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authorJoerg Roedel <joerg.roedel@amd.com>2011-01-14 16:45:01 +0100
committerAvi Kivity <avi@redhat.com>2011-02-09 18:31:36 +0200
commit893a5ab6ee7d51b231ed45aa844f8088642cb6bf (patch)
tree9bb299eb2b957b47371d09fd33a307882e7b9e7a /arch
parent0b0abeaf3d30cec03ac6497fe978b8f7edecc5ae (diff)
KVM: SVM: Make sure KERNEL_GS_BASE is valid when loading gs_index
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/svm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 25bd1bc5aad2..54ce246a383e 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1150,8 +1150,8 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
kvm_load_ldt(svm->host.ldt);
#ifdef CONFIG_X86_64
loadsegment(fs, svm->host.fs);
- load_gs_index(svm->host.gs);
wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
+ load_gs_index(svm->host.gs);
#else
loadsegment(gs, svm->host.gs);
#endif