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x86/kvm/vmx: Add MDS protection when L1D Flush is not active

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commit 650b68a062 upstream.

CPUs which are affected by L1TF and MDS mitigate MDS with the L1D Flush on
VMENTER when updated microcode is installed.

If a CPU is not affected by L1TF or if the L1D Flush is not in use, then
MDS mitigation needs to be invoked explicitly.

For these cases, follow the host mitigation state and invoke the MDS
mitigation before VMENTER.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jon Masters <jcm@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner
2019-02-27 12:48:14 +01:00
committed by Greg Kroah-Hartman
parent 20041a0ebf
commit 3a8e7f6993
2 changed files with 4 additions and 0 deletions
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1
arch/x86/kernel/cpu/bugs.c
View File

@@ -61,6 +61,7 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb);
/* Control MDS CPU buffer clear before returning to user space */
DEFINE_STATIC_KEY_FALSE(mds_user_clear);
EXPORT_SYMBOL_GPL(mds_user_clear);
void __init check_bugs(void)
{

3
arch/x86/kvm/vmx.c
View File

@@ -9206,8 +9206,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
vmx->__launched = vmx->loaded_vmcs->launched;
/* L1D Flush includes CPU buffer clear to mitigate MDS */
if (static_branch_unlikely(&vmx_l1d_should_flush))
vmx_l1d_flush(vcpu);
else if (static_branch_unlikely(&mds_user_clear))
mds_clear_cpu_buffers();
asm(
/* Store host registers */