| Message ID | 20200128235344.29581-1-sean.j.christopherson@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Mark CR4.UMIP as reserved based on associated CPUID bit | expand |
Sean Christopherson <sean.j.christopherson@intel.com> writes: > Re-add code to mark CR4.UMIP as reserved if UMIP is not supported by the > host. The UMIP handling was unintentionally dropped during a recent > refactoring. > > Not flagging CR4.UMIP allows the guest to set its CR4.UMIP regardless of > host support or userspace desires. On CPUs with UMIP support, including > emulated UMIP, this allows the guest to enable UMIP against the wishes > of the userspace VMM. On CPUs without any form of UMIP, this results in > a failed VM-Enter due to invalid guest state. > > Fixes: 345599f9a2928 ("KVM: x86: Add macro to ensure reserved cr4 bits checks stay in sync") This one in only in kvm/next so just in case another force-push is around the corner I'd suggest we squash this change in :-) > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/x86.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 7e3f1d937224..e70d1215638a 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -898,6 +898,8 @@ EXPORT_SYMBOL_GPL(kvm_set_xcr); > __reserved_bits |= X86_CR4_PKE; \ > if (!__cpu_has(__c, X86_FEATURE_LA57)) \ > __reserved_bits |= X86_CR4_LA57; \ > + if (!__cpu_has(__c, X86_FEATURE_UMIP)) \ > + __reserved_bits |= X86_CR4_UMIP; \ > __reserved_bits; \ > }) Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
On 29/01/20 00:53, Sean Christopherson wrote: > Re-add code to mark CR4.UMIP as reserved if UMIP is not supported by the > host. The UMIP handling was unintentionally dropped during a recent > refactoring. > > Not flagging CR4.UMIP allows the guest to set its CR4.UMIP regardless of > host support or userspace desires. On CPUs with UMIP support, including > emulated UMIP, this allows the guest to enable UMIP against the wishes > of the userspace VMM. On CPUs without any form of UMIP, this results in > a failed VM-Enter due to invalid guest state. > > Fixes: 345599f9a2928 ("KVM: x86: Add macro to ensure reserved cr4 bits checks stay in sync") > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > --- > arch/x86/kvm/x86.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 7e3f1d937224..e70d1215638a 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -898,6 +898,8 @@ EXPORT_SYMBOL_GPL(kvm_set_xcr); > __reserved_bits |= X86_CR4_PKE; \ > if (!__cpu_has(__c, X86_FEATURE_LA57)) \ > __reserved_bits |= X86_CR4_LA57; \ > + if (!__cpu_has(__c, X86_FEATURE_UMIP)) \ > + __reserved_bits |= X86_CR4_UMIP; \ > __reserved_bits; \ > }) > > Queued, thanks. Paolo
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7e3f1d937224..e70d1215638a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -898,6 +898,8 @@ EXPORT_SYMBOL_GPL(kvm_set_xcr); __reserved_bits |= X86_CR4_PKE; \ if (!__cpu_has(__c, X86_FEATURE_LA57)) \ __reserved_bits |= X86_CR4_LA57; \ + if (!__cpu_has(__c, X86_FEATURE_UMIP)) \ + __reserved_bits |= X86_CR4_UMIP; \ __reserved_bits; \ })
Re-add code to mark CR4.UMIP as reserved if UMIP is not supported by the host. The UMIP handling was unintentionally dropped during a recent refactoring. Not flagging CR4.UMIP allows the guest to set its CR4.UMIP regardless of host support or userspace desires. On CPUs with UMIP support, including emulated UMIP, this allows the guest to enable UMIP against the wishes of the userspace VMM. On CPUs without any form of UMIP, this results in a failed VM-Enter due to invalid guest state. Fixes: 345599f9a2928 ("KVM: x86: Add macro to ensure reserved cr4 bits checks stay in sync") Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+)