KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest

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Intercept RDTSCP to inject #UD if RDTSC is disabled in the guest.

Note, SVM does not support intercepting RDPID.  Unlike VMX's
ENABLE_RDTSCP control, RDTSCP interception does not apply to RDPID.  This
is a benign virtualization hole as the host kernel (incorrectly) sets
MSR_TSC_AUX if RDTSCP is supported, and KVM loads the guest's MSR_TSC_AUX
into hardware if RDTSCP is supported in the host, i.e. KVM will not leak
the host's MSR_TSC_AUX to the guest.

But, when the kernel bug is fixed, KVM will start leaking the host's
MSR_TSC_AUX if RDPID is supported in hardware, but RDTSCP isn't available
for whatever reason.  This leak will be remedied in a future commit.

Fixes: 46896c73c1 ("KVM: svm: add support for RDTSCP")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-4-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Sean Christopherson 2021-05-04 10:17:22 -07:00 • committed by Paolo Bonzini

parent 85d0011264

commit 3b195ac926

1 changed files with 13 additions and 4 deletions

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arch/x86/kvm/svm/svm.c

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