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authorThomas Gleixner <tglx@linutronix.de>2018-05-11 15:21:01 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 18:54:05 +0200
commitb1a6028c23748afc3b970bf2a740a3ebc7424e12 (patch)
tree6f2cbc2619907ac4918c3733bb42eecc01567b9d
parentbd2059282934fc009d755d24527187df5fe448de (diff)
KVM: SVM: Move spec control call after restore of GS
commit 15e6c22fd8e5a42c5ed6d487b7c9fe44c2517765 upstream svm_vcpu_run() invokes x86_spec_ctrl_restore_host() after VMEXIT, but before the host GS is restored. x86_spec_ctrl_restore_host() uses 'current' to determine the host SSBD state of the thread. 'current' is GS based, but host GS is not yet restored and the access causes a triple fault. Move the call after the host GS restore. Fixes: 885f82bfbc6f x86/process: Allow runtime control of Speculative Store Bypass Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/svm.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f432968fe42e..2f2ecd21616a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5109,6 +5109,18 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
#endif
);
+ /* Eliminate branch target predictions from guest mode */
+ vmexit_fill_RSB();
+
+#ifdef CONFIG_X86_64
+ wrmsrl(MSR_GS_BASE, svm->host.gs_base);
+#else
+ loadsegment(fs, svm->host.fs);
+#ifndef CONFIG_X86_32_LAZY_GS
+ loadsegment(gs, svm->host.gs);
+#endif
+#endif
+
/*
* We do not use IBRS in the kernel. If this vCPU has used the
* SPEC_CTRL MSR it may have left it on; save the value and
@@ -5129,18 +5141,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
x86_spec_ctrl_restore_host(svm->spec_ctrl);
- /* Eliminate branch target predictions from guest mode */
- vmexit_fill_RSB();
-
-#ifdef CONFIG_X86_64
- wrmsrl(MSR_GS_BASE, svm->host.gs_base);
-#else
- loadsegment(fs, svm->host.fs);
-#ifndef CONFIG_X86_32_LAZY_GS
- loadsegment(gs, svm->host.gs);
-#endif
-#endif
-
reload_tss(vcpu);
local_irq_disable();