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authorOliver Upton2020-08-18 15:24:28 +0000
committerPaolo Bonzini2020-10-21 17:36:32 -0400
commit66570e966dd9cb4fd57811d0056c6472a14a2c41 (patch)
tree06172486c1b55c545ea71bc0cd23c288c7b19fd1 /include/uapi
parent210dfd93ea3dc63e8c21b75ddd909447341f6382 (diff)
kvm: x86: only provide PV features if enabled in guest's CPUID
KVM unconditionally provides PV features to the guest, regardless of the configured CPUID. An unwitting guest that doesn't check KVM_CPUID_FEATURES before use could access paravirt features that userspace did not intend to provide. Fix this by checking the guest's CPUID before performing any paravirtual operations. Introduce a capability, KVM_CAP_ENFORCE_PV_FEATURE_CPUID, to gate the aforementioned enforcement. Migrating a VM from a host w/o this patch to a host with this patch could silently change the ABI exposed to the guest, warranting that we default to the old behavior and opt-in for the new one. Reviewed-by: Jim Mattson <jmattson@google.com> Reviewed-by: Peter Shier <pshier@google.com> Signed-off-by: Oliver Upton <oupton@google.com> Change-Id: I202a0926f65035b872bfe8ad15307c026de59a98 Message-Id: <20200818152429.1923996-4-oupton@google.com> Reviewed-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/linux/kvm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 58f43aa1fc21..ca41220b40b8 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1052,6 +1052,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_STEAL_TIME 187
#define KVM_CAP_X86_USER_SPACE_MSR 188
#define KVM_CAP_X86_MSR_FILTER 189
+#define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
#ifdef KVM_CAP_IRQ_ROUTING