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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-03-05 23:19:52 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-03-17 12:21:39 +0100 |
| commit | 93c4adc7afedf9b0ec190066d45b6d67db5270da (patch) | |
| tree | 8b941c7e959fab7a677df0d6d7c4052ec468342d /arch/x86/kvm/cpuid.c | |
| parent | 36be0b9deb23161e9eba962c215aece551113a15 (diff) | |
| download | lwn-93c4adc7afedf9b0ec190066d45b6d67db5270da.tar.gz lwn-93c4adc7afedf9b0ec190066d45b6d67db5270da.zip | |
KVM: x86: handle missing MPX in nested virtualization
When doing nested virtualization, we may be able to read BNDCFGS but
still not be allowed to write to GUEST_BNDCFGS in the VMCS. Guard
writes to the field with vmx_mpx_supported(), and similarly hide the
MSR from userspace if the processor does not support the field.
We could work around this with the generic MSR save/load machinery,
but there is only a limited number of MSR save/load slots and it is
not really worthwhile to waste one for a scenario that should not
happen except in the nested virtualization case.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 18aefb4d0927..64fae65730f3 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -47,7 +47,7 @@ u64 kvm_supported_xcr0(void) { u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0; - if (!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported()) + if (!kvm_x86_ops->mpx_supported()) xcr0 &= ~(XSTATE_BNDREGS | XSTATE_BNDCSR); return xcr0; @@ -259,8 +259,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, #endif unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0; unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0; - unsigned f_mpx = kvm_x86_ops->mpx_supported ? - (kvm_x86_ops->mpx_supported() ? F(MPX) : 0) : 0; + unsigned f_mpx = kvm_x86_ops->mpx_supported() ? F(MPX) : 0; /* cpuid 1.edx */ const u32 kvm_supported_word0_x86_features = |