msrs.h

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2

arch/x86/kvm/x86.c

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