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KVM: nVMX: Always set required-1 bits of pinbased_ctls to PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR

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Similar to exit_ctls_low, entry_ctls_low, and procbased_ctls_low,
pinbased_ctls_low should be set to PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR
and not host's MSR_IA32_VMX_PINBASED_CTLS value |=
PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR.

The commit eabeaaccfc ("KVM: nVMX: Clean up and fix pin-based
execution controls") which introduced '|=' doesn't mention anything
about why this is needed, the change seems rather accidental.

Note: normally, required-1 portion of MSR_IA32_VMX_PINBASED_CTLS should
be equal to PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR so no behavioral change
is expected, however, it is (in theory) possible to observe something
different there when e.g. KVM is running as a nested hypervisor. Hope
this doesn't happen in practice.

Reported-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220830133737.1539624-31-vkuznets@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2022-08-30 15:37:34 +02:00 committed by Paolo Bonzini
parent 9d78d6fb18
commit 66a329be4b
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kvm/vmx/nested.c
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@ -6589,7 +6589,7 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps)
rdmsr(MSR_IA32_VMX_PINBASED_CTLS,
msrs->pinbased_ctls_low,
msrs->pinbased_ctls_high);
msrs->pinbased_ctls_low |=
msrs->pinbased_ctls_low =
PIN_BASED_ALWAYSON_WITHOUT_TRUE_MSR;
msrs->pinbased_ctls_high &=
PIN_BASED_EXT_INTR_MASK |