KVM: SVM: Make sure KERNEL_GS_BASE is valid when loading gs_index

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The gs_index loading code uses the swapgs instruction to
switch to the user gs_base temporarily. This is unsave in an
lightweight exit-path in KVM on AMD because the
KERNEL_GS_BASE MSR is switches lazily. An NMI happening in
the critical path of load_gs_index may use the wrong GS_BASE
value then leading to unpredictable behavior, e.g. a
triple-fault.

This patch fixes the issue by making sure that load_gs_index
is called only with a valid KERNEL_GS_BASE value loaded in
KVM.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

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Joerg Roedel 2011-01-14 16:45:01 +01:00 • committed by Avi Kivity

parent 0b0abeaf3d

commit 893a5ab6ee

1 changed files with 1 additions and 1 deletions

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arch/x86/kvm/svm.c

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