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KVM: SVM: Move spec control call after restore of GS

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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: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner 2018-05-11 15:21:01 +02:00 • committed by Greg Kroah-Hartman
parent 0109a1b0a5
commit 7f77d36ab3
1 changed files with 12 additions and 12 deletions
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24
arch/x86/kvm/svm.c
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@ -3998,6 +3998,18 @@ 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
@ -4018,18 +4030,6 @@ 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();