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authorOliver Upton2022-03-01 06:03:47 +0000
committerPaolo Bonzini2022-03-21 09:28:41 -0400
commit6d8491910fcd3324d0f0ece3bd68e85ead3a04d7 (patch)
treeb5ff91162ae5eb371f8a4c94d9916ba2bf799684 /arch/x86/kvm
parent5e17b2ee45b941fb7bc46107810d727088be392e (diff)
KVM: x86: Introduce KVM_CAP_DISABLE_QUIRKS2
KVM_CAP_DISABLE_QUIRKS is irrevocably broken. The capability does not advertise the set of quirks which may be disabled to userspace, so it is impossible to predict the behavior of KVM. Worse yet, KVM_CAP_DISABLE_QUIRKS will tolerate any value for cap->args[0], meaning it fails to reject attempts to set invalid quirk bits. The only valid workaround for the quirky quirks API is to add a new CAP. Actually advertise the set of quirks that can be disabled to userspace so it can predict KVM's behavior. Reject values for cap->args[0] that contain invalid bits. Finally, add documentation for the new capability and describe the existing quirks. Signed-off-by: Oliver Upton <oupton@google.com> Message-Id: <20220301060351.442881-5-oupton@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/x86.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c58265d9f1b2..fe2171b11441 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4363,6 +4363,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = enable_pmu ? KVM_CAP_PMU_VALID_MASK : 0;
break;
}
+ case KVM_CAP_DISABLE_QUIRKS2:
+ r = KVM_X86_VALID_QUIRKS;
+ break;
default:
break;
}
@@ -5909,6 +5912,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
return -EINVAL;
switch (cap->cap) {
+ case KVM_CAP_DISABLE_QUIRKS2:
+ r = -EINVAL;
+ if (cap->args[0] & ~KVM_X86_VALID_QUIRKS)
+ break;
+ fallthrough;
case KVM_CAP_DISABLE_QUIRKS:
kvm->arch.disabled_quirks = cap->args[0];
r = 0;